High Velocity Porting - Does it work?

From the deep genius that is motoman comes the astonishing dark art of high velocity porting - but on a serious note, does it work? I have an example of another port related situation that can shed some light on this.
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[@scottsmith2113]

Great vid man! Ive been taught that its about where in the RPM you want your power band. As in the smaller or ''restrictive'' port is good for low rpm torque but sacrifices high RPM power, due to having high velocity at lower RPM but unable to produce enough volume for the higher RPM.

[@NoferTrunions]

When the words Laminar, Turbulent, and Recirculation are not not found in the discussion...

[@brianhaygood183]

...or flow separation, or pressure drop, or Bernoulli, or energy loss. He's got an awful lot of confidence, which would be great if he were correct.

[@NoferTrunions]

@@brianhaygood183 we forgot Reynold's Number (!) LOL (Actually just a few weeks ago when thinking about a flow problem, it struck me that at lower speeds, viscosity dominated while at higher speeds, inertia. And then I reread the definition of RN and guess what? RN is used to determine what regime the flow is in! My fluid dynamics professor could have made that point crystal, especially since it is a monumental and very intuitive metric. But Noooooooo....

[@turkeyboyjh1]

At the end of the day it all depends on valve size and port shape and port size, smaller ports will make more power AT a lower rpm but you will restrict power at higher rpm, I built a non cross flow, siamesed 292 Chevy 6 I did what we call a lump port which adds a chunk of aluminum right before the intake valve which was proven to gain power over a flat intake port

[@NoferTrunions]

@@turkeyboyjh1 I have a friend that mastered carbon reading (heads off after every trip to the strip) - he became a voodoo engine builder whose engines got town down after every win and the tech guys would notice things he did and say, "if you fixed that, you'd go faster." Reading carbon is huge regarding combustion chamber. It's all about the wet flow. He never used a flow bench and saw no reason to use them. And yet he built the fastest engines. His all Chevy parts small and big blocks were amazing.

[@mceperformance8978]

Quick comment regarding your short side example of filling it in. You can fill that in to let the air straighten itself out before hitting the throat/seat. The part you may be leaving out (or not) is that you should also widen that part of the port to keep the area the same. I agree with you that restricting the flow is bollix. Raise the short side but widen it at the same time. 2 cents from an old geezer. The "restriction" should be the valve throat. That's where you want to speed up the air (in the throat). The throat should be the smallest part of the entire port. Cheers. -Matt

[@samerca1]

This is what David Vizard recommends.

[@recrdholdr]

it's all about Balance, too big a port makes for a lazy port and terrible acceleration. the goal would be to have as small a port as you can while maintaining flow #'s. In Motorsports Flow is great but Velocity is king! Port shape can also have a huge effect on flow. You make fun of the use of epoxy's well let me tell you, I have been building performance and racing engines for over 20 years I have used Epoxies(not JB Weld) in Intake ports many times and have never had it come loose. When using the proper epoxy and applied properly you would almost have to chisel it out of the port. I currently race a 10,000 RPM 4 cylinder, with ports that flow over 400cfm with Epoxy in the port, Don't Knock it until you've tried it.

[@dirtygarageguy]

"In Motorsports Flow is great but Velocity is king!" @ one set rpm. Flow is volume over time which means that velocity plays a big part in this.

[@recrdholdr]

If you can maintain flow #'s and increase velocity you will fill the cylinder better. which is essentially what it's all about. More air more fuel bigger Boom More Power.

[@davidrose5613]

jb weld in racing engines?? haha okay that is the least professional thing ive ever heard

[@SajtosPoga]

@@davidrose5613 That's because you can't read.

[@farmonious420]

Raise the roof and the floor for more power. Cast a new intake or add good epoxy. Which would you choose?

[@polyanthemos]

Wow, some interesting comments. I wont try and tell people how to port. I have my own ideas and have a home made flow bench. Im no expert. What i will do is mention all the things that need to be considered. Port size (volume), port floor shape (radius into the bowl), port roof, guide boss restriction and flow and turbulence. Area in the port at the guide boss. Area at the turn. Area in the ‘bowl’, shape of bowl to the valve seat, shrouding, shape of back of valve. Surface finish, blending in valve seats. People talk ‘velocity’, well yeah you need this for torque but what about velocity if the charge needs to turn a corner? Can you corner at an intersection at the same speed as you do in a straight line? The charge has to turn at the valve also. Simetrical ports or biased? The bigger the valve guide boss the more turbulence behind it? What is more important in a turn, the floor or roof? Do you know why? Knife edges (which i hate).

[@axelriet]

The beauty of the present times is anyone can make a video and tell whatever they want. I advise not to waste your time watching this.

[@dinosshed]

It’s not the same for every single engine, for example, the ports on a 351 Cleveland V8 are too big in standard form but work well with a more aggressive cam. The 351 Windsor has smaller ports which are suitable to the stock cam, not as beneficial with a more aggressive cam. Velocity and flow are as important as each other, it’s not a one size fits all, it’s the complete combination from compression ratio, port design, cam profile, valve sizes etc. Bigger is not always better

[@mbsnyderc]

I never heard of this silly shit before.sounds like a good way to destroy your engine when you run a big chunk of J.B. weld through it.

[@dirtygarageguy]

Always great when your piston plays 'smash the expoxy' game lol

[@veoverse4286]

The Workshop you make great videos :). thanks a lot man.... could you pleace make a video where you explain how the 2 stroke direktinjektion engine like brp gets a ignitable mixture during the upstroke? i mean it works, but how it works in this short amount of time and the shit air flow of a 2 stroke. please keep up your good work. best regards from germany ^^

[@dirtygarageguy]

Already done the video, just need to edit it and post - matt

[@wing_nut_1018]

We owe it to gas gas for dirt bike injection. anyone who says ktm did efi on 2 strokes is full of shit. Gas Gas brought efi to the 4 stroke dirt bike world, and then, they brought it to the 2 stroke world. some of their current 2 stroke trials bikes have efi

[@63turbo]

Yes, a good explanation of why putting a restriction in the port like that is a really badidea. Now, IF the entire port was simply straighter, (like pro stock drag racing ports are)then the port can and should be smaller... but for most engines that have to have a kinkin the port, it is much better to have the port larger to compensate for the turn, even ifit costs some speed. A lazy port can always be taken care of with better cam, but a too fast, plugged up port with too much turn causes the fuel to not follow the port shape verywell as it is much heavier than the air, leading to fuel separation and bad mixing withinthe cylinder, leading to power losses.

[@h0g2s]

ok , i haven't got a clew on how did the epoxy port filling come up or the arguments that were being used, but after a while it´s just too much, so let´s get some things clear: 1-the biggest port possible" open head bla bla" IT´S NOT THE BEST OPTION, with such port you would only be able to achive a maximum 100% VE (cylinder volume at atmosferic pressure), a well designed head can actually achieve well over 100%, get the f20c for example it gets 110% VE from 6500-7500 rpm. 2-a well designed port will create an "air ram" due to the air mass momentum when the piston is at bdc and the intake valve is still open, explaining point 1. 3-epoxy , or any other type of filling, can be beneficial if for example you want to straighten a port and have to remove alot of material but still want a reduced port volume so point 2 can be achieved! 4-when you close the throttle you only increase air speed near the butterfly valve and not the entire port like you need for it to work! 5-if you have an engine that isn´t direct injection the fuel atomization will be better with a faster moving air charge. greetings, hope you give it a thought

[@TurboAcki]

They main issue is mistuned camshaft timing - intake manifold length, exhaust etc. pp. -> less pressure drop is always a good thing - but you need to get you intake/exhaust timings tuned to this. At carb engines a massive reduced pressure drop is an issue like on old V8 engines, the vacuum is too low to keep the carbs proper working. So you run into different issues (slider doesn't open maximum for example or slider spring is too weak and bouncy), you have to understand the impacts. And yes big does not mean ideal .

[@QuickJoe]

Just found you, watched 3 videos, and I love the way you tell verything! I gave u my Sub! keep them up man! love for 2 stroke.

[@TRX450RVlogger]

Velocity Porting is not to improve over all HP, it's to increase throttle response and torque DOWN LOW. Also It works the BEST mainly with FCR Style Carburetors to create more of a Vacuum on the back side of the Carburetor. Mostly used for Track Racing so you can get off the line and out of a burm faster. I actually Velocity Ported my own TRX450R head it make a Huge increase in throttle response and torque off the line as I stated just before this. I had each port job I would get a Base Line test. 1st Dyno Test (Stock Head --- 43HP at 7510 RPMS / 29FTLBS of Torque) 12:25 Air Fuel Ratio 2nd Dyno Test (Velocity Ported --- 48HP at 7238 RPMS / 38FTLBS of Torque) 12.10 Air Fuel Ratio 3rd Dyno Test (Port Opened Up --- 55HP at 8200 RPMS and 37FTLBS of Torque) 11.97 Air Fuel Ratio I read those off my Dyno Charts exactly how they were printed. From Racers Edge Arizona. I actually recently ported a new head that I'm going to test with +1mm Valves and the Valve Guides are sharpened and the port floor is un touched and exhaust ports polished with sharpened guides. Velocity porting does work. I was able to feel it when I would accelerate but had not very much top speed. Not for me unless I was racing on a Track. but I'm a lot more of a WOT person and to cruise on a long stretch rather then in and out of the throttle pumping it a lot.

[@johnbecay6887]

TRX VLOGGER absolutley correct...velocity makes a big difference on a high performance street driven engine as well...throttle response--which you get from good velocity--- is fun...soggy response due to high flow and low velocity not so much fun...it's like a car with turbo lag but no turbo...thanks for posting....

[@ezequielartigas454]

i see a lot of torque gain with velocity, but 3rd dyno test is with velocity and the port opened up too? thats change the curve of the intake

[@mikaniemelainen347]

how does those torgue curve is acting, when you acclereate you will need wide torgue

[@lpmorgan90]

Down low torque is no good if you're on a race track... a proper race track not one of those straight line things...

[@arthurdombroskie3083]

I watched the entire video with a open mind. This is pure bench racing. He has a lot to learn. A for effort...

[@dirtygarageguy]

Go on then, lets hear it?

[@bsharpe]

The proof is in testing and experimentation. He needs to prove his theory. I know from experience too large a port hurts drive-ability and too small can limit power.. it’s all about balance and where you want the torque.

[@dirtygarageguy]

Experience in what, I.e what type of engine...

[@cherrypicker8897]

It's all a balancing act, swings and roundabouts. Air volume or can velocity ram a bit more in. Length of stack at certain RPMs. Great subject, many have spent many hours to achieve the optimum.

[@ANDY5]

Excellent analogy with the butterfly valve, poor old Motoman, stitched up again. lol

[@stuartjakl]

There are some odd conclusions made here. You have several logical fallacies in your argument against a "high velocity" port. Perhaps we need to be talking about Volumetric Efficiency. Yes, you can achieve better volumetric efficiency with a PROPERLY DESIGNED port that might be smaller in size and volume than the original stock port. By adding material to a port we are not trying to create a restriction, we are attempting to remove a dead air zone where little air flow is happening. This is port design 101. By your logic "bigger is better" and we know that simply is not true. Porting is a science and a huge industry. The porting industry exists because ports are not perfect. The best ports are not the biggest. The best ports don't just flow the most CFM. They need to be able to flow is at as high a velocity as possible to raise the VE beyond 100%. Sometimes we need to remove material from an area of the port, sometimes we need to smooth areas, sometimes we need to add material. Usually all three if the OEM port was not well designed. A case in point is a motorcyle port I changed to be smaller and better designed than the OEM port. The new port was MUCH smaller but we picked up substantial flow. On the dyno we increased a 1000cc motorcycle's power by 15HP. This is with no compression or cam changes.

[@robingrantgast2065]

"raise the VE beyond 100%" Heh funny guy

[@Samqdf]

@@robingrantgast2065 It's known as "inertial supercharging", see here: en.wikipedia.org/wiki/Volumetric_efficiency en.wikipedia.org/wiki/Inertial_supercharging_effect

[@Samqdf]

@@robingrantgast2065 I found one more for you: www.autospeed.com/cms/article.html?&A=1127

[@cstavro]

@@robingrantgast2065 top race engines achieve 120% volumetric efficiency (a better term is Delivery Ratio).

[@rjreynold2372]

@J You need to review the basics if that's what they are telling you. Please educate yourself and stop relying on whatever you are calling common sense. If you are interested i'd recommend books Harold Bettes , David Vizard and John Baechtel. You are full of crap and this is coming from a person who actually owns a flowbench and does dyno testing every tuesday (engine) and wednesday (chassis)

[@SendItGarage]

The issues that you face with a too larger Port is loss of air velocity which equals a loss fuel atomisation which will cause loss in power so if you don’t atomise the fuel properly then you don’t get correct combustion of the fuel in the combustion chamber which equals a loss of power even if you have good injectors it still doesn’t atomise the fuel as efficiently as air velocity will so there’s a fine balance between having your ports to Big and having them too small

[@kensmechanicalaffair]

Wouldn't the fix be to send more air/exhaust through the port, to gain velocity?

[@crackedemerald4930]

how2powah 1) get sheitloads of air 2) get arseton of fuel 3) make the perfect mixture 4) dump into de engine 5) kaboom 6) profit

[@MotorDanko]

AGREE, put ALL the air and fuel that you can even if you have to pushhh it inside!!! then make the mixture the most perfect possible and HELLO 200% POWAAAAH

[@wing_nut_1018]

how2powah. turbo. Will this fit in my Honda? (anyone who gets the reference, I'm proud!)

[@stephengardin2423]

The guy who said that restricting the port size to increase flow is off his nut. Ports are by their very nature funnels. The limiting diameter is the size of the opening that the valve covers when closed. The shortest distance between two points is a straight line except in the case of guns. They have spiralled tubes and that spiral gives the bullet rotational momentum to stabilize the bullet after discharging from the barrel. The length of the barrel and the pitch of the rifle spiral determines the final velocity along with the powder charge and make-up of the projectile etcetera. In short, the longer the barrel the faster the terminal speed of the projectile exiting that gun barrel. Enlarging ports is only a part of cramming more air into a combustion chamber. The main goal is to straighten out that port and runner to allow the air to enter/exit as quickly and smoothly as possible. Spiralling that runner could potentially allow a larger volume of air into that port because of centrifugal force acting on that column of air somewhat similar to a bullet. Dimpling the runner, similar to golfball dimples, could also be another way of stabilizing that column of air. Reducing the vortices that would build up as air flows through a funnel tube is the other consideration. Diffusing striations, similar to the rear undercarriage of racecars, would also reduce vortices in the runner. The fewer the vortices the straighter the path of air. Slightly dished in valve faces could be employed to give a negative vortex in the combustion chamber sucking in more than otherwise would be possible. Using exhaust scavenging is another way to suck in more air. The mere fact that the size of the valve restricts the flow is the ultimate determiner of air velocity. Squeezing a large volume into a much smaller volume speeds up that air mass. That was quantified by Mr. Bernouli and Mr. Venturi. I hope that I haven't made an asshat out of myself. I haven't studied physics for many years and I haven't worked on large shipborne diesel engines for about as long. Thanks for the segment.

[@dingerjunkie]

If I see "does it work", I'm not looking to watch a theoretical discussion...do it, dyno it and prove his method to be invalid if you're that strong on it. Talk is cheap, and that headline is "expensive."

[@Nobody-zq8bl]

AHAHAHA! Some chart grabbed from the internet with NO context or validation.. and... the HP doesn't even cross torque at 5250. HMMM. If hp = torque x RPM / 5250... then... every chart in the world must cross at exactly that point and no other. FAKE dyno sheet.

[@aaronchadwick2682]

@@dirtygarageguy Ouch. People need to stop arguing on the internet and destroy some heads and post a video. PSST Engine masters has does this test and getting as much air in as possible with the least struggle is the best because the moving parts aren't trying to pull things in.

[@chestrockwell8328]

@@@aaronchadwick2682 … you mean because the moving parts ARE trying to pull things in; things in this case being air and fuel. If the pistons didn't create a vacuum how do you suppose those things would get in there?

[@aaronchadwick2682]

@@chestrockwell8328 I mean't struggling to pull air and fuel in. r/corrections Good lord if you have a brain about engines you shouldn't need to use technical terms. If there a vacuum is present then don't create areas for there to be friction (velocity idiots) which causes loss of power

[@rjreynold2372]

@J well golly gee... I wonder how it is possible to achieve 120+% volumetric efficiency in a normally aspirated engine ? I"m going to give you a hint: it has something to do with charge velocity and that old saying "an object in motion tends to stay in motion."

[@beachboardfan9544]

This was well done for a subject that people act as if its black magic, well explained with simple and understandable analogies, good stuff. A great sequel to this would be intake plenum size!

[@michaelovitch]

You don't undestand. reshaping a port is not closing a throttle. reducing a section with a good aerodynamic profile allow to increase air speed ,so ability for air to go deeper in the cylinder,pulling more air behind itself. closing a throttle plate create a lot of turbulences behind it ,reshaping a port do not,but oinly changes air speed. air is compressible,It's not a flow of water.... It's a basic aerodynamic concepts . Look at Bernoulli principles, Venturi principles etc... You have not a real idea of what you talk about by lack of knowledge. With your idea of air flow, planes and birds couldn't fly...

[@dirtygarageguy]

Obviously never heard of a choke point and mass flow rates - shame for you that you're an idiot.

[@michaelovitch]

Like i said,air is elastic. You can have more mass flow rate with a turbo while it's squizzed in the turbine...

[@dirtygarageguy]

Poor choice of words there - elastic is generally described as 1 of 2 things - Elastic deformation when a material 'springs' back to its former shape/profile. The region before yield an plastic deformation begins. or Linear elasticity - based on hooks law etc. These are all solid elastic transformations. Liquids and gases do neither, because liquids and gases do not form crystaline structures that are bound through the metallic or covelant bonding.

[@michaelovitch]

Yeah, Try to explain yourself in technical french without looking at google like you did to get two definitions,and then you will can open your mouth (in french of course) You understood me : air is a fluid,compressible, contrary to a liquid (wich is too ,but just a little) You can push or pull a compressible fluid through a reduced section without loss of flow mass ,simply because its speed (flow on time) is good enough. It's exactly what you do in an engine head when well designed. Formula 1 cars did use that during the naturally aspirated era and had a huge volumetric efficiency,they were even able to have positive pressure in the intake when the valve was closing. The fact that air speed is appropriate and compressible.

[@jaredmartin3798]

When you get to the limit of the flow of the valve slow moving air will not help you, high speed air will however as well higher pressure. The valve is only fully open for a very small time but its opening and closing time is a lot longer. This is why we want fast moving air to actually hold some pressure behind the valve waiting for it to open. Air is quite heavy and getting it up to speed takes a while and so we want to keep it moving and not to lose momentum

[@dirtygarageguy]

What? Do you know what this is? PV = nrT

[@jaredmartin3798]

@@dirtygarageguy I know putting up the ideal gas law makes you seem smart, you have however missed the point.

[@evil_me]

In all actuality yes "high velocity" porting can cause resonance to occur and create more power, but I think motodouche doesn't understand the actual science once again. The power gains will be miniscule and at such a tiny rpm window that its not even valid! Plus as matt explained rather humorously, it will decrease overall topend power and power under the curve. People who poorly understand something, take 2% of the facts and draw a incorrect conclusion are the bloody worst, sod off motodouche lol

[@timsharpe3498]

This video is all opinion and no science.

[@jy1235689]

You have an anime profile picture

[@nicholash8021]

Ford solved this in the 1990's by adding intake manifold runner controls (IMRC) that block the 2nd intake port in their 4V "b" heads (most commonly associated with the Mustang Cobra), opening the 2nd port after 3250rpm. They just weren't getting enough torque at low RPMs without this and emissions were simultaneously below requirements. The down side (beside the extra mechanical parts) was that the secondary valves stems built up with carbon to the point the valve stem was easily double the diameter as it passes through the port due to lack of fuel to keep them clean in daily driving. I know because I am rebuilding one.

[@ipwn951]

I think what these idiots don't get is that the manufacturer has matched the port geometry to the engine's optimum air flow at rated power, so what they are probably doing is choking the engine at the higher end. You could generate a bit of charge motion for low end torque, if you carefully optimised the port (nowhere near a chunk of plastic randomly thrown in there) and it would probably have to be actuated.

[@mikerieck306]

Modern bike ports are very, very good. There isn't much you can do to improve them. Use an OS intake valve and bore the seats to .9 of the OS valve OD. That will get volume up. On the other hand I have ported CB750 and GS 1100/1150 heads and used epoxy on the floor. They flow very well with very good velocity and have made great power through the RPM range. I use a Superflow 260 with a FlowCom and pull @ 10". The FlowCom is nice as it monitors velocity.

[@TheFARM2019]

Well explained! People think high velocity means more air... there is a reason why cylinder head manufacturers advertise volume and cfm... on a fire truck the pumps are rated at 150 psi for max volume and when you go up to 200 and 250 psi the volume of water goes down... if you want more power you need to remove the restrictions

[@exothermal.sprocket]

The way I see it, you have atmospheric pressure outside the throttle body and dropping pressure in the cylinder (as the piston falls). The tendency of atmosphere to equalize itself is where the molecule movement moves the outside air down the port toward the lower pressure in the cylinder. The absolute BEST that could happen outside of forced induction is a 100% equalization of cylinder pressure to atmospheric pressure. We know that's not possible. Air has mass, and mass in motion will have momentum. Engine builders who want to tune a given engine to have greater lower end torque typically employ several things to achieve that. One of which is smaller port sizes per a given cylinder displacement. That achieves higher flow velocity through the port at lower engine RPM. Among other things, this creates faster cylinder filling, greater air mass momentum, at lower RPM and increases torque at lower RPM. Of course these types of setups result in limited upper RPM power due to less efficient flow at high RPM. The perfect theoretical engine would be one that has infinitely variable port size, infinitely variable intake runner length, infinitely variable valve timing, infinitely variable valve lift, infinitely variable compression ratio, and infinitely variable exhaust runner diameter. Wouldn't that be some engine!

[@goodfellasinc.5648]

I been porting 25 years and your right on it ..it's all about shapes Port design heights what to remove so much more I really like porting 2 stroke banshees

[@kinglouis6974]

Goodfellas Inc. I’ve got a kdx220 can you give me some advice on porting pls 👍🏼

[@thegit8698]

it's like a bend in a river isn't it? the water on the inside of the bend slows down, and adding material will just increase the angle of the bend and slow the flow even more

[@mxcollin95]

This is a super interesting subject! I’ve heard really well known high performance engine builders talk about how equations and modeling only get you so far (roughly in the ballpark) when trying to increase performance and it takes lots of experimenting and dyno testing to truly arrive at a winning design due to the many interrelated variables that effect engine performance. (It’d be cool though if people could talk about their ideas without talking down to people with different ideas or understandings.) When it comes to intake paths not all restrictions are the same. Your analogy of pushing people through double doors isn’t completely comparable due to the Bernoulli principle, which is roughly the idea that as a fluid moves through a pipe past a restricted area (think of the restriction being a curved surface like an airplane wing and not like a flat butterfly valve) that fluid speeds up around the restriction which also causes the pressure of the fluid to drop at the restriction. People being pushed through double doors wouldn’t be subject to the effects of the Bernoulli principal like a fluid would. So I could see how someone could think that using the effects of the Bernoulli principle by slightly decreasing the diameter of the intake through the use of a curved restriction would increase the velocity of the air thereby increasing the amount of air getting into the combustion chamber as it rushes past a given size opening/intake valve, however from a physics standpoint, you can only get as much air into the combustion chamber as you get into the intake first which agrees with what you were saying in the video to a point. Although, increasing the speed of the air entering the combustion chamber may cause the fuel and air charge to be more thoroughly mixed which would allow for a more complete combustion of the fuel air mixture which would increase hp. In addition to the complexities of intake geometry, I know acoustics/harmonics have an impact on how the air/fuel moves into and out of the combustion chamber which is another whole level of complexity. Also it’s has been proven that texture is also important to a degree and having a slightly rough texture on the intake surfaces does allow for better performance as opposed to having a mirrored finish do to creating a smaller boundary layer of air close to the surface of the intake thereby creating less overall drag. Anyway, I think it’s badass subject and I’m sure no engine builder is ever done learning. ✊🤙

[@arthurguidry9252]

why didn't you just use the carbarator example....you know the ventura principle. or is that too much for you...........what's the difference between you and a rotorary engine?

[@sammiecaisley]

It’s not about reducing the port size it’s about keeping the bend smooth. If the bend is too tight the flow will delaminates and cause turbulence, this turbulence will drastically reduce the flow rates.

[@wontputrealname]

I agree with you that this idea doesn't work, except possibly over a very narrow rev range. I will add, however that if an engine at full throttle seems to go a little faster with the throttle slightly closed, it needs the main jet to be replaced by one which is slightly larger, as the aforementioned condition indicates a weak mixture at wide open throttle (or WOT).

[@cho2jzfe90]

I wanna here your thoughts on dimple porting and polishing

[@findtherightbeat]

I think what Motoman was trying to do is improve the short turn of the port, I think it's along the lines of applying Bernoulli's principle, the same way flow is improved at the valve seats at low lift through various seat angles

[@darianistead2239]

lol. So true.. I remember my old man who's built race cars forever though explained an example of this where velocity over volume worked with ford 351c V8's with 2v and 4v heads whereby the restriction was in the exhaust ports of the greater flowing 4v heads and you would make more power utilising smaller 2v heads with 4v exhaust valves and porting as the problem wasn't getting gases in but getting it out. This was for an improved production series but was the same for a tough street engine.

[@keithianlocke]

My ports are too big. They're restricting my free flow exhaust!

[@joeb1895]

Almost every engine I've seen in BSB & BSS is running high velocity ports. Mainly fillling the ceiling to alleviate sharpening the bend. I've personally gained large chunks of power and rideability filling ports on various engines, and know many other tuners who have too - In some fairly interesting fashions. Don't knock it until you try it!

[@dirtygarageguy]

No they don't. I have a friend (Andy Firth) in BSB. Stop talking shite.

[@arthurguidry9252]

port means to match intake and exhuast port to head to manifolds exhuast and intake use the gasket to measure how much metal you need to grind off polish only needs to be done to the intake side of the heads making the fuel flow easier into the cylinder

[@mech5]

Both Yoshimura and Tom Houseworth used JB Weld on their ported heads in the air cooled GSXR's.

[@dirtygarageguy]

Definately - its easy to mod ports in hind sight.

[@crosscustomsracing2848]

It was common to raise the port floor on early R6 s look at tony homes and other iom sidecar engine builders .. I would give 2-3 hp on the 99 600's just saying...?

[@geogineer]

way I see it, I trust manufacturers to calc out this shit to perfection. that said, if I'm working on my own machine, I'll polish out all the casting shizz for a clean port. not because it does any good- but because I fucking like it that way.

[@michaelwalker1119]

geogineer Thats what a old engine tuner told me. Get the inlet and outlet ports as smooth as possible. From the factory they ate a bit rough to say the least.

[@flyfaen1]

They don't... Perhaps in F1, they put som effort to it, and look at those ports... their smallest cross section is actually quite small compared to valve size vs. a normal production engine, and the venturi-style port has a good diffuser section before the valve and seat insert area. As there is none to little pressure recovery to be had in the very flat combustion chamber... Typically the port mCSA of a F1 engine is roughly 75% of actual usable valve curtain area. Your typical OEM car cylinder head often has it the other way round... Port mCSA is often larger ( often 125%) of valve curtain area... Production engines (other than bikes) as a whole seldom moves above 100hp/liter without the aid of forced induction... their ports flow just "good enough" to get the job done and is mostly configured towards meeting emmisions, and quick/easy casting and manufacturing. And with regards to "polishing" a intake port... if your engine got anything else than direct injection you loose power with "shiny" ports... If you want a port injected engine that has poor start and idle, and low to mid-range power, whithout having any added benefit at high rpm WOT, In addition to be more prown to end-gas detonation... by all means... go ahead and polish the living shit out of it... It's not my loss :)

[@exothermal.sprocket]

Slick ports don't allow for efficient fuel vaporization. Better to have roughness and small surface turbulence.

[@wrenchg3954]

WELL PUT!

[@Baard2000]

Njål Nilssen you are completely right: the port in production engines is bigger then what the curtain area flows. In doing this the valve seat controls the amount of air entering the cylinder. Not the incosistent cast port. Therefore a smaller port works !!!!!!!!

[@brianrhubbard]

With the vacuum of the piston sucking, still the chamber will only allow as much air to come in as it's volume will allow. The orifice of the intake is tiny compared to the orifice of the cylinder. Why restrict it more?

[@bsharpe]

At some point you have to test your theory that it doesn’t work, you’ll learn something . do you think the engineers in formula one test their theories?

[@brianrhubbard]

@@bsharpe Absolutely, I do this for a living. LOL

[@stevenmullen8402]

It's like sticking your finger over the end of a hose pipe

[@69waveydavey]

A few people on here would do well to read the works of David Vizard, a man who spent his whole life on a flowbench and dynomometer. What he doesn't know about porting etc.. (That's a serious one for a change!)

[@v8trauma]

69waveydavey or Graham Bell. his 4 stroke tuning book and his 2 stroke tuning books are updated as new vehicles and theories happen along.

[@skinnersmith7528]

Independent throttle body with long strait intake it will stack the air and create a creator force against the valves. However, you need a long and as straight as possible intake pipe so positive pressure is still traveling to the heads. If it reverses direction your screwed. Look to steam injectors for the concept of velocity.

[@brentsmith4394]

Even me being a numpty got that good video

[@flyfaen1]

I don't know who this motorman you are talking about is... But I think he has missunderstood the consept if he does it the way like you draw it here..., it's too close to the valve, the port should have been straighten out, the bowl filled slightly in the roof after the valve stem and It has nothing to do with resonance, but more so about increasing velocity WITHOUT restricting flow. Closing a throttle a little is a pure restriction, because it has a very poor pressure recovery behind it, so all it does is creat a restriction as there is no working diffusor behind it to convert velocity back to pressure. Most of the instances where "velocity-porting" (stupid name really) works are on engines with combustion chambers that give a poor pressure recovery AFTER the valve. like most 4 valve head and especially on high compression MC-style heads with a very flat pentroof. Usually the valve window it self is the main restriction, thus shrinking the port in the correct manner (as it's usually overkill compared to the actual flow of the valves) you gain both higher velocity and flow due to better pressure recovery due to the formation of a proper diffuser (aka the means of converting velocity to pressure) the higher velocity you achive without restricting anything gives you a better "ram" effect due to higher inertial forces, and 120+ % trapped VE is common on NA engines. And believe me... not all OEM engineers has got the ports right in a long shot... sometimes perhaps with regards to emissions, and emissions only, but what performance goes, not by far...

[@crtinkering7323]

or if you want to turn around the other way you could use a Shop-Vac as an example take your normal to inch hose and modify it to a 1 foot opening completely sealed no leaks will probably not even be able to suck up a leaf or a piece of grass now when you reduce it back to the original 2 in diameter size hose it has plenty of suction for that size displacement pump whatever you would like to call it ... there is always a certain size for the correct flow volume velocity pressure however you like to put it for different applications bigger is not always better

[@mattyadarab]

I actually do understand what they want to do with this porting. They want the venturi effect to help. But the problem is, what you really want is air mass in the cylinder. Not pressure, or volume or something. The venturi effect seems to help because it speeds up the air in the crossecion of a venturi tube, but it also reduces its pressure, and with pressure it reduces the density of the air and it leads to less airmass. And mass is basically the "number of atoms of something" you can have different Volumes with the same amount of air by changing the temperature and the pressure, and that is this porting would do changing the pressure to increase speed, but you need mass, and not speed.

[@dirtygarageguy]

You do need speed, as cylinder filling is time dependant. And the higher the rpm the less time you have...

[@mattyadarab]

Yeah, It is true, but you want speed without airmass restriction

[@hellishgrin4604]

JB weld in an intake would scare the hell out of me.. That stuff dries rock hard, but I wouldn’t feel good about it.

[@lauriedooker1031]

Toyota uses a method of steering the inlet gases over the top side of valve ‘as per drawing ‘ to better mix gases in cylinder . Similar ?

[@dougharvey9766]

Mate you have no idea... if you close off the port at the throttle body you are restricting the air flow. if the port gets smaller as it gets closer to the valve the airflow will speed up.

[@dirtygarageguy]

You are forgetting mass flow rates, the speed of sound and pressure differentials

[@dougharvey9766]

I don't pretend to know all that stuff... you should learn the basics before loosing yourself in all the other stuff that way you would get less negative comments.Learn to take your mistakes on the chin or understand the stuff you are talking about first.

[@lpmorgan90]

@@dougharvey9766 actually he's pretty much spot on... it's something motorcycle race engine builders focus on... a restrictor plate on the intake is used to keep HP figures down... same with race car engines if the car goes above HP limits they install a restrictor plate to reduce the amount of air getting into the engine... all this does is amplifies this practice... if you blank off 10% of each port on a 4 cylinder engine you are losing 40% of usable airflow... however, if you look at the ports on a factory turbo application they are shaped in such a way because the air has no way of returning back to the intake because it is being "forced" into the cylinder...

[@maxjamieson3341]

I do love the moto man rants lol keep them coming mate they always make me smile lol

[@thomasmanion2903]

No one is talking about temp. Doesnt thermal dynamics have the biggest part of what we are discussing . You have a cool air charge trying to be forced into a hot chamber. ie higher pressure, yes the piston is in the charge stroke but the temp is fighting that action. The pistons vacuum capability decreases exponentially with rpm. so isnt speed of the charge the answer. IDK just thinking out load

[@dirtygarageguy]

Temp of what?

[@zach9116]

i have run epoxy ports in a drag bike for nearly 10 years and it is considerably faster than similar spec engines at ALL engine speeds.It was in the worlds fastest and quickest bikes right through the 90s on any serious drag strip.Each one of youre seemingly reasoned arguments had ignored the reasons that make this work,although you are right on the point that this is about volumetric efficiency and massively affected by cam timing but youre just quoting it ,3.05 proves you just dont really understand.There is so much that you have proved here that you dont know that the simpleist thing i can say is just because you ignore something wont stop it from happening.This HAS been proved at national level in races to work no matter how much it makes you swear.I dont see it working with modern down draught Ports tho and also doubt you have ever sucesfully ported many heads(ye gads please dont)or you wouldnt only understand half of the picture.You have surprised me opening u a port like you describe will KILL any decently designed head,.read what others have said here and you may lern something,youre half way there,5 out of ten

[@erikeggenbakstad]

Funny thing this, that people don't understand the basic physics at all but still cling onto "facts" that brakes all of the physical laws possible... Guess a simple explanation as in this video is not enough lol..

[@wayneireland4802]

What people talking about velocity or mean port velocity is all true to a point.there are so many variables in port designs. It's a inch below and above the seat that's where 65 percent of the flow is 25 percent around short turn and vavle guide and the runner 15 percent. a well designed port should extend a inch or 2 into your intake runner .flow brench and mathematical jumbo will help in performance gains . another place not to over looked is overlap just when piston is parked a tdc its overlap that's helping incoming charge to be drawn in.but on saying that a longer stroke engine is parked at tdc longer then a short stroke engine .Cam, angles cut into seat and valves crank angle and it doesn't stop as I port heads and I'll share this variables that's what it's about

[@v8trauma]

So going by this mortorman logic, I plug up the inlet tract completely, I get infinite power. Good to know.

[@exothermal.sprocket]

That's not his logic. That's your attempt to trash him.

[@johnlmcgary]

The ONLY place that I could conceive of this having any benefit at all would be in NASCAR restrictor plate racing but even then you would not be reducing the entrance size but just matching the size of the "plate" so your flow does not bunch up along the hard edge of the restrictor plate.

[@therider3939]

Want more air go turbo lol

[@erikeggenbakstad]

There are those that never will understand an engine. And there are those that will understand them. Most likely the latter is the majority unfortunately...

[@Dr_Xyzt]

Amen! Big valves and ports aimed at the valve curtain, with the whole thing canted and aimed to match whatever the fuck the engine is for, is the way to go. As for free-valve, FUCK Freevalve. Just put on a good camshaft.

[@dirtygarageguy]

LOL

[@magnum357225]

The problem is he does not understand an engine is basically a compressor,amd the easier u get air in and out it makes it more efficient, so shrinking the port makes no scense

[@splitdecision71]

It does when your ramming air in there from the velocity! Once in motion an object tends to stay in motion! Cylinder is still filling at bottom dead center from the ramming effect cause by the velocity of the in coming air. Piston is already bottomed out but you still having incoming air. I.E volumetric efficiency.

[@robertmurphy2960]

I don't understand how people come to dumb conclusions that make no sense. Matt saving the world one video at a time. From an engineers aspect, I enjoy your content.

[@paulrawlins5878]

There is tune head porting. Depends on the application you are porting for, because if your goal is low end torque you dont need huge ports for large volumes of air/fuel mixture to enter the cylinder. You need smaller ports for more velocity to keep the air/fuel mixture in suspension to reach the combustion chamber at low speeds. Where at higher speeds you just need to get the air/fuel mixture in the combustion chamber as soon as possible, this where having larger ports within reason makes sense. Filling the combustion chamber with as much fuel/air mixture as possible is called volumetric efficiency. the goal depending on the application is to improve the volumetric efficiency at your applications engine RPM. To get the best volumetric efficiency at all rpm ranges, is to use two intake runners per a cylinder on the intake manifold, that has one larger shorter port, and one smaller but longer port. There is a valve that controls the flow through these ports for different engine requirements. Then on the cylinder head port is large for both low and high engine RPM needs.

[@louigi6001]

The fiat twin air system is a variable intake valve opening system and does without throttle by controlling the amount that the intake valves open instead .... not sure if it's a fiat patent though.

[@233kosta]

If you want high mean velocity, then why not just block off one of the runners? Better yet - go back to a 2 valve cylinder and not a 4 valve one! In all fairness, many car engines do that at lower rpm, presumably with the intent of using inertia to ram more air into the cylinder. Some say it also creates additional swirling due to asymmetry, but that asymmetry is always present as intake valves are on one side of the cylinder. The only practical benefit I can see is reduced throttle sensitivity for smoother city driving, but it hurts efficiency regardless.

[@Patricks_Projects]

You haven´t ported many heads haven´t you? In short: Motomans ideas are not wrong, just a bit or a big bit excessive. When portiing a head you want a 'small' area(venturi) in the runner to add speed to incoming air. This area needs to be at a certain distance from the valve, to tune it for a certain rpm range. Your example of lifting the head and dropping a shitload of air in doesn´t increase VE above 100%(not making any big power numbers) Racing engines got about roughly 120% VE, experimental engines have reached up against 130%. How to do that? Well you add speed to air to get high inertia of airflow(but you cant go over mach1). This can load cylinder more than 100%, creating a positve pressure at the valve. This 'venturi' needs to be carfully shaped(certain area of valvediam) and in correct place to let air after venturi diffuse and get higher pressure again before reaching the valve. If this is succesful you can this way overfill the cylinder and get above 100% VE. Study on..

[@dirtygarageguy]

Not even gonna start with this one. Wait for the fucking videos, like I said IN this video - jesus

[@Patricks_Projects]

*lol* Study on little wannabe. (but i must confess, you talked so much mumbo jumbo i got tired and didn´t watch the last minute)

[@Patricks_Projects]

well.. As i have seen a lot of your clips and many of them are some kind of just mumbo jumbo. put on a cool shirt and draw some stuff on a whiteboard doesnt make you mr knowitall. it might feel like it. question though: did you ever read my first sentence in my first message? a advice for the future: be careful what you are preaching people might belive you. advice two: take a couple of hours study on shaping ports on speedtalk forum. then get back to me. study on!

[@nuvey7939]

The way it was explained to me is you don't want to decrease the size of the ports, so no JB Weld. You just want to smooth the transitions out. If you don't hog out the ports, and just leave them basically factory diameter, but smoothed a bit, you get more low end torque. Porting the runners all out gives more high end torque. Never heard of using JP Weld. Factory engineers knew what they were doing, they were just limited on what they could do in the time allowed, so all we need to do is fix the stuff they couldn't. Adding JB Weld is just fucking stupid anyways. Even if it 100% increased power, I'm not putting something that might let loose and get sucked down into my cylinder, or wedge a valve open.

[@cygnus1965]

Well you will Never be one of the great engine builders of the world because they do use the epoxy trick when needed and it won’t ever come off if done correctly. As for everyone saying it will cause catastrophic failures that is not very likely as it’s softer than every material in the engine if the correct products are use. If installed properly there can be impressive numbers to be had.

[@seven9766]

I guess the point they got wrong was mistaking lateral velocity of the air for Volume stream i. e. Flow. Pressure, Flow and resistance are interlocked: Pressure is equal to Flow times Resistance. But it is important to note where these Values are measured. The Pressure in this formula is the Pressure needed to create that flow through the restriction. It is not the Pressure of the fluid after passing the restriction. If you keep the flow constant and add a restriction, then the Velocity of the air DURING THAT RESTRICTION will increase, as well as the Pressure in front of the restriction needed to keep the flow constant. This will not give you more Horsepower though, because the limiting factor for HP is how much volume of air you can squeeze into the Cylinder to burn more fuel to get more power. So, you want to maximise Flow. And to do that you can either increase Pressure (crank up your boost or reduce the volume of the intake by making it SHORTER, not NARROWER because that would increase restriction) or decrease Restriction. These rules are true, but keep in mind that they are for static pressure and constant flow, which is not the case during the full engine cycle, only holding true for the explicit intake/exhaust stroke. But the effects of the pulsating pressures and flows in the intake runner do not completely invert the rules stated above. My guess is, that someone really mistook flow for velocity and tried to maximise that, which would make narrowing down the intake make sense. Unfortunately that is not true. The only point where i think narrower channels would be viable is, when the intake volume is so big, that the Turbo/Supercharger/ambient pressure cannot replenish air and Pressure in the manifold fast enough (analouge to a too big voluminous intercooler increasing turbo lag).

[@LokiPilotAlpha]

Well explained again Matt. Doesn't matter. Some people will never understand. Same kind of people that think they can use their car's engine driven alternator to crack water into Hydrogen and Oxygen and get better fuel mileage. Or they think because they saw a guy with an electric supercharger making boost on youtube then electric superchargers must be a thing. The only time velocity matters is at the venturi of a carburetor. No one racing bikes, or even cars for that matter, is going to be using a carburetor unless it's a class rule. Even then, they are not at idle/part throttle most of the time. So it still doesn't matter. Mass flow makes power. Small ports ruin flow. Thus they ruin power. You can white board all the diagrams in the world and motodouche is never going to change his mind.

[@dirtygarageguy]

"Well explained again Matt. Doesn't matter. Some people will never understand." - aw well, if I can deter 1 young lad then its worth it lol

[@bulwinkle]

The old adage, you don't get something for nothing, is very true.

[@scottsmith2113]

Fact is that the smaller port WILL have small gains ONLY IN LOW RPM. But without the large ports, the engine will suffer the mid and high range.

[@dirtygarageguy]

Motoman was talking about peak HP and torque

[@dohc22h]

Sorta Like Honda with having the Secondary Butterfly's (IAB's)

[@blkmustang007]

i was about to comment this...my prelude has these

[@michaeldemetriou1399]

Never heard of too big of an inlet ps I have seen magnetically actuated valves that have a stroke of 8mm in 3 m/s

[@shaunobrien6425]

Another swing and a miss

[@darrenmatson8712]

Maybe this point has already been mentioned in these comments.. To say that the 'biggest port' possible will flow the most, or that 'no port is too big' is not accurate. The limitation in most cases is the valve diameter (i.e. The area around the valve seat). Given that restriction.. the port that would flow best into that restricted area is not the largest port, but the port with the size to optimise velocity and flow.

[@darrenmatson8712]

In other words.. Choosing to place a restriction before another restriction (that you had no choice in.). can make sense. If the restriction you placed is less restrictive than the valve seat area there should be no issue. A port can easily be too big for the valve seat area (restriction).

[@MasterChief-sl9ro]

I think their missing the point.... F1 cars. NASCAR and high performance Motorcycles use closed Air Boxes. "This is what increases air velocity" and removes back pressure. One reason they dimple the head surface and ports. They want to keep the air flow from hugging the walls. This also promotes better fuel economy. As today fuel economy means more laps per tank of fuel....And if you can go 3-4 laps more then your competitor per tank. That is equal to seconds in lead times over the course of the race...It means shit on the street...

[@dirtygarageguy]

"They want to keep the air flow from hugging the walls." - this is called boundary layer effect - and you can't stop air from hugging anything LOL

[@MasterChief-sl9ro]

Like hell you can't... It's why they run water injection. It cools the air charge to stop fuel from hugging the intake ports and pooling up. No to mention other benefits.. So trust me son. I had access to a flow bench on engines making 700+ HP.. You can see the difference is huge! Good Luck

[@pgtmr2713]

That guy IS doing it wrong for sure. He probably does have gains somewhere, probably at lower RPMs... but, unlike a system designed to keep the velocity up like a Toyota 4AGE's T-VIS, he cannot remove the restriction for higher RPMs (not counting the J.B. Weld breaking away unintentionally.) A dyno plot would probably show both the claimed gain and the loss elsewhere. The T-VIS uses a throttle like valve to close off one intake runner to each cylinder, and over 4500 rpms or so it opens them up and you feel all the fury the Japanese could put into a 1.6l 4 cyl. in the 80's. It's one reason why the NA Toyota AE86s and MR2s were great.

[@IcedOverLord]

@theworkshop Do you think you would see better vol. Efficiency at lower RPM range with this nozzle idea? I agree at high RPM you want that baby wide open. The reason I bring this up is I was running some engine simulations with 2 valve vs 4 valve and the 2 valve had better vol. Efficiency at lower RPM. That was a head scratcher for me but concluded that it was because of higher velocities...

[@HemiJoel]

Either this guy is joking, or he is completely ignorant of the fact that the valve is not fully open 100% of the time. Filling in the dead areas of the port to increase velocity increases the momentum of the charge pushing its way past the partially open intake valve. When the intake valve is not fully open, it is more of a restriction to flow then the added material in the port.

[@dirtygarageguy]

LOL dude, you're making yourself look stupid. Momentum is mass * velocity and doesn't mean anything in terms of volume, or better put mass flow rate. And i'm not ignorant of valve rams - but considering that valves have a duration of say 200 degrees on average, what percentage of that duration is during the ramp section? "When the intake valve is not fully open, it is more of a restriction to flow then the added material in the port." - But you're forgetting, because you're ignorant of that fact that the piston, say on the intake stroke hasn't travelled down the bore that much. One word - idiot

[@MC-Racing]

search freevalve. this is already in the making.. :-)

[@dirtygarageguy]

You mean this - kzbin.info/www/bejne/jqO8pWSAfbOgnpY

[@meckanicall]

Hi there. When you suggest putting the carb butterfly (6m 20s) at the same position as the epoxy filler you are over looking the fact that the flowing air would be trapped underneath the butterfly and cause massive turbulence and energy loss. However, the smoothed shape of the epoxy in the same position , if shaped correctly, will guide and funnel the moving air column into a faster moving one with little turbulence. Energy isn't really lost, it just gets converted into a faster moving slug of air which now has the ability with its extra inertia to supercharge the cylinder by drawing in extra air behind it, assuming the valve timing has a long enough port timing to allow it to do so and then closing at the right time to trap it.(By the way some engines do feel more powerful with a slightly closed throttle but this is simply because the main jet (fueling) is set too lean and the mixture at full bore is now too weak. This can easily be rectified) The new shape also guides the slug of air to hit the back of the open valve more evenly rather than have the air flow mostly hit the far side of the valve seat. By making better use of the entire circumference of the valve seat the flow rate is improved as the valve can pass more air in any given time. Finally, another bonus is the higher velocity charge of the new port shape will swirl better as it emerges into the cylinder. Higher swirl speeds allows faster and more thorough combustion and less chance of detonation.

[@dirtygarageguy]

"When you suggest putting the carb butterfly" - just a butterfly - nothing to do with carbs. "Energy isn't really lost" What energy? What is this energy and where does it come from? "with its extra inertia to supercharge the cylinder by drawing in extra air behind it," - Dude, I'm sorry but you don't understand how air works or what inertia is. "The new shape also guides the slug of air to hit the back of the open valve more evenly rather than have the air flow mostly hit the far side of the valve seat." - This is something you have just made up... "Higher swirl speeds allows faster and more thorough combustion and less chance of detonation." - and now you've made it clear you don't know what detonation is.

[@233kosta]

0:47 Since when does SW Flow Sim pass for CFD?

[@ModshackMerlin]

If Motorman's comments were true, then the brass restrictor plates with holes in that they fit to some Aprilia and other Italian scooters should make them go at eleventy million miles per hour, as they restrict the ferk out of the inlet port, there's something wrong with this argument. The key word is 'restriction', anything that does that will potentially strangle an engine. I'd love to see the Reynold's numbers for his JB Weld mods, I bet they are crap and introduce loads of turbulent flow, the opposite of what he wants to achieve with 'high speed porting'.

[@exothermal.sprocket]

As with anything in interpretation, people take things to the utter extreme to make their point, valid or not. Volumetric efficiency and air velocities have more to do with the relationships between the size of the port and the displacement of a cylinder, and a given RPM. Things need fine tuned, not swung completely to one extreme or another to prove a lousy point.

[@georgedicker9789]

I love your stuff

[@brotangyoust9252]

On my car I considered opening up the ports a bit but they're already a fair bit bigger than the area of my open valve so to my thinking.....unless I enlarge my valves there's no fuckin point. I gave it a new cam with a bit extra duration and lift and still don't feel like the ports need tinkering with. For the money if I wanted more flow I'd wack a turbo kit on.

[@basketballcory2]

Seen plenty of Dyno tests comparing intake port sizes. A set of Afr 195cc runners be will out perform a set of 220cc on the same engine with a displacement of 383 cubic inches. It's also common porting knowledge that you port the roof and keep away from the short turn radius. Opening up that radius area hurts performance. Believe me I've seen it. So who's to say closing it up a little wouldn't increases hp on specific engines with certain flow demands?

[@dirtygarageguy]

If you're talking about American v8s (which i think you are) then stop right there. I'm taking about well designed engines, not shit ones

[@basketballcory2]

@@dirtygarageguy what I said applies to all porting basics, so your insult on amarican v8's isn't really necessary

[@basketballcory2]

@@dirtygarageguy I however have not personally put epoxy on that radius. It's not effective when you buy good cylinder heads to begin with

[@dirtygarageguy]

LOL I don't know how you know if I insulted American V8s, did you ask them? And it's not an insult, it's the truth. American V8 engines are cheap first and then everything else is secondary. I think that because you called it an insult that you took it personally. Are you a V8 engine?

[@basketballcory2]

@@dirtygarageguy I personally own American v8 engines. They get me to and from work every day with no problems. Does my motor get as great of gas mileage as your little 4banger? No. But I have what's called balls. This isn't driving Miss Daisy. Where is your manhood?

[@Olsu123]

just like squeezing a garden hose, water goes faster but theres less of it.

[@LChem1]

My Cheby 350 revs to 7800 and i use 2.02 heads.Camel Hump cast iron, of course. Supposedlymore 202 make more hp than 1.97 but if so its only above 6000. I had a truck 454 with peanut heads. Small valves. I never reved it over 3700rpm. The 350 also has a 530 lift 300 duration cam, both sides. Amount of flow via cam lift and duration and volume of air via valve size will basically resolve any velocity issues. And restrictions reduce volume over time. Oh, the bottom end suffers with an 800dp Holly but the 650dp pulls like an ox off thr bottom, probably 50hp below 3500rpm but then the 800 rules by 50hp on top and above 3500 it pulls strong. Again, big holes win.

[@iwasatoad]

love the explanation... funny side note i tell people who ask me how to make more power " the difference between your Hemi and Top fuel Hemi,,, more air than most jet engines suck in, Fuel that contains air because why not and spark plugs that draw more amps than your friends speakers in his trunk... why all this you might ask well,,, it's like they say there is no replacement for displacement how ever it is the air they are talking about not the engine size displacement" that is normally when i get the what look so i dumb it up. get more air in the cylinder and follow suit with every thing else more air more fuel more spark and timing if you dare.

[@JPMotorhead1993]

Hey Matt, this could probably be a topic for a whole other video itself but I'm curious what your take is on the "golf ball" dimples used in ports and the supposed theory that the eddys they create allows for less drag therefore higher velocity/flow vs. polishing which supposedly exposes more of the metal surface to the air flow therefore increasing drag having the opposite effect.

[@dirtygarageguy]

Already in the pipeline. Added surface area also has the effect of charge cooling, but also charge evaporation increase. Back and forth we go lol

[@mattgoodmangoodmanlawnmowi2454]

@@dirtygarageguy Moderation I always say, and lots of it! 😎

[@timsharpe3498]

If this were true there would be no such thing as a port, intake or header primary tube that's too large. Port filling doesn't necessarily impede flow. Port filling is usually used to eliminate dead areas where the manufacturer made it too low. The older Big Block Chevy exhaust port is a prime example. The port was too big and killed torque. Some dude used to sell a d port conversion plate that increased torque output by 20 foot pounds. This drastic increase was accomplished by simply filling in the bottom of the port.

[@timsharpe3498]

Next time try some real evidence instead of a lot of blah blah and a squeaky dry erase marker.

[@timsharpe3498]

Real evidence would be an actual experiment that included ways to measure the different approaches to porting. Are you afraid of a little old flow bench or a big bad dyno? I challenge you to bring an entry to the Engine Masters Challenge since you know so much about port design Mr. dry erase master.

[@timsharpe3498]

I wont be watching any more of your videos unless I need a good laugh. Only a moron would claim that theory trumps experimentation. Fools like you dread having your theories tested because you know they wont hold up. I saw a well known engine builder use epoxy to fill in intake ports on a set of high dollar race heads that flowed over 420 CFM right out of the box. Guess what happened? They flowed way more when he was finished. Bigger isn't always better. Port shape is very important. Some places need to get bigger and some may need to get smaller.

[@timsharpe3498]

Just weight. Priceless!

[@timsharpe3498]

My next video is going to be on how to install your new power band. That should be right up the alley of your target audience. V Tech kicked in Yo!

[@Topsiekku]

bigger hole is not always best way get good flow. Flow speed is important. If you put weber 48 to 1300cc toyota corolla is not better than smaller carburator.

[@rolleric68]

switches.. and nobody knows that a1952 Chevy you're the best switch. . like a 1995 maybe I don't know here you're still always going to be the same switch operating, good to say that you find yourself working with 50 other switches. .but that's all .. personally I really love working without having any problems by just me it starts I know.. runs and I don't need to get an interpreter for the other switches to see why they refuse too understand me..

[@martgryfny]

You might (but not must) be right of what you said about performance. But the reasons you made out are wrong, and i tell you why. This is not about port flow diameter, speeds and pressures, but this is about flow direction, anf if it is laminar or turbulent. If you place any element like throttle butterfly (which you mentioned) it will just spoil flow laminarity and that would be completely different thing. When you place there anything smooth, like some sort of resin, you are basically changing port geometry, not only its diameter. You direct the flow, giving it more space to turn before reaching valve seat, ensuring that it will flow on every place around the valve with similar parameters. You work on better laminarity. And this is very difficult - without computer simulation it might be completely unpredictible. One man can get some good results, other one will spoil everything - this is why it seems to be some sort of voodoo. That's why i mentioned it in the begginning, that you might be right, but you may be not.

[@leeeng478]

Porting and polishing is the best way to go for efficiency and performance without a big build. This does not mean altering the intakes and ports that's what the pros with a complete rebuild performance cranks pistons cams etc. etc. What he is talking about is a little more hardcore with engineering involved timing and massive headaches. For the standard guy porting and polishing should just be about smoothing the intakes and ports like glass. Basically smoothing the imperfections from the factory. My dad did it all the time for the 60's Nortons, Triumphs and Ducatis. The other basic was getting the exhausted balanced with the RPM of the motor via the size of the muffler. Poor mans performance port polish and balance. If you open up any motor specs unless the motor is designed for a performance build from the factory it is a headache to do a major build were talking open up your wallet, just buy a motor specked for a performance to start with.

[@J__C__]

That motoman guy is still around? I first heard about him like 10 years ago. It didn't make a lot of sense back then, either.