What not to do when porting heads

[@randalljames1]

My mentor told me once.. "You may have been mowin your own grass for 40 years, does not mean you were doing it right" ... ya know that stuck with me for 50+ years

[@paradiselost9946]

watching some people mow, that hits home :) lol, just revived memories of some of the most random mowing i ever seen...

[@waywardshed9721]

I have always said “you can do something wrong for 50 years if you just believe it’s right

[@stuart207]

As a professional grass cutter, I appreciate, and approve of your comment ☺️

[@justintime5411]

I stumbled across your video by accident really. But, I'm glad i watched. Ive been a mechanic pretty much my whole life. Couple years ago i got into ls building, tuning with hp tuners, and took my first stab at porting. I followed a particular person that seemed to have a good reputation. After building the vehicle i noticed a small misfire on a couple of cylinders that couldn't be tuned around. Almost felt like an injector was clogged. Now I believe I opened the throat too much

[@stevejohnson7132]

I was always told the reason not to hog the throat on a 'street' engine was to preserve the venturi effect and maintain flow velocity. What you're saying is it's the necessity to maintain a smooth angle transition. I think this is an excellent video.

[@WeingartnerRacing]

It’s both things. Thanks for watching.

[@stoosee]

@@WeingartnerRacing hello can i ask. i dont get the hog and bigger throat. do u mean i dont need to touch the throat part? only the bowl partv

[@chrislangdell117]

So I'm sure I won't get a response to this and I am not sure If this is covered in another video but how do you measure the throat for your 90% are you using a special pair of micrometers or something. Since this accuracy is very important then it has to be measured and ported very carefully. Kind if have to sneak up on it.

[@1crazypj]

@@chrislangdell117 Chris, you don't need any expensive tools. It can be done with just a rule (if your using a tape measure you probably don't have tools to do porting anyway!) The easiest thing to do is just measure the valve and use calculator to get (my preference from what I've learned and read in last 50+years)) 88% for intakes and no more than 90% exhaust. Couple of fender washers and 1/4"(or ~6mm) longish bolts and nuts (to use as 'handles') file them down to the diameter you came up with from valve head diameter (electric drill and bench grinder is quicker ) One 'secret' I found out early on, air, at the velocity in ports (or anywhere else) doesn't want to change direction more than about 7 degrees ( I think you can still look it up in old (1940's) NACA documentation. There is a 'mountain' of information available, problem is finding time to go through it all (pretty sure it's impossible?)

[@1crazypj]

@@stoosee just open throat to 99% and you'll be fine on any street engine. Even F1 with 18,000rpm engines doesn't go over 90%

[@fredsmachinewerks4811]

Hey Eric This video hit home. I have seen what guys do to there heads, Then when they re install think they took all the material off, the motor does not pull like it use to . Well you example is out stand. Makes so much sense. I have never done any porting at all just some little clean ups. Great video. These kind of jobs should always be done from someone like yourself that know the physics of head porting. Thank you so much Fred

[@chrismannifield3222]

I like to show folks pouring water out of a bottle, and that spinning it, can make it flow faster than the glug...then dump out a glass, and see that it runs to 1 side. That the air has to spin to be as efficient as possible. For beginners, just clean the flash and make the surface finish uniform for your application, dont change the geometry , and youll do just fine.

[@ltwig476]

I started grinding and polishing valve seats on small bl chevs. at 14 years old. I never changed any of the flow dynamics. Only cleaned up small casting imperfections. That is all it takes to improve the flow where the valves are concerned. To finish waking up the engine, best bang for buck is tuned exhaust. DIY port matching is kind of the same concept. Just grind the very top of the port to match. Don't get crazy on removing a lot of materiel and again, clean up casting imperfections. If you need particular track race heads, go purchase them from the pros. Basically to wake up a stock engine, simply clean up the manufacture's slop. Their numbers are close enough to perfect.

[@peterdarr383]

There's work to do relieving the intake to combustion chamber clearance which improves flow at ALL valve positions. Some castings can shift around so every valve needs to be checked.

[@mitchcoop1]

Very good points...I might add that an easy mistake is to hog into the short side radius with a porting tool (Specially on the intake port) which will cause major turbulence across the valve. New Guys, Read Smokey's book for the basics.

[@441rider]

A good Hi Pro book for porting tips is Phil Irvings Tuning for speed. Bikes but I got a BSA up to 12-1 comp and over 100mph

[@mjb242]

To funny someone disliked the video, must have been Eric's wife or one of those bowl hog guys. Great video Eric very insightful.

[@curvs4me]

I do it inadvertently when I have a weak signal. Page is jumping around and you hit it by accident. So you hit it again and it doesn't change (so you thought) then hit it again 5x because it's irritating the crap out of you. Then close the window. I can't say for sure, but I can gather that is how most of the dislikes get there.

[@peterrivney552]

I watch many videos before I decide there are different ways to to the but can get a person teaching that give you wrong way to do things I will watch this and expand my knowledge before I go hog wild. 90% is safe any more is dangerous...true...,good job nice teaching g

[@Engine_biulds]

I'll bowl hog the piss out of my head because I know what works in the real world. But Im not gonna be stupid and go so far its unrealistic I just feel im waisting my time on this video with no proof that I can see as to why he states we shouldn't do this or that. The point of the matter is a flow bench is the wrong tool if your using only that to teach others because nothing the flow bench shows you is present in the real world and allot of what effects flow on a bench may not affect flow on a running engine take for instance pulse flow how can you determine how and what rpm this will change or what rpm will be effected with what your doing as far as im concerned when you tell me the air NATURALLY will flow around a valve as in thats what it wants to do then your a joke. Becuase in the real world the intake port flows into the chamber with the valve completely in the way the air will take the least path of resistance so it inevitably will go around the valve. If you take metal away air will fill that spot this can be bad but it can be good . But as far as im concerned I find massive flow (in the real world) cutting off the third angle on the intake port gaining 4-6mm without a bigger valve. Then rounding the edge on the back cut "on the intake valve" The exhaust is another story instead of an average "angle cut" ill do a radius and polish the last angle into the port he says this will effect reversion I find this vary minimal and could car less about reversion because this is something a good cam can take care of and in most circumstances isn't even a big issue if you help reversion if you are gaining more with flowing the proper direction. In my opinion i think we got a couple people on here that are a little stuck in there ways and like to point the finger at who is doing it wrong for 30 years and bashing others that have studied and learned a bit about flow dynamics. Its a toss up.. I say just do what you want but don't tell people they are wrong if you don't have a way to prove it because its all words and no proof

[@bigboatben]

I have one hater who dislikes every one of my videos within 5 mins of posting lol. Haters gotta hate!

[@curvs4me]

@@bigboatben That's hilarious 😂. People are out there so sour their face hurts. Definitely not the brain trust. Still haven't figured out that shyting on someone else only makes you feel worse over time lol. A grade school lesson.

[@taskmasterhorni]

Great video. Love your comment about people saying "I've been doing like this for 30 years". I've been responding to them by saying they've been doing it wrong for 30 years for awhile. Great minds think alike I suppose 😂

[@mikerieck306]

Good video. I have used 90% on the intake ( with a back cut on the valve) and 85% on the exhaust for years and years (motorcycle heads) with excellent results. Bored on a Serdi for uniformity. Low lift #'s at .100 and .200 are very good (bike cams have .300 to .400 lift in general). Low lift #'s are critical as the event happens twice during the opening/closing cycle.....I am glad you made that point about them being important.

[@stoosee]

can i use 87 percent on exhaust?

[@christhorney]

so many sharp angles inside that combustion chamber, and between the valves, talk about detonation points lol. i love your info about the valves such good info thanks!

[@erickieffer8440]

Thank you for this informative video. Porting heads is a difficult subject to teach and I appreciate all those who make the effort to share their knowledge.

[@robertwest3093]

If I had just dropped $2,000 on a set of cylinder heads I wouldn't have the cajones to take a grinder to them!

[@Thumper68]

I was taught entire point of porting is to move most air possible with least restrictions. Now I’m a water well driller pump installer by trade and have a ton of experience understanding how water flows and restricts so it only makes sense to me how air moves and small restrictions with water make tons of splashing etc so a tiny turn making a restriction will definitely cause tons of air turbulence.

[@1crazypj]

Interesting. I read somewhere about fluid dynamics and water can be a good substitute for air/fuel mix but is around 1,600 times denser (and not about 1000 times as is mostly quoted) so you can use a much slower flow but high volume. I had a friend who sold his flow-bench (he stopped professional porting) He had a 55 gallon drum on top of shed to see where and how fluid discharged through valve. (he 'invented' measuring devices to use it as well) He said it was real handy if a customer wanted to 'see' where his money had gone plus it extrapolated very well with Superflow' bench results This was a long time before any 'wet flow' flow benches came into being (early 1970's through to mid 90's) He also told me, the biggest issue was waiting for the water drum to fill up though

[@kimberlysteller2556]

And though, sonetimes an crappy port and an good intake length make an excellent combo.

[@flinch622]

Least restrictions, yes. But the limitation is keeping fuel droplets in suspension. There's always some that drops out/finds the floor, and as mentioned, enough people have done enough work to show that 15 degree changes is a very good guideline - a pure radius does worse. Things get weird in the 4 valve world regarding throats - numbers in the 85 to 87% suggest there is a minimum step change [throat vs valve diameter] needed to flash fuel back into suspension during early intake opening event.

[@T51B1]

The seat angles help the air/fuel charge to stay closer to the seat and curl around it due to molecular cohesion, rather than it coming away from the sides of the throat and seat and slamming into the valve which causes bad turbulence and a high pressure area. It is for the same reason that the short side radius is very critical for flow.

[@cammontreuil7509]

How do you figure that ? You could sell swamp land in Florida.

[@woodsmanNo1]

Wouldbe interesting to try cutting angles in the short radius. Very difficult task.

[@TurboJohn74]

Best quote this week: "They just assaulted the head" I was chuckling at that one, because this science/ machining /craftsmanship is your passion. I felt that

[@KimiWallrus]

This is so much better than watching David Vizard on 2x speed 😂 Great vids! Thank you! The clarity was good, it's harder than people think to get the shot and explain too lol

[@erniemathews5085]

Since I am way ignorant if I pay attention I can avoid mistakes on my 2-valve BMW motorcycle. Thanks for this.

[@1crazypj]

If you have the earlier 'boxer' motors there is an awful lot that can be done. Most difficult but dramatic is angling carbs outwards so you no longer have air doing 110+ degrees to get into cylinder I don't know if you ever saw the twin plug modification that gave around 11bhp due to high dome pistons being used in race motors? (probably around 1979~80)

[@VinnyMartello]

Whenever I do porting, I typically just try to remove all the rough edges. I’m not looking for 800hp on anything I build. So a gasket match and a de-burring is all you need. Unless it’s a Chevy inline 6, then you have a little work to do.

[@VinnyMartello]

The crux of the 250 is that the head bolts run straight through the middle of the intake ports. You don’t even need to port a 250 to boost power. Just cut out the head bolt pillars and add a short bolt instead. Use the “lump port kit” for even more power. It’s how you can turn 200hp into 250hp with no other modifications.

[@VinnyMartello]

Glad that info was useful! It’s a very cheap upgrade that yields impressive results and does not take away from overall reliability.

[@cammontreuil7509]

Best advice I have read here.

[@cammontreuil7509]

Also match the head to the cylinder. Place head on block with no crank in it. You'll be surprised what you see. Improvement can be made here.

[@cammontreuil7509]

I'm a Ford engine builder. 40 years. Don't like chevy engines. I have my reasons. But the 250 is a great engine. I have one in my boat. Good on gas mileage and power.

[@Supanova70]

well the felpro 1266 did not work i have deeper issues.. Great Vid. I have a fresh 355 with Dart heads that were from a circle track car. Heads were milled and i can see light on #8 intake through my victor Jr intake. My machine shop said to use washers on all 4 corners that equal gasket I'd. Then mold BB` model clay on all runners top and bottom. Slice in half and measure depth. Going to try tomorrow. Also china wall close but not hitting yet. Anything else i can try? Thanks. John

[@HalferLandPerformance]

Great video Bud. Yup we specialize in Honda Big Block (V6 J-Series engines) and offer PnP parts, with our great gaining Venturi Stage 2 PnP Throttle Body...people doubted gains and we literally had to educate people of what a Venturi does..😎

[@ru2yaz33]

It's basically dealing fluid pressure head, the angles and flow cross-section area determines the fluid velocities and pressure heads. On a more critical examples are the design of wind tunnels and nozzles.

[@mathewboyd3746]

Geat info! Not many talk about what not to do and newbies like me would get caught.

[@ianhale4466]

I honestly believe while the flow would hurt, it's still a good tool in some cases. If you remove those angles, the mixture has to go straight, the valve is in its straight path. And a big thing in combustion is when the fuel hits that hot valve, it vaporizes and you get a better burn, so if more fuel HAS to hit the valve... it's good for trucks and street/drag cars

[@351cleavland]

Never have the words been uttered by a craftsman with such pride "This Thing is Gunna Suck!" (7:52) and the customer is happy.

[@ottoolsen9676]

You say a lot here that makes sense regarding the venturi effect and make sure that you do not exceed 15 degree angles so that the air does not detach and cavitate, which is well known in the aircraft industry. with such large valves and so little mass left between them, I would be worried about cracks between the valves, and maybe a lot of sharp edges for detonation. but now I'm not an expert on this, I've been an engine mechanic for 30 years for boat engines + various hobby tuning projects on the side of this. but in terms of porting, I have limited this to minor fixing in casting errors and port matching

[@trip9567]

Glad you clarified that it applies to the intake only. I did a set of turbo Buick heads that are 92% intake and 91% exhaust. Flow numbers are excellent and the exhaust side is the highest I've seen on a 8445 Buick head. 91% on a 1.5 valve forced a very narrow 45 which is not ideal but everything is a compromise. Your doing a great job.

[@mr.know_it_all]

How does a higher exhaust flow % help when there is 20+ lbs of back-pressure?

[@63turbo]

@@mr.know_it_all Always remember... a huge amount of the gasses are expelled the instant the exhaust valve lifts at all. Right before the exhaust valve even opens there can be between 50 and 100 psi, and this is more than plenty to spool the turbo. If work on the exhaust port leads to more flow, then the cam doesnt need to start lifting the exhaust valve as soon, and more of this excess pressure can be used to continue pushing down on the piston, making more power that way. The turbo is always supposed to be the exhaust restriction and nothing else, and is easiest to change, via a different exhaust housing. If the exhaust port flows better, then all of a sudden perhaps the turbo exhaust housing doesnt need to be so small for best spooling. This is how a higher exhaust flow % can help the boosted engine.

[@Engine_biulds]

I seriously doubt it matters on the intake having those angle because the flow is in the opposite direction which those angles ate of little help. This is why the tesla valve works so well at restricting flow in one direction and not the other. I believe the opposite of what this guy is stating in his video. I say prove it (on the intake side)

[@andrewkelly1225]

@@Engine_biulds, When compared to those with experience, your position is the minority. The burden of proof falls to you. Also, remember there is a great big restriction in the way for most of the intake cycle (valve). In fact even for a fairly hot street engine, the valve is never out of the way. Pretty sure David Vizard has some #s in some of his books if you want someone else to do the testing for you.

[@fastredcar97]

@@Engine_biulds The boundary layer of the air flow coming out of the intake port will widen as it exits. Remember the boundary layer barely moves any air. The harder the turn the air must make the less of degrees the boundary layer moves. This creates a false wall that the velocity must overcome. the reason you see long slow sweeping "trunk" areas on very fast vehicles is the accommodate this principle, allowing the boundary layer to transition to the chamber surface as fast as possible.

[@mrmrwilem4789]

I love it man… I apparently ruined a set of heads 6 years ago, but man they were crap when I started. I want to clean up some 5.3 heads but I know better than to do more than clean em up a little.

[@havebenthere]

Love the comment" I've done it this way for 30 years". Done it wrong for 30 years. I always tell them nothing wrong with some old school just don't be an old fool! Ther's a reason for learning ..... it's to get smarter not dumber. Good video!

[@cammontreuil7509]

Even if done wrong. The physicological thought of hogging out heads make you think it's got to work. A big hole has got to flow more air or water right ?

[@DaveMcArthur-b1e]

Thanks!

[@matthewjenkins1161]

Simple rule is don't mess if you don't understand. Port velocity as important as flow and bigger ports reduces velocity.

[@rhostatton8944]

indeed

[@oscarhedden9524]

I think Ford has finally realized that

[@superkillr]

@@oscarhedden9524 Explain?

[@superkillr]

Port velocity is only relative to the engine it sits on. A 454 at 7500 RPM can use a much much bigger port than a 454 pulling a trailer up a hill.

[@matthewjenkins1161]

@@superkillr The inlet ports on a European Ford 2 litre Pinto engine are huge for a road engine. Wouldn't know about American built engines.

[@needmetal3221]

I've always used 85 percent fwiw. I've found that Japanese bike heads are 85 percent as well. I used a new way style cutter as a boring tool. Worked in a pinch

[@DirtTrackDave]

In my realm of 4 link suspension I tell my customers real data and numbers is what you go by. Never so and so said this, or dude runs that and bla bla. No facts, no data, no using of components or services. Good video man.

[@bicylindrico]

I have really enjoyed your channel Eric. Do you have a video on what us cheapskates 'should' do? Should we leave the dimensions intact but smooth out original castings? I am asking for us that are running oddball heads that don't fit the domestic realm but want to make improvements while our heads are off the engine. Again, love & respect your insight.

[@terryhill4732]

I thought that was what it was all about was smoothing out the castings

[@roygustafson7729]

You are Amazing and HILARIOUS 😆 I just died when u told your joke because I'm married and going through a divorce.. I know there's a level of truth to that. I have 3 Mustangs and 3 Chevy trucks. Mine would def do it😉😆🙏😇💪😎👍

[@HOVREDDY]

It’s all Bernoulli’s Principle and fluid dynamics! Newton has a few laws as well. Good stuff Eric

[@taz4100]

35ish degrees is what the seat should be. Check out David vizards videos on porting. He is a absolute wizard on them and wrote the books about porting. The tinniest change can make a big difference if it's in the right spot. It's all a balance of port velocity and flow.

[@WeingartnerRacing]

That is completely and utterly wrong. The only place for those seat angles is a diesel because they have very little lift and it helps with seat wear.

[@toddedman3549]

35 degrees is the angle he suggest from the widest part of the bowl up through the edge of the throat on the cylinder wall size. That isn't the seat angle. On the cylinder center side he suggest the angle should be 10ish. That's about bowl dimensions and doesn't have anything to do with the cut angle on the valve seat.

[@performancenaveia7821]

Eric activates the translation to avoid losing details of the video,Thank you

[@performancenaveia7821]

Thank you Eric

[@deanstraathof2721]

If the intake flows poorly with too much throat, but the exhaust is helped, would adding a supercharger be a benefit to the enlarged intake heads?

[@themoose4386]

+1

[@johnbryner9052]

Video randomly popped up because I was searching for headboard last couple days so I push play almost right away. Cut your Whataburger taking the wife out joke oh my God had me rolling bud had me rolling. I’m subscribing right now because of that joke😂 👍

[@dufusemerge4780]

That same thing that goes for the valve-throat, goes for the port-throat as well. Pressure-waves can not pass a taper angle steeper than 10-12 degree something without losing energy. So when the valve-throat is right you get slightly less flow with the valve in place compared to when it is removed (A Graham Bell). Other really god useful references for headporters is the (De Laval nozzle).

[@Holaroznic1]

Very informative, about to rebuild a magnum and need all the info I can find. Thanks!

[@dimensionsevenofficial3721]

@EricWeingartner Where can I purchase the cutter your using? Same with the the 5 angle blade? Any videos of you using it? Doing port work on a la1 with a lx9 head and intake swap. 12:1 comp w/turbo here I come lol

[@WeingartnerRacing]

They are custom cutters I had made by Serdi.

[@1crazypj]

'Anyone' can buy SERDI cutters, they are not cheap though. Last time I priced them, (around 2009) the cutter blades were about $90.00 (US) and the most basic SERDI set up cost $160,0 although you could go for fully automatic (industrial head production) for around $3~500,000

[@carmiethompson2676]

Good video, thank you. STOP apologizing about the use of terminology or any technical dialogue. That information allows the user to better understand advanced flow/velocity cutting & porting techniques. I'm not saying bombard the viewer w/ technical jargon, you've got to present it w/ a low to medium pace but, if someone has big issues about the technicalities then they need to stop watching & go back to their 'macro may' channel & leave the rest of us alone. I'm glad you discussed the difference between the intake & exhaust porting. They're completely different but it still goes over some peoples' head. Use as much terminology as necessary & please don't get into the habit of calling a feature, component or term a 'thing', 'this', 'that-here' etc. That's nonsense talk that doesn't belong in a technical setting. Suggestion: Substitute open-cell foam batting for the regular pillow in the pillow cases, you'll breath easier.

[@ChiefCabioch]

Short side radius is the most important part of good flow...

[@mr.know_it_all]

I’m curious to how much of a power loss there really is, especially with overlap. You should ruin a set of heads and put them up against a good pair of heads to see the power loss/gain. Dyno Data is better then speculation. Maybe I can set you up with Richard holdner.

[@WeingartnerRacing]

Put me in touch. I have another thing I want to test.

[@rockfordhx2768]

I have a great set or iron heads you can have to do your testing there super clean hot tanked everything is still on them there a vortec 350 head from a 1998 Chevy Silverado 062 head casting you just pay for the shipping and I got you brother I love the channel

[@hotrodninja458]

Can we see comparisons on a flow bench please. Maybe before and after references to further explain in detail.

[@cammontreuil7509]

True. If not, everything else b.s. and speculation.

[@hotrodninja458]

On our performance heads, all the sharp angles are blended smooth. Improved flow. Very precise when done by hand. Most seat and guide machines have a cutter that does this easily.

[@cammontreuil7509]

@@hotrodninja458 nothing new.

[@stuart207]

The air favours one side of the valve, as far as I understand it. You do most of the work there.

[@upfactoryracing4148]

Are there differences in porting when running NA or Forced induction? Like raising the roof and dropping the floor for NA or more volume on intake and exhaust for turbo?

[@rocketsurgeon11]

Air flow is air flow. The only difference is biasing for turbos versus everything else (or nitrous). The same principles apply.

[@noahjames6103]

Depending on the original port size and application more csa can help efficiency. Typically you dont want to remove material from the floor it will increase short turn angle

[@upfactoryracing4148]

I was thinking port velocity for NA draw but I see that flow is flow wether NA or boost the amount you can get into the cylinder is key. Great info in these videos!

[@rocketsurgeon11]

@@upfactoryracing4148 it's common for people to equate "boost" to velocity, but it's not. It is *density*. Now, this is NOT to say that velocity won't be affected, because at higher pressure differential velocity does increase (how supersonic and hypersonic wind tunnels work). I would have to see flow bench measurements, but I would think that the velocity increase would be local to the throat or MCA. I know Larry Widmer has been making supersonic ports for a long time. If memory serves, at that point it is choked flow and the only way to get more through is density (more boost).

[@upfactoryracing4148]

@@rocketsurgeon11 ok that is interesting so the choke point causes a pulse that the air bounds back off of around the valve into the cylinder. Man I would love to see a cutaway of that.

[@erichuff2538]

Pay it forward , and your right... we hardly hear about the good things out there. 👍

[@keijokojootti7790]

5:30 Basically what you described here is the angle that flow is able to follow the throat wall without separation. Separation would cause low pressure area and/or vortex and those will cause drag. You agree?

[@jdrissel]

Basically the same thing as an areodynamic stall as the air flows through the valve.

[@shitbox7413]

I used to think the throat is more of a restriction than anything in some heads, then it occurred to me that it might be there for Venturi effect and to help direct airflow toward the seat, then I realized I shouldn’t attempt my own port work. 😄

[@fc3sboy1]

There is 2 things a flow bench are worthless for. One is a rotary engine. Complete an utter waist of time with trying to flow test the ports on a rotary. Those engines are all about volume and timing not the amount of flow. One can also argue this with 2 stroke. And the second is boost application. Especially on small displacement high rpm engines. Granted there is more usable information with the flow bench on a boost head then an iron of a rotary but one can argue your theory about bowl size and choke points when you put pressure behind that valve above atmospheric at any given lift point. Object is volume at that point not creating a Venturi to speed up air flow. I come from rotary. Both na and boost. One thing I have learned with them is it does not take psi to make power but a massive charger at a lower boost level will make power and at a safer level. Example take a 13b with a gt35 . That engine will and has made north of 600bhp but at above 28 psi on pump gas and will stop producing tq at about 5500 rpm . Now take that same engine bolt a gt4202 to it now to make north of the 600 bhp you only need 18psi an tq production does not fall off and exceeds what the 35r did at all rpm points and is just as responsive . Same can be said to a point on a 2.3lt turbo 4 cylinder engine head port. Not the turbo size but volume of air flow being forced into the cylinder. I recently did one with taking the port bowl to full square to the seat. Much like you explained in this vid and said was wrecked. The results with the same turbo was about 500 rpm sooner spool gained about 50 to 70 tq depending on rpm point and gained about 25 whp and the power curve pulled 2000 rpm further out as this particular engine was always a lower rpm power peak from the get go now seems corrected. Explain that

[@KimiWallrus]

I'm calling hillbilly, shed shop diy porters "Bowl Hogs" from now on😂😂😂. Everytime I've seen someone "open ports" it's like you explained, they don't get the bending of flow. When I was younger and dumber and raced go karts I've dynoed motors that made less hp full hogged than a wka legal "stock" motor with a properly placed seat and good angles. I don't know anything and won't without 100s of hours testing but what your saying aligns with what Darren Morgan has preached and he was the head porter at Reher Morrison for 20 years or something. He's at Bishoffs now, the dude who did awesome at the engine masters with multiple platforms against the big names.

[@tomosborne5949]

Perfect explanation. It becomes obvious when you flow the head from the sonic sounds that transpire over the sharp corners of the 45 degree top cut.

[@terryjacob8169]

If you hunt around, here on KZbin, you'll find some pieces on how to build yourself a flowbench on a budget. I built one around forty years ago, inspired by an article in Car Craft magazine. It proved a real aid to my engine building, along with articles on cylinder head modification written by the genius David Vizard.

[@Garmoo5600]

This will be one to watch 100x over

[@markginter8354]

Thanks for the great video. The reasoning for throat ratio not being critical for exhaust make sense but it begs the question: would the poor flow characteristics of the throat being cut too wide be lessened with an increase in pressure of the intake charge (i.e. forced induction)? Thanks for the informative videos!

[@richardlee2488]

The point is with forced induction you no longer need skill. Just boost and more boost. If you blow fuel straight through it doesn't matter as you can brag the dyno results. Normally aspirated is like a musician in perfect tune across the spectrum. 250bhp per litre was achieved in the 1960s. Many turbo engines can't get close now. Except F1... £1000000 engine, 250 miles Now that's a bargain.

[@95Sn95]

Great video. Back in mid 90s I was in my 20s I bought a set of "performance GM iron heads" from Aerohead, they were the best of the worst 993 76cc heads with screw in studs .525 springs and 3 angle valve job. I payed for optional 2.02/1.60 s/s undercut stem valves (aeromaxx?) And a $100 "bowl port special" when I delved into porting about 10 years ago I did all the staple mild porting procedures with full exhaust polish, I left the bowls alone I figured where I heard Areohead was a division of INDY Cylinder head they knew more about a bowl port than me. You must remember seeing adds for Aerohead in the lower tier car magazines back in the day. I think the base price was $250 +/- not terrible with the options back in 93ish. And my 355 with a Howard's .480/.480- 232° @.050, 108lsa, (max torque 112031-08 best SBC cam I've ever used and I've tried a pile most underwhelming was crane 450 lift Saturday night special) Torker 1 intake (with 2" spacer) and flat tops it actually runs surprisingly lively for mild smallblock in a pickup. That cam is magical tho, I recommend it to practically everyone with a warmed over 350 and wants a nice broad power band and nice roudy idle with no power brake issues and stock converter will work fine, a 2500 stall was bit un necessary.

[@burtvincent1278]

What is the effect of reversion pulses when the valve closes? Would deep bowels act as accumulators and have pressurized air for the next opening cycle?

[@bajanboyhood]

Show us some dyno comparisons.

[@nickma71]

Magazines occasionally have cylinder head shoot outs. The good ones are where they change the head only, to show why you don't want a race head on a street car. Then, with all the supporting modifications including RPM. That is comparable.

[@wolfparty4234]

I’m new to the game. I tried doing some head work on some Honda’s I must say that you make a lot of sense and I know what your talking about Bc I lost a ton of low rpm power but I am able to rev higher, 2000 rpm’s higher but the engine has to stay up in the high revvems for that power. Again, it is just a 4 banger anyway! I learned a lot, thanks for sharing 💪🏼🔥👍🏻🤣

[@travispeoples]

Makes sense... the angles help the air make the turn into the chamber.

[@keyvanjahan3366]

Thank u so much for all good things u teach us bro.u r great

[@maryannmoran-smyth3453]

Cutting the intake seat, too close to the exhaust tends to warp it, which is something I would avoid through my experience 2:30

[@rokkebill]

Thanks for the nice video. Could you explain how to actually measure the throat, where and how to measure to get it accurate.

[@TheProchargedmopar]

Yes Please.

[@Peter-V_00]

On point Eric, way too many heads are butchered by people that don't have a flow bench and if they do they dwell on full lift flow only ignoring the mid to low lift numbers which you know is in a way almost more important than total lift because the valve passes through those lower lifts twice!

[@Dave5843-d9m]

15 degree angles between flats give the same flow as a continuous curve. If gas has to turn more than 15degs (at one point) around the valve there will be turbulence. Inlet opens gas inertia starts the flow, Exhaust opens and almost instantly drops cylinder pressure below atmospheric sucking in more inlet flow. Exhaust closes and inlet continues to pour in, even though piston is well on its way up the compression stroke.

[@williamcharles9480]

Thanks for sharing your knowledge. That aluminum head looks maxed out since there appears to be no room between the intake and exhaust valve to go with a larger intake valve. Am I correct? Some people don't think to do any research before they start hogging out their heads. Even if you were get one of the intake and exhaust ports correct is that novice person going to be able to repeat the same dimensions with seven more intake and exhaust ports? They don't think about that factor. If I've invested several thousand dollars in a set of heads, you can bet that I'm going to take them to a reputable head shop for porting. If head work was as easy as some folks think, it's obvious that you wouldn't be in business. Personally, I can do a lot of engine work in my small garage, but I'm just not set up to do anything to those heads but some flash and rough casting clean up, plus I'd have a real problem living with a dumbass, (myself) if I screwed them up. Thanks again for the video.

[@censorshipiscommunistic]

@12:00 Venturi Effect Amplifies Air Speed. Kill the Venturi... Kill the Air Speed. Confucius Say, don't cut the tip off the garden hose nozzle, water fall out end of hose.

[@TPVPRO]

The more I watch your videos the more I realize i just got lucky with my LT1 heads. Because I don’t know ish. 😂

[@madmaxsdog8040]

Back in the 1980s I used to race two strokes, not applicable you may think but it absolutely is, everyone tried to "tune" their own engines as it was so easy to do, "the ports are as big as they'll go, it's a f*****g rocket" and they got passed on the straights by a nearly standard one which had had minor modifications and a port clean up. Gotta admit I went big port to begin with and when that didn't work and I ran out of money for more cylinders I started using metal filler in the big ports and some of the "mistakes" when I made the port "too small" got better results, yeah, size matters, but it isn't always biggest is best.

[@paradiselost9946]

two strokes are the bomb... i love that everything we know about porting them is mostly imagination... visualising flow and that sort of thing. half a degree on the transfer floor and the scavenge is circulating the wrong way... or not! who knows? amazing how two nearly identical port jobs can give such wild results. thats a winner, thats an anchor... wanted to setup a strobe light and fog machine, acrylic head, get an idea of the flow by pulsing the strobe 1 degree later (or earlier?) every revolution... poor mans "slo mo". havent two smoked since they banned my motorised pushies...

[@ericgossard8808]

Have you toy'd around with low to medium viscosity dye's added to the incoming airflow? If so we're your findings a + or - as a whole? Thanks. Like your videos. They're not only "Just the meat" of it all, and you get into why and what happens for alot of people who aren't as fluent with all of this as you are. I'm sure you've kept a lot of castings from being trash canned by the overenthusiastic guy who just bought a die grinder.

[@b.c4066]

All your vids prove one thing.. unless you have dreams of doing head port work and development as a career and spending the time and money to buy the equipment to do it right.. it's cheaper to just start with a good head and then pay a pro to modify them if you've maxed out the combo as is.

[@superkillr]

As much as I hate to accept defeat.. this is probably the wisest move for almost everyone. The stuff produced now on CNC's is really really good. For ANYTHING on the street there is no reason to need a professional head porter.

[@cammontreuil7509]

True. Doing it yourself is more just for fun. Like playing guitar or painting.

[@jamierodriguez3554]

@@superkillr I totally disagree you can get more overall power in the entire range and better fuel economy if you have the heads ported for high-velocity and a multi-angle valve job and no one can see you modified it which is the best part

[@WarpedSpeed]

good video, it is more important to know what not to do than what to do.

[@jamierodriguez3554]

That's my motto for everything in life

[@Engine_biulds]

I would argue: porting the throat BIGGER makes for the valve to be more "out of the way" Like you say when you go to a bigger valve but don't port it out to that golden ratio, which i hardly believe is a good idea to begin with to go to a larger valve unless there is real-estate on both sides of that valve to allow for it. What I actually like to do is port the intake as wide as the seats sealing angle area and I typically get a finnished throat that is 4-7mm larger on the throat, this is taking into consideration of flaws and all WITHOUT going to a larger valve. but on the exhaust you absolutely need this chamfer in order to help guide the air INTO the port (THE KEY->INTO the port) so you would want to go to a larger valve if you plan to port the exhaust side any larger than it is factory unless casting is just that bad lol. But you do NOT need, "in my honest opinion", this shrouded radius on the throat of the intake because the air "in this configuration" is guided out the port necked in closer to the valve it is going the opposite direction and will not benefit having this radius as it is making more drastic turns than needed had you just ported it out wider to clear the valve more. the faster the air can EXPAND through the valve seat and around the valve into the chamber---> the better, WE DONT CARE ABOUT THE AIR BEING TURBULENT GOING INTO THE CHAMBER" even if that was a thing, this would have its own benefits with fuel mixture as the air has already made its trip. And the fact that any turbulence induced from no shroud at the intake guide could be negligible being that the combustion chamber is so large there will be no time for negative interferance i.e. pulse sound etc. prior to combustion even that can be detrimental because at this point the air is already where it needs to be.. If anything,it Having the shrouded radius "wich you say needs to be there" literally guides the flow of air RIGHT into the back cut of the valve (valve being COMPLETELY in the way of the air flow no matter how much it opens) so if you widen the throat you allow less restrictions 2x fold MORE of an opening for the air to get out the port+ more freely around the valve. In This instance a smaller valve is actually DESIRABLE with a larger throat imo """":only on the intake"""" can you port the throat all the way to the seating surface and have nothing but gaines, you cannot do this on the exhaust side it will kill any flow gained that you think you may have because the turbulence induced st the beginning get worse as the exhaust travels and expands as a result of having no "funnel" so to speak preparing the exhaust to enter the ports, and because the spent air is being forced into in a smaller space this turbulence is detrimental and kills flow the LONGER the port is there after the mistake, you have to have a way to direct the air in a smooth manner if your changing direction, angle, shape, to a smaller area, not so much if going to a larger diameter at the end of the port, though there is losses there too, just not as bad as going to a smaller area without a "funnel" at the beginning of a port. I also see flow increases on the exhaust by polishing a soft radius back cut on valve and then also polishing a soft radius angle leading into the throat there after the valve "seat" angle instead of a grinded angle. It just cost money to do this kinda work.

[@WeingartnerRacing]

You should dyno that and let me know what happens. You are backwards. The air flares out around the valve not just straight down. That’s why you need angles on the intake throat.

[@Engine_biulds]

@@WeingartnerRacing there already is one.. the seat angle. If this was true why don't manufactures put angles on the exhaust tip.. because it literally helps nothing once it exits the exhaust. Why do they put what known as a velocity stack or larger radius on the intake... because it helps direct air in to a smaller space With less turbulence. The valve area is literally the opposite would would do the same thing to the intake valve area as you would for the exhaust sayyy by going g to a larger exhaust. And vice-versa making a velocity stack on the exhaust valve area for the same reason you you a carb

[@WeingartnerRacing]

They don’t put angles on the exhaust because the angles help wet flow. We don’t have to worry about that on exhaust. So instead radius. You also don’t want angles on the exhaust because it helps the reverse flow. That’s why I say you are backwards. Watch my exhaust video and you will see. Im sure I will do another video later where I remove all angles and flow it. Since I have done this before here is what happens low and mid lift numbers suck. Peak numbers are decent because the valve is out of the way and the valve job is less important.

[@Engine_biulds]

@@WeingartnerRacing ok but also you have to think in terms knowing as your learning that flow benches also allow the valve to see nearly every environment that is NOT visible in a port or around the seat NOR happen long enough for some tmof the turbulence issue to arise withing fractions of a second where as some can greatly cause issues like a bolge or casting flaw or lip near the seat We are talk pulses faster than sound faster than a blink of an eye so another restriction would be knife edges causing sound turbulence not calculated in the tuning of the port, so vacuum and surge pressures wich are most important are all not visible so we literally will be hurting ourselves if we take what we see on the bench and apply it to, as if its the real world condition because if anything allot of the turbulence you are seeing will not be seen or be drastically increase because the forces at wich are increased massively, like a knife edge it will help drastically on a flow bench but in REAL world having a knife edge on an intake devide detween valves WILL create a sound resonance that can easily hurt flow more than casting flaws.

[@Engine_biulds]

@@WeingartnerRacing what im referring to is on the outside of engine

[@jcnpresser]

That’s for sharing all the head porting wizardry!

[@terryhill4732]

When he took out to much metal of the valve it's amazing that he didn't grind thru into the next one

[@danieldesimonedanny1827]

Note the throat is actually a venturi. And the laws of physics apply.

[@cammontreuil7509]

What laws of physics ? Explain.

[@cammontreuil7509]

@@Faolan161 I studied laminar flow in the water jet industry. I worked in research and development. There's none of those characteristics in an intake port or exhaust because angles are not straight.

[@joeretro]

How about a boosted engine? Does it work to open the throat on the intakes, for the same reason it works on the exhaust? Very interesting video, thanks.

[@rocketsurgeon11]

Air flow is air flow. The only difference is biasing for turbos versus everything else (or nitrous). The same principles apply.

[@joeretro]

@@rocketsurgeon11 Thanks. I'd like to hear more about "biasing" for turbos.

[@rocketsurgeon11]

@@joeretro some may disagree, but from what I have seen, going above 75% of the intake for flow capacity in forced induction helps. It may be due to the marginal heads I am used to, but that's been my, and a few other's observations. Also, low lift flow characteristics are very important to prevent reversion of exhaust back into the chamber.

[@joeretro]

@@rocketsurgeon11 Thanks. I get your point about low lift flow being important with a turbo due to increased backpressure--hadn't thought about it that way. By 75% are you referring to intake to exhaust valve size? If so I understand. Watching more of your videos right now.

[@rocketsurgeon11]

@@joeretro Yes, valve size. I *WISH* these were my videos! LOL I watch these all over YT to learn as well. I was simply iterating things that I have witness works and from other experts that know WAY more than I do. This work used to be very "secretive", but it's much more accessible nowadays. It takes a combination of talent/skill and the correct machines to pull off what these guys do. Unfortunately not a lot of DIY guys can really replicate it 100%. But, applying the knowledge, you can STILL get benefits and gain power. I was happy to see a custom cutter here. I'd been wondering why I hadn't seen it yet, but this video answered my question! I also take in what I can from guys like David Vizard, and still go back and reference Larry Widmir of Endyn posts on "The Old One" forums (wish those were still active...I learned SO much back then!).

[@finnroen2334]

I always enjoy seeing the holes into the head bolt. I have to try this myself. 93% throat on a 2.3 valve becomes 91% when using av 2.35 valve so it should work ok I guess.

[@BigT27295]

You gotta go wit the flow . Amen brother.__

[@scottsigmon926]

This video is exactly why I watch!! It’s all in the details!! Nice job sir

[@jeffrykopis5468]

You have thoroughly discouraged me from EVER attempting to port my own heads. Which I'd only do because I can't afford aluminum heads, nor can I pay a pro to port my iron heads. So I will run stock heads and be slow for the rest of my life 🙄

[@a2cryss]

You could still clean up casting flash and other irregularities and do a pocket port. Clean up the squared off valve guides and stay away from the throat except to make sure it has no sharp angles below the seat. Also use a back-cut on the intake valve. That all should get the most bang for your buck.

[@LD9user]

So what you're saying is size matters, but not in the way we generally consider it. ;)

[@Moparmaga-1]

Eric have you ever tested a valve with multiple back cuts ? I was messing around at work. Took a 460 stock valve and put a 15°, 30°, 45° and 50°. Then reversed my cuts from 50, 40, 30, 20 and that blended into the 15. With .070 width. Just curious what you or anyone who's actually flowed something like this (surely its been done a million times) ill get the flow bench at work going and see. Vs a few other used valves with different angles

[@utahcountypicazospage5412]

I have a question would it still ruin the head under boost since air is jammed in .NA is more picky

[@classicrestouk]

I would say yes. A Boosted engine should be thought is as NA with higher ambient pressure. It still draws air into the cylinder, just higher manifold pressure. It's generally not ramming air in as you would think. The piston moving down still creates a draw into the cylinder where there will be a pressure drop, and the pressurised air enters the vacuum when the valve opens.

[@PotatoeJoe69]

I'll gladly do my own port polishing.... but I dont mess with porting them out. I'm very mechanically inclined, I could learn the right way too do it if I really wanted; but for now at least, I leave it to the professionals lol

[@morganpowell2999]

I feel ya buddy😂 my wife is plotting how to end me with the car parts I’m buying

[@llewvirtue861]

Big ports are not always better, it's all about velocity. Toyota get Yamaha to design Theire heads. On the 4age engine, the big port head makes less power than the small port head

[@officeuser1480]

Excellent explanation Ty

[@MikMech]

You got a thumbs up with the Pillow Joke. You got a Sub with the Macca's Story. 👍

[@msgofast]

Do you less small choke percentage if you are limited to lower lift cams? Does a radius undercut help over multi angles?

[@WeingartnerRacing]

If anything in that case I usually try make the throat larger as long as I don’t compromise the angles of the valve job too much. Radius valve job should only be used on exhaust because you need that angle on the intake to help with atomization.

[@keeperofthegood]

Its basically a horn (or a or rocket jet but horns are older and the math is the same). If you did a 2-d graph of the system in to out, and did the calculus on it, you'd see what changing each of the three elements does. I'm surprised no one has made a model of this, with sliders to give a good idea in advance what each modification may or may not do.

[@1crazypj]

I think they have but it was 'too new' and they couldn't sell it, plus, it still only gave a starting point which needed physical verification and often modification. I'm sure major auto and motorcycle manufacturers now have software to do it as that would explain the incremental power gains year on year to sell more motorcycles (and why 600cc 16,000rpm engine now make 140 bhp instead of 55~60bhp @ 12,500rpm) The REALLY surprising thing though, they still 'pull' from around 2,500rpm and idle at 1000~1300rpm. Foll race' 1000cc motorcycles are producing around 220bhp (probably more but they don't want competition to know just how much) without forced induction or power adders (NA and race gas)

[@erichuff2538]

Great video , very informative.

[@karlknudson4644]

on the exhaust they weld up the botttom of the port build up a tonsel looking likr floor of thhe port aka e port head and they have a flat bottom of port caled a d port head they also have port stuffer plates to put on exhaust port

[@Cruiser2B]

What seat and guide machine and tooling are you using?

[@stevehammel2939]

great information, much appreciated!

[@joshuashuck3994]

Did the exact same thing on the first set of heads I ever tried to port. Ran terrible after that. Bet I lost over 100hp

[@victordahn2150]

i always like to make the bowl a little egg shaped near the short side. then you dont need such a big throat. Eric you are doing a great job on the videos!

[@michaelblacktree]

I'm just a hobbyist. When I port heads, I don't even touch the undercuts. I'd rather not risk it.