What not to do when porting heads

Going over one of the worst things you can 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%

[@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

[@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

[@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.

[@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

[@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?

[@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..😎

[@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.

[@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!

[@mathewboyd3746]

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

[@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

[@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!

[@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.

[@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.

[@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.

[@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 💪🏼🔥👍🏻🤣

[@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 😂

[@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.

[@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

[@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.

[@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.

[@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.

[@jcnpresser]

That’s for sharing all the head porting wizardry!

[@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.

[@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

[@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.

[@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.

[@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.

[@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😂 👍

[@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!

[@scottsigmon926]

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

[@performancenaveia7821]

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

[@performancenaveia7821]

Thank you Eric

[@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.

[@terryhill4732]

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

[@Garmoo5600]

This will be one to watch 100x over

[@ChiefCabioch]

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

[@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

[@travispeoples]

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

[@stuart207]

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

[@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

[@keyvanjahan3366]

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

[@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. 😄

[@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. 😂

[@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!

[@ubatooba8467]

I really like the 2 "booster ports" that aluminum head has now! Talk about thinking outside of the box. They look super trick and will become craze of the future no doubt.

[@KCadbyRacing]

We did a lot of R&D at a shop I worked at (flow bench, dyno AND track testing) and we ended up with custom cutters that include the smooth blending radius below the inside valve angle = every port/bowl was perfectly sized and concentric, with inside radius blended in one step (extra bowl boring steps need if head was stock and or installing oversize valves). I find it interesting that one thing you don't see or hear about much (if at all) is the "critical choke area" = where you want/need _max velocity_ in the port to make max power, but that's an entirely different subject that includes very complex math formulas 😜

[@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 ?

[@440cubicinch]

Best video I have seen so far for people just getting started in head porting!!! Your video really helped me understand what David Vizard video meant by hip the port. Subscribed

[@cammontreuil7509]

True. Good for beginners.

[@Holaroznic1]

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

[@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

[@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.

[@officeuser1480]

Excellent explanation Ty

[@The340king]

Thanks for the tutorial. I hear a lot of the lingo, but haven’t had it explained in detail.

[@davidelliott5843]

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.

[@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.

[@BigT27295]

You gotta go wit the flow . Amen brother.__

[@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...

[@erichuff2538]

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

[@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

[@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.

[@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

[@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

[@MikMech]

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

[@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.

[@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.

[@suicidal_racing]

good tips eric.alot will kill the throats and dont get how much just a good valve job is even worth.

[@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

[@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.

[@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.

[@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.

[@erichuff2538]

Great video , very informative.

[@stevehammel2939]

great information, much appreciated!

[@doctorwhodj]

Thanks for letting me know I ruined my pontiac original iron 670 heads when I cammed it and massaged the throats.

[@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)

[@thomasblueschke6938]

See what you mean, it simply took away the koander effect. So you can assume that the air is stalling on the surface of the port.

[@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.

[@kentdixon5716]

Really enjoyed the video, very well explained, thanks for posting!!

[@modeverything1]

Great info, thanks for sharing. Makes me want to spend more time porting!

[@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

[@LD9user]

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

[@crazyantny9161]

People don't quite get that you want maximum velocity. Maximum velocity equals great flow

[@cammontreuil7509]

In a race car with wide open throttle.

[@StainlessTIG2]

Very informative. Thanks again for a great video!

[@michaelblacktree]

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

[@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

[@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?

[@morganpowell2999]

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

[@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.

[@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.

[@adelinomartins582]

Very educative.

[@RepreKent1221]

I personally have always enjoyed the head with the more throat

[@ValladolidArde]

what a superb video, very well explained

[@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

[@andrewnewman1248]

Thanks for the valuable knowledge 🙂

[@wlsnpndrvs8593]

Gee whiz... I was going to learn something. But then, an ad came on, and I had to change it. again I learn nothing on KZbin anymore. I don't know what else to do.

[@Mikej1592]

a simple way to describe it would be removing those minor angles for the air to smoothly flow around causes pockets of turbulence and that messes with the overall flow and can in some cases block flow as some of the pressure is pushing back against the inward flowing air/fuel mix (correct me if I am wrong but this is how I see it)