When we think we know it all is when we need to open up more to learning what others know.I learned that even the least knowledgeable person can have great ideas at times. Listen to everything then you your knowledge to determine if it may be useful.
Eric Weingartner, a very successful head porter, also suggested that we amateurs limit ourselves to 90%, to be safe. He says it's far better to remove too little metal, than too much. He also said he sees many heads that were completely ruined by guys who opened the throats to 92 or 93%.
Thanks David. I’ve been looking forward to this episode since you mentioned it. I’ve read your book but hearing and seeing you explain things is really great. Regards.
it is great to have you full of energy and willing to teach your valuable knoledge, I consider your book as the great bible for porting! thank you very much.
David, you forgot to mention how important it is to comment as well. Like, subscribe, set the bell and comment are all important for the algorithms. 👍 Can't wait for the next one.
I am subscribed, and I do Like every video I've seen. Ive been binge watching them, along with Andy from Unity Motorsports, Eric Weingartner, and others, as I have a lot of catching up to do! I think I've learned nearly as much in the last few months as I did in my previous 56 years, about engine design, engineering, building, and performance mods. Most of that, thanks to you and Andy. He is a very fortunate man to be your friend and protege. Thank you for all you do, and all you've done.
During a few classes. I was able to design a cylinder head that did not use tulip shaped valves. Instead it used gates. No push rods or rockers where needed. Its works just similar to a rwo stroke or rotary type air port. I know there has been "ball" style valves experiment with that work like a water garden hose type valve. Iam still looking forward to contributing to your channel if your still interested.!
Auto manufacturers are starting to do away with camshafts, electric solenoids that’s open the valves, endless possibilities in cam timing . Sounds like a cool idea you got there.
@@jcnpresser we also tried electrical solenoids for valve functions. The valve itself becomes the limited factor. Just as David showed. There is also reversion in addition to this with a valve that move back into its pocket. The gate style doesnt have that. And a port window in the door can be tapered to control port speed with a transitioning shape. The idea is what started some of the two stroke snow mobile designs currently being used. They are using gates. Just like the gates in a predator carb. Engine draw is what opens the gates in these power plants.
Great video Mr. Vizard!! A small ask, at 15:10 in the video for example, please use a different camera angle when pointing to critical port modifications. Thank you!
What a find! THE David Vizard! Read the books going to bed and in the shop. Could never get enough. Can't practically use it all, but nevetheless so enjoyable to learn.
Very well explained David. I always tell my customers that most of the gains are found in the valve and seat profiles and most ports will follow a good seat, valve,and bowl job with not much work to be done on the port itself.
Its easier for me to understand on the video than from the books. (Its been two yrs i own ur books, n still got a lot of questions 😂) Cant wait for part two!!!
Hi Mr Vizard, I have been reading you book mini A+ engines as I have a 1380 in mini 76 mini. What a fantastic read it is. Thank you for your knowledge and wish you all the best! Dino, Brisbane Australia
There's next to nothing that directly applies to a Chevy 250 inline 6; everything that I am trying is a mixture of things from Mr. Vizard's books on building horsepower, and porting/flow testing. This video building on what's in the porting book seems to be more applicable to what I want to end up with. Even Santucci's Chevy 6 book isn't as well suited as this. The 91% rule is new to me; perhaps I've missed it in the porting book. There's so much there, it's entirely possible that it could be missed. I'm convinced the inline 6's head can be made to work much better than it does stock, but the pictures/examples I have in Santucci's book don't look 'right' after reading Mr. Vizard's books.
Like I always tell people you're never a know it all and people who are aren't experienced enough. I am 27 and learn a lot every year about engines and porting and so on.
From a father of a little girl to another. God bless you David 🙏🙏 I can't begin to imagine life without my sunshine. May Gods healing light shine down from heaven and give you comfort and peace. A-men
Excellent! Amused to see an actual pointer instead of a cursor! Technology that works. I've just rebuilt a 1981 Vizard spec A series engine, originally built using all your articles - its a flyer! Remember your 1430cc / 649 cammed racer? I haven't gone to that extreme, just built a more modest torquey cruiser. 👍👍👍👍
The exhaust side is not as specific. Generally the escaping exhaust gases dont need help getting out. More attention to exhaust reversion is key. If you have ever fired up a engine without the tubes attached. You will see flames kick out about 8-10" from the port in a straight shot from roof of port. Yet exhaust manifolds and headers have very sharp turns. On sone engines the exhaust port even takes a drastic turn before entering the manifolds. Like pontiac or olds type motors. The general rule for exhaust size and flow is 60% of the intake. But 1.60 valves will flow enough to keep up with 2.10. On sb combinations. 91% is the intake side. The exhaust will benefit with reversion if that number is lower for the exhaust.
One thing I noticed is when before I clean the head. Where eddies form on the intake ports it will leave greater deposits because its stalled flow. I tend to take note of deposits on the ports. Exhaust is pretty difficult to use this but the intake with a crank case ventilation system will show me where I should focus. Not gonna be able to eliminate the eddies entirely but can reduce them pretty well.
It is a very good idea. Altought I had problems using it on the intake side as the fuel injectors washed the bowl are pretty clean. On the exhaust I was able to locate the thick carbon deposits where the flow stalls.
I like to use the newen cutters and set the seat almost at the outside of the valve, then i blend the area below the seat into the bottom cut of the 3 angle cutter form. Then when the porting is complete I use a stone and dress the seat spinning the stone holder by hand until I get the seat width and runout I want
Great thanks for this David! A larger intake valve will most likely restrict the flow pass the valve dish, inside the combustion chamber? Could please also explain how to address that issue?
@Mikko Kuorttinen, I know about nothing about this matter, but what I know is that Saab changed the shape of the combustion chamber in order to make the flow better after installing bigger intake valves. I am speaking about the Ford V4 engines they used in the model 96 cars.
After I watched my first DV vid I realized I’ve “got it all wrong” I felt I wasn’t getting much result so I stopped matching intakes and heads a long time ago. I have a set of 241’s bound for the heap so I’m going to get the grinders out and make an attempt with what ive learned so far. I’m going to machine some valves down to 90% of valve size to use to check the throats. Is that ok? I have absolutely no development equipment. I could probs use a cylinder and a decent vacuum/make a smoke machine. I don’t think I could do pico tubes capillaries and all that jazz for a half ass flow bench. Can I improve heads (for me and a few friends) and get results or should I just spectate and leave port work for people with equipment and cnc machines? Can’t wait for next vid.
Is it best to have the throat straight out thru the seat or to have it back cut larger diameter behind the seat so it makes a venturi as it goes through the smallest id of the seat?
You make the point momentum controls, and there is greater flow on the long side, yet you make the throat radius greater on the short side. Why is that?
Thanks David for your reply to my comments . You didn't my basic question What does the number of 91% of valve dia apply too & how do you put that number to design. use
Bruce, I did answer it a few posts back but just for the record the 91% refers to 91% of the valve diameter. So a 2 inch valve would need a throat diameter of 2 X 0.91 =1.82. DV
you mentioned that you're limited to intake valve size to what will fit in the bore. what about the 52% rule. intake valve size to be no more than 52% of the bore size or is that number not relevant?
David, I have noticed that many amateur engine builders, and some lesser known pros, have You Tube videos about gasket matching intake ports in heads and manifolds. But they never show any before and after Dyno results. I'm inclined to think that, without work in the rest of the port, it's a waste of time. My theory (untested) is that enlarging just the openings and making them match just creates a wide spot that slows down the charge, which is of no benefit. What say you?
Thanks for a good video. Just getting started with the IOP program. Like to mention that I already found a confirmation for my thoughts about port size simple by adding measurements to the program. IOP program assumed Cylinder Head Port Area HP Limitation in a Renault F7R engine and regarding the homologations from 90s, Megane Kitcar engine was restricted by inlet manifold adapter plate (smaller area). I have also found a chassis dyno sheet, where the power curve continue straight close to same HP and RPM. I'd like to ask: Is this power curve keep going straight indication, that the engine has an airflow or port area limitation? I know I'm asking about the port, but the video dealt with restrictions and this was rule number1. Thank you, -juhana
Juhana - I am not sure I fully understand your question here. Tell you what, make the questions out in bullet form and as simple as you can. I believe that what you are asking will be covered in the next episode. DV
@@marvingvx1 Thanks, I keep that in mind. I got too excited and telling, because I have no secrets in my carage. I have better torq in my engine compared to competitors. In the end its about how do you perform in a race day..
91 92 % of what . I thought valve seats were concentric cut to various degree angles. Go with the way air wants top flow. How does a individual determine path of air flow. Is a flow bench required
The 392 snowflake bbc head is about as good as factory heads came. They actually where dealer installed heads on performance option cars. They are rectangular port heads. So basically they are copied by about ever head manufacturer today. After about 1973, chevy never offered a head in this performance level until the latter crate engines.the phase 2 might indicate a later over the counter option. Normally a larger valve or spring package. They are the head for bbc pure stock classes. They sacrifice low end torque for a substantial flow increase above 6000. Very common to be used on 496 stroker combos. Easy 650hp capability.
Point of most restriction is the intake valves ability to pass gas!! Hmmm... kinda stinks! I'm going to have to watch this another 897 times to start to get some kind of comprehension of what's being said here. I'm not sure I'm getting the percentages thing or what I'm suppose to be doing with them. OK, after watching again, is the percentage based on outer diameter? So if my outer diameter is 2.02 (apparently, outer valve diameter, not outer seat diameter?), my inner (seat?) diameter should be something like 1.838 (91%)?
Mr Vizard If you take a torque graft and check the horsepower then move that graft to the right, the latter will have more horsepower. But will the latter outrun the first. If so,why. You are the only one who can explain this with logic. I believe with the gearing optimal for both they will perform the same. I have built many engines from your knowledge and have excelled,na. I am now building a turbocharged engine with my son. Your book doesn't have enough detail on performance camshafts for turbocharged engines for me to make a solid decision and have it ground. I try to do things once.
There’s a lot of analogies people use to explain this, but torque is a force whereas HP is work over time....a good way to think about it is in extremes.....an example being one engine that makes 1/2 the torque of another but spins twice as fast, and they are both run at the engine speed that correlates those figures ONLY.....in this example (if they both had a CVT transmission and the RPM’s were held constant), they would accelerate at roughly the same rate with optimal gearing for each, because the amount of work being done is the same......in more realistic scenarios the most average torque over the intended operating range of engine speeds will be fastest given the same gearing, but in instances where you are shifting, or the gearing (both transmission and final drive) can be changed , an engine that makes a bit less average torque over the previous engines RPM range but has a wider operating RPM window can be faster given each gear “gets you further“ via. additional work being able to be done in each gear.....(You should check out Richard Holders channel if you’d like to see a lot of camshaft tests with boost).
@@ericschumacher5189 I understand that,it makes sense. I watch Richard, I've had his followers argue ,with a turbo all camshafts are the same, throw one in, it don't matter.
I agree with you; in my opinion a good way to pick a camshaft on a turbo application (besides how it acts N/A like a Richard says) is to think how the entire vehicle your building will be used, If you’ll be octane limited, and if it will be traction limited......an example that may help you out, is if a car that runs on pump gas, adding a cam that makes a lot of midrange torque may not be very good given how much timing will need pulled in that area to limit detonation, the same could be said for a vehicle that can liquify street tires N/A already (more torque down low isn’t very important). On the flip-side if the turbo is huge for the application your likely to have a rising boost curve, and that same cam with good low end / midrange characteristics may help to make the power a bit more linear / street-able (if that matters to you) and lower the boost threshold.....I’d focus mostly on that in your cam choice to narrow the list of choices down a bit.....also I forgot to mention but if you transmission is an automatic, torque-converter choice will be just as important as the considerations mentioned above.
@@ericschumacher5189 you are knowledgeable, are you of the same last name in racing for generations. I have been specing camshafts for years, na and nitrous. Turbo and blower are different. A positive displacement, overlap goes out the ex. Turbo camshafts I think you need to look at the pressures boost pressure to back pressure. I don't think I have it all figured out. I'm not sure about opening ex or closing in. Or for that matter if you have low back pressure will a little overlap help spool the turbo. People argue but I know if both valves are open together flow will go to the lower pressure side and you hope that is not in the wrong way.
Thanks for the compliment; I’m not, my family is into racing (as a hobby), there’s a lot of people with my last name w/German heritage......in terms of the trade off point with overlap I can only speak from my personal experience / what I’ve read, but on a turbocharged engine I think it has a lot to do with the turbo’s size & efficiency at the boost level you intend to run.....The easiest way I can articulate this is if you were to put a large turbo on a small engine and run right near the center of the turbos efficiency island, it’s likely the back pressure would be equal to or lesser than the boost pressure (2-to-1 ratio), which would likely require less overlap to ensure that your not inducing EGR when both valves are open......in summary the camshaft overlap is likely closer to an N/A cam when running low boost with an appropriately sized or large turbo, the overlap likely needs to be less the harder you push the turbo or a small turbo on a large engine (like a lot of OEM production vehicles are)......my experience with this has to do with 2L 4-cyl stuff when moving the adjustable cam gears. From looking at the mass airflow logs / airflow per pound of boost, and how much Ignition timing it can tolerate without detonation, this is why I think this to be true.....also I have seen more overlap helping with boost response on pump gas when running rich AFR’s because some mixture is making it to the exhaust side (burning) and raising the EGT’s helping spool.
Dear David Vizard, I have been watching your channel for a long time from Russia and I am your subscriber .. There is no such thing in Russia even close .. I beg you to include subtitles if it is possible .. If it is costly or some kind of prejudice towards Russia due to sanctions, etc. .d. I understand ... Just let me know ..
It is a shame that east and west don't see eye to eye at political levels. I have met quite a few Russians during technical team get togethers to explore trade possibilities. I can honestly say that the folk I met where a great bunch of people. Can you tell us your name spelt out just how it sounds. I am sure I am not the only one here who would like to help you out. Please expand on the 'subtitle' part of your comment. DV
Thank you for your reply .. My name is Alexey Evdokimov .. I think my name and surname will not tell you anything ... I just really would like to watch your videos with subtitles, that is, with translation .. Until recently, all your videos came out with the function of subtitles, that is it was possible to read the subtitles in Russian ... the last couple of videos are already released without the function of subtitles in various languages ... Okay, we are from Russia ... maybe there is some misunderstanding ... but as I understand it, you are popular not only in Russia but throughout the world ball ... That is, you can only be watched by people who speak English ... I mean, in a nutshell, I wanted to ask you to release your videos as before with the function of viewing subtitles in different languages ... Thank you)
I'm building a 408 stroker mopar for a 1970 dart... im itching to start porting the factory heads after watching this. I have ported heads before and I can tell you I made all the mistakes 😂
Think you have accidentally gotten your numbers back to front. If the short turn radius is less important then why would you have 93% there, and only 91% on the long side where the greatest flow occurs? If your numbers are right it seems to contradict everything you said in the video.
Must not have explained this as well as I could have but no, everything is round the right way. On the long side we are emphasizing the flow efficiency at higher lifts and this means a bigger seat radius on the approach but on the short side we are favoring area as the flow separates at anything over about 0.200 lift. DV
@@marvingvx1 OK understand your thinking now, because the short turn radius air flow becomes virtually null and void at lifts over 0.2" lift, you are compensating by making that side a little bigger to get some kind of use out of it. but where majority of the flow heads to on the long side above that lift you are more concerned with exit shape, since that will dictate maximum airflow.
I have a few small scooter engines I'm building, trying to get power from, if you can call any gains from a 2-3.4hp engine power, the ports and valves are just sad, but I have a head I can send you if you would be interested, it's a hemi style , over head cam, I went from a 39mm bore, to a 50mm and 52.4mm bore, and from 16/18mm valves, to 18/21 and 21/23mm valves, with the largest bore, I would like to get all possible from these little engines, and considering a stroker crank, going from 41.4 to 44mm stroke, coming to about 95-96cc from a 50cc engine, but I can send you the stock head if you would be interested in playing with it, port it, cut it up, what ever!
David you never answered my email! My engine suffers!! I know you have alot of workload now you are in your 30's , but please remember the small guys like me ;) I'm not trying to waste your time
Well it is obvious that the valve is a restriction. So raise it as high as practical. So supercharge ! Ugh. No one simple solution. Having larger ports has no effect with a short duration cam or small valves.
Wrong. Large ports work well with small cams. Majority of factory performance engines have ports that are larger then the cam profiles are designed for. For max performance effort engines, max port flow is achieved. And need additional flow.
@@approachingtarget.4503 you mean american "performance" engines ? They always have too big ports for stock power. 2 valve heads should not be called performance these days.
Read your books since I was a child. Your the man! Thank you.
When we think we know it all is when we need to open up more to learning what others know.I learned that even the least knowledgeable person can have great ideas at times. Listen to everything then you your knowledge to determine if it may be useful.
DV thanks much for explaining the 91% rule. This is greatly helpful. I can't wait for the next installment.
Eric Weingartner, a very successful head porter, also suggested that we amateurs limit ourselves to 90%, to be safe. He says it's far better to remove too little metal, than too much. He also said he sees many heads that were completely ruined by guys who opened the throats to 92 or 93%.
Amazing class Mr Vizard, thanks a lot!!!
Cant wait for the next episode, great content as usual. Thank You
This makes perfect sense. Thanks again David.
I Wish I would have had this knowledge 30 yrs ago..Thank You Sir
David is BRILLIANT! Some of this is so elementary and common sense, but explaining the physics and realities is priceless.
Thanks David. I’ve been looking forward to this episode since you mentioned it. I’ve read your book but hearing and seeing you explain things is really great. Regards.
Thanks again DV for sharing your vast knowledge on cylinder heads and airflow
This is good stuff! I'm glad Mr Vizard is on TH-cam. 👍
Incredible insight with flow analysis
Fantastic content, Thank You David and crew.
Sharing your cyilnder head porting tricks are worth there weight in gold
it is great to have you full of energy and willing to teach your valuable knoledge, I consider your book as the great bible for porting! thank you very much.
David, you forgot to mention how important it is to comment as well. Like, subscribe, set the bell and comment are all important for the algorithms. 👍
Can't wait for the next one.
yep, what he /\ said.
(random comment to help the algorithm).
I am subscribed, and I do Like every video I've seen. Ive been binge watching them, along with Andy from Unity Motorsports, Eric Weingartner, and others, as I have a lot of catching up to do! I think I've learned nearly as much in the last few months as I did in my previous 56 years, about engine design, engineering, building, and performance mods. Most of that, thanks to you and Andy. He is a very fortunate man to be your friend and protege. Thank you for all you do, and all you've done.
No word... Just lissen and learn by the Master
DV is the best at explaining how to get the most out of your head
First on Race Day FORD! great video... People don't realize that what is obvious doesnt always appear as obvious...
During a few classes. I was able to design a cylinder head that did not use tulip shaped valves. Instead it used gates. No push rods or rockers where needed. Its works just similar to a rwo stroke or rotary type air port. I know there has been "ball" style valves experiment with that work like a water garden hose type valve.
Iam still looking forward to contributing to your channel if your still interested.!
Auto manufacturers are starting to do away with camshafts, electric solenoids that’s open the valves, endless possibilities in cam timing . Sounds like a cool idea you got there.
@@jcnpresser we also tried electrical solenoids for valve functions. The valve itself becomes the limited factor. Just as David showed. There is also reversion in addition to this with a valve that move back into its pocket. The gate style doesnt have that. And a port window in the door can be tapered to control port speed with a transitioning shape. The idea is what started some of the two stroke snow mobile designs currently being used. They are using gates. Just like the gates in a predator carb. Engine draw is what opens the gates in these power plants.
Tuneing escorts and capries by David Visard
I found it in on a shelf in a good will shop
When i was kid and have loved cars and tuneing ever since
Pure gold. Thank you.
Great video Mr. Vizard!! A small ask, at 15:10 in the video for example, please use a different camera angle when pointing to critical port modifications. Thank you!
What a find! THE David Vizard! Read the books going to bed and in the shop. Could never get enough. Can't practically use it all, but nevetheless so enjoyable to learn.
Very well explained David. I always tell my customers that most of the gains are found in the valve and seat profiles and most ports will follow a good seat, valve,and bowl job with not much work to be done on the port itself.
Thank you for yet another great video!
Its easier for me to understand on the video than from the books. (Its been two yrs i own ur books, n still got a lot of questions 😂)
Cant wait for part two!!!
Really appreciate the physics and the why on the theory of flow.
Hi Mr Vizard, I have been reading you book mini A+ engines as I have a 1380 in mini 76 mini. What a fantastic read it is. Thank you for your knowledge and wish you all the best! Dino, Brisbane Australia
Fantastic video as allways Thanks
There's next to nothing that directly applies to a Chevy 250 inline 6; everything that I am trying is a mixture of things from Mr. Vizard's books on building horsepower, and porting/flow testing. This video building on what's in the porting book seems to be more applicable to what I want to end up with. Even Santucci's Chevy 6 book isn't as well suited as this. The 91% rule is new to me; perhaps I've missed it in the porting book. There's so much there, it's entirely possible that it could be missed.
I'm convinced the inline 6's head can be made to work much better than it does stock, but the pictures/examples I have in Santucci's book don't look 'right' after reading Mr. Vizard's books.
Like I always tell people you're never a know it all and people who are aren't experienced enough. I am 27 and learn a lot every year about engines and porting and so on.
Bless you David 🙏....uh and Andy 2
Don't forget MARVIN!
From a father of a little girl to another. God bless you David 🙏🙏 I can't begin to imagine life without my sunshine. May Gods healing light shine down from heaven and give you comfort and peace. A-men
Excellent! Amused to see an actual pointer instead of a cursor! Technology that works. I've just rebuilt a 1981 Vizard spec A series engine, originally built using all your articles - its a flyer! Remember your 1430cc / 649 cammed racer? I haven't gone to that extreme, just built a more modest torquey cruiser. 👍👍👍👍
Great stuff as usual!
Thanks for speeding up the audio!!
Does the 91% rule apply for the exaust seats as well ?
fart
I’ve seen in other videos that you can go 2-3 percent higher, but it’d be interesting if DV would give his thoughts on it.
The exhaust side is not as specific. Generally the escaping exhaust gases dont need help getting out. More attention to exhaust reversion is key. If you have ever fired up a engine without the tubes attached. You will see flames kick out about 8-10" from the port in a straight shot from roof of port. Yet exhaust manifolds and headers have very sharp turns. On sone engines the exhaust port even takes a drastic turn before entering the manifolds. Like pontiac or olds type motors.
The general rule for exhaust size and flow is 60% of the intake. But 1.60 valves will flow enough to keep up with 2.10. On sb combinations. 91% is the intake side. The exhaust will benefit with reversion if that number is lower for the exhaust.
Thanks for the very informative reply. Am just the son of a 2 cow farmer trying to make his race car faster. Thanks again
Thanks for sharing expert knowledge looking forward to more real porting videos
Godspeed Jacque
Excellent explanation and analysis.
One thing I noticed is when before I clean the head. Where eddies form on the intake ports it will leave greater deposits because its stalled flow. I tend to take note of deposits on the ports. Exhaust is pretty difficult to use this but the intake with a crank case ventilation system will show me where I should focus. Not gonna be able to eliminate the eddies entirely but can reduce them pretty well.
It is a very good idea. Altought I had problems using it on the intake side as the fuel injectors washed the bowl are pretty clean. On the exhaust I was able to locate the thick carbon deposits where the flow stalls.
Cheers mate..I've been waiting for this.
Mr. Vizard thank you so much! My favorite channele very informark r
Great video! Looking forward to the rest of the series!
Thank you
I like to use the newen cutters and set the seat almost at the outside of the valve, then i blend the area below the seat into the bottom cut of the 3 angle cutter form. Then when the porting is complete I use a stone and dress the seat spinning the stone holder by hand until I get the seat width and runout I want
Love it thanks dv
Wow...I was saddened to learn of Jacque. I had no idea. Obviously it's been a while, but still, condolences.
Great thanks for this David! A larger intake valve will most likely restrict the flow pass the valve dish, inside the combustion chamber? Could please also explain how to address that issue?
@Mikko Kuorttinen, I know about nothing about this matter, but what I know is that Saab changed the shape of the combustion chamber in order to make the flow better after installing bigger intake valves. I am speaking about the Ford V4 engines they used in the model 96 cars.
katoppa PowerTec 10 EP 7 -video, missä DV näyttää tekniikoita.
After I watched my first DV vid I realized I’ve “got it all wrong” I felt I wasn’t getting much result so I stopped matching intakes and heads a long time ago. I have a set of 241’s bound for the heap so I’m going to get the grinders out and make an attempt with what ive learned so far. I’m going to machine some valves down to 90% of valve size to use to check the throats. Is that ok? I have absolutely no development equipment. I could probs use a cylinder and a decent vacuum/make a smoke machine. I don’t think I could do pico tubes capillaries and all that jazz for a half ass flow bench. Can I improve heads (for me and a few friends) and get results or should I just spectate and leave port work for people with equipment and cnc machines? Can’t wait for next vid.
Thankyou mr vizard.would wet flow testing be a guide to finding your flow path.peace
Very cool. Enjoy that you aren't doing ls like everyone else.
Is it best to have the throat straight out thru the seat or to have it back cut larger diameter behind the seat so it makes a venturi as it goes through the smallest id of the seat?
The dislikes have got to be a slip of the thumb no one in their right mind would dislike a single episode
You make the point momentum controls, and there is greater flow on the long side, yet you make the throat radius greater on the short side. Why is that?
Thanks David for your reply to my comments . You didn't my basic question What does the number of 91% of valve dia apply too & how do you put that number to design. use
Bruce, I did answer it a few posts back but just for the record the 91% refers to 91% of the valve diameter. So a 2 inch valve would need a throat diameter of 2 X 0.91 =1.82.
DV
you mentioned that you're limited to intake valve size to what will fit in the bore. what about the 52% rule. intake valve size to be no more than 52% of the bore size or is that number not relevant?
Thank you for showing telling, see you on the next time see ya bye bye.
David, I have noticed that many amateur engine builders, and some lesser known pros, have You Tube videos about gasket matching intake ports in heads and manifolds. But they never show any before and after Dyno results. I'm inclined to think that, without work in the rest of the port, it's a waste of time. My theory (untested) is that enlarging just the openings and making them match just creates a wide spot that slows down the charge, which is of no benefit. What say you?
Can you please put all the golden porting rules in one folder so they can be all found easily. Thanks DV
Is the short side more important when adding boost
Thanks for a good video. Just getting started with the IOP program. Like to mention that I already found a confirmation for my thoughts about port size simple by adding measurements to the program.
IOP program assumed Cylinder Head Port Area HP Limitation in a Renault F7R engine and regarding the homologations from 90s, Megane Kitcar engine was restricted by inlet manifold adapter plate (smaller area). I have also found a chassis dyno sheet, where the power curve continue straight close to same HP and RPM.
I'd like to ask: Is this power curve keep going straight indication, that the engine has an airflow or port area limitation? I know I'm asking about the port, but the video dealt with restrictions and this was rule number1. Thank you,
-juhana
Juhana - I am not sure I fully understand your question here. Tell you what, make the questions out in bullet form and as simple as you can. I believe that what you are asking will be covered in the next episode. DV
@@marvingvx1 Thanks, I keep that in mind. I got too excited and telling, because I have no secrets in my carage. I have better torq in my engine compared to competitors. In the end its about how do you perform in a race day..
Thank you for all your work making the combustion-engine-world faster by using intelligence instead of Just poweradders.
Both even better!! 😁
Redundant cross sectional areas... that's wothy of explanation/exploration. I don't recall anyone else mentioning the subject.
,,,,,,,,,,,,,,,,,,,,Thank you Sir......................................................
I am trying to get CAD porting models...
Nothing.
David... do you like money???
David. One question. Would you of opened up the throat percentage on the 6oclock (opposite side of the short radius) position? Or am I mistaken?
Mr. JCWJAMES sir, Look at the big block section of the video again as I cover just that.
@@marvingvx1 thank you David appreciate the reply. Really enjoying your videos!! 😁
*marvin activates the translation so as not to lose details of the video thanks*
91 92 % of what . I thought valve seats were concentric cut to various degree angles. Go with the way air wants top flow. How does a individual determine path of air flow. Is a flow bench required
91% of the valve diameter.
DV
Hey Mr Vizard are chevy 392 phase 2 heads good and what took there place thanks
The 392 snowflake bbc head is about as good as factory heads came. They actually where dealer installed heads on performance option cars. They are rectangular port heads. So basically they are copied by about ever head manufacturer today. After about 1973, chevy never offered a head in this performance level until the latter crate engines.the phase 2 might indicate a later over the counter option. Normally a larger valve or spring package. They are the head for bbc pure stock classes. They sacrifice low end torque for a substantial flow increase above 6000. Very common to be used on 496 stroker combos. Easy 650hp capability.
Point of most restriction is the intake valves ability to pass gas!! Hmmm... kinda stinks!
I'm going to have to watch this another 897 times to start to get some kind of comprehension of what's being said here. I'm not sure I'm getting the percentages thing or what I'm suppose to be doing with them.
OK, after watching again, is the percentage based on outer diameter? So if my outer diameter is 2.02 (apparently, outer valve diameter, not outer seat diameter?), my inner (seat?) diameter should be something like 1.838 (91%)?
Mr Vizard If you take a torque graft and check the horsepower then move that graft to the right, the latter will have more horsepower. But will the latter outrun the first. If so,why. You are the only one who can explain this with logic. I believe with the gearing optimal for both they will perform the same. I have built many engines from your knowledge and have excelled,na. I am now building a turbocharged engine with my son. Your book doesn't have enough detail on performance camshafts for turbocharged engines for me to make a solid decision and have it ground. I try to do things once.
There’s a lot of analogies people use to explain this, but torque is a force whereas HP is work over time....a good way to think about it is in extremes.....an example being one engine that makes 1/2 the torque of another but spins twice as fast, and they are both run at the engine speed that correlates those figures ONLY.....in this example (if they both had a CVT transmission and the RPM’s were held constant), they would accelerate at roughly the same rate with optimal gearing for each, because the amount of work being done is the same......in more realistic scenarios the most average torque over the intended operating range of engine speeds will be fastest given the same gearing, but in instances where you are shifting, or the gearing (both transmission and final drive) can be changed , an engine that makes a bit less average torque over the previous engines RPM range but has a wider operating RPM window can be faster given each gear “gets you further“ via. additional work being able to be done in each gear.....(You should check out Richard Holders channel if you’d like to see a lot of camshaft tests with boost).
@@ericschumacher5189 I understand that,it makes sense. I watch Richard, I've had his followers argue ,with a turbo all camshafts are the same, throw one in, it don't matter.
I agree with you; in my opinion a good way to pick a camshaft on a turbo application (besides how it acts N/A like a Richard says) is to think how the entire vehicle your building will be used, If you’ll be octane limited, and if it will be traction limited......an example that may help you out, is if a car that runs on pump gas, adding a cam that makes a lot of midrange torque may not be very good given how much timing will need pulled in that area to limit detonation, the same could be said for a vehicle that can liquify street tires N/A already (more torque down low isn’t very important). On the flip-side if the turbo is huge for the application your likely to have a rising boost curve, and that same cam with good low end / midrange characteristics may help to make the power a bit more linear / street-able (if that matters to you) and lower the boost threshold.....I’d focus mostly on that in your cam choice to narrow the list of choices down a bit.....also I forgot to mention but if you transmission is an automatic, torque-converter choice will be just as important as the considerations mentioned above.
@@ericschumacher5189 you are knowledgeable, are you of the same last name in racing for generations. I have been specing camshafts for years, na and nitrous. Turbo and blower are different. A positive displacement, overlap goes out the ex. Turbo camshafts I think you need to look at the pressures boost pressure to back pressure. I don't think I have it all figured out. I'm not sure about opening ex or closing in. Or for that matter if you have low back pressure will a little overlap help spool the turbo. People argue but I know if both valves are open together flow will go to the lower pressure side and you hope that is not in the wrong way.
Thanks for the compliment; I’m not, my family is into racing (as a hobby), there’s a lot of people with my last name w/German heritage......in terms of the trade off point with overlap I can only speak from my personal experience / what I’ve read, but on a turbocharged engine I think it has a lot to do with the turbo’s size & efficiency at the boost level you intend to run.....The easiest way I can articulate this is if you were to put a large turbo on a small engine and run right near the center of the turbos efficiency island, it’s likely the back pressure would be equal to or lesser than the boost pressure (2-to-1 ratio), which would likely require less overlap to ensure that your not inducing EGR when both valves are open......in summary the camshaft overlap is likely closer to an N/A cam when running low boost with an appropriately sized or large turbo, the overlap likely needs to be less the harder you push the turbo or a small turbo on a large engine (like a lot of OEM production vehicles are)......my experience with this has to do with 2L 4-cyl stuff when moving the adjustable cam gears. From looking at the mass airflow logs / airflow per pound of boost, and how much Ignition timing it can tolerate without detonation, this is why I think this to be true.....also I have seen more overlap helping with boost response on pump gas when running rich AFR’s because some mixture is making it to the exhaust side (burning) and raising the EGT’s helping spool.
Dear David Vizard, I have been watching your channel for a long time from Russia and I am your subscriber .. There is no such thing in Russia even close .. I beg you to include subtitles if it is possible .. If it is costly or some kind of prejudice towards Russia due to sanctions, etc. .d. I understand ... Just let me know ..
It is a shame that east and west don't see eye to eye at political levels. I have met quite a few Russians during technical team get togethers to explore trade possibilities. I can honestly say that the folk I met where a great bunch of people. Can you tell us your name spelt out just how it sounds. I am sure I am not the only one here who would like to help you out.
Please expand on the 'subtitle' part of your comment.
DV
Thank you for your reply .. My name is Alexey Evdokimov .. I think my name and surname will not tell you anything ... I just really would like to watch your videos with subtitles, that is, with translation .. Until recently, all your videos came out with the function of subtitles, that is it was possible to read the subtitles in Russian ... the last couple of videos are already released without the function of subtitles in various languages ... Okay, we are from Russia ... maybe there is some misunderstanding ... but as I understand it, you are popular not only in Russia but throughout the world ball ... That is, you can only be watched by people who speak English ... I mean, in a nutshell, I wanted to ask you to release your videos as before with the function of viewing subtitles in different languages ... Thank you)
I'm building a 408 stroker mopar for a 1970 dart... im itching to start porting the factory heads after watching this. I have ported heads before and I can tell you I made all the mistakes 😂
Make some vids!!
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More more more
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Think you have accidentally gotten your numbers back to front. If the short turn radius is less important then why would you have 93% there, and only 91% on the long side where the greatest flow occurs? If your numbers are right it seems to contradict everything you said in the video.
Must not have explained this as well as I could have but no, everything is round the right way. On the long side we are emphasizing the flow efficiency at higher lifts and this means a bigger seat radius on the approach but on the short side we are favoring area as the flow separates at anything over about 0.200 lift.
DV
@@marvingvx1 OK understand your thinking now, because the short turn radius air flow becomes virtually null and void at lifts over 0.2" lift, you are compensating by making that side a little bigger to get some kind of use out of it. but where majority of the flow heads to on the long side above that lift you are more concerned with exit shape, since that will dictate maximum airflow.
Thanks a lot!!! All agony)
I have a few small scooter engines I'm building, trying to get power from, if you can call any gains from a 2-3.4hp engine power, the ports and valves are just sad, but I have a head I can send you if you would be interested, it's a hemi style , over head cam, I went from a 39mm bore, to a 50mm and 52.4mm bore, and from 16/18mm valves, to 18/21 and 21/23mm valves, with the largest bore, I would like to get all possible from these little engines, and considering a stroker crank, going from 41.4 to 44mm stroke, coming to about 95-96cc from a 50cc engine, but I can send you the stock head if you would be interested in playing with it, port it, cut it up, what ever!
David you never answered my email! My engine suffers!! I know you have alot of workload now you are in your 30's , but please remember the small guys like me ;) I'm not trying to waste your time
/fistpump
Well it is obvious that the valve is a restriction. So raise it as high as practical. So supercharge !
Ugh. No one simple solution. Having larger ports has no effect with a short duration cam or small valves.
Wrong. Large ports work well with small cams. Majority of factory performance engines have ports that are larger then the cam profiles are designed for. For max performance effort engines, max port flow is achieved. And need additional flow.
@@approachingtarget.4503 you mean american "performance" engines ? They always have too big ports for stock power. 2 valve heads should not be called performance these days.
The dislikes have got to be a slip of the thumb no one in their right mind would dislike a single episode