PolyQuad - How the worlds most powerful 4v heads are built.
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- เผยแพร่เมื่อ 5 ก.ย. 2024
- In this, episode 124, DV details what it takes to convert a conventional 4 valve cylinder head to a PolyQuad head. This type of head is typically about 100 hp and 110 lbs-ft better than a conventionally ported race head on a 2.0 litre engine. In this, part 1 of a 3 part mini series, all the pertinant details are explianed and both a low and hi-buck version is thrown into this hi-power brew!
Guys, I intend to talk of differential cam events to creat swirl. Done the tests so you get the results!
Would it work on three valve staged size ?
Damn! Thought I was onto something original for once 🙄
Awesome!
Would seem the cam profiles, port shapes and valve heights in the chamber would all work together to achieve the best overall results.
Your attention to detail in theory and design, backed with solid testing results are what have always impressed me.
Your "How to Hot Rod Your 2.0 Ford" was my bible when I was tweakin the 2.0 in my Capris many years ago!
Honda did that with their economy vtec of the early 2000s on the “K” family of engines. The cams had 2 profiles, an extremely wimpy profile and a normal one. Under normal low throttle and low load driving, the wimpy cam controlled one valve and the normal cam controlled the other, creating an extreme swirl in the combustion chamber. Under higher throttle and load, the VTEC switched the cam profile to the normal one for both lobes
There are 2 standouts in my mind when it comes to innovative automotive tech, David Vizard and Smokey Yunick. Thank you David for sharing so much of what you've learned!
F1 are way ahead of this they just arnt giving the info away,
@@krusher74 Oh, I'm sure, but yeah they're much better funded and waay more tight lipped. Sheesh, ever looked at some of their intercooler tech? Mind booglin complexity and built with dollars squared budgets.
This guy is an international treasure!
It makes me so happy to see a master of his craft sharing a lifetime of information like he does. Sadly many people hoard their experience and secrets.
Mr Vizard as a 32 year old engine enthusiast I learned more in the past weeks from your videos than in the last ten years from anyone else! Thank you so much for sharing your knowledge, even if we are just on top of the iceberg here!
I have no experience in american V8s except some simple repair and service stuff but been working on mostly european engines since I was twelve years old, but I‘m very thankful to have the oportunity to transfer some of your highly appreciated advises to my next BMW turbo engine build.
Thank you so much and keep this good work going, you are a true inspiration and a great teacher for anyone who‘s after some serious knowlege!
Kind regards from Germany
Alex
🔔😎🇺🇸
Einstein said +- If you cant explain it simply in a few sentences then you dont know enough about it.
DV you are a genius. 👍👍😎🇺🇸
Lots of good info into designing a 4 valve head for a 300 Ford 6 Cylinder
Fantastic info! I'm 31 and really into cars & engines, and have never heard the term "polyquad" in my life. Super interesting!
POLYQUAD ...... sounds like a colourful exotic birds gay party down in Florida.😅
David is genius could listen to him all day 👍
I've lost count of how many of DV's tricks and tips I've used over the years on SBC, SBF, and factory intake mods.
Could you please do an episode of all of your books in order and timeline. Where to buy them as a package. There's not a package available. Guarantee I would buy and a lot of people would benefit from being able to buy all of your books in a set.
Thanks for the video David. Would love to see you team up with George Bryce and set up some Poly Quad heads for one of his M8 Harleys!
Thanks!
SAAB used differing cam lifts on their 16V heads around 1988 but soon went back to equal cam lifts. It would be interesting if SAAB ever told the reasons why?
Saab was always low on Money, so the Engineers couldnt always keep stuff going! Later was buyed by GM and then slowly faded away
I had seen it but now realise what it was, After trying differing inlet cam lifts ( 1 large 1 smaller) on 900 series 16V, SAAB changed 9000 series to use 2 large lift lobes but raised intake port floor in the RH lower corner to improve swirl! Its supposed to work best
Maserati did it on their engines like you show us, but in late seventies and early eighties, Maestro.
So in 1990 Alfa Romeo maked a 30746/30747 engine with same valve sizes but the camshafts has a different profiles and timings for the any valve (big opening and long duration left and low opened and short duration right, and big/long intake was instead of a low/short exhaust). So they position the fuel injector on the big/long valve and low/short valve got some mixture but largest fuel mixture streamed thru big/long valve port.
It was very nice engine, I love it thru the all of my life.
This guy is great at layman's terms explanations.
Genius content.
I liked the poly quad valve layout the moment i saw it. Kind of like the spool valve idea on twin scroll turbo turbine housings that lots of guys are beginning to realize the potential for.
Spool valves were tried and forgotten 20 years ago.
Wow thank you for sharing . I remember reading one of your books or watching a seminar way back in mid 2000s and you mentioned 4 v heads tumble the air and they weren’t figured out yet. It’s good to here the progress you’ve made . I will be implementing your ideas on a 4v Harley .
Would be a revelation in my humble NA 4L inline six with dual cam VCT and of course the turbo version of the same engine. Thanks DV.
But they make 2000hp on ported heads and near on 1000hp on stock heads already?
@@Low760 huge power capability. Obviously the turbo has better power potential, however it would be satisfying to see a 400 HP (crank) and high torque NA inline 6.
This is absolutely fantastic stuff for us 4 valve enthusiests DV. I look forward to more on this subject and seeing the progression on the Mustang. Keep up the great work👍👍
Wonderful Information David absolute pleasure to listen to your knowledge and vast Experience. on many aspects of engine performance, and sharing your wealth of research, is beautiful to be shared amongst the racing worlds.
Being a Mechanical Engineer Myself, i have dabbled with Cosworth Pistons deepening the valve pockets in my Apprenticeship my boss told me at the time not to scrap these Pistons as they were 75 Pounds Sterling per Piston, i was only Earning 15 Pounds Per Week At That Time, this was for a Super Stock, Stock Car, Anyway He won the Scottish Championship with that engine i worked on think it was 1976-1977 His Name was Les Clarke, think his son has taken over his Dads slot, wish i had Gained the Knowledge I have from you now back in the day, I Take My Hat Off To You David And Many Thanks, Graham Bell
Really pleased there is now discussion and advice for 4 valve engines. I want to get my motorbike engine up in power and efficiency. Most are 4v but with no variable timing so this is going to be brilliantly useful if can run a wilder cam whilst maintaining lower end torque😊. Thanks David.
I always enjoy getting the privilege to spend my time thoroughly enjoying Grand Master Dave, teaching us special things about IC engines.
Grazie Mr Vizard. Grazie, grazie , grazie. Non si trovano facilmente persone altrettanto autorevoli, e di altrettanto esperienza che condividono così tanto. Non vedo l'ora di studiare il prossimo video su PoliQuad. Ho un progetto attualmente fermo che devo assolutamente finire. È una Mini Cooper 1600 cc del 2004, voglio usare questa tecnica. Saluti da un suo studente Italiano
I love how you're so honest about events and names and who named a certain thing that may have been me but I don't remember if it wasn't me it was my student and you give him credit. They're honesty and your factual experience and decades upon decades of testing and working knowledge is amazing to me. You are one of a kind. I would love to meet you someday if you ever come to California. If you ever do any more seminars or anything like that please post them on your channel so people have a chance to meet you. Only if you enjoy that sort of thing but thank you for all of your wisdom.
Lap records will be broken using what you have revealed here .... Your description gives us the vision to understand how all this works too. Go to the top of the class (the class for teachers that is). Another proud moment . Thankyou .
That little quip at the bottom of Jaque's lovely pic is very intriguing as well!
Modern 4V heads control the lift of one intake valve, or the runner flow by putting a flap / valve in it to control velocity, as it is cheaper than multiple valve sizes. Still a cool design though, DV.
Looking forward to more.
I know one guy who have read about this in your books and wanted to try this himself on a Cosworth Yb engine. This was true DIY and limited budget. We agreed that only one of the intake runners would be portet to the the tradisional Cosworth size and the oposite runner on the exhaust. Then the intake camshaft only would be grinded but only on the knocks for the valves for the portet runners. In the cheep and fast way, LCI was not even moved to make the closing ramps as paralell as possible and the openings ramps as different as possible to promote swirl. Even with this the improvement was way bettar than expected.
Here way back in 2006 with traditional porting and camshafts: th-cam.com/video/2Y495D7Bg34/w-d-xo.html
Here in 2011 after the mentioned mods, and the turbo is a Garrett GT3076R A/R0.82 turbinehousing and this most of you just will not believe, the compression ratio is 6.8:1 and YES, you did read that correctly. The build thread is called Capri Special in the fmcn.no forum. Listen do how much faster he goes through the gears. :) This really works and I have now designet my own cams with four different centerlines to maximise different lifts on all the valves in TDC overlap. Thank you. :)
th-cam.com/video/SLYCIWH2Nrk/w-d-xo.html
www.youtube.com/@caprimkI/videos
Wow did I learn a lot from this video. Thanks!
I can't wait to see the power gains of a Polyquad Ecoboost! Im betting close to 50hp
I love all the work you and Andy do to share new ideas and provide proof of the gains, Iv been working on a 22r Toyota head design, and I wish I knew more about making castings and machining but Iv learned so much from watching you, Andy and Uncle Tony, I sware by the things Iv learned from you and Iv been working on applying them to a cyl head Iv been working on and applying some of my thoughts on airflow and improving the design of the factory early and late model 22r heads
Great to hear more on polyquad tech there thanks DV, Working on high performance modern 4 cylinder engines , dictates that 4 valve or 5 valves is the comon challenge so anything to understand your best devellopment on trhis configuration I relish! thanks for passing on this knowledge it is awesome stuff! keep up the great work. All the best.
I think the mustang is going to have some traction issues when you’re done with it... but I guess that could be considered a good thing... great video
I have heard of this as well as shaping the tops of the pistons to help induce swirl from Larry Widmer of Endyn back in the early 2000's. I don't know if he was using you ideas, or just two really smart guys came up with the same solutions. I've always wanted to build an engine using these techniques, but can't find a shop willing to mess with the engines I want to build that would employ these methods.
Great insight DV
Makes total sense
The manufacturer's missed that design tweek
Can’t wait for the next in the series
You keep throwing in tidbits from past work on the A series BMC Mini work you and others did. I love it. Not only because I still love those cars, and Midgets; but how what you learned on them still has influence on what you do today.
Been waiting a long time for this.
I wish I could learn from you guys in person, man it would be a treat and a half to, if I had one wish I'm pretty sure that's what I would want
Looking forward to seeing how this goes on the Mustang.
This is groundbreaking!
It coincides with another IP application that we are preparing, aimed at exactly the same goal (swirl promotion in multi-valve heads), yet the method we apply is completely different.
It is also interesting, that a particular air-metering innovation (that's also in progress), seems to also contribute to a swirl-inclined intake air-mass "cornering".
If Mr.Vizard is interested in these developments, I'd be delighted to share more.
Thanks heaps & keep up this fantastic innovation spirit!
Cheers!
Gives me new interest in the 4.6L 3V and 4-V top-ends!
A physics professor and automotive engineer all rolled into one. All applied into practical applications David’s projects prove his intellect….
After DV gives us a master class on the 4 valve , I'll explain why all the 5 valve stuff was a complete failure .
well Roland, you are a mind reader. I was going to do one on this but go ahead.
You have my full attention, my dad has a 4age -20valve engine in his car...
The vw passat 2.8 5 valve was one hell of an engine
Yes. And anyone in the Love/Hate relationship with a VW 1.8t are curious too!
The 5 vpc head isn't necessarily bad, it's just that it was developed before CFD. If packaged properly a 250-270cc cylinder can make close to 4 HP/ci.
Oh hell yeah
I’ve been following this for many years now. I’ve been looking at some 3v and 4V heads to work with.
I’ve found some interesting cylinder heads that I believe would be great to work with.
Honda CRF 450 heads have some port shapes that look like they would help this effort. One side of the intake port has some bias to it.
ive been looking forward to this for a long time now!, you touched on poly quad at seminar in australia and ive been intrigued since. Thank you David, Real tech shared!!.
Posted on a Saturday Night …
It’s Saturday Night Live
With Sir David Vizard…
That 621hp video is awesome..
The 632cid big block too - the sound of her
Unreal …..
Love your content, David! Happy Saturday.
Rotax used it as an upgrade from the 1125cc to 1190cc Buell engine. They use swirl by the same method.
As have I since around 2016.
Thanks! I've been holding off on a set of caddilac northstar heads for this info. Dont have the budget for custom valves so was going to deshroud and work over the valves and pockets on 1 in and 1 out valves to mimic the poly-quad. Wasn't sure about port biasing, but now i have a clue. Thanks again for all you share!🎉
I've recently gotten into Northstars thanks to my Fiero. Any particularly interesting work you've done on them?
@ethandearman3965 Sounds like a fun project. I've only delt with the later, 2000 + engines myself. If you are rebuilding the engine have the block decked .035". There's about .073" of clearance between the piston and head stock. Tightening the quench area will make a big difference on power. If you're using stock cams, make sure they are from the 300hp version and use an extra set of intake cams in place of the stock exhaust cams. If you are planning to do head porting, work the bowls, valve, and deshroud the valves, but don't make the ports any larger. Unless you only want hi rpm power, they're already oversized. And if you're building your own headers, consider making them 180° . If you're using the stock manifolds consider replacing the tubes from the manifold to the stamped "collector" with 1¾" tubing and up size the outlets. That's a good start. The stock valvetrain is said to be good to 8000rpm. And my understanding is the con rods only to about 500hp, but forged ones are available if you're going higher.
Hi David , first of all thank you , that was and idea which cross my mind before but was wondering 🤔 and was not to sure if that will work or not , I can't wait to have more info on this subject and really looking forward to a number of video one the poly quad with in depth result analysis .
Best regards
Julien Dubray
Great video! Here's an oddball question. On a 4-valve setup, could you get a similar effect by grinding the cam lobes differently? For example, one of the intake lobes has more lift and duration than the other one. And likewise for the exhaust. I ask, because getting cams reground might be cheaper and easier.
Yes. It was realize in 1990 on Alfa Romeo 30746 and 30747 engine, fully stock factory boxer engine. Same valve sizes but different profiles and timings for each one. So fuel injector sprayed the fuel to common intake port but on the big/long opening valve. You can see it in person in internet.
Thanks for sharing mr vizard.allways very interesting and informative thankyou sir.peace
Thanks DV! Awesome video and content, as usual!
Thank you Mr. Vizard the info you give us is invaluable. I had a pair of Ford dohc "C" heads I'm going to try this on.
You said to sink the exhaust valve. The question is "How much"?
I would like to see polyquad done on a gen 3 coyote motor. Cost and benefits. Great channel.
Interesting info. Priceless info as always, David.
Thanks 👍
This explanation, especially about the overlap, flow of mixture into and not into the exhaust port but passing by the valve top due to different valve seat depth, needs more visuals to understand better! ...and does different height of valve seat depth also make a 8v four cilinder bath tub chambered head/motor run better?
Great information Mr. Vizard. Will you test the difference between computer controlled cam phasers, locked phasers and adjustable locked phasers. BMW S14 engines used adjustable exhaust cam gear that improved midrange performance but sacrificing top end. Thoughts please. Thank you very much for all your knowledge and time. 👍
David this is one of the most interesting engine tech insights Ive watched, I wonder if COSWORTH picked up on this with there latest engines.
David is like you to check out Bain racing's theory on this Polyquad, I think he is 100% correct
Would different optimized cam lobe profiles be employed for the two different size intake valves?
Perhaps the maximum effects would be realized with completely isolated inlet ports and runners?
I've always thought for maximum efficiency at part throttle, a four valve design could use just one isolated inlet tract optimized for that condition, and the second could be brought online at full power demands, and also optimized for that condition.
The Honda D15Z1 VTEC-E engine does this.
I am very interested to now if DV thinks this approach would be viable in the 4 valve DOHC VW/Audi diesels that turn 5000+ rpm as well?
Why would it not?
Can you do a video on Ford Cleveland 4 v heads and Austrailian Heads
I'm going to work on talking him into that! It might be a while.. but that is on my list!
Thanks DV.
Could you attain a similar effect by grinding the camshaft in a way that opens the valves at slightly different times?
By that I mean opening the two intake valves at slightly different times to each other and similar for the two exhausts.
This is genius, I think it might work.
can you explain more about how to lower or sink in the exhaut valve as you talked about in the video, thank you!
Thank you sir, for the the thorough explanation! Did I understand it right, that center spark plug 4V chambers don't benefit of this?
O’ wow …I thought it was a dog toy.
One piece rear main seal - copy as a sub for two piece:)
Thanks again Sir David - KRE :)
I've seen some manufacturers made little bit different cam profile and timing for swirl I guess. Like ex. for the same cylinder intake valves one lobe 268 deg and other 263 deg and little bit shifted
Thank you david for the amazing info here . Will this info work on a 4cyl motorcycle engine . Great video
Sounds to me like the polyquad setup We'll make a very distinct powerband almost kind of like the characteristics of AV Tech or variable valve timing engine the way I understand it. Could be wrong.
What about split lobe camshafts? IE: leading 1 intake valve say 10-15 degrees ahead of its neighbour?
Could this desired swirl effect be induced with staggered cam timing for each respective intake and exhaust valves? ie: one opens first, then the other closes last?
Looking forward to seeing how much your 1/8th mile E/T drops with this head work on your Mustang
Do you also employ different throat percentages in each intake and exhaust valves? Also do you modify the chamber in any way to complement swirl? If so how. Additionally, do you use different seat angles for each valve or the same throughout?
Thank you DV you are the best!
Coyote Poly Quad Head???
Without VVT ???
The Leadfoot / Vizard Head:)
Why not with vvt?
Another guy mentioned this as well, one valve bigger than the other to increase swirl. He is also on youtube cant remember the channel name
I have not heard of the combination of swirl and tumble called "twirl" but have heard and seen the term "swumble" in a number of publications.
What should the flow differential be between the 2 intake valves? Is there an ideal, or a range? Is more better?
How do you measure this differential? Do you clog up on side of the port and put it on the flow bench?
What are the ideal seat angles for this arrangement?
Does "close clearance" mean no deshrouding on that part of the seat?
My closed chambered BBC heads have quench on two sides and gives me lots of quench for swirl.
I totally comprehend the intake side of this, but why the exhaust? What does it matter how it exits the camber? Is it to create a swirl to induce a swirl in the incoming charge? Also, if the larger valve dictates the direction of swirl, then the intake would swirl clockwise, but the exhaust would exit in a counter-clockwise flow.... I think.
How is effectiveness being determined / measured? Base line with stock heads, then poly quad, and delta of BSFC?
Also interested in the sinking exhaust valves and minimizing “cross flow”, over scavenge…
I’m curious what your thoughts are on 4 vale pushrod engines, specifically the Ford 6.7 powerstroke head. There seems to be nothing at all said about this type of layout whether in the 6.6 duramax, or the 6.7 Cummins. Your help would be greatly created.
Thank you, Mr Vizard. Excellent content. Thank you for sharing this information. I had a question. Would your suggested modifications to the valve sizes, the exhaust valve depth, and the port bias benefit or hinder four valve heads with variable valve timing? I'm thinking about the Honda VTEC engines from the 1990s. Thank you again, sir!
Honda uses staggered primary lobes to induce swirl. Curious if the polyquad setup would be beneficial on top of that.
I am curious to, I am building a h at the moment , an yes they have staggered primary lobe , but not only on the primary lobe .I know that there is only one secondary lobe (big lobe) but by reading the actual Honda manual there is a difference of hight of the VTEC pine in the rocker to , so when VTEC ingage you have actually a little more lift one valve .I think that if we apply the poly quad keeping those in mind that should be beneficial,I am certainly thinking of trying it ,and looking forward off the next video to have more info about it .
Thoughts for polyquad on a full vertical 4 valve head like found in a diesel?
What is the difference in cylinder pressure at BDC of the intake cycle produced by a swirl cylinder head vs that produced by a non-swirl cylinder head? IOW, does the swirl motion contribute to a lower pressure due to the increased velocity produced by the swirling action?
Great vidja guys 🤙🏼
Большое спасибо! Ценная информация.
Do you think, only one larger intake valve per chamber with the intake runners angled slightly toward the larger valves, would create a majority of this twirl effect? Possibly using a Colt tri-flow regrind? To create staggered lift between the intake valves.
I would be doing this with a turbocharged Honda d16a6.
As for the pseudo poly-quad, did you bore the i.d. of one valve seat larger?
I am going to build a truck for sled pulling and drag racing. Those are pretty big things in this part of the country. My aim is to build a first gen 6.7 powerstroke with the 6r140 trans. Thing is the intakes and heads are backwards. I know that’s asking you to branch out but your opinion would be greatly appreciated. I don’t have the truck yet but I’ve bought the heads and intakes and I’m getting ready to cut them up and see what can be done.
Would the effect of different valve seat angles be beneficial? Intake- big valve 50°, small valve 30°. Would different seat angles work better on the exhaust as well?
BMW, i saw in my younger years, had some interesting tactics employed in theyre 2.5 heads....
After listening to this... i feel like the 1.8t ive been playing with, is a waste of time at this point... i know, they will make a 1000hp bone stock, in cast trim.. but the tall deck, 2.0L crossflow motor, with the Brazilian head.. may be worth ones efforts is what im hearing..
Is it possible to do this on a 94 Cadillac STS Northstar engine? I would like to build a Can Am replicate with this engine and fwd transmission in the back. You can call me crazy if you want.i know the suspension is going to be difficult for me. Thanks for the videos. I have alot of your books and have learn alot.
I didnt catch this on the video-do lift left the same or we need two cams for each side?
Is it a bit like a modern 4V Diesel, a swirl channel and a fill channel?
This is revealing.
Have you considered staggering the throat diameters instead of the valve diameter, say 87% and 89%, to stagger the individual discharge coefficients.
While I agree with your assertion that 4 valve heads frequently have too much cross sectional area, I’m thinking the largest part of this issue is due to, too large of throat diameters, that kill port energy. 88% resulting in the best overall power band, 89% being a critical max, unless getting into high lifts.
Yes, final full PQ has biased ports as well.
Hola estaria bueno que expliques si un puerto con agujeros como la pelota de golf ayuda o no a el flujo , atomizacion del combustible , velocidad del aire etc , ya sea turbo o aspiración natural gracias te veo desde argentina
Love The info.👍👍
So technically speaking if i have the intake valves raised in a pair of 4 valve heads with different seat heights it will improve low lift flow? Ready to send out my 4.6 aluminator heads to be fully cnc ported and would absolutely have this done if its worth the money, please David where would i have this work done???
I support this content.
DV , l have some vague recollection of a cam with some lift bumps very early to the intake stroke . Was this how you generated the swirl in the unmodified heads ,,, ? ,,, btw , what did you think of my 5 valve take down . Well , it's not my take down , it just didn't make it through the elvolutionary cycle ,,, !