Vizard's PolyQuad valve system

[wobblywalrus]

The PolyQuad valve system is for four and five valve cylinder heads.  The intake valve on one side is larger than its mate, and the exhaust valve on the other side is larger than its neighbor.  It is claimed to promote swirl in the combustion chamber.  This idea has been around for awhile.  Has anyone tried it and how did it work?  Any increase in peak power?

[SPARKY]

I know from my GM Trainer days that swirl is very important in the 12-2500 RPM range toward producing torque and fuel economy--hence Vortec heads  and bumps in the intake bowls/ runners.

[fordboy628]

The PolyQuad valve system is for four and five valve cylinder heads.  The intake valve on one side is larger than its mate, and the exhaust valve on the other side is larger than its neighbor.  It is claimed to promote swirl in the combustion chamber.  This idea has been around for awhile.  Has anyone tried it and how did it work?  Any increase in peak power?

"Swirl" is used to help combustion efficiency in two valve engines.   Imagine, if you will, a small 'tornado' in the cylinder as it is being "squeezed".   Rotation is vertical with respect to the cylinder axis.

"Tumble" is a similar, but different phenomena, in 4/5 valve engines.    It is theorized that tumble is swirl, produced horizontally.   Rotation is horizontal with respect to the cylinder axis.    Duckworth's original description of the phenomena was "barrel-roll".

The efficacy of swirl & tumble is evaluated based on the reduction in ignition timing required to produce an equivalent amount of torque or bhp, inferring heightened efficiency.   The control baseline would be the same engine without the phenomena.    Very sophisticated flow measurement devices are used to quantify swirl or tumble while flow measurements are being done.

Increased swirl or tumble doesn't always produce more bhp.    Often an increase in swirl or tumble results in a similar bhp with lesser ignition requirements.    This is less stress on engine components, always of value . . .     Poorly performing combustion chamber shapes typically benefit the most from swirl/tumble.    Well designed chamber shapes typically have these effects designed in.

PolyQuad is Vizard's copyrighted concept for combining the two effects.     To the best of my knowledge, which is more limited these days, only Vizard is publishing about any effects or results.   One of his books describes this work on a Mitsubishi (?) 4 valve in detail.  Sorry, I don't recall the % differences.

If I was using the concept successfully, I would NOT be talking about it, as Vizard would be entitled to a fee under his copyright/patent (?).

 
Fordboy

[Milwaukee Midget]

Hopefully Woody will chime in on this - the head he and Burton Brown are developing REALLY sparked interest at PRI last winter, including with the engineers at Ford.

Mark and I briefly discussed using two different inlet and exhaust valve sizes on the 4 valve K - my thought being that it might encourage swirl - but further discussion - actually, me just sitting with my mouth shut for a few minutes - brought to light that in order to do it right, we'd be headed into uncharted territory with respect to bowl and port shape.  Lacking the ability to properly model it, there was no guarantee we would actually produce more power, and if done wrong, would likely mess it up.  And then comes the question of valve timing - can swirl be induced with different lobe centers for the valve pairs?

His final comment was "It's complicated".

I will say this, though.  Vizard is working at a level where he's looking for that final 1-2%, and is capable and willing to do the research and testing to find it.  But I think you will find that that final 1-2% is likely going to eclipse the cost of the initial 98%.  If you're on the bubble, it might be worth pursuing, but if the engine isn't already completely developed using common methods, I think you'll find cheaper horsepower on a more common path.

[WOODY@DDLLC]

Chris, consider yourself chimed! 
http://www.motortecmagazine.net/article.asp?AID=1&AP=1
http://www.engineprofessional.com/epQ215.html
Any development program starts with: "Compared to what?"

[Buickguy3]

       Buick had success with swirl technology in 1938. We are thinking that we may try to use their "old" design in the next Salt Cat engine.

     https://news.google.com/newspapers?nid=1917&dat=19380412&id=y08uAAAAIBAJ&sjid=yn4FAAAAIBAJ&pg=3589,5211031&hl=en

     Doug 

[Rex Schimmer]

A couple of comments:
First to Woody: Thank you VERY MUCH for both of the articles. They were GREAT! Viszards "PolyQuad" system is extremely interesting and another step in the on-ward development of the recip engine. Your work on the "Twin Vector Induction" concept is another extremely interesting concept and making 400 hp from a two liter engine without a hair dryer is F1 level work. The BMEP of that engine is actually quite alot higher than an F1 engine at around 290 psi but it doesn't turn the rpms of a 2.4 liter V8 F1 engine, 18,000 rpm.

Mark: I think you and I read some of the same stuff, lots of Kevin Cameron in your comment.

Doug: Interesting reading on the 1938 Buick piston modification. I would guess though that the .4 increase in compression ratio could easily account for the majority of the 7 horse power increase.

In general all of the articles and comments support one of the basic "rules" that Kevin Cameron talks about and that is, ignition lead (or lack there of) is a good measure of combustion chamber efficiency . Great reading!!!

Rex

[wobblywalrus]

Thanks for the help.  One person I e-mailed last night is the fellow that installed the 2mm larger valve seats a few years ago, installed the shim under bucket kit, and made my valves and guides.  He is familiar with the conversion, has done it, and knows the subtleties.  All of this top end stuff are one-off hand made parts and the cost is similar using a conventional or PolyQuad build, except for a 7% royalty to Vizard that happens with the PolyQuad.  The recommendations from the head builder will be taken seriously.  Everything on the bike is sorted.  The only thing left is the motor so I can funnel some $$, sweat, and time in that direction.  It is time for serious speed.   

 

[fordboy628]

       Buick had success with swirl technology in 1938. We are thinking that we may try to use their "old" design in the next Salt Cat engine.

     https://news.google.com/newspapers?nid=1917&dat=19380412&id=y08uAAAAIBAJ&sjid=yn4FAAAAIBAJ&pg=3589,5211031&hl=en

     Doug 

I'm gonna go out on a limb here and theorize that the increased bhp Buick netted was because of the C/R increase.    During this period of internal combustion development, C/R increases usually followed the development and the availability of the higher octane fuels needed to: resist detonation and pre-ignition.

Higher C/R's, with their resultant higher expansion ratios, require fuels that resist uncontrolled combustion.    The "Octane rating system" is how fuels are "graded" for this resistance.

When building a very high or ultra high C/R engine, fuel consistency becomes of paramount importance.    You MUST make the commitment to carry your own "known fuel", test with that fuel, and race with that fuel, whether it is a gasoline or a fuel.    "Highly tuned" engines need consistency in the fuel used, to prevent parts breakages and so you don't drive yourself looney with inconsistent performance on the track or the dyno.     There are enough variables, don't make the fuel one of them.

BTW, exposure to certain fuels/fuel components can be hazardous to your health, so take the proper precautions.

 
Fordboy

[WhizzbangK.C.]

Reading Woody's article was very interesting, especially looking at the pictures,  .

It made me think and brought up a couple of questions.

I understand that the concept is based on four valve configurations, but looking at the pics comparing a single intake tract and the dual converging intakes it appears to me that a two valve head would see some benefit from this set up also, by eliminating the tripping point at the "heel" of the intake valve pocket.

Right or wrong?? If wrong what am I missing? If right would it work on a single carb set up with twin tracts diverging and converging again at the valve pocket?

[wobblywalrus]

The PolyQuad application is discussed in not much detail in the 2012 book by David Vizard "How to Port and Flow Test Cylinder Heads."  The applications shown are for heads with more than two valves.  I am not sure if the principles can be used on a two valve head.  Swirling flow in two valve heads is discussed in the book but not in the context of PolyQuad.

Flow bias between intake valves can be done by varying the port size and shape, the valve seat angle, the valve shape, the the valve size, and the cam or rocker action.  One of the PolyQuad intake valves is cut with a 30 degree seat according to the fellow who does my head work.  This aids bias by promoting flow through one intake valve at low lift.   This seat angle is discussed in detail in Vizard's 2102 book.  The seat configuration can be more problematic than the usual 45 degree seat at high rpm and in engines with thermal distortion.  This sorta describes the Triumph and it is a big concern.  Right now, I am not fully convinced this is the best setup for LSR using air cooled bike engines.

[fordboy628]

The PolyQuad application is discussed in not much detail in the 2012 book by David Vizard "How to Port and Flow Test Cylinder Heads."  The applications shown are for heads with more than two valves.  I am not sure if the principles can be used on a two valve head.  Swirling flow in two valve heads is discussed in the book but not in the context of PolyQuad.

Flow bias between intake valves can be done by varying the port size and shape, the valve seat angle, the valve shape, the the valve size, and the cam or rocker action.  One of the PolyQuad intake valves is cut with a 30 degree seat according to the fellow who does my head work.  This aids bias by promoting flow through one intake valve at low lift.   This seat angle is discussed in detail in Vizard's 2102 book.  The seat configuration can be more problematic than the usual 45 degree seat at high rpm and in engines with thermal distortion.  This sorta describes the Triumph and it is a big concern.  Right now, I am not fully convinced this is the best setup for LSR using air cooled bike engines.

I would not recommend a 30 degree seat for any air cooled engine, because of the thermal distortion.    HOT, high pressure leakage rates are where the power disappears . . .

IF, I were building an air cooled race engine, I would be going in the opposite direction with respect to valve seating angle.   Say, 50/55 degrees, on exhaust for certain, probably on intake as well.    That will kill the low lift flow a bit, but full lift flow will be improved.    You'll need to do the requisite flow work, and compare areas under the flow curve to make an intelligent decision.     I would only consider this if the rest of the valve train could support the required valve motion.

Send me a PM.

 
Fordboy

[SPARKY]

two comments ---my head hurts from my brain spinning out of control seeking understanding


geezzes guys  what great stuff for gear heads

Thanks to all for your posts

[wobblywalrus]

Sparky, reading what these folks post is helping me, too. 

The engine will have 12:1 compression and an 8,400 rpm power peak.  My plan is to see if the engine can be fed all it can use by low risk conventional means.  Those words "all it can use" are critical.  There is no sense in trying something risky to get mixture the engine cannot rev high enough to use.   

[fordboy628]

The engine will have 12:1 compression and an 8,400 rpm power peak.  My plan is to see if the engine can be fed all it can use by low risk conventional means.  Those words "all it can use" are critical.  There is no sense in trying something risky to get mixture the engine cannot rev high enough to use.   
 

Exactly.   That, is a smart plan.

 
Fordboy