Vizard's polyquad.. valve size theorization....

[crazyman]

I know he shaped the left/right bowls differently, but what if large valve large port/small valve small port were utilized as well?

[swatson454]

The two intake valves are different as well as the two exhaust valve sizes. I'm sure they are contoured differently at the seat area but I'm not sure if the entire port is different.

[Unkl Ian]

The part I don't understand, if this idea is to create swirl in the cylinder:
the intake bias, and the exhaust bias, caused by the different valve sizes, are in opposite directions.

Or am i looking at it the wrong way ?

[vwchuck]

What would the purpose of two different sized exhaust valves be??? Why would you want to create swirl in the exhaust?

[swatson454]

Here you go. http://www.motortecmagazine.net/article.asp?AID=1&AP=1

I think this article might go a long ways on the Aero head thread as well.


Shawn

[Enigma]

My understanding of Mr vizards polyquad is that the design is less about creating swirl, and more about how the intake and exhaust valves work to create a stronger pull on the intake tract. Opening the smaller intake first/closing the larger intake last. Something to do with how the valve placement and timing of the intakes react to the valve placement and timing of the exhaust. Creates a stronger intake pulse and lessens reversion.

[rookie]

From page 3 of the link Swanson posted.

Although VVT will always add to the power band width it is possible to emulate its use on an otherwise conventional head at near zero cost. This is what PolyQuad does and, shown below are its primary features.

The natural tendency to swirl produced by the valve sizing difference is also supplemented by the port shaping on each of the two intake ports.

The Polyquad was designed to simplify all the different offset cam approaches with similar or better results.

[ijames]

In DV's V8 test it would have been great if he had included a standard set of Arao 4 valve heads so he could show how the polyquad and the standard 4V setup compared - that's half his theoretical argument, that there is a gain compared to a standard 4V head.

[sbcharlie]

we have Q4 head design that we use in motorcycles. we use stock size valve and 2mm oversize. on both the intake and exhaust. we use a 45 degree contact seat angle on the small valve and 50 degree in the larger valve. these heads work great. we have performed this set up on a honda crf 450 and kawasaki 450. these engines produce over 65hp. we just finished at harley v-rod set of cylinder heads. waiting to hear back from our customer. i want to get cam ground with four different lobe designs to compliment this head design. short block charlie

[Larry Widmer]

Honda's been using two different cam lobe profiles for the intake valves since 1989 on their 4-valve VTEC cylinder heads. One intake valve has less lift and less duration than the other, which induces swirl. When RPM, throttle position, and engine load dictate, a central rocker arm that's operated by a high-lift / long duration cam lobe locks together with the other intake rockers to open both valves the same amount, which is best for power. The system allows you to have a clean running engine that's fuel efficient that'll still make big power when needed.
One large and one small exhaust valve doesn't work efficiently, as we found in testing back in the mid-eighties.

[ibmorjamn]

we have Q4 head design that we use in motorcycles. we use stock size valve and 2mm oversize. on both the intake and exhaust. we use a 45 degree contact seat angle on the small valve and 50 degree in the larger valve. these heads work great. we have performed this set up on a honda crf 450 and kawasaki 450. these engines produce over 65hp. we just finished at harley v-rod set of cylinder heads. waiting to hear back from our customer. i want to get cam ground with four different lobe designs to compliment this head design. short block charlie

Welcome Charlie, I have watched a couple of you video's on youtube .
As I recall reading about the polyquad one of the intake ports came in high and the other low so the porting was also designed to create "twirl" tumble and swirl.
Let me just say I have never used this set up but I remember reading and viewing the pictures about it before Mr. Vizard retired.

[Caprimaniac]

I've been thinking of this a while. I wanna see some test results on a 4- valve engine with/ without the polyquad (ALL other variables kept constant) and a good explanation on how this one large valve/ runner and one small valve/ runner setup creates swirl VS tumble.

I have tried to picture like this: 4- valve pentroof chamber. Let's say you let one of the inlet valves closed at all times. Will the 2. inlet valve see this? OK; a slight change in the combustion chambers pressure zones may do something. But I cannot see a total change from tumble to swirl?

Let's say: this setup works. But i am not sure if the theory behind is iall all about tumble & swirl. Enigma is onto a stronger intake tract pull. I dunno, but please step up & give me a lesson....

Thanks
RS

[Erland Cox]

SAAB:s first 16 valve in the mid 80:s used the same intake port and valve sizes but one of the intake lobes only lifted half.
Next came a head with one port roof different and the same lift on both lobes.
Best result using stock parts if power was your interest was by using the early head with both ports the same and the later camshaft with both lobes the same.
Four valves have tumble anyway.

Erland

[The Dark Side of Will]

Ran across this looking for polyquad info... http://forums.nasioc.com/forums/showthr ... ?t=1800972

[The Dark Side of Will]

Is this more of Vizard's test data? http://www.motorman.co.uk/index.php/pol ... olyquad/25