PolyQuad
 

A recent discussion left me wondering if David Vizard, a brilliant man with a long history of making power and teaching others how, had released any information regarding 4 valve engines. Most of his writings pertain to old Detroit iron (v8's), but being the genius he is, he has a great knowledge of 4v engines as well. Now I'll let his writings speak for themselves:
http://www.gofastnews.com/board/tech...r-concept.html


I wonder if this technology can be used by some of those looking to go all out with the EG33. For example, is there enough room in there to utilize valves of different sizes. I assume there is no way to reduce the valve size, so the only way to use different size valves is to go larger? Also, do our ports and combustion chambers lend themselves to the type of modifications necessary to support the "swirl". And I would think that the exhaust valve position in the chamber is kind of stuck where it is. Seems like it would be difficult to recess that any. Is this something that someone with unlimited resources would be able to accomplish on stock heads, or would it require brand new heads (which I don't think we'll be seeing)?

Re: PolyQuad
 

I have heard of this work before, it is designed to get around the way the inlet ports flow air across the combustion chamber roof and out the exhaust valves, during the overlap period. His work is interesting, and I follow it with interest.

The older two valve chambers had the inlet port angled so that the inlet flow was directed away from the exhaust valve, to spiral down the cylinder.

The question is, why increase the overlap. We have 4 valve 800cc engines reving to 19000 rpm delivering 230 HP, that rely on the sonic system to induct the air.:)

Harvey.

Re: PolyQuad
 

There are many more benefits to this than only the ability to increase overlap, though increasing overlap is still a benefit. It is understood that wave tuning is used in filling the cylinders in nearly every NA engine. However, more overlap with correct exhaust tuning also enables a lower pressure in the cylinder, hence better cylinder filling. The main benefit of this design, however, is the swirl that is introduced into the cylinder, resulting in a better burn. Another benefit is the increased flow that comes along with the different sized valves.

This is not an modification that would simply be slapped on an otherwise stock engine and expected to make significantly more power(though it might make some). Rather it is one part of a more complex equation. Different cams, manifolds, and engine management tuning would obviously be needed to make the most of this approach. I believe it is silly to say that because that's not the way Subaru did it, it shouldn't be done. As we all know, OEM's ALWAYS leave a lot on the table. While Subaru did a great job designing the EG33, with it's 95% VE, they still designed a 230 HP engine. Anybody wanting to make much more power than this will need as many tricks up their sleeve as possible. And this, my friend, is a very neat trick! The results are right there in the article, and it would be silly to think that this approach would not be a benefit to anyone trying to make power. NA or FI, this design has potential. The simple fact that is is brought to us by Vizard should be enough to prove it is the real deal. This man has always been out in front of the rest with revolutionary ideas, and this is one more.