4AGTE 350rwhp/260rwkw build!

[Ken_T]

My experience is with SR20's. I haven't heard of anyone with a 4A doing it but I have seen the image that trdee is talking about. I only remember it because of the word joggles, lol.

The only thing that I can think of the quench pads becoming a negative to the combustion is that maybe the super dense charge is too turbulant and the flamefront gets torn in two and begins it's own flamefront? When the two collide, you get detonation. I never really looked into it and thought you might be able to shed some light on it. I personally don't think it's a simply a heat thing.

FWIW the GTiR (the more motorsports oriented car) head has no quench pads whereas S13 and S14/S15 do as do 20VE's.

[SHEPPO3930]

in the case of the sr20, a stock 20VE head on a turbo bottom end makes spastic power. way more than a normal DET head on the same bottom end, and the same mods/boost levels. i dont think it's all due to the quench/squish differences, as the VE head is better in pretty much all aspects to a normal DET head, but it does make you think. port design isn't the only contributing factor to how well a cylinder head performs. the chamber design along with the piston crown profile have as much to do with how power productive a motor is, and how knock limited it is.

[trdee]

bet you most of the performance gain from the VE head is narrower valve angles, angrier cams and VVT