M4T5 wrote:If it did increase performance, it would be in the upper mid to upper rpm ranges.It may even impact low end torque. Shorter intake runners give more low end torque, but may limit the upper rpm power.Longer intake runners give more mid to upper rpm power, but sacrifices low rpm power.I was thinking the spacer was for just lengthening the intake runners, rather than decreasing heat soak. I'm not sure how much power would actually be created or lost with just a spacer. The heat soak temp decrease from the use of a composite spacer would probably be very minimal due to the under hood temps getting very hot anyways.Would be pretty "cool" if it worked out like it would be expected to.
J
It's actually the other way around. Longer for torque - shorter for HP
plenum spacers have proven themselves in other cars not just the VQ. Pretty much every car I've seen makes torq and hp on an average of 4-7hp and 4-7tq. These cars have all been dyno tested same day, temp, and whatever.
These cars the plenum spacer as a direct function has no impact on injector spray patterns and that is where our engine differs from the others. We may gain all the aformentioned benefits but because we increased the distance of the injector to vale then now the spray pattern is off potentially causing drivability problems.
Another reason why I abandoned the idea...I really would like to see a vk56 intake on a vk45 - the whole damn thing is plastic so no need for a phoenolic spacer then! We'd just loose the power valve and gain longer runners.
I have tuned cars with short runners and long runners on same day - same dyno and the longer runners have had no ill effects on top end power - this would be on a smaller displacement v6 tho.