Boostmaniac

Actually, on piston motors, this is kinda true but it comes from exhaust wave scavenging that happens during valve movement. It is also the same thing that makes people believe that small headers give them low end torque. It does give them torque, but at the massive expense of horsepower in the higher revs. I'll explain more later.



-Maniac

iceblue

Simple it is called velocity. The art of tuning exhaust is exhaust gas velocity or velocity pulse tuning. As the rev range is low the volume is down and a smaller diameter pipe is more suitable for higher velocity to induce scavenging. As the RPM's rise the volume is increased thus the pipe diameter must increase to keep velocity high without causing back pressure that causes loss of power. And its low end power not specifically low end TQ, TQ is mostly irrelevant to us.

j9fd3s

the other one on evil, is quite possibly the dumbest thread ive ever read, and its got plenty of competition.

Boostmaniac

bingo, I was wanting to add that in but I had just gotten off work and I really wanted to leave. As for the low end power being irrelevant to us, you are basically right, I was just bringing it up because one of the previous posters was talking about someone who had been building motors for 40+ years and I thought alot of his basic thought process on it sounds like a veteran V8 tuner. Nothing wrong with it other than it doesn't apply to us

Boostmaniac

Yes, the fact that people are still arguing with the proof right in their face is astounding to me.

j9fd3s

the fact that theres no real "facts" until like page 15 is kinda funny too.



actually i just looked at it again, and there are 2 people who have dyno numbers, changing nothing but the port. one gained 60 hp, one lost 46 hp.



this tells you a lot. just by those two data points, it should be telling you that the bridge can work, but you need to have a plan of attack, and some skills to make it work.



but really what does "making it work" mean? if you're going racing, you need to look at the rules, and what you're racing against, figure out the powerBAND you NEED, and then build the engine that best acomplishes that.



to just build a half bridge cause it might work is backwards.



you should be saying "i need 400hp, with a powerband from 4000-7500rpms, whats the best way to do it?" or something like that

BDC

I agree with you, Mike. It ought to be looked at as an overall setup -- what's the goal of the car? What's the best way to accomplish it? Etc. etc.



B

Comitatus

Man...haven't been here in a while, but geez...I love this forum so much more than the evil one. There are so many idiots over there...it's rediculous.



+1 for the cooler heads.

iceblue

I find it baffling how people can find this negligent. I agree with you 100% and the fact that people do not see this is just astounding.



Now experimenting and trying new stuff and theory's is one thing but to argue tested already for a setup and then do something blindly is just foolish.