Wednesday, Oct 03, 2007 at 22:14
I concede they look pretty terrible, but I can show you a series of tests on very similar chev manifolds where the difference between them and extractors was very small. And Rams Horns ( type of Chev manifold with 2x2 into centre dump) were AFAIR better. Also the V8 is a low revving engine and with an auto should rarely exceed say 2500RPM in day to day use.
However I have no doubt that it is possible tio get up to 15% extra peak power, and you will certainly feel it. But you will not see 15% better economy.
However I am not saying that a complete exhaust system will not give more power across the range, just that most sellers compare the complete system with a standard system and never tell ( or maybe know) where the gains are.Pipe size? mufflers? extractors?
It may be that you will get 80% of the improvement with just a free flow muffler for $200. And this improvement will be only at high gas velocities, ie full throttle, as most of the time the muffler passes plenty of air for part throttle operation with low back pressure.
Second, in the real world you are not driving the car like on a dyno ( full throttle), so from the point of view of fuel economy on say 10%TPS setting, I think the gains are very small.
ask the exhaust supplier
1 where are the gains muffler? pipe size?extractors? %s?
2 Show me a dyno chart at 10% throttle at 2000RPM
3 Show me the specific fuel usage at 2000RPM on equal loads but maybe different throttle settings, if in fact more power is made.
I bet they can/will do none of those things, and its not in their interests to sell you just a muffler when their business is in selling extractors/systems with far more profit.
Regards Philip A
FollowupID:
526771