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Re: SVO: XR racing, and downpipes...

Ric Gillis wrote:

> I had run quite a few tests with a G-Tech, always set at a car weight of
> 3100#, always used 2nd gear to run the test and my best ever HP reading was
> 197HP, the car is an XR with a few mods but most importantly a Borla
> downpipe(2 1/2"), stock cat and Borla dual exhaust.  I bolted on a MP 3"
> downpipe and ran my first and only recorded run with just the pipe change
> and got 203HP.

Cool.  So, we have a 5ish hp gain depending on the relative conditions
of the two days and how the car was running.

> Ok to be fair the tests were done on different days so weather may have been
> a factor, but it was not colder out for sure the day of the 203 run, and I
> had never gotten better than 197HP ever (yes I did run it more than once
> before), and now got a 203. 

Sounds reasonably conclusive that you got *some* gain.

Good data, now the question is why?  I don't buy the expansion chamber
thing, but I could buy that there's a turbulence factor, plus the slightly
lower resistance to flow that could combine to give you this gain.