On Tue, 24 Nov 1998, Sam Parthemer wrote:
> >The key here is that Sam was referring to the bottom end. If you were
> >towing a trailer at 1800rpm's, you might be better off with a TWO inch
> pipe.
> >The point of a 3" high flow cat is to help you when you're wrapping it
> out
> >at the track going "c'mon - c'mon - c'mon!!!".
> >
> >Tate
>
> I didn't want to scare anyone, just merely share my experience.
> After comparing my 1/4 mi times/speed with previous runs (I.E. w/Hi Flo
> CAT and TB), and based on conditions, I ran better times with the new
> setup. The only real 'possible' decrease in performance that I can
> detect now is from idle (~550 rpm) to roughly 1000-1200 rpm... from
> there is turns/burns nicely. Mileage figures are still up in the air,
> but so far 15.00 mpg solid on my last tank, so I don't think that it
> really has been affected at all (TB and HI-FLO cat).
>
> I am going to talk to Ed Hanson either today or tomorrow to see what
> he thinks about the back pressure issue/noise level. I'll post the
> results.
>
Sam,
Another aspect to consider is traction off the line. Right now, I've
got a fairly free flowing exhaust, except for a crimp up at the
end of the Y pipe where I'm using some temporary exhaust tubing to
go around a crossmember. I've got the JBA headers, a 2.5" -> 3" mandrel
bent Y pipe, then its 3" all the way to the 3" Gibson, then 3" mandrel
bent out the back. (no cat) I'm not sure wether I lost some low end,
or the high end increase was just more than the low end increase, but
my truck definitely cranks out its power higher up in the RPM band than it
used to. I haven't towed with this setup yet, but one favorable
thing at the track is my 60' times improved. (I think its due to a
reduced low end allowing the tires to bite quicker.)
Another thought is maybe you can put some sort of fitting on your
tailpipe so you can put "restrictor plates" on there. I think
there's a motorcycle exhaust that lets you do this (Supertrapp?).
Anyway, you could leave it uncorked most of the time, but if you have
to tow something or haul a heavy load and you need some low end,
just snap a restrictive plate on there...
-Jon-
.--- stei0302@cs.fredonia.edu ----------------------------------------.
| Jon Steiger * AOPA, DoD, EAA, MP Race Team, NMA, SPA, USUA * RP-SEL |
| '96 Dodge Dakota v8 SLT CC (14.58@93.55), '96 Kolb FireFly 447 |
`--------------------------- http://www.cs.fredonia.edu/~stei0302/ ---'
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:11:06 EDT