Re: hi flow cats, exhaust mods and realistic gains

From: Jon Steiger (stei0302@cs.fredonia.edu)
Date: Sat Aug 15 1998 - 22:31:24 EDT


At 05:34 AM 8/15/98 -0400, you wrote:
>In a message dated 98-08-14 23:06:11 EDT, you write:
>
><< Gibson claims that the cat-back system on my truck gains about 30hp.
> I haven't dyno'd the truck before and after, but based on strip testing
> alone (calculating the horsepower from ET's and trap speeds), that
> figure seems accurate. >>
>Jon,
> I appreciate your comments, however, beware of advertised 30 hp gains with no
>more than a cat-back system. For marketing purposes, companies will take their
>very best dyno result and advertise it. Also, not having read Gibson's ad, I
>venture they claim "UP TO" a 30 hp claim, which is probably true for ONE of
>their test results. As for Thrasher, these are a group of full time automotive
>engineers who have Thrasher as a part time business, so I think their claim of
>1 hp decrease for each 1" bp is probably accurate. Regardless, the purpose of
>my original email was to educate those on the list, contemplating spending
>money on exhaust mods, so an informed decision could be made with respect to
>realistic hp gains and "bang for the buck."
>Regards,
>Steve Waller in Houston
>

  Gibson has a performance comparison chart at:

http://www.gibsonperformance.com/single.html

  They claim 175hp and 230lb-ft at 4,000 rpm for the stock system, and the
Gibson gained 30hp and 40lb-ft. One thing I did notice is that a torque gain
like that is nice wherever you can get it, but at the torque peak, the gibson
was good for only 18lb-ft more. So its not like you're getting 40lb-ft more
peak torque, which it would be pretty easy to deduce from just glancing
at that chart. They didn't say "up to" (that I noticed) just stock HP and
torque at various RPM's and Gibson HP and torque at those same RPMs.

   I agree; its always good to do your homework and make an informed
decision whatever the mod. From my personal experience, a cat-back seems to
be an easy way to free up a healthy chunk of extra power in the Dakota.

                                               -Jon-

  .--- stei0302@cs.fredonia.edu ------------------------------------.
  | Affiliations: DoD, EAA, MP Race Team, NMA, SPA, USUA. RP-SEL |
  | '96 Dodge Dakota v8 SLT CC (14.85@90.72), '96 Kolb FireFly 447 |
  `----------------------- http://www.cs.fredonia.edu/~stei0302/ ---'



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