Tom,
Damn good question. I have not done any real life dyno testing. I do have
Performance Trends Engine Analyzer Pro. This is a fairly sophisticated
engine simulation program, a big step up from "Desk Top Dyno".
I have run my engine using all the particulars for my build up and exhaust
system. I went and reran it with everything the same except I used "log
type stock manifolds" Instead of the specs I derived for the CAT headers.
This program assumes optimal jetting for the engine specs. Here are the
results...
RPM CAT Trouque LOG Torque CAT HP LOG HP
2000 228 213 86.7 81
2500 280 258 133 123
3000 315 294 180 168
3500 329 312 219 208
4000 348 327 265 249
4500 357 335 306 287
5000 351 331 335 315
5500 334 316 350 331
6000 310 296 354 339
6500 282 272 349 337
With CAT headers 357 ft-lb @ 4500, 354 HP @6000
With Stock Log Manifolds 335 ft-lb @ 4500, 339 HP @ 6000
Only a gain of 22 ft-lb and 15 HP at the respective peaks.
The 22 ft-lb represents the max gain at any RPM (matched at 2500) but the
max HP gain is 20 HP just below the peak at 5000.
Interesting, this is in general agreement with the findings you have
referenced. Hmmmm... Header Hype? 20-ish HP and torque improvement is
probably worth it, at least that's what I'm going to keep telling myself.
Frank
B9471116
>-----Original Message-----
>Subject: Re: Headers
>
> I'm just curious if anyone has ever dyno-ed their Tiger before and after
>ONLY installing headers (and tuning mods relating to the headers - richer
>jets etc.). The reason I ask is that I have a Mopar 318. They did test on
>a
>360 that was mildly/moderately warmed over with stock 318 manifolds, 340
>HiPo manifolds and various headers up to 5,800 RPM. They did not use
>mufflers, only 24" of pipe off the manifolds. The end results were about a
>10 HP increase with exspensive ($800) TTI headers, and about a 5 HP
>increase
>with exspensive ($350) 340 HiPo manifolds over stock 318 manifolds! The end
>rating were in the 315HP to 325HP range. I would also think that the
>addition of mufflers would better work to the advantage of the lesser than
>the greater.
> I realize that every model of motor is different much less any
>modifications (cams, heads intake manifolds etc.). Regardless, for all the
>trouble headers seem to be, I wonder on a stock to mild Ford Small Block
>typically driven in the idle to 4,500 RPM range if a significant increase
>is
>noticable.
> I know that there are header power increases that are often stated by
>the
>manufacturer, but I don't doubt that the comparision is probably for a
>single exhaust car choked through a single factory muffler. Additionally,
>touring auto museums I often see boat and aircraft engine displays that
>even
>with attempts to have maximum horsepower still use a cast, log type exhaust
>manifold.
> I'm not trying to get down on anyone who installed headers (you all
>deserve a purple heart for doing so) but rather trying to take a balanced
>look regarding cost, effort perpetual problems and end results.
>Regards, Tom Witt
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