[beemergary]

Any noticeable gains (ET) with an H pipe? Don't like the sound of an X. 63 tempest 421 2.5 pipes with 50 series flowmasters. thanks

[beemergary]

Any noticeable gains (ET) with an H pipe? Don't like the sound of an X. 63 tempest 421 2.5 pipes with 50 series flowmasters. thanks

[68GTOConv]

If you notice a gain, it's only because you know you put it on. I'm sure there are benefits, but my butt dyno isn't calibrated!

The biggest difference I noticed is in the sound. It is much better after the install, even at idle.

Mike M

[buwalda]

David Vizard has done much work & testing on exhaust systems & also written articles on them. He claims he has NEVER seen a hp loss when using a crossover, & nearly always sees a gain.

[68GTOConv]

No way you would see a loss - that wasn't what I was saying. I was just saying that there are benefits that you may not notice by seat of the pants.

An H arrangement is great for high RPM flow, which could only help horsepower ... even if only slightly. The sound difference alone is enough for me to do it.

Mike M

[shotgun]

First,the disclaimer,I never ran an h pipe on a dyno.
I have done a lot of research and the pattern I see is an h pipe increases low end torque with no loss compared to a dual exhaust at high rpm.
The thoery is it balances the exhaust pulses at low rpm,after a certain point(rpm) the gases are moving too quick to make the 90 degree turn and your exhaust acts like a true dual system.
An x pipe system is supposed to do the same,only threw the whole rpm range.
Makes sense too me.

[beemergary]

Sounds good and makes sense. How come I didn't think of that?

[wheelspin]

Connecting the head pipes allows each cylinder to "see" both mufflers and tailpipes resulting in lower sound levels and modest low speed torque increases, utilizing an "H" pipe crossover.

The difference between properly sized "H" and "X" crossovers is dramatic as my GTO runs as quick thru the full exhaust (Doug's headers, 3" X pipe and muffs, 2.5" full length tailpipes) as it does un-corked, providing maximum power @ all times.

Les

[Polar-Pontiac]

This seams to work for nascar a friend took this pic at Daytona this year.

[Tom Hand]

Go to www.drgas.com and you can see some more NASCAR system shots.

[Z Code 400]

One very respected Pontiac tuner accused me of dishonesty when I posted that we have personally seen zero gains with the famous and popular Dr. Gas X-Crossover. Here is an article by Vizard that confirms what we have been seeing on the Dyno:



"Virtually all V-8 exhaust systems can be refined by the addition of a balance or X-pipe. These have two potential attributes: increased power and reduced noise. Extensive dyno testing on both of these factors has indicated balance and X-pipes are 100 percent successful at reducing noise. The reductions amount to a minimum of 1 dB to a maximum of 3 dB with 2 dB being common."

"As far as power is concerned, things are a little less certain. With engines between about 325 to 550 hp, experience indicates that in about 60 percent of the cases (mostly with balance pipes), the engine can deliver as much as 12 additional hp, with 5-8 being the most common. The other remaining 40 percent tested showed virtually no change in output either up or down."

Elroy Newberry of Newberry's Muffler (local) who developed the 'coffin muffler,' contends that once an exhaust system has adequate flow for a given power level, the addition of an X or H pipe will often yield little if any benefit...an opinion that would seem to be supported by Vizard's article above.

I would simply caution those who expect large gains, with a given exhaust component, proceed carefully, as a performance increase is not a guarantee in each and every case.

Keep in mind Cliff Ruggles' Ventura is running deep into the 11.00's with compression-bent exhaust tubing, a simple H-pipe and early 2 chamber Flowmasters...Robert

[Z Code 400]

By the way....I recently read an article in a Stock Car publication that showed a full 4.5 HP increase on a 800 horse Winston Cup engine...far from the 20 horsepower gains on in several Dr. Gas Articles...Robert