thevetterisbetter

Can I expect more HP from the addition of an H pipe on my exhaust system?

Fevre

should give you a small bump in hp and a little bigger bump in torq, the higher the output of the eng the larger increase you will see. It also quites the exhaust sound or at least smoothes it out.

L82-JWS

Also, from what I have read, going with an X pipe configuration is the way to go. Smoother bends, better flow......

Tom73

Not enough to feel in the seat of the pants but it will make the exhaust sound better.

mrcorvette79

It's more of a question of efficiency over horsepower. A H-pipe or cross over pipe allows the exhaust pulse to scavenge from the opposite bank and pull the exhaust flow out of the head. The pulse increases speed and increases flow and in a small order makes better use of availabale horsepower.

CGGorman

Take a listen to a similar engine running an X before going that route. You may not like the sound. It's much less lumpy and higher pitched on the ones I've heard. Better power though...

BrandonS

You'll enjoy the X-pipe, i promise. If you go X-pipe though, you might as well get a full exhuast. I have a 71 wiht about 420hp at the crank. I was running 2 1/4'' exhaust with some cheap raptor mufflers. Now i'm running 2 1/2'' all the way back, X pipe, and flowmasters! BIG BIG difference! Also, my X-piple setup was pretty nice, and a good idea if you have a good exhaust man. You simply merge the left and right exhaust pipes together to form the X-pipe. This minimizes the bends, and assures a higher flow rate. Well, good luck!

Brandon

thevetterisbetter

Thanks. I am putting out about 420 hp as well. The exhaust is already 2 1/2 inches all the way back from 3 inch collectors. The sound is awesome, but I am wondering if I am loosing something because of the absence of some sort of crossover system.

Shark Racer

I switched from Dynomax Super Turbos to Ultraflos without a h-pipe. The resonance on the freeway could get pretty obnoxious. Then I threw in an H-pipe(also increased the intermediate piping from 2.25" to 2.5") and the resonance dropped substantially.

I do not think it made the car sound worst at all; in fact, it cancelled the annoying noises and left the good noises over. For what it is, my car still sounds almost race-car like when you free rev it to 4500.

-Steve

BrandonS

Oh yea, as for the sound of the X-pipe.... that portion of my exhaust redone after the origonal setup was installed. To me it sounds tougher, barks better, a little louder, and is more responsive with the X-pipe. It could just be my imagination though!

Brandon :flag

CGGorman

I've got a 2 1/4" Magnaflow cat-back system with an X on my Linc and love it. Added about 10hp, or 4 1/2%, over stock. Have heard the same engine (3.9L DOHC V8) with 2 1/2" Dynomax/H-pipe, Factory H/Magnaflow mufflers, and Borla. The magnaflow X sounds similar to the Borla while the Dynomax was much more authoritative.

As I understand it, Dr. Gas (www.drgas.com) is the authority on X's and claims construction (geometry) makes a big difference in hp gains. Lot's of my people swear by Bassani as well.

That and a $1.09 will buy you a Coke.

PRNDL

If you need an increase in hp to justify putting in the H pipe, I recommend doing before/after testing either on the dyno or the dragstrip. Otherwise you may not be able to tell.... even a 10 hp change in hp because it will sound different also. My car "feels" faster after an oil change..... or a good washing so I wouldn't rely on feel alone to determine if I got extra hp from a new H pipe.

71coupe

Here are a couple of sites with sound clips between H & X pipes:


http://www.mustangexhaust.com/5.0sounds.htm

http://www.dynomax.com/sounds.stm

79ls1

LOL PRND21

comp

on the link

77stingray

There will be a slight increase in horsepower beacuse there is less back pressure in the exhaust system. The H pipe acts the equalize the exhaust backpressure. The H pipe can also be called and equalizer pipe. As it was stated before, the X pipe is the best choice becuase it severely reduces backpressure. One last thing, don't go for 3 inch tube unless you've got a monster under the hood. If the pipe were too large in diameter, there wouldn't be enough backpressure and the engine would not run as good. You still want some backpressure. Good Luck!