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Discussion Starter #1
I have a dual 2.5 inch exhaust system with 2 chamber flowmasters and would like to add an H-pipe. Obviously clearance is an issue, but is there an ideal spot to put the H pipe (for instance, so many inches from the collector)for optimal performance. I understand how the H-pipe helps performance (by reducing turbulence) but can I also expect the sound level to come down any? Your feedback is appreciated.
 

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I would start with a base-plate of pre-fabulated amulite,
surmounted by a malleable logarithmic casing in such a way that the
two spurving bearings were in a direct line with the pentametric fan.
The latter consisting simply of six hydrocoptic marzelvances, so
fitted to the ambifacient lunar waneshaft that side fumbling is
effectively prevented. then place in panendermic semi-boloid slots in the stator, every
seventh conductor being connected by a non-reversible tremie pipe to
the differential girdlespring on the "up" end of the grammeters.

You may encounter some difficulty in nubing
together a regurgitative purwell and a supramitive wennel-sprocket.
Indeed, this proved to be a stumbling block on my exhaust system until I
found that the use of anhydrous nangling pins
enabled a kryptonastic bolling shim to be tankered.

Let us know how it goes.

Scott.
 

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Most of the H-pipes I've seen on first gens are right behind the rear of the tranny for tranny removal clearance...plus this is where the pipes begin their parallel journey to the rear of the car. As far as performance, my guess is that the closer the H-pipe is to the engine, the more "open" the system is. As far as tone, most will tell you you'll get a sweeter, flatter, hollow sound that's somewhat quieter with the H-pipe. Let us know the difference on your car.
 

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Can't help from a performance point of view but I have noticed that most are far enough back to allow the trans. to be taken out if need be.

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Robert

'69 getting better every day... (every pay day)
 

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What Scott was trying to say is they sell a kit with a crayon type paint marker and you place a line down the length of pipe from collector to muffler and go for a drive. Where the mark isn't burnt off is the spot for the H pipe! Now what you will find is it almost always will be in the worst possible place!!

My own opinion based on lots of listening to quality exhaust pros, it's a waste of time, effort and money. What you have is a void in the pipe. Exhaust flows past the H pipe creating a vacuum action (sucking on the H pipe). Well, that is if there wasn't an equal amount of exhaust sucking on the other side of the H pipe!! Basically there is a vacuum created in the H section.

At idle and very low rpm each cyl firing 1 at a time the pulses may actually cause a little scavaging effect. Get that baby reving and the pulses become a blur and the H pipe does nothing!! Again only my opinion/theory!!

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...Dennis
'69 RS Convertible w/SS trim
'96 Z28SS #1679 of 2410
"The Club"
 

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Dang, I was typing at the same time as Sleepy. I hope that doesn't count as a "me to" answer.

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Robert

'69 getting better every day... (every pay day)
 

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In my opinion, be it ever so humble, the H pipe does help. Your V8 engine has two cylinders on each side that fire within 90 degrees of each other. On the left side they are number 5 and 7. On the right they are 4 and 8. These pulses travel down the pipe extreeeeeemly close to each other. At low RPM, the H pipe allows some of the pressure to flow into the opposite pipe, improving torque. At high RPM, the H pipe has no effect.

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68 convertible
 

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from a performance viewpoint, the closer to the exhaust ports, the better. but anywhere helps. put it where it is practical.
ibjoe
 

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hi I installed my h pipe just after the rear of trans. i wanted to put three chamber flowmasters on my car. the shop advised that a two chamber flowmaster system with an h pipe would sound much like a three chamber system without the h pipe. bull s%$% my car is way to loud. i don't know what your looking for as far as sound, but beware of this mellow sound theory
dave [email protected]
69 z28 hugger/ white
 

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I had a 2 1/2" duel system with Flowmaster series two mufflers on a 68 with a 300 hp SMC. Without a crossover, it sounded like ... BLAT, BLAT, BLAT! In other words, like crap. I had an "H" pipe installed and it really mellowed the tone. Tt was still loud, but it lost that annoying BLAT noise. As far as increased performance, I didn't notice and difference.

Roy
 

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There are some mufflers out there now like Walker & Dynomax (made by Walker) that have been track tested on back to back runs against open headers with less than a tenth difference in et's. With that kind of performance in modern mufflers why bother with H or X pipes?

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...Dennis
'69 RS Convertible w/SS trim
'96 Z28SS #1679 of 2410
"The Club"
 

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There are more tracks out there becoming subject to local noise ordinances. As a result, racers have had to put mufflers on their rides. Surprisingly, some have found that they have more power and actually run faster WITH mufflers.

To me this proves that a well designed exhaust system is worth the effort. X pipes are the latest advancement and dyno tests have shown significant horsepower gains. Gains of 25 HP (per Hot Rod Mag) over dual systems with no crossover and 10 - 15 HP over H-pipe systems. My friend saw 35 HP at the rear wheels on his 396 Chevelle just by installing an X-pipe.

Why bother? It's free horsepower.

[This message has been edited by Eric68 (edited 06-15-2001).]
 

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Discussion Starter #15
Thanks for the feedback. Just for the hell of it, I'll give the "base-plate of pre-fabulated amulite surmounted by a malleable logarithmic casing" test a try.
 
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