Oldguard 7

I have read several posts about the "benefits" of having an H-pipe.
Most of us with 75-82 vettes have converted their exhaust to true dual exhasts. Here is my point of debate. If an H-pipe makes a car sound better, flow better (as I have read in previous posts since I have been a forum member) The 68-74 dual exhaust vettes came from the factory without an H-pipe, so what is the "great" benefit of an H-pipe?

GruntyPants

From what I understand, the H or even an X pipe will help equalize pulses in the exhaust stream. This will increase scavenging and produce a nicer tone. Lots of folks swear by them, I've never seen a dyno comparison, but I'm sure there's one somewhere.

Philvet

If you have read the posts on the benefits of a H pipe there is no sense in going over them again.

68 technology is 38 years old.

SLVRSHRK

632C2 did an excellent job of describing the benefit and provided Dyno results with his engine.

Here's the X-Pipe thread

http://forums.corvetteforum.com/show...ghlight=x-pipe

Do a search for his other posts, they are really great and backed up with proof.

Oldguard 7

Point taken, but that does not answer the question. What is the benefit of an H-pipe??? There is not much "technology" to welding a small section of pipe between two pipes, if so, I'm quite sure the factory would have done this back in 1968 if there was some benefit. Maybe someone will chime in with some info or perhaps direct me where to do research so I can get a satisfactory answer.

73383

I put an H-pipe in mine. I put flowmaster 50s w/2 1/2 duals. It was to loud for me and had a drone at 2000-2400 rpm that would hurt your teeth.
The H-Pipe made it quiter plus took 75% of the drone out. What drone was left came in at 1500 rpm and was gone at 1600 rpm. I love my H-pipe. If I got 3-4 HP out of it I consider it a bonus.

hubes

the c5, and Im assuming c6, has an h pipe

Ironcross

All the high HP early Vettes were factory equiped with a balance tube and those are over 40 years old.

vetteaddic

Ive heard 5 to 15 hp just from the h pipe ,mine arrived today x pipe that is from Summit.
632 thread convinced me.

SanDiegoPaul

On a conventional car with chassis headers and room underneath, the perl of wisdom is that you want an equalizer tube located 18 inches behind the header collectors.

Old OLD exhaust tuning trick.

But on a C3 that's not possible so we use H pipes further downstream, in the middle of the body. Exhaust equalization has been around for decades.

I remember when I was a kid, pulling the exhaust off my '57 Bel Air so I could put headers on it. The OEM pipes had a crossover wrapping under the engine.

TopGunn

Interesting info.........I put an "H" in my 2 1/2" new system also and it has a very slight "drone" at 1500 also. It immediately goes away at 1600 too.
I had the exhaust shop put an "X" in mine but it was a really poor fit, I didn't like the way the pipes had to be routed with the quick bends to get into the "X" and had him remove it and re-do the system with an "H". It came out much, much better.

desi

Is H better than X for drone issue? My chambered pipes have horrible drone between 1200 - 1800 rpm. Gotta do something about it.

theandies

Didn't some of the early Chevy V8's have a crossover built into the intake manifold or was that passage only added when EGR valves came into play?

stingr69

YUP!

The EFE system uses a passage under the intake manifold for fast warm ups. The heat riser is part of that system. If you block the heat riser passage on an otherwise stock setup you WILL hear a difference in the exhaust tone. The heat riser passage is similar to an "H" or "X" pipe in that respect. It gets a little "rhaspy".

-Mark.