In the future I plan to build up my little 318 pretty good. However, I am starting cheap and small. One of the first things I am doing is a nice dual exhaust. Summit headers first ($99 can't go wrong?)

Now, I have been told by several people that I need to do a H pipe or X pipe.

I have heard that an h pipe will give you more power (mainly torqe) low in the rpm range. It will also have a deeper exhaust tone.

The x pipe will give you more (hp) higher up in the rpm range. It will have a little bit higher pitched exhaust tone than the h pipe.

So, which is better, and why?

 

engines fire like so: LRLLRLRR and its those double pulses which are killing you.
In an H configuration, your basically working with two straight pipes since the gasses rarely make a 90 degree turn - especially at high pressure (why the power gain is lost at high RPMs). So when the gas is travelling very quickly, your still running down one pipe
In an x config, those double pulses get a better chance to split up at the x junction. So then its like doubling the net diameter of your system.

In either case, your better off then a single exaust.


h pipe:
- possible backfire on downshift
- cheaper
- less power gain, because the gasses "tumble" which is why you get the next point
- sounds better (more grrrrburble burble burble burble burble pop burble burble)

x pipe:
- more power (at higher RPM range)
- more money
- less ballsey noise becasue gasses travel faster, which is where more power comes from

http://www.carcraft.com/techarticles.../photo_10.html - pictue of h and x compared
http://www.carcraft.com/techarticles...ion/index.html - article about both

these guys got a 12 HP and 5ft-lbs increase with X over the H. I think that an increase of 8 is ambitious for our trucks...



anyhow, nothing can beat this http://kalecoauto.com/index.php?main...;products_id=3

 

X pipe

http://www.popularhotrodding.com/tec...ech/index.html

equally good technical exhaust article written by the guy NASCAR hired to run their engine education college degree at the UNC-Charlotte:

http://www.superchevy.com/technical/...exh/index.html

 

You may regret the cheap headers though. I'd rather get a set with thick flanges at the headsthanreplace gaskts all the time.

 

That's hilarious!

[sm=drooldude.gif]

 

I'll second that. Headers are known to leak badly unless you spend the money and get a decent set with thick flanges. Cheap ones will leak at the heads and the collectors and aren't worth it.

Derek

 

The Headers are fine, I have a pair on my 91 D150 from Summitracing and I have no problem with them. All Summitracing parts are Edelbrock. Summit buys there parts in Bulk from Edelbrock and puts there name on it. I also have a H-pipe Muffler on my truck too and it sounds pretty good too...

 

Thanks for the additional input guys!!

 

that whole site has some funny stuff.

 

Before I buy an exhaust system for my D150 should I just try out the open headers and see how they sound? Any links on how to do this?