Peanut sized Y-pipe ???

[YULLOSE]

Man... I was crawling around under my Tahoe yesterday and had a look at the factory Y-pipe coming off the manifolds...

I couldn't believe how small the pipes are !

Holy smokes, they look like 1-3/4 - 2" pipes.

Does anyone know if there is a larger factory made Y-pipe, say from a 2500 or 3500 that will bolt-up to the factory manifolds ???
I don't feel like dealing with leaky header gaskets... so I'd like to keep the factory iron manifolds and just do a complete manifold-back dual system in 2.5" pipe.

Any suggestions or advice ?

[YULLOSE]

For what it's worth, I just looked under a 96 3500 2wd stakebody truck here at work... The Y-pipe on that sucker is HUGE. The downpipes look to be at least 2.5 inches or bigger.

I think I just answered my own question. lol

[TEE]

That's because the 3500 has a big block.
And YES the stocker 1500's Y pipes are very small. I put a set of headers and ctaback on mine and I noticed it then, but didn't replace it til' a year later because of a donut gasket. I had a local muffler shop put 2 1/4" on it I believe. Immediately sounded better and the seat o meter said cool :)
And BTW....good headers won't leak. My Edelbrock Ti-Techs don't leak after 4 years.

[Pauly]

the LD Vortec 350's in the 1/2 tons have 1 7/8" headpipes, whil eth HD Vortec 350's in teh 3/4 ton and 1 ton trucks have the 2 1/4- 2 1/2" headpipes.

The Vortec 454 has even larger pipes, but just because the truck is a 3500 or a 1 ton doesnt mean it has a 454 as it can have a Vortec 350 as well.

My 97 1/2 ton had the dual 1 7/8" headpipes and when I went to Hooker longtubes and dual 2 1/2 headpipes the difference was very noticeable.

peace
PAuly

[YULLOSE]

Our 3500 Stakebody definitely has the 5.7 Vortec.

LOL... I'm not THAT stupid guys.

[TEE]

o.k...YOU FIGURED IT OUT

[Fast305]

Originally Posted by Pauly

the LD Vortec 350's in the 1/2 tons have 1 7/8" headpipes, whil eth HD Vortec 350's in teh 3/4 ton and 1 ton trucks have the 2 1/4- 2 1/2" headpipes.

The Vortec 454 has even larger pipes, but just because the truck is a 3500 or a 1 ton doesnt mean it has a 454 as it can have a Vortec 350 as well.

My 97 1/2 ton had the dual 1 7/8" headpipes and when I went to Hooker longtubes and dual 2 1/2 headpipes the difference was very noticeable.

peace
PAuly

Alot of the 5.7 G1500 vans had the larger pipes as well. My 1997 G1500 has the 2 1/4 head pipes that step up to 2 1/2 after the cats. I've seen the tiny little 1 7/8" pipes and had a good laugh.

I just bought a 3.4 from a Camaro that had 2 1/4" pipes running out of the manifolds on each side.

[snowdog]

it all comes down to back pressure. more back pressure is good for low end torque and less is good for top end power.

how its measured i have no idea.

[Pauly]

Originally Posted by snowdog

it all comes down to back pressure. more back pressure is good for low end torque and less is good for top end power.

how its measured i have no idea.

You NEVER want backpressure, you wnat high velocity to promote torque. Backpressure equals restriction, restrictions are NEVER good in an exhaust system.

Some pople repoort torque loss when installing larger tubing, this is because the exhaust pulses lose velocity, tehrefore low rpm scavenging falls off.


FAST035, those tiny 1 7/8" headpipes sure are laughable, esp since they have pretty bad bends in them as well.
I have also seen some 1/2 ton Tahoes with teh larger 2 1/4" headpipes.
It seems like the Vans get a lot of teh goodstuff. Larger exhausts, L31's driven by 411 PCM's, L31's with TBI fuel sysetms on top. List goes on and on. I'm glad that all this van stuff applies directly to my truck. Goodold GM interchangeability.

peace
Pauly

[snowdog]

Originally Posted by Pauly

You NEVER want backpressure, you wnat high velocity to promote torque. Backpressure equals restriction, restrictions are NEVER good in an exhaust system.
Pauly

http://warnertechnology.com/Cars/backpressure.shtml