exhaust on my GTU

Guest · Post by **Guest** » Mon Dec 17, 2001 8:13 pm

I don't know if its just me or what, but when I start the car and it runs, the exhaust is kinda loud. Louder than it is on my Z26. Is it just because its old or what?

gar187er · Post by **gar187er** » Mon Dec 17, 2001 9:38 pm

its cause the GTU has the 2.8, those engines/exhausts have always been inheriently louder then even a 3.1....they sound nice!!!! do bad they give the 3.1/3100 that sweet sound stock.....

Guest · Post by **Guest** » Mon Dec 17, 2001 10:04 pm

Gar's right. It's the way the intake was design (i think) that gives the extra loudness and the "growl" as I like ot call it. But don't try to argue that when you get ticketed for loud, defective exhaust, like I did.
On a similar note: My new dragger muffler (replacing the old DTM) is only able to deepen the sound while still retaining original decibel level.

Guest · Post by **Guest** » Mon Dec 17, 2001 10:05 pm

Ryan what are you smoking the 2.8/3.1 MPFI motors have the same ehaust manifold. The reason your 2.8 sounds so "mean" is because where GM put the Y on the pipe, it's in a location that creates alot of turbulance which in turn creates alot of noise.

Guest · Post by **Guest** » Mon Dec 17, 2001 10:08 pm

A ticket for your exhaust on your GTU to loud?! OKAY, that is nuts and if it was stock at the time..

Guest · Post by **Guest** » Mon Dec 17, 2001 10:10 pm

Y pipe? Beretta's came with Y pipes? This is news to me!

One of the reason's why the 2.8/3.1 is so much more aggressive sounding than the 3100 is because the 3100's have a resonator in place after the cat... a rather long resonator (the longer it is, the more it quiets the exhaust). Also remember that the 2.8/3.1 had MPFI, versus the SFI in the 3100's... allows for a smoother running engine with a smoother idle. I believe the other difference that affects the exhaust note would be the design of the camshaft. In the 2.8/3.1, I BELIEVE it is a hydraulic lifter design, whereas in the 3100, it is a roller lifter design... I don't think I worded those right, so if someone feels the need to correct, feel free...!

Take the resonator off your Z26, I bet they would sound similar then.

Guest · Post by **Guest** » Mon Dec 17, 2001 11:18 pm

#### I don't know I think it's called a downpipe then Geoff I jsut rember reading it somewhere, that because of where the two pipes meet it makes that low rumbling sound. Also the 3100 have different manifolds right??

And you are right Geoff the 2.8/3.1 are conventional hydraulic lifter design.

Thanx for pointing that out MR.BORLA

Guest · Post by **Guest** » Mon Dec 17, 2001 11:44 pm

There is only one length of pipe on the stock exhaust... the downpipe, which goes from the rear manifold to the cat, then the pipe from the cat to the muffler (or to the resonator, then the muffler on the 3100's). The front manifold connects to the rear via the crossover pipe, and all exhaust gas exits through the rear manifold.

And that's Mr. Borla to... er... wait, you already said that... oh well

gar187er · Post by **gar187er** » Mon Dec 17, 2001 11:47 pm

i never said it was the manifold....when me and my buddy tore apart his Z24, i didnt notice a y pipe...but then again i was really wasnt looking for it......as far as what im smokin.....nothin, just lack of coffee today...only two cups

Guest · Post by **Guest** » Wed Dec 19, 2001 3:22 pm

The 3100 has hydrualic lifters as well. Mine are noisey and make a metallic tickin noise for a few seconds on start up until the oil gets back in them that drained out while sitting.

Guest · Post by **Guest** » Wed Dec 19, 2001 8:16 pm

mine sounds the same way and i think its stock too....it sounds way better when i first start it up rather than after i drive it for awhile.it sounds the best at aproximatly 2340 rpm's.try it out maybe its the same.cant wait till i get a real exhaust ive been talkin bout it way too long.

Guest · Post by **Guest** » Wed Dec 19, 2001 11:14 pm

The 3100 is a Roller lifter desing not a hydraulic design. The sound you are hearing comes from the rockers and the engine heads in general, they make a ticking sound because after sitting over night the oil drains out of them and threrfore when started in the morning they make a ticking noise because they arn't lubricated.

Guest · Post by **Guest** » Wed Dec 19, 2001 11:25 pm

Our 3100's don't have roller lifters... I don't think the new 3x00's do either... we have a roller CAM... but that's it (and some 3100's have partial roller rockers).

The ticking that alot of people here is actually piston slap, which goes away once the engine warms up... it's because we don't have skirts on our pistons... I think this is what I mean...

Guest · Post by **Guest** » Wed Dec 19, 2001 11:37 pm

Actually on some it's the Pistons wrist pin that makes that noise but not on all. I could be wrong geoff but I don't think so.

GM recommends replacing all six pistons!! Yeah sure that will only take one hour in my backyard.

Guest · Post by **Guest** » Sat Dec 22, 2001 12:46 am

My car makes this stupid ticking sound too when you first fire it up. Its kinda annoying. It makes the car sound like its a POS or something.
Where I used to work there was a guy with a grandpri. His made this sound only it was louder then mine. So I guess mine isn't that bad
So, is it the pistons or the rockers?
It sure seems like its the rockers to me.

My parents have the 3100 in their 95 lumina. I do not recall ever hearing this sound. If I'm up tommorow night when moms about ready to leave I will go start the car and see if I can hear it.

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