2 1/2” or 3” Exhaust ?

[askiles]

So I had an ’06 SS/SC donor build, and my kit came with a 2.5” exhaust system. I was just helping AMack with his TC/SS build last night, and his exhaust is 3”. Did I get the correct exhaust? Should it be 3”? Thanks!

 

[Ross]

My 06 SS SC is 2.5" and sounds great.

 

[askiles]

To clarify, I am talking about the DF supplied exhaust.

 

[Ross]

To clarify, I am talking about the DF supplied exhaust.

Yes, my Goblin has the DF supplied 2.5" exhaust. Sounds a way better than the Cobalt exhaust.

 

[askiles]

Gotcha. I wonder why they provide a 3” exhaust for the TC/SS guys? It has a deeper tone that sounds pretty great.

 

[Briann1177]

If I had to guess, it's probably due to the increased HP.

 

[Ross]

The turbo engine chops up the exhaust... maybe it needs 3" to get the right note.

The SC engine is probably producing close to the same amount of power as the turbo
(If you measure the engine power before the SC parasitic loss), so the exhaust volume should be similar.

 

[Desert Sasqwatch]

The exhaust from the SC is essentially the same as the NA exhaust and a small amount of back pressure is good to promote a scavenging effect from the 4 into 1 exhaust manifold. On the other hand, the TC cannot have back pressure on the exhaust as it will hinder the proper operation of the turbo. o having a 3 inch exhaust on the turbo outlet minimizes the back pressure that the system will have.

 

[Christopher Sanchez]

The exhaust flanges are completely different between the 2 engines. The LNF is 3" 4 bolt flange right off the back of the turbo so i assume that is why they went with 3". I am only guessing when i say the S/C exhaust is probably 2.5. stock s/c 205hp stock t/c 260hp definitely more flow but at the same time i seriously doubt these exhausts cause much restriction at all and with that S/C whine who cares about the exhaust note! haha

 

[Tinkles]

The exhaust from the SC is essentially the same as the NA exhaust and exhaust velocity is good to promote a scavenging effect from the 4 into 1 exhaust manifold. On the other hand, the TC cannot have back pressure on the exhaust as it will hinder the proper operation of the turbo. o having a 3 inch exhaust on the turbo outlet minimizes the back pressure that the system will have.

Back pressure makes it harder for the burnt air/fuel to exit the cylinder. Proper exhaust velocity helps to scavenge the cylinders. But with any form of boost the fresh unburnt air/fuel mixture will help push the burnt leftovers out of the cylinder.

My understanding of exhaust size is that it is based on the amount of power you are expecting to make. The 2.5" exhaust will not allow for sufficient flow/velocity over a certain horsepower number.

 

[Wes]

My kit originally came with the 2" exhaust, I had a 2.4 N/A. I wound up getting the zzp manifold which has a 3" outlet so I got a 3" exhaust from Adam last fall because I didn't like the sharp 2 to 3 transition at the collector. Sounded horrible but it definitely revved higher and felt quicker, I kept it on because I was adding the supercharger. After adding the blower it was still so obnoxious, I wore earplugs on longer trips and just really hated the droning resonance when cruising. Don't go 3 inch if you plan to just tool around unnoticed and able to hear when you arrive at your destination. Can't speak to the turbo models though...

A few weeks ago, I finally made a custom 3 inch inlet to 2 1/12 inch setup from the original 2 inch can and flange. It has a long transition not just the short coupler type. Sounds so much better and I really don't notice a difference in power.

Also, I have a 3 inch setup for sale on the cheap lol

 

[JeffsGoblin]

Pictures of both?

 

[askiles]

Here is the 2 1/2” exhaust that came from DF.