Exhaust pipe size, 2,5" or 3"?

[Doktor-t]

I´m about to build a new exhaust for my 88 Vette.

I think about using dual 2,5" pipes but would it be better with dual 3" pipes instead?

What is your opinion?


Tobias, Sweden

 

[vette-dude]

3.0". You can buy 3.0" and other sizes mandrel bent U's (180 degree bend) at JC Whitney and fabricate your own exhaust if you are a good welder. I think I might even have four or five 3.0" U's left over from a previous racecar project. Make you a deal on them if you need them. Let me know.

Randy

 

[Doktor-t]

exhaust

I appriciate your offer Randy, but since i live in Sweden it´s much easier for me to buy them here

 

[Toms007]

I'm not an expert in this field, but I think you sacrifice some low end power by going to the 3" pipes. Now if you do NOT have a stock engine or want your power in the upper RPM band, you might be OK.

 

[vetteboy86]

I think dual 3" is too much. However I do not know anything about your previous setup.

 

[Doktor-t]

exhaust

Loosing lowend power isn´t very nice, the TPI-engine has its powerband in a kind of low rpm-range so it might be a possibility. If my engine was a highrevver it would perhaps be better with the 3" pipes..?

The engine won´t see to many mods more than TB-bypass, modified MAF, higher fuelpressure, frisbee delete, sliced up air-lid a better intake/runner setup and one day a pair of headers. Okey, maybe some better rockers in the heads.

Anyway, since the stock exhaust manifold doesen´t measure more than 2,1/4" I have a hard time seeing any improvement in exhaust tubing beyond 2,5". Is that correct? I will delet cats and stuff like that.


Tobias

 

[AdvancedAutoCC]

Stick to 2.5"... your engine doesn't require 3" exhaust (unless it's single)

 

[G Winter]

3 in from cat back

Will 3 in pipe from the main cat back hurt low end at all ? The reason I ask is I have enough scrap 304 stainless pipe that costs me almost nothing that I can use to fab the pipes. I assume that anything behind the main cat shouldn't make that much diff.

Glenn

 

[Doktor-t]

exhaust

What I´ve read about exhaust systems is that generally bigger is better. But most important is that you never should over dimension headers.

I found a pic of an exhaust (ok it is a mustang) but it was custom built for a magazine by a wellknown exhaust/muffler company.

The pipes are in following sizes. From the header: 2,5" to X pipe to 3,5" and it necks down to 3" mufflers.


Tobias

 

[G Winter]

I find it intresting that they increased the pipe size after the X . Must be a reason for that.

Glenn

 

[vader86]

If its true duals, 2.5" will be plenty.