2.5" or 3" downpipe?

[krazy4]

Starting a super low budget 14b nitrous car.

I'm going to make my own down pipe for the car. It's only going to have a downpipe.

The turbos outlet flange opening is only 2.5" so does it make sense to up the size to 3" as soon as possible or just leave it 2.5"?

Thanks for the help.

 

[mitecl96]

I would go to 3" for better flow and IMO a better sound.

And you should make a build thread.

 

[krazy4]

I would go to 3" for better flow and IMO a better sound.

And you should make a build thread.

Yeah, most likely what I'll do.
I'll make a build thread in a week or two.

Just picked up the car on monday. Got it for $250. Body is pretty beat up, but I could care less. I'm a function over form kinda guy. When I got it, the car had about 4" of water in the passenger side where the seat was. Got rid of the water, pulled up the carpet and absolutely no rust. I was pretty excited. Gonna try to get it running tomorrow.

Got the car gutted pretty well now. More lightening will come.

 

[1g20g]

I would go with three inch. That's crazy that there was no rust under that. Goodluck with the project.

 

[mitecl96]

I'm the same way I rather it function and everything work right than I'll work on the looks. But that looks like a great deal on that car I really need to find me a parts car so I can get a few things together and fixed. I take it your removing all the interior you should also thinking about selling a few things.

 

[krazy4]

I would go with three inch. That's crazy that there was no rust under that. Goodluck with the project.

Sounds like the general consensus. Yeah I was surprised there wasn't any rust too. Thanks.

I'm the same way I rather it function and everything work right than I'll work on the looks. But that looks like a great deal on that car I really need to find me a parts car so I can get a few things together and fixed. I take it your removing all the interior you should also thinking about selling a few things.

The interior was pretty beat for the water and what not. I just threw away most everything. What do you need?

 

[GSXftw]

3 in for sure. As the exhaust cools off its more dense and can use the extra flow, even if its 2.5 right out of the O2

 

[mitecl96]

Really what don't I need. Depends also on your color. The speaker covers for the back and the cup holder and ash tray. I really want to switch to black I hate gray.

 

[krazy4]

3 in for sure. As the exhaust cools off its more dense and can use the extra flow, even if its 2.5 right out of the O2

Alright sounds good, 3" it is.

Really what don't I need. Depends also on your color. The speaker covers for the back and the cup holder and ash tray. I really want to switch to black I hate gray.

Already threw that stuff away. It wasn't in great condition anyways. Don't have much interior stuff left.

 

[clipto]

Nothing is wrong with 2.5 downpipe to 3, most o2 housing out there arent even 3 inch and the 2.5 inch off the neck is not ganna bottleneck you for a long time if it even ruins your flow.

 

[krazy4]

Nothing is wrong with 2.5 downpipe to 3, most o2 housing out there arent even 3 inch and the 2.5 inch off the neck is not ganna bottleneck you for a long time if it even ruins your flow.

Cool, good to hear.

 

[josh1095]

ive heard 2.5" turbo back, cat less, is good for near 400whp. but most recommend 3 cause we all eventually want more power and why do it twice? im going 2.5" downpipe to 3" turboback. mainly for sound and ill have the 3"turboback if/when i upgrade o2 housing to handle a 3" down.

 

[clipto]

ive heard 2.5" turbo back, cat less, is good for near 400whp. but most recommend 3 cause we all eventually want more power and why do it twice? im going 2.5" downpipe to 3" turboback. mainly for sound and ill have the 3"turboback if/when i upgrade o2 housing to handle a 3" down.

True True, but as for he was saying just the downpipe being 2.5 and the exhaust if it is 3 inch will handle alot. But a full 2.5 exhaust you might as well definetly just get the 3 inch and be done, but nothing wrong with the dp neck being 2.5

 

[krazy4]

Also, I'm just going to be running a very short downpipe. No catback for me. Don't need the weight.

 

[TSIfreek]

3" all the way back

 

[jed344]

might as well just do it the first time so later you don't have to make a new down pipe in my opinion.

 

[krazy4]

3" all the way back

I'll be making it 3", but it's basically just gonna be a 90 degree bend off the turbo and point down. It's a racecar so screw it.

 

[re-rx7]

Im running a 2.5'' Dp to 3'' catback. Garrett turbochargers has a good write-up on exhaust flow.

 

[Bud92gsx]

Remember the difference between od and id.I have a 3 inch thermal, turns out it's 2.8 id.So robbing a small amount of power but I doubt you would notice.