breds2k

iTrader: (1)

Just talking with a guy on facebook who has a custom one on his car (he has it on a big turbo LNF) .

I know they don't make them but would there be any gain from having one custom made? More turbo noise? I remember I rode in a 4" open DP 04 STI and it sounded insane!!!!


4" turbo 20g:

https://www.facebook.com/photo.php?v...type=3&theater

cmiller8006

iTrader: (3)

Not on a 20g. I was thinking about a 4 inch exhaust however that way I could re-route the dump into the exhaust and not loose to much power.

breds2k

iTrader: (1)

Why you think its not a 20g?

cmiller8006

iTrader: (3)

A 4" inch dp on a 20g is not worth it is what I mean

breds2k

iTrader: (1)

Any cons? Im basically wondering if you used it on a K04 what would happen? Just more turbo noise?

tomj77

iTrader: (2)

Why would there be cons?

breds2k

iTrader: (1)

Well off the top of my head, Cons would be:

too little back pressure
boost spikes

not sure though for our cars.

not sure what else, that's what a guy who had it on a WRX told me (not the same STI that I rode in that had it)

ECaulk

iTrader: (6)

get rid of that back pressure idea right now, its a turboed car, you want the exhaust heat to leave a quickly as possible for better spooling

breds2k

iTrader: (1)

^but I have heard the opposite in relation to electric cutouts, saying exactly what I said, zero backpressure is bad for the turbo, needs just a little bit.

ECaulk

iTrader: (6)

Ever see a honda with the exhaust out the hood at the strip? zero back pressure

EDIT: I say zero back pressure but that is impossible, there is such a thing as to big to soon if you're trying to flow the air out of a long tube, all the exhaust air will not flow very well and actually cause more issues. If youre wanting to run a 4inch dp off a tubro it better be open to the air quickly

tomj77

iTrader: (2)

turbo cars should not have back pressure. that's for na cars

Pleass

iTrader: (1)

Do you have an **** poor base model?

What's your concern with this topic?

andrewcarr1993

iTrader: (5)

You really don't have to be an ass. It's a discussion whether it pertains to himself personally or not. Since you can't read I'll post the section.

2.0L LNF Performance Tech 260hp and 260 lb-ft of torque Turbocharged tuner version.
Technical Discussions ONLY!

Please reread the last line and don't be an ass.

cmiller8006

iTrader: (3)

Turbos make the back pressure. Don't need any more then that. Any real cons? Prolly not. But you get made fun of prolly lol. I was going to do a whole 4 inch exhaust.

southal cobalt

iTrader: (3)

atmospheric pressure is fictitious.

but seriously, id imagine there would be fitment issues with a 4" on a cobalt. my 3" looks awfully cramp back where it bolts to the cat-back

Corey V

But you would have a full 4" exhaust, if you went that route and you use a different flange or use the same as stock but flipped upside down

serega12

iTrader: (1)

On a TT built supra 4" exhaust makes sense... on our cars with stock turbo - not so much..

Terminator2

Everyone thinks in terms of back pressure when they should be focusing on exhaust gas velocity. Too big of a dp slows exhaust gas velocity which hurts overall performance and turbo spool in the process. Engines hate backpressure and also hate very large inlet or outlet pipes.

breds2k

iTrader: (1)

Exact answer I was looking for. I will be buying a HHR SS soon, and my buddy just got a 09 LNF so this question applies to both, and now I finally can add that doucherag to my ignore list.

DCsnow1000

Even on some of the Crazy Turbo Jeeps builds some of us have. We only step up to a 4" DP when we go 88mm or higher. There are guys running 76mm with a 3.5 and that is all that is required.

I would not recommend going 4" on this car ever unless your doing a crazy hybrid huge turbo build thats only running a 1/4 mile at a time.

Term hit it on the nose.

spike

3" is more then big enough for almost all cobalts. My buddies evo has 780awhp and still on 3"down pipe/external waste gate. 4"=lots of wasted money and time

breds2k

iTrader: (1)

Good answers, thanks! Now that I blocked Plees or whatever his name is this thread stayed on track!

Terminator2

I did the same. That asshat never has anything constructive to say in all 300 posts he has he is always mocking people for no reason. I guess he never got hugged enough as a child.

Staged07SS

iTrader: (25)

This.

I always mention this to the LSJ guys as well. Good exhaust gas velocity is key.

Slowing down exhaust gas velocity with too large of a pipe can create unwanted turbulence.

I'm sorry, but a 4" downpipe is way overkill. That car in the video is from my area.

I've seen him driving around every now and again.

breds2k

iTrader: (1)

Changing the subject here a bit....I knew a guy that had a 2.5" header back exhaust on a 3.0V6 with about 200hp, then he downsized from the resonator back splitting to 2 2" pipes with no rear mufflers, said it helped back pressure.

Any truth there?