Exhaust size???

[ebxr8240]

Turbo's are a BIG muffler....The exhaust energy is much less volitile...

[bigcliff]

I just put a Mitsubishi EVO 2000cc 4 cylinder turbo on the road and managed to fit 2.5 inch most of the way...It is quiet....really quiet but great torque.
I think many of us try to get the maximum performance all with the influence of the advertisers...who tell us what we need or really what we want to hear.
We are so easily swayed into turning the civilized sedan into a gutless loud hard to drive magnet for the law to catch.
It alway makes me smile when a quiet ride out performs that loud wannabe.
http://www.turbo-owners.com/forum/im...lies/smile.gif

[efdup_booby_job]

i know everyone is saying youll get power, im not arguing that, but youll only get as much flow as the size of your turbine inlet/outlet. so if your turbine inlet is 2.75" then a 3" pipe is only creating volume not flow...

[ebxr8240]

So if my 07 WRX has a 50mm housing ? I should take the 2.5 exhaust off and fit a 50mm ?? No I don't think so!!
Turbines work way better with very little back pressure..
You could go 20% over with no issues..
I went from single 3" exhaust to twin 3" exhaust and gained another 100 rwkw to 482 rwkw.. The twin 3" dump pipes have not been changed..
On my turbo 330ci Ford..
By increasing exhaust flow.. It helped turbo's to spool way sooner also..

[Wally]

Correct, by increasing the dump pipe diameter and the PVT rule applying, the volume will increase while the pressure drops. The turbine works better the higher the pressure drop across it.

[JoeThaMan]

When it comes to exhaust on a turbo car, bigger is better (to a point). The turbo is always going to be a restriction in the exhaust system, so getting exhaust through the turbo as fast as possible is the goal.

On an N/A car the exhaust can make a big difference because the change in exhaust velocity. A smaller exhaust is going to have a higher velocity speed than a larger one, which will help with low end power/torque, but suffer up top, and vice versa. Same thing with an intake manifold, like an carburetor intake manifold for a V8. A small runner dual plane manifold will provide better low end power, where a single plane large runner high rise manifold will provide better top end power. Of course, this stuff really doesn't pertain to a turbo application. Bigger is better.

[bigcliff]

This topic hurts my head.
I know that you can get more power on the exhaust sizes...but I always worry about folks wasting money and finding out that what they have gotten is not quite what they wanted....but then it never will.
I have been close with a muffler repair shop and watch many people returning with their street rides to have the whole system reset to standard due to disappointment in the improved package.
They will spend on one area and not realize that in order to really have useful performance they need to spend on other areas too.
The difference of a turbo spooling from 2000 rpm and another from 3000 can make a difference on what gearing can be used in that particular application.

[ebxr8240]

Turbo's respond to load so in some cases higher gearing brings spool on sooner..
A baffled muffler is bad news for performance on a turbo exhaust system..
There is no way a bigger turbo exhaust system would have less power.. Maybe too much noise !! That comes down to quality of product etc..
Yes in some cases on N/A engines bigger is not better and in 90% of cases makes too much noise.. Especially on high rpm engine.. Honda's, VVT Toyota's etc..

[efdup_booby_job]

i see where your coming from... although ive owned two previous turbo'd applications im more familiar with n/a engines. with an n/a engine the smallest point on the system is the choke point so the whole system might as well be the same size (before the choke point that is...) so thats why i said the exhaust inlet size should be relative to the pipe size. i failed to mention i meant between the turbo and the engine.
that would create velocity up to the turbo then the dramatic pressure drop from the smaller diameter pre-turbo to the larger after would spool faster per what wally said?

this is how i understand it now so am i right? please correct me if im still dim the the head, lol. im doing a custom remote build on my 02 blazer (starting at 6 psi and moving up from there) so id really like to make sure i understand the dynamics before i mount this thing

[ebxr8240]

In my Ford V8 I have 1 1/4 primaries to 2" into turbo EACH side.. Out of turbo I have 3" dumps and all the way to rear... On a 2 litre you would halve that...
Turbo's are Precision SC61's..I can gain another 50 rwkw's by removing 2 x's 3" exhaust from dump pipes...With exhaust fitted etc 483 rwkw...