Could anybody tell me what they would recommend for an exhaust on a
TurboCharged Engine?

I am going to be getting the Stafford Engineering Turbo Kit and I am going
to be putting an exhaust on it at the same time.

 

id say 2.25 or 2.5 inch and a high flow type of resonator and i'd also use some sort of free flowing muffler aka straight through or if you got money get an aero turbine.

 

If you really want to improve performance, one of the key's is the down pipe and mergining the wastegate gases to the main pipe as far down as possible. This is more custom and will be more expensive than a simple pipe connected to the turbo.

Although you'll have a turbo, it's attached to an engine not made for turboing, therefore you won't be running the boost many turbo cars run, therefore the pipe diameter doesn't need to be much bigger than stock. Keep in mind, too big DOES reduce performance.

If I knew how big our stock pipes were, then I might be able to suggest a size, but I don't. Ball park, I'd guess get something about 1/4" to 1/2" larger than stock.

 

you will be fine with a 2.5" piping (mandrel bent). you can do 2.75" (mandrel bent), but the SF turbo is low boost if i remember correctly, so it is not really needed. those would be the sizes two choose from, but it must be MANDREL BENT.

 

I agree. 2.75" in my opinion should be the absolute limit, if not too big already. I know some people who run 2.5" with 14psi, and they get a decient increase in hp, but nothing gained from 3". Some lost hp. But they do see increases when they boost to 17psi, 21psi with 3". That's 2.5" or 3" for 3 cylinders manifolded.

Turbos for these cars will only boost from 6psi to maaybe 8psi. 8psi would be too risking in my opinion. The exhaust pipe will also be exhausting from 4 cyclinders as opposed to 3 cylinders which has been my experience. The 4 cylinders will exhaust more air through the pipe than 3 cylinders, but it will also only be about 6psi/8psi. Personally, I think 2.5" should be fine.

Of course, we are all speculating here as the best way to know is raw data from a dyno, before and after. Obviously, mandrel bending should be used at all times..

 

I use 2.5" aluminized... it's crush bent, but care was taken not to crimp it shut when done... it is a large improvement over stock on my turbo'ed xB. I use a Magnaflow XL 2.5" Center inlet/outlet muffler and a 2.5" Magnaflow cat. I have no check engine lights, or anything

 

Oh, and you wont lose power when going as large as possible with a turbo vehicle. The turbo creates a substantial amount of backpressure on the engine itself, and experts say that a turbo would love an open downpipe

Anyhow, 2.5 or larger would be the best for turbo. 2.25 for N/A.

 

agreed. larger piping is great for when you're in boost.

IMO stay @ 2.5" increase piping will decrease velocity and rob low and mid range power.

but then again who cares about low end when you have boost. I know i didn't when i was turbo... i wouldnt hit full boost until 4k rpm!

 

Actually, we've learned that their is a problem with having too big. We have actually found horsepower by taking advantage of the scavanging effect from the exhaust pulses. After there is a high pressure exhaust pulse traveling the pipe, it creates a vaccum behind it. This vaccum attracts the following pulse, and vice versa. I pipe that is too big would not take advantage of this. The length and bending of your manifold is done in such a way to take advantage of this. On the 3.0l V6 TwinTurbo that my experience has been with, we've been able to get additional horsepower by using an X-pipe after the turbos, trying to take advantage of the scavanging effect. The X-pipe exhausts make more horsepower than the traditional more individul exhaust pipes with an H-pipe cross over.

Also, there is an additional downside to having too big an exhaust too, as some of you may already know, you lose more low end torque.

 

I'd go with 2.5 inch exhaust for a turbo. But that's me, and i don't know jack.

 

This is very untrue, low end will stay intact even with an open downpipe. The turbo and manifold creates a substantial amount of backpressure itself. The increase will be felt acrossed the whole board, especially while in boost.

Your theory only holds true in N/A engines where a backpressure decrease will usually put a hit on low end torque.

 

on a DOHC 2.0 mitsu motor.. with a td06h 50 trim turbo. open downpipe robbed my low end. mid range a little (but i didnt hit full boost then so dont know if that matters)

Just speaking on experience here people.

 

I would say your best bet is to match the diameter of your down pipe... I don't see there being much if any gains from going larger than that.

 

assuming you don't choke after your downpipe and go smaller.. anything downpipe and bigger is going to make a HUGE difference on the top end. same as open downpipe. robs low end but top end HAULS @$$

 

My buddies and I have found given a diameter downpipe and exhaust are the same, and only increasing the diameter of the downpipe, we did see hp increases and turbo spoolup differences, although I agree with you, a large size the whole way back give the best performance and least restriction.