Turbo Exhaust
Turbo Exhaust Well Im running my 6.0 manifold kit with a GT-42 76mm T6 flange turbo with about 14psi on my forged 347 with stock heads and 224 cam.
Question
my downpipe is 4inch and I have it reduce to 3inch and the 2 bends that take it to the passenger side are NOT mandrel bent.The muffler is a 3inch dynomax bullet.
How much is this hurting me??????
Question
my downpipe is 4inch and I have it reduce to 3inch and the 2 bends that take it to the passenger side are NOT mandrel bent.The muffler is a 3inch dynomax bullet.
How much is this hurting me??????
Originally Posted by SuperZ
Well Im running my 6.0 manifold kit with a GT-42 76mm T6 flange turbo with about 14psi on my forged 347 with stock heads and 224 cam.
Question
my downpipe is 4inch and I have it reduce to 3inch and the 2 bends that take it to the passenger side are NOT mandrel bent.The muffler is a 3inch dynomax bullet.
How much is this hurting me??????
Question
my downpipe is 4inch and I have it reduce to 3inch and the 2 bends that take it to the passenger side are NOT mandrel bent.The muffler is a 3inch dynomax bullet.
How much is this hurting me??????
I havnt got a full boost dyno run yet.In the begining process it dynod 530rwhp with 8psi and peaked around 5500.Im not sure where it would now.It does better if i shift around 6200 oposed to 6k.Im just wondering if It would be worth it to upgrade to a 4inch system or not??
Why not put a cutout there instead?
I have a 5" necked down to 4" with a bullet dumping at the rear. If there was one thing I would change on my car today it would be to put a super quiet muffler out back and an electric 4" cutout up front.
/old guy
I have a 5" necked down to 4" with a bullet dumping at the rear. If there was one thing I would change on my car today it would be to put a super quiet muffler out back and an electric 4" cutout up front.
/old guy
I could do I cut out under the drivers side before the 3inch pipe make a bend towards the passenger side.It would be pretty darn loud like that but Im sure it would flow good.
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TECH Enthusiast
Joined: May 2004
Posts: 567
Likes: 0
From: Colorado
You have to think of it this way.. any bends in the system is going to cause a psi drop.. less is more... You just have to work with what you got.. mandrel will help.. but having a straight shot it ideally what you want.. it will def. help on backpressure..
but seeing you have a t6... i dont think backpressure would be much of an issue for you.. Could you just run the pipe on the drivers side instead of bringing it back to the pass. side?
but seeing you have a t6... i dont think backpressure would be much of an issue for you.. Could you just run the pipe on the drivers side instead of bringing it back to the pass. side?
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Single 4" exhaust is good to about 600 hp, while single 3" is good to about 400hp.
If you're looking for top end, it will negatively affect your top number.
If you have to absolutely put in the reduction, do it as far away from the turbine as feasibly possible.
If you're looking for top end, it will negatively affect your top number.
If you have to absolutely put in the reduction, do it as far away from the turbine as feasibly possible.
To many guys are making well over 500rwhp with 3 inch exhaust for me to belive that 3 inch is good for 400hp. I have personally pushed a 5.0 mustang past 620rwhp with a single 3 inch exhaust. Of course it will create more back pressure than the 4 or 5 inch single setups but we have limited room to work with as you know.
That is correct. I too have seen exhaust pushed to its limits. The above is a general guideline and yes - more backpressure is involved. I have also see gains in the area of 30 - 50rwhp when going to a more appropriate size exhaust.
This is why when I build our RACE turbo kits, I always over size the DP at least 1/2".
This is why when I build our RACE turbo kits, I always over size the DP at least 1/2".
Originally Posted by NOSjohn
Single 4" exhaust is good to about 600 hp, while single 3" is good to about 400hp.
If you're looking for top end, it will negatively affect your top number.
If you have to absolutely put in the reduction, do it as far away from the turbine as feasibly possible.
If you're looking for top end, it will negatively affect your top number.
If you have to absolutely put in the reduction, do it as far away from the turbine as feasibly possible.
Yes, especially on a turbo application. You have to remember, the turbo acts like a bottleneck in the turbo system. You have 8 cylinders running to one T4 or T6 opening, then going around in a circle, only to be expelled out ONE single exhaust port (turbine exhaust).
Your setup and that number was done with a supercharger, correct? It's a little different but still restrictive. A 5" exhaust or larger, when class racing rules dictate, is not uncommon (10.5" Outlaw class comes to mind). Most times this is why you see uncorked exhaust or DP's in the unlimited big dog classes.
Your setup and that number was done with a supercharger, correct? It's a little different but still restrictive. A 5" exhaust or larger, when class racing rules dictate, is not uncommon (10.5" Outlaw class comes to mind). Most times this is why you see uncorked exhaust or DP's in the unlimited big dog classes.
Outlaw 10.5 is where I started my turbo gig. Back in the day when mid 8's where the norm. We ran 4 and 5 inch down pipes when we could. Granted backpressure is the enemy with a turbo setup for sure. The average street car will be fine with a 3 inch DP. All my kits have them due to routing clearnaces. Yes, I can make a 4 inch DP fit with a tube k-member, but a my setup is designed around the factory k-member.
My point being is that for a street car all out HP is not the goal. Use what work s and makes the power goal you have set out for. For a race car, go as big as you can fit. Try get every once of performance you can from the setup.
PSJ: With 867rwhp I dont think you have much to worry about. Sure there may be a few HP left on the table, but you have plenty to do the job.
My point being is that for a street car all out HP is not the goal. Use what work s and makes the power goal you have set out for. For a race car, go as big as you can fit. Try get every once of performance you can from the setup.
PSJ: With 867rwhp I dont think you have much to worry about. Sure there may be a few HP left on the table, but you have plenty to do the job.
FormerVendor
Joined: Dec 2001
Posts: 2,444
Likes: 2
From: WWW.SPEEDINC.COM
Originally Posted by Pro Stock John
So I have 4" exhaust with a bullet to my 9", are you saying it's restrictive for me? I've made 867rwhp, you think it will be a bottleneck at the track?
No. Our shop car had a 5in downpipe transitioning to a 4in single exhaust and magnaflow muffler exiting at the rear bumper.
Made 995rwhp through the exhaust and 995rwhp through the 5in cutout. (T400 car)
Also trapped the same at the track through the exhaust or through the cutout.
So no, a 4in exhaust ending at your axle is absolutely not a restriction.
INTMD8 - his car doesn't have a 5 inch to 4 inch transition. You are speaking in terms of apples to oranges. He had a supercharged car that probably had headers with 3" outlets going into a single 4" outlet.
Mathematically speaking, two 3" pipes will out flow one 4" pipe. It's a restriction. Does he need it, probably not as he doesn't need top end power all the time.
On the other hand, if he were racing for a class championship, I would highly recommend it.
Mathematically speaking, two 3" pipes will out flow one 4" pipe. It's a restriction. Does he need it, probably not as he doesn't need top end power all the time.
On the other hand, if he were racing for a class championship, I would highly recommend it.
FormerVendor
Joined: Dec 2001
Posts: 2,444
Likes: 2
From: WWW.SPEEDINC.COM
Originally Posted by NOSjohn
INTMD8 - his car doesn't have a 5 inch to 4 inch transition. You are speaking in terms of apples to oranges. He had a supercharged car that probably had headers with 3" outlets going into a single 4" outlet.
Mathematically speaking, two 3" pipes will out flow one 4" pipe. It's a restriction. Does he need it, probably not as he doesn't need top end power all the time.
On the other hand, if he were racing for a class championship, I would highly recommend it.
Mathematically speaking, two 3" pipes will out flow one 4" pipe. It's a restriction. Does he need it, probably not as he doesn't need top end power all the time.
On the other hand, if he were racing for a class championship, I would highly recommend it.
My point is, if our shop car made 995rwhp through a full 4in exhaust, and gained nothing by opening a 5in cutout, than PSJ's car certainly isn't restricted by a 4in exhaust at the 867rwhp level.
