open dp vs turbo-back

[V8KLR]

I'm upgrading to an evo3 16G and have a question. What would be the power difference between a stock open DP (2 1/4") vs a complete 3" turbo back exhaust?

 

[toofast82]

I'm upgrading to an evo3 16G and have a question. What would be the power difference between a stock open DP (2 1/4") vs a complete 3" turbo back exhaust?

It is really hard to say which would make more power
But if the e316g turbine outlet is 2.5" than going to a 2.25" dp would be a restriction
Plus if you're driving with open downpipe, im sure the cops will love you!

 

[spooln4fun]

Louder- Stock downpipe
More efficient- 3in turbo back exhaust

You could always buy a 3in down pipe and run that if you are wanting to run just a downpipe,but I would run with a complete exhuast for legal reasons

 

[talonturbotsi94]

From what ive seen with my old evo3 setup with 3 inch exhaust compared to my friend who was running open down pipe i must say that the loss in tq in the lower rpms was huge. When i drove around in his car it felt very sluggish and just didn't have the response in the lower rpms that it should. It was noticeable to the point that when he rode in my car the first thing he mentioned was how bad he needed a exhaust after felling the difference. Me personally i would stick with a full 3inch exhaust for better overall power.

 

[1badtsiawd]

i have a evo 3 16g on 20psi and a full the 3inch exhaust from the downpipe back and i love it. would not run anything else.

 

[Dsmj89]

Get a full 3" turboback and call it a day. Don't look for trouble with authorities or hurt performance. Running the open downpipe will just be a lose-lose situation.

 

[1badtsiawd]

Get a full 3" turboback and call it a day. Don't look for trouble with authorities or hurt performance. Running the open downpipe will just be a lose-lose situation.

100% agree

 

[dsm-onster]

From what ive seen with my old evo3 setup with 3 inch exhaust compared to my friend who was running open down pipe i must say that the loss in tq in the lower rpms was huge. When i drove around in his car it felt very sluggish and just didn't have the response in the lower rpms that it should. It was noticeable to the point that when he rode in my car the first thing he mentioned was how bad he needed a exhaust after felling the difference. Me personally i would stick with a full 3inch exhaust for better overall power.

I'll bet something else was wrong with HIS car that neither of you know about. You should compare your own setup by dropping the exhast and tell us what happens. I did with my small 16g setup even logged the results. 3inch exhaust vs. no exhaust. Faster spool in the low rpms. Quite a bit of flow increase in the middle rpms. Higher peak flow by redline. Same boost (no creep).

 

[habitatguy187]

From what ive seen with my old evo3 setup with 3 inch exhaust compared to my friend who was running open down pipe i must say that the loss in tq in the lower rpms was huge. When i drove around in his car it felt very sluggish and just didn't have the response in the lower rpms that it should. It was noticeable to the point that when he rode in my car the first thing he mentioned was how bad he needed a exhaust after felling the difference. Me personally i would stick with a full 3inch exhaust for better overall power.

The turbo provides all the back pressure needed to create torque in boosted cars. One of the biggest myths is that we need a little backpressure, we want absolute zero back pressure after the turbo.

But to the OP, if you run open downpipe you probably want to at least get a 3in. downpipe, it will flow better and probably be quieter (weird I know) than the stock downpipe.

 

[pboglio]

There is still pulse tuning or wave tuning involved and ditching the exhaust on a street car is a bad idea for several reasons. Do everybody a favor and just run the full exhaust or a cutout at least.

 

[Jeff99GS]

1+ for the cutout...Im running a full 3" exhaust. But its too loud for me, so im going to put a quieter dual tip muffler on the end of my 3" and run a 3"cutout pipe out the front end just under the side marker light.

This way it will sound stockish on the street and RACE ready for the track! Best of both worlds.

In some states cutouts are illegal though.

 

[dsm-onster]

There is still pulse tuning or wave tuning involved and ditching the exhaust on a street car is a bad idea for several reasons. Do everybody a favor and just run the full exhaust or a cutout at least.

The pulse tuning out of boost? The turbine wheel slows (stretches) the pulses as they travel through the blades so that they pile up on each other as they reach the down pipe. When is a 16g with stock cams and manifolds out of boost? and do you care about throttle response below those rpms? As I proved to happen, you can't beat having a better throttle response by having a faster spool.

 

[pboglio]

I'm running a 2.5" downpipe/2.5" testpipe/3" thermal catback with a 5" Borla muffler welded into the main pipe right after the testpipe. I love it and the sound level is very civilized. When I run the 2.5" high flow cat it gets extremely quiet. I'm somewhere around 440 h.p. & 44 lb/min on my EVOIII 16g and don't feel compelled to change my exhaust setup. Even if I dropped the exhaust at the downpipe and gained 10 h.p. I still wouldn't run it. Fast with class

 

[pboglio]

The pulse tuning out of boost? The turbine wheel slows (stretches) the pulses as they travel through the blades so that they pile up on each other as they reach the down pipe. When is a 16g with stock cams and manifolds out of boost? and do you care about throttle response below those rpms? As I proved to happen, you can't beat having a better throttle response by having a faster spool.

Matt,

On my car, I'm a sitting duck below 3000 rpms and there are times I need to pull out of slow corners without downshifting and upsetting the cars balance. That miniscule increase in power from open dumping isn't worth a further loss on the bottom end off boost, I'm speaking for myself here.

I think what happened, and me and Buschur talked about this ages ago, is that radically changing the exhaust system can mess with the a/f ratio. I don't believe the MAF entirely can compensate for it and part of the power loss occurs here without a significant retune.

You know, I haven't run open dump and it's just not my style. I'm building a car that can lug out of corners at low rpm for auto-x duty, as well as scream on the top end under full boost. All the while maintaining good exhaust muffling.

 

[dsm-onster]

If you want the lugging power at 2500rpms, then just retune for the MAFs lack of speedy response ??? Probably harder than it sounds. But, I think the hellatious increase in flow at 4500rpms would be MORE than worth the effort. Or MORE than worth the loss at 2500rpms for a "street" car. Pretty notes are for the symphony . BTW this guy hasn't even stated his intents for the car. He may want a street car that likes to see the strip.

 

[rock1t]

The turbo provides all the back pressure needed to create torque in boosted cars. One of the biggest myths is that we need a little backpressure, we want absolute zero back pressure after the turbo.

But to the OP, if you run open downpipe you probably want to at least get a 3in. downpipe, it will flow better and probably be quieter (weird I know) than the stock downpipe.

Finally, someone posted this, turbo cars require no back pressure, since your turbo is your back pressure, run a 3 inch open downpipe, and blow off next to local law enforcement. They love me here in Kentucky, always drawing that unwanted attention. But luckily for myself, Kentucky does not have emission requirements, just make sure you have a turn down at the end of your downpipe so you blow your exhaust towards the ground and not the fuel lines and brake lines.