Open downpipe or 3" exhaust. Power Difference??

[tsi1991awd]

I had a question here...I was contemplating running 3" open DP and was wondering if there is any power gain over running a 3" catback with a Magnaflow muffler. I'd think the open DP is less restrictive, so it might yield a little more power. Any input?

 

[habitatguy187]

Loud!

 

[dcshoeco1041]

you might lose top end power, without a full muffler and piping, you lose back pressure, some backpressure is good. You might notice a slower start. and itll be very loud.

 

[nytescion]

I don't know what turbo you're running right now. but I'm using an hx-40 on open downpipe. cause my catback got trashed. It sounds very mean at idle and while driving. Sounds similar to a turbo diesel truck. I'm going to try and find a catback that doesn't muffle this sound too much. as far as power difference/spool. I feels like it spools a little faster, but doesn't really feel like there is a power difference. but that's just the butt dyno.

 

[knochgoon24]

An exhaust will help keep the cops off you. Cops in my area don't really like loud setups.

 

[nongthep]

very loud and very loud

 

[fwdmaster]

Are you going to run open dp as a daily driver or for track use only, but running open dp will yield you more spool time, but the con, is that your car will sound loud as hell

 

[pboglio]

Here's a little info to help you out:

Buschur Racing dyno thread.....new developments. - Page 5 - evolutionm.net

I see no practical reason to do it on the street.

 

[324vr4]

I have a semi-open exhaust setup...3" DP to a 16" "race muffler" (flow-thru design) and side exists right in front of Driver's side rear tire...it is VERY loud...only running a 16g but damn when getting close to cars the medians its seems like I'm inside a noise machine...I suggest not using an open setup for DD as it will annoy you after a while like rattles sometimes do after a while driving...

As far as power gains...quick spool and quick launches but the top end tapers off...not sure if its related but I'm assuming it is...good luck with your setup!

 

[tsi1991awd]

What about using a cutout where the cat is, and still have a full 3" exhaust? If it allows the turbo to spool faster, maybe leaving it open on launch and then close it near 4 or 5k?

Loud doesn't bother me...I had a foxbody running shorties with an H pipe and Flowmaster 10 series dumped right before the rear axle. THAT was loud.

 

[pboglio]

An electronic dump valve of some sorts or mechanical? What sized turbo are you running?

 

[tsi1991awd]

An electronic dump valve of some sorts or mechanical? What sized turbo are you running?

Electric cutout. Running the 14b, about to up the boost to 15psi. When I get my injectors and DSMLink, I'll up it to 20psi.

 

[pboglio]

Take a look at this:

VES-ASSEMBLY - out of stock again until unknown date due to production delays: atpturbo.com

Apparantly the electric dump valves don't hold up as well, thats what I hear anyways. Basically an external wastegate for your exhaust.

 

[bmoha2]

electronic of boost activated cutouts but they all have one thing in common. Choppy airflow when open or closed. I'd like to see a setup that flows smoothly open or closed. That 90 degree thing just doesn't fly.

 

[tsi1991awd]

No no no, I mean an electric exhaust cutout. Like these http://www.badlanzhpe.com/

 

[chico904]

you might lose top end power, without a full muffler and piping, you lose back pressure, some backpressure is good.

Not for a turbo.

 

[rstare]

you might lose top end power, without a full muffler and piping, you lose back pressure, some backpressure is good. You might notice a slower start. and itll be very loud.

http://www.dsmtuners.com/forums/fre...8578-exhaust-straight-scoop-backpressure.html

 

[pboglio]

And I see an assload of heat conducting straight thru the butterfly shaft into the electric solenoid assembly.

I'll take a pneumatic wastegate style over the electric, how you mount it in the exhaust stream is up to the individual.

All butterfly valves have some loss, welcome to the world of compromises. You could use a swing valve design similar to Turbonetics Evolution wastegate.

 

[420a-t]

My buddy gained 3lbs/min on his 60-1 going from a 3" exhaust to using a 3" electric cutout. It's definately worth it, but I'd for sure get an electric one so you can have a full exhaust, or a cutout at the flick of a switch.

 

[MattratfTSI]

this weekend i ran an open 3" downpipe for a couple days. to tell you the truth I didnt notice much power gain but my 14b did seem to spool a bit faster. However, its not practical at all due to how loud it is. Its REALLY LOUD! Id suggest leaving your whole 3" exhaust on there unless you want that evil sound of an open dp.

 

[tsi1991awd]

If leaving a full 3" exhaust, what muffler would be the least restrictive? One of the reasons I was contemplating the open DP is because it will have no restrictions at all.

 

[chico904]

Pretty much any straight through muffler would be the least restrictive. I know from personal experience that the ebay Apexi N1 cat back system is straight through. That, and the fact that I basically "blew out" everything that was in the muffler one night while driving which preceded a louder, and throatier sounding exhaust.

 

[JusMX141]

Running the 14b, about to up the boost to 15psi.

Wow, you wouldn't even need a 3" exhaust with a 14B at that boost level.

Expect some boost creep when trying to run lower boost levels with a low-restriction exhaust system. You WILL have creep issues with an open 3" downpipe.

 

[tsi1991awd]

So you're just using a knockoff ebay exhaust? Is it holding up well? When did you do to connect it to the downpipe? I'm not wanting to run a cat.

 

[chico904]

Yes it is holding up beautiful after 2 years. No rust on it whatsoever, and I live in Pittsburgh and drive during the winter. It bolted up perfectly to the megan racing downpipe that I got. All in all, I got a 3 inch turboback for a little over $300 thanks to ebay.