Simple SOHC

Just did some researching about open downpipes on turbo setups...and I know they have all sorts of benefits, but at what point though? Some people said that at low PSI it doesn't help. I'm running 8psi right now...goin to up it to 10psi soon hopefully. Is 8 psi or even 10 too low for any gains? Does turbo size matter as much also? I am running a 14b right now and don't know if it's too small to be affected.

Setup:
Stock D16Z6
ZEX 59300 Cam (Next week)
SpoolinPerformance Log Manifold
14B
2.5" DP w/ open dumptube
2.5" exhaust

nsxmatt

It benefits any setup, you just need to decide if the added noise and gas smell in your interior is worth the added performance.

USDM 4G VTEC

ona turbo car, u want the LESS amount of backpressur epossible

with a 2.5" downpie and exhaust, u have some backpressure still on that setup
u can add a E-cutout and releif all that, and it will be optimal

Simple SOHC

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by USDM 4G VTEC &raquo;</TD></TR><TR><TD CLASS="quote">ona turbo car, u want the LESS amount of backpressur epossible

with a 2.5" downpie and exhaust, u have some backpressure still on that setup
u can add a E-cutout and releif all that, and it will be optimal</TD></TR></TABLE>

Yeah...that is what I am plannin on doin...so it's not open all the time. I just didn't know if my turbo is so small that it might actually hinder performance. I guess you're right since I have a 2.5" dp...there is still some back pressure.

Boosted Power

Get a cutout....that way you can not have the exhaust system connected when you are racing and have it connected when you are daily driving it.
Running open downpipe will get very annoying after a while.

PHDZINE

I have made 590Whp @ 28psi on a full 3.0" exhaust system with a muffler and no cut outs. Open down pipe not worth it because of the noise. So I don't think your 8-10psi will out flow a 3.0" exhaust system. Right now I'm at 31 psi making 667whp and thats when I started noticing a difference. I assuming that over 600Whp is to much flow for a 3.0" exhaust system

null.

plus the open downpipe or cut out is not SFWD legal. 3" full exhaust

msmotorsports

Any turbo setup WILL benefit from an open downpipe. Turbine housings are already a restriction in exhaust. Adding an exhaust further restricts exhausts. Power is decreased with an exhaust due to the motor not being able to use the maximum intake charge possible. I'm sure with a 4" full non restricted exhaust the power gains would be similar to an open downpipe. 3" will still create a small backpressure where maximum power will not be obtained.

Simple SOHC

This is all good info...keep it coming. Thank you to those who have replied.

_gurusan_

You always want the pressure difference in the turbo inlet to be much greater than the outlet.

Bigger piping = less pressure on the outlet side.....making the turbine spool faster

PHDZINE

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by msmotorsports &raquo;</TD></TR><TR><TD CLASS="quote">Any turbo setup WILL benefit from an open downpipe. Turbine housings are already a restriction in exhaust. Adding an exhaust further restricts exhausts. Power is decreased with an exhaust due to the motor not being able to use the maximum intake charge possible. I'm sure with a 4" full non restricted exhaust the power gains would be similar to an open downpipe. 3" will still create a small backpressure where maximum power will not be obtained. </TD></TR></TABLE>

The Turbine housing has to be a restriction in order to spool up the turbo. Thats why you have different A/R to choose from...to control the amount of back pressure in the turbine housing...To big A/R no bottom-end...to small A/R no top-end. I think there is a misconception about turbo's needing the most free flow exhaust...to a point it is true depending on the application (street, drag or even how much power one is making) but remember that when your not in boost your engine is still working like a N/A engine so it needs a little back pressure to get you spooling. Like I said before I made 590Whp @ 28psi with a full 3.0 exhaust and I did run on the track with a full exhaust system but a soon as I made over 600+Whp I stepped it up to a full 3.50" exhaust system.

PHDZINE

Unless you are making a ton of power you don't need a exhaust system that will flow 600+Whp. My boy Dave makes 560 Whp WITH a 2.00" down pipe. Talk about restriction.

nsxmatt

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PHDZINE &raquo;</TD></TR><TR><TD CLASS="quote">Unless you are making a ton of power you don't need a exhaust system that will flow 600+Whp. My boy Dave makes 560 Whp WITH a 2.00" down pipe. Talk about restriction.</TD></TR></TABLE>

Why build a setup for that much power with a 2"dp. Thats just dumb

00civicsohc

The other night i unbolted my exhaust before the cat and it made my car a hell of a lot faster with open downpipe. I was really surprised. This is on my d16y8, gt28rs at 7-8 psi with 2.5" downpipe to stock cat to 2.25" magnaflow muffler.

mr_hahn73

open downpipe is cool for a weekend warrior but for an everyday driver its not worth it.

PHDZINE

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxmatt &raquo;</TD></TR><TR><TD CLASS="quote">Why build a setup for that much power with a 2"dp. Thats just dumb </TD></TR></TABLE>

It might be dumb but he's got 560Whp...SORRY

Blaze45

Open DP is the ONLY way to drive a boosted car. lol I have a 3in DP that goes into a cutout and then through the stock exh. I havent put on the cutout butterfly on yet, but it gives me the option to be quiet and pass emissions while still being able to enjoy hearing the turbo spool and whistle.... My buddy ran open DP for quite some time on his boosted 4 door d15b7 14b. 5-11lbs. (wg was going out, new one fluctuates from 7-10lbs now) He thought that a 2.5in exh that another friend had would help his setup dip into the 14s. We had been running consistant 15.0- 15.1s with the open DP. He put on the full 2.5in it on and he ran low 16s. Some of it was driver but I think his best time with the exh on was a 15.7. So after he pulled that 15.7 with the exh on I told him to take it off, he did and pulled a 15.10. lol. Open DP rocks, no matter how small the setup... Have fun with your seutp!

Blaze

19t EX coupe

When we first installed the Greddy 19T kit on my car, the CP had been hacked 4in short of reaching the stock exhaust, so until I could get it fixed, I ran open DP. The spool was FAST, almost like a BB turbo, but it basically rattled my car to death. Now that I have the stock exhaust hooked up, I can feel the difference. It takes longer to spool. All of this is at 8psi. Open DP is beneficial at any psi no matter what people "speculate", I experienced it first hand