simike

I would prefer to dump exhaust from the wastegate back into the downpipe. I see a lot of people say you will loose power doing this. If you run an open loop system w/a 2.5" downpipe and make a set # of hp, would a 3" downpipe with a closed loop make the same # of hp? I am thinking the larger downpipe would allow you to run a closed loop system w/o adding more back pressure. At what hp level do you think a closed loop system will start to effect performance? Thanks for any help that can be given!

bigTom

it will effect it at all stages

Dee

As long as the dumptube re-enters the exist atleast 18" from the header flange there shouldn't be much flow disturbance. Try to blend the w/g dumptube into the exhaust at an angle of 45degrees or less. 90degree entries will cause some hellafied flow problems.

As soon as my tranny parts arrive I will be making a closed system that uses a stepped DP (60mm/70mm/76mm) connected to an 80mm race cat and a reconbungulated 80mm 5Zigen exhaust from a 180SX with the w/g dumptube re-entering the exhaust about 2 inches before the cat. I will be doing a before and after dyno on this install.

Gimme about a week or so because I only get to work on my car on weekends.

Projekt20

What you said about the angle of the dumptube....I was just thinking about that last week. I see what your saying....you want it to point torwards the exit of the DP w/o bouncing off the inner pipe head-on and disturbing the flow. Checkout Dustin's DP....he said he dyno'd the open Vs closed and had no significant loss. I'm gonna have mine made like his.

-Trung

SiR Kid

Best closed loop wastegate design I've heard of yet... I should be rebuilding another downpipe soon, and here's what we'll be doing...

We're going to get a 3 way 2" piping collector, and have a single 2" for the wastegate, and cut the middle out of the other two, expand them to roung to have ABOUT a 2.5" pip to meld with it into a 3" final size downpipe UNDER the car, probably about where the midshaft is. This feeding into a 3" Thermal exhaust would be NIIIIICE

What do you guys think? I'll post pics once we make it on a mocked up engine...

Total'd GSR

Best word ever!!! LOL!

On a serious note... what's the problem with having an open dump tube?


[Modified by Tanabe'd GSR, 12:34 AM 3/26/2002]

Dee

I have an emissions inspection coming up soon and the w/g attracts too much attention. I'm also going to run a closed loop BOV.

Total'd GSR

Besides emissions (here in FL emission laws don't exist ) is there any reason not to run an open w/g and BOV other then noise?? Cuz I want my set up to be loud as hell. My friend's w/g on his 16g eclipse vents into the atmosphere and it's sounds SICK! I love it!

simike

The reason's i wanted a closed loop system is keeps the carbon off the underside of your car, hood, engine depending on dump tube length and wastegate location. It doesn't attract as much attention from the police and is more of a sleeper, and of course is emmissions friendly. I can see a local garage letting you go with a bov and valve cover breather if they even know what they are dealing with but an open wastegate is hard to overlook!

Dee

Running a closed BOV actually helps to spool the turbo between shifts and since there isn't a power loss I don't see a reason why a closed w/g shouldn't be run on a street car. Running an open w/g is fun but I'd like to get my sleeper status back.