how to get rid of open dump noise

[ka-t 300]

running tial 38mm external waste gate with open dump and have 3" turbo back exhaust with no cats ,and i want to run 20 - 25 lbs of boost about 400 whp. i want to illiminate all that open dump noise. thought about recirc to 3" exhaust line but called a couple turbo shops around here and they didnt recomend that for the possibility of boost creep . so what can i do to eliminate all that noise ?

[C-Kwik]

I doubt boost creep will be an issue, however, if it concerns you enough not to do it, run a separate exhaust pipe for the wastegate dump and add on a small muffler.

[ka-t 300]

what would be the proper way to dump it back in to the 3" line ? or what is the best way ?

[scheffler]

What I would do is like my set up. My set up is an open dump setup but i fabed up a seprate dump pipe out of like 1.5" tubeing and ran it down with the exahust pipe and just stoped it right where the down pipe starts to bend toward the rear. So if you wanted to recirc it back into the exhaust i would just do the same thing but connect the WG exhaust and the turbo exhaust right there where the exhaust starts to bend toward the back. It should be far enought away and compleetly againt the flow of the exhaust so you shouldnt have to worrie about boost creep.

[Blown240sx]

Unless your running undersized tubing the only way you would boost creep on a recirculated Wastegate is if you put the pipe in at a 90 degree angle (going against the exhuast flow) or had to small of a wastegate for the setup. 38 if fine for anything to 500 or so but after that Id go to a 44 or bigger.

[ka-t 300]

Unless your running undersized tubing the only way you would boost creep on a recirculated Wastegate is if you put the pipe in at a 90 degree angle (going against the exhuast flow) or had to small of a wastegate for the setup. 38 if fine for anything to 500 or so but after that Id go to a 44 or bigger.

The dump tube size is 1 1/2 " going into 3" exhaust turbo back.

[Blown240sx]

just run it back into the exhaust about a foot away from the turbo exit. it will be fine.

[ka-t 300]

ok thanks !

[j-z]

im assuming you have an SR downpipe.... i dont know how youre setup is configured (dont remember) but, is it possible to run the dump tube all the way to the SR DP right where it starts to do its almost 90 degree bend to go underneath the chassis?? if so, i would route it down there and have the dump tube enter at that bend from the front of the car, that way when the wg opens it will merge into the exhaust quite nicely.

so hows she running these days?? i built a s13 coupe ka-t that had more balls than my s14 and the s13 had a stock motor LOL.

[GTR PrYdE]

Like others have said,

Dump recirc's work great as long as the merge is smooth and as close to parallel as possible with the exhaust.

BTW, how long did it take you to start getting annoyed by the dump?

I love the sound personally, but i hear most people get tired of it

[j-z]

it only justifies itself when youre tearing up the track, or a nice parking lot. on the street its annoying. every boosted car ive built has always been open dump (because of the ease of doing it that way). if someone pissed me off on the road i would just drive by them full boost and make them def. other than that, i wish i wouldve ran it back into the exhaust.

[ka-t 300]

im assuming you have an SR downpipe.... i dont know how youre setup is configured (dont remember) but, is it possible to run the dump tube all the way to the SR DP right where it starts to do its almost 90 degree bend to go underneath the chassis?? if so, i would route it down there and have the dump tube enter at that bend from the front of the car, that way when the wg opens it will merge into the exhaust quite nicely.

so hows she running these days?? i built a s13 coupe ka-t that had more balls than my s14 and the s13 had a stock motor LOL.

Well its running great still but i have this built motor thats been done for a a year or so that i'm putting now. I was runnig 14psi about 300 whp for about a year on the stock block 172,000 miles 20,000 of that was turbo miles till i pulled it out last weekend . I did a compression leak down test on it before I pulled it out and it was 180-185 across the board. I'm very impressed with the ka motor, I think it does great for a motor that was not designed to be boosted. I need more boost now sooo in goes the built motor. While its out I want to recirc the open dump. No i don't have a sr down pipe.

[ka-t 300]

Like others have said,

Dump recirc's work great as long as the merge is smooth and as close to parallel as possible with the exhaust.

BTW, how long did it take you to start getting annoyed by the dump?

I love the sound personally, but i hear most people get tired of it

Well Its not so much that it annoyes me as the fact that it draws quite a lot of attention to those cars that like to enforce the law. I like the sound of my reguler exhaust better apexi.

[SullivanRacing06]

why hook up the dump pipe? no way lol!

[oz240red]

I recirc'd it because I personally like the whistle the turbo makes when spooling better than the dump pipe sound. Open dump sounds like when you are purging the water off a compressor, recirc'd it sounds like the whistle jets make, pretty cool IMO.

I bought a metallic flex hose in Napa, welded it to the dump pipe and connected the other end like 2 feet away from the turbo. I had the muffle shop weld a small pipe to the exhaust as parallel as they could which was like 30 degree angle. Then I plugged the flex hose to it. Pretty happy.

This doesn't cancel all the "relief valve-like" sound though. If you have a cone filter, you will hear the turbo sucking all that air in and it sound pretty similar to the open dump pipe sound, just not as loud. I guess only by having an air box and intake silencer would it be quiet..... but who would do this when looking for horsepower right?

I'll take a pic when I get home today if it helps ya.

[oz240red]

Here is the picture, maybe it helps (you have to look at it sideways, the dump tube goes into the exhaust on one side)

[j-z]

yeah thats the area im talking about, but have it go into the bend on the downpipe from the front of the car. if you can make it work like that thats what id do. i would say bring it over to my house, but my welder took a shat.

[klattr1]

the higher the boost you run past your wastegate spring level, the less the noise will be (wastegate begins to close or not bypass as much)