Open wastegate vs. re-circulated

[a91eagletalon]

Got a simple question I like to get your guys opinions on stuff because it helps be decide whats the best way.

Should I go with an open vented wastage or re-circulate it. I don’t think there is any performance gain either way but the open vented waste gate makes more sound and i am not sure that what I want or not what do you guys think in your opinion.


Thanks
MP

 

[bradselph]

in my eyes a atmosphere dumped wastegate is better.

reason being your not recirculation that exhaust back into the already too small exhaust to choke up.

if your driving on the street with a small turbo like a 20g and your worried about noise a good recirculating wastegate would be fine.

 

[Canadian_CD9A]

Dumped wastegates will make more power. Just make sure the discharge isn't point at your intake (duh). The less your wastegate flows (more boost), the less effect it should have on power.
Some people just prefer the quietness of recirculated gates.

 

[4G63gst1990]

Atmosphere dump waste gates will help control or prevent boost creep all a recirculating does is keep it quiet it will depend on your setup and what you plan to do with the car imo
i would run the atmosphere dump

 

[boost97gst]

Dump the exhaust AND the wg. No backpressure ftw dude!
Seriously, i think dumpin to atmo is fine. Use some of that flex line to get it away from anything important if you have fitment issues and you'll be fine bud.

 

[eDeclpse92]

I vent to atmosphere and from experience, it can get pretty loud. I have mine coming up through the hood because I didn't want it venting on intercooler piping, and it was getting pretty tight fitting in that spot anyways. If it's a daily driver, I would recirculate it. If it's a racecar, I would vent to atmosphere as it is better with preventing boost creep. When you have a waste gate that recirculates, it disrupts the flow of the exhaust that does not not bypass the turbine. Good luck with your decision!

 

[renovatdkitchen]

To help keep costs down by not buying an external wastegate for my 1G while still having good boost control, I went with an open dump. Keep in mind, I am also only using a 2.5" downpipe to keep cruising volumes down.

It is slightly on the loud side, and you definately cant hear the turbo once it opens unfortunately. This is on a e16g set at wastegate pressure (fully open by about 10 psi, creeping about 1-2psi to redline) until my ecmlink chip arrives.

 

[LandSpeed-DSM]

You are leaving a not-insignificant amount of power and spool time on the table by recirculating it. Dump it, whether you are internally or externally gated.

If you are worried about noise, run more boost. Seriously.. more boost means less bypass and the turbine acts as a muffler. The gate will also open later so you will hear it less often.

Where noise is a real concern there are mufflers you can run on the wastegate dump
38mm big bore muffler CNC end short style [WMPS0S78] - $19.00 : Wholesale Motorcycle Spare Parts, Cheap motorcycle spare parts

You can try and find one off a Porsche 930 as well..

 

[Dyesuperman]

You are leaving a not-insignificant amount of power and spool time on the table by recirculating it. Dump it, whether you are internally or externally gated.

If you are worried about noise, run more boost. Seriously.. more boost means less bypass and the turbine acts as a muffler. The gate will also open later so you will hear it less often.

Where noise is a real concern there are mufflers you can run on the wastegate dump
38mm big bore muffler CNC end short style [WMPS0S78] - $19.00 : Wholesale Motorcycle Spare Parts, Cheap motorcycle spare parts

You can try and find one off a Porsche 930 as well..

I've never seen those mufflers before, or even thought of that...wonder how it sounds

 

[iBoostDSM]

I run mine recirculated. I highly doubt you'll have any trouble with boost creep on a external wastegate recirculated or dumped. I also enjoy the sound of the holset more than really loud exhaust.

 

[Hillala]

I run dumped to the atmo with 3' straight pipe on top of that, I don't think it's all that loud. Don't get me wrong it is loud but not to the point it'll kill you every time you drive somewhere. Just don't have that same setup with an rx7, I made that mistake with my old Fc3s... never again.

 

[LandSpeed-DSM]

I've never seen those mufflers before, or even thought of that...wonder how it sounds

With a bike muffler? My guess is an aggressive, sustained howling fart

 

[My1GLaser]

You are leaving a not-insignificant amount of power and spool time on the table by recirculating it. Dump it, whether you are internally or externally gated.

Can you elaborate some? I wasn't aware of this! I am guessing it is probably contributing to higher than desirable exhaust back pressure I've been dealing with on my Holset. Damnit, now I gotta fab another O2 housing

 

[Canadian_CD9A]

Tale of a dump tube .... a different approach ; power loss to perfection ! - SRT Forums - SRT4, SRT6, SRT8, SRT10 & Dodge Forum

Guy gained 38whp by dumping his external gate. Your results may vary

 

[mygsx2120]

LIL EVO just gained a bunch of HP just by switching to a wastegate dump and 4" exhaust

 

[LandSpeed-DSM]

Can you elaborate some? I wasn't aware of this! I am guessing it is probably contributing to higher than desirable exhaust back pressure I've been dealing with on my Holset. Damnit, now I gotta fab another O2 housing

You will hear some folks try to rationalize and tell you "well, a proper merge angle.." etc., and so forth.

Sure, that will help make this less of a problem, but it is still the same problem. A divorced system will spool/recover faster and make more power at the same boost pressure.

Due to lower EGTs and higher VE, you should also be able to add more spark advance and/or take out fuel as a result. Making yet more power. Especially on a fuel (knock) limited setup.

Any pressure downstream of the turbine is multiplied by the turbine's working expansion ratio, which is then additive to the pre-turbine drive pressure.

Fact is, the wastegate gasses are also hotter than what is leaving the turbine, they will expand faster and take up a greater volume in proportion to their mass.

 

[eDeclpse92]

And your car will only be loud when you hit your max boost that you have set. The wastegate will stay closed any other time so it will be quiet while cruising and city/ highway driving.

 

[ColtiXim]

LIL EVO just gained a bunch of HP just by switching to a wastegate dump and 4" exhaust

Yes : 50HP gain

 

[TSicktalon]

Vent to atmosphere, as stated repeatedly above. I daily drive mine with the wg dumped straight down to right below the oil pan, and, as stated, its only loud at WOT. sounds like a medium exhaust leak, not ridiculous like a straight piped honda/chevy/mustang.

 

[a91eagletalon]

Ill Take all that in to mind I appreciate the help.

I have a dnp header that is not set up for an external wastegate can I just install a tube from the collector to a flange to bolt the wastegate on. and then i am running a 20g turbo do I just weld the old wastegate flap open or closed. or should i run the wastegate after the turbo.
Or what do you suggest


Thanks
MP

 

[StarionGSX]

Your 2 main concerns on a street car should be,

Noise, most open dumps sound terrible IMHO. They may attract cops too.

Smog, an open dump will never pass smog.


I wont run one on my street car.

 

[delta448]

PUNISHMENT RACING STAINLESS STEEL ATMOSPHERE VENTED O2 HOUSING FOR ECLIPSE/TALON - Punishment Racing

Assuming you have a mitsu flanged hotside on that 20G, an O2 housing is all you need to VTA your wastegate.

 

[Boomdeeze]

On a street car and a 20g, I would run it recirculated. I ran open dump on a 50 trim turbo and I hated the open dump tube while driving around. If I ever wanted to get on it, it was obnoxious. Now on my s362 ett setup, I am recirculating my dump but I am also installing an electric cutout after my down-pipe for the track.

But honestly if the car is for street use, I would just recirculate it. With your upgraded exhaust, you would be fine to recirculate. It also depends how much back pressure you exhaust has as in which muffler you have.

 

[a91eagletalon]

Where do you install the wastgate if you were using the o2 housing noted above.

 

[LandSpeed-DSM]

You can use the internal gate on your 20G with a dumped O2 housing. I ran all my TD05H flanged turbos this way.

This is using a dumped O2 housing with the internal gate on an S200sx in a BEP DSM Bolt-on housing from a few years back:

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Or you can cut the dump tube off and weld a flange on for your wastegate of choice and then use a flange to fab a dump tube.