Dumping or recirc exhaust

[Guillaume]

I'm currently dumping at the wastegate, I have a 3" cat less exhaust and was wandering if recirculating the exhaust would create back pressure or affect overall performance (I run at 35 psi).

I want to do this to attract less attention when on boost....

 

[craig4g63]

It will likely have a minor negative impact on performance. You can mitigate this by directing the wg exhaust dump at a 45 deg angle with the main exhaust.

 

[TSicktalon]

Downsides would be a loss in power and less boost controllability.

To what degree these effects will be varies greatly by setup.

 

[Guillaume]

In what ways do you lose controlability?

 

[iBoostDSM]

It was actually dyno proven that dumped made a bit more power.

And as for controlabity, I'm at 30psi recirculated and have no problems. I would think the gate would effect that more.

 

[Guillaume]

Loosing a bit of power isn't such a big deal (600 whp is more them enough for me), what I want to avoid is to increase turbo lag.

 

[bud09]

it's going to increase turbo lag, by recirculating back into the exhaust. it will create a back pressure, small. not as mush as the turbo itself produces, should only be by around 500rpm more lag, depends from turbo to turbo.

 

[Nvrloze1]

it's going to increase turbo lag, by recirculating back into the exhaust. it will create a back pressure, small. not as mush as the turbo itself produces, should only be by around 500rpm more lag, depends from turbo to turbo.

So it would be better to dump for a quicker spool?

 

[maximum9898]

it's going to increase turbo lag, by recirculating back into the exhaust. it will create a back pressure, small. not as mush as the turbo itself produces, should only be by around 500rpm more lag, depends from turbo to turbo.

It will defiantly will not ruin lag time by 500 rpm, that's huge in lag time. It will at the most be 50rpm, in reduced spool time. When I switched from recirculating to not recirculating the difference wasn't even noticeable. The gains were very little when it was logged with Ecmlink. But I didn't do it for power gain, I did it for boost control and the awesome sound of open dump. Every car is different and you may gain more or less than I did. But I can say it's not gonna be near 500 rpm.

 

[iBoostDSM]

No way it'll effect spool by 500rpm.

 

[Guillaume]

It will defiantly will not ruin lag time by 500 rpm, that's huge in lag time. It will at the most be 50rpm, in reduced spool time. When I switched from recirculating to not recirculating the difference wasn't even noticeable. The gains were very little when it was logged with Ecmlink. But I didn't do it for power gain, I did it for boost control and the awesome sound of open dump. Every car is different and you may gain more or less than I did. But I can say it's not gonna be near 500 rpm.

Thanks for the info, as much as the sound is cool I would enjoy attracting less attention while doing a pull...

Also can you elaborate on the loss of boost controllability I would suffer if I went to a recirc setup.

Thanks

 

[codym]

Also can you elaborate on the loss of boost controllability I would suffer if I went to a recirc setup.

Thanks

Because of how the turbo works, it is best to have the exhaust flowing freely out. When you recirculate your forcing air into the already flowing exhaust stream, causing a restriction.

When you dump you essentially have no restriction on how the wastgate operates, it can open and get the necessary air out at the set psi, without having to push through the exhaust flow.

 

[maximum9898]

^^^^Couldn't of said it better myself, that's exactly what it does.

 

[Purple_Demon]

Could have the best of both worlds, recirculate the exhaust back in after the oil pan XD. Should be too far back to cause restriction or turbulence.

 

[My1GLaser]

Mine is dumped and I made a separate 1.5" exhaust that ends just behind where the passenger seat is. You can't even tell it's dumped with this muffler on there!

 

[turbo98eclipse]

Mine is dumped and I made a separate 1.5" exhaust that ends just behind where the passenger seat is. You can't even tell it's dumped with this muffler on there!

Pics?

 

[Guillaume]

^^ good idea! I might do something like that actually....

As for the boost control, I understand the principles but since I never ran on a recirc setup I don't really have an idea of how much holding boost at set psi can be a challenge for some.

Anyways good info guys, much appreciated

Cheers!

 

[Lou98GSX]

i ran my gsx both ways and it was to loud for me and it drew to much attention . as for boost control i didn't see any difference . i believe as long as you run an external waste gate you shouldn't have any problem with boost control .

 

[Guillaume]

i ran my gsx both ways and it was to loud for me and it drew to much attention . as for boost control i didn't see any difference . i believe as long as you run an external waste gate you shouldn't have any problem with boost control .

Good the know, I run an external Tial WG so I shouldn't have to much problem I guess...

 

[My1GLaser]

Here's the best I can get without it being on a lift or on jack stands.

 

[Guillaume]

^^ Looks good! I might try something like that as you get best of both world and I wouldn't need a new o2 housing

 

[417EricM]

You won't see a huge difference in performance. I'd monitor your boost afterwards though, you may see a fluctuation compared to before.

 

[89Patches]

If your doing this to draw less attention I don't think it will work Gui.

Because for the waste gate to start making noise your getting into boost and when you get into boost with 600whp your going to accelerate very fast drawing much attention.

Either way your car is still going to be loud and draw attention. Also you have a 1G which by it self draws much attention. Lol even looking behind your car will draw attention with that JMF fuel cell hanging back there

 

[turbo98eclipse]

Here's the best I can get without it being on a lift or on jack stands.

Does that run the whole length of the car?

Edit:: never mind I just read your original post again

 

[Guillaume]

If your doing this to draw less attention I don't think it will work Gui.

Because for the waste gate to start making noise your getting into boost and when you get into boost with 600whp your going to accelerate very fast drawing much attention.

Either way your car is still going to be loud and draw attention. Also you have a 1G which by it self draws much attention. Lol even looking behind your car will draw attention with that JMF fuel cell hanging back there

I know... I'll try to paint that fuel cell black or something... But I guess you're right about not attracting unwanted attention while flowing 70lbs... it could be challenging.

Cheers!