open dump pipe???

[turbo buicks]

tonite i got my exhaust dump pipe got put on. WOW! its not as loud as much as i thought but its got a lot more drone. it seems to have better low end torque w/the dump capped. probably due to the reduction of backpressure and my car being close to stock. i think it sounds mean i asked the guy who helps me tune my car and he said i shouldnt have to turn my FP up unless it starts to miss or anything else that would be caused by KR. i only took it to 10 psi to test it. cant wait to get it all tuned in. anyways, my dads like be careful b/c you can burn a valve w/an open dump. ive heard this before but some people say this doesnt apply to our cars due to the turbo. first of all, will running an open dump burn a valve and secondly, how is a valve burned by running a dump? i assume its b/c it runs leaner and there fore hotter but thats just my guess. anyone one know exactly why? overall i think this mod was pretty good investment seeing as how it was free.

 

[turbo buicks]

can running an open dump pipe in a TR burn a valve or not?

 

[Devil Car]

No you won't burn a valve. Driving with the dump open won't hurt your car. I drove my car with the dump open for at least 6 months straight.

 

[turbo buicks]

thank you devilcar

 

[TR Custom Parts]

Buy an electric exhaust cutout and have the best of both worlds. Quiet when you want and noisy on demand!
http://www.buickgn.com/electricexhaustcutout.htm

 

[turboman38]

Sorry but I disagree with your mechanic. You should bump you fuel pressure up when running an open dump. Open dump means more HP. More HP means more fuel used. Better to have too much fuel instead of not enough.

 

[b4black]

Even though you have zero back pressure with an open dump, this is after the turbo. Before the turbo (where the valves are) still sees PLENTY of backpressure (~2 x boost psi). That turbocharger thing is a pretty big restiction in the exhaust

 

[V8KILLR@msn.com]

b4black,
You CAN’T have zero backpressure!!!!!! If this were the case then the exhaust gas would not flow (static). In order to have flow there always needs to be pressure and a pressure drop. This pressure drop is why the fluid flows…………high pressure to low pressure, without it NO FLOW!!! It is simply fluid mechanics.

Jason

 

[UNGN]

Originally posted by V8KILLR@msn.com
b4black,
You CAN’T have zero backpressure!!!!!! If this were the case then the exhaust gas would not flow (static). In order to have flow there always needs to be pressure and a pressure drop. This pressure drop is why the fluid flows…………high pressure to low pressure, without it NO FLOW!!! It is simply fluid mechanics.

Jason

You can have zero back pressure (absolute) if your turbo exhausts into a vacuum (That TR thats blasts off into spce would be experiencing zero backpressure)

You can have zero backpressure (gage) if the static pressure after your turbo is atmospheric. Gas will still flow because the static pressure before the turbo is greater than atmospheric.

 

[V8KILLR@msn.com]

That was funny UNGN, hahahaha!!!!

This is true, but having a dump means that there is still a pipe that is between the turbo and the atmospheric. Hence it does not hit atmospheric pressure until the exist of the pipe. Therefore, at the exist of the turbo, before the start of the dump, there is greater pressure then at the exist of the dump pipe. This pressure drop causes the gas to flow.

 

[T-Type Mike]

Do you guys believe that there really is a big gain by opening up the test pipe? I have run without mine in the past and did not notice any kind of difference, with the exception of more downpipe problems?

 

[turbo buicks]

IMO, i have lost some low end it feels like. probably due to my car being close to stock.

 

[Roc87]

My GN feels slower with the Dump open. Never tried tuning it with it open though.....

 

[Go For 1]

If you open the dump, you will definitely want to increase your fuel pressure. Less exhaust back pressure creates a leaner fuel mixture, and typically an increase of 1 or 2psi of boost.

 

[Mr. Tee]

if you are saying to increase the fuel pressure...how much should it be increased?

 

[V8KILLR@msn.com]

Very well said Go For 1!!! Depending on what exhaust you have after the dump, you will have different power gains. I don’t think that there will be that much of difference in low-end torque with the dump open vs. it closed. If so, just launch at higher boost. Plus with the dump open, your trap speed should be higher.

Jason

 

[b4black]

Originally posted by V8KILLR@msn.com
b4black,
You CAN’T have zero backpressure!!!!!!

But you can have negligable backpressure, which therefore becomes zero.

Which has to do with the original question about burning valves. The backpressure before the turbo (which is where the valves are) is great, making the backpressure from the downpipe (with an open dump) insignificant, negliable and therefore zero.

Pressure is relative. So was my answer.

 

[turbo buicks]

V8KILLR, i have a stock exhaust and DP and no cat and the dump so i think my gains would be pretty good. i havent gone WOT yet b/c i am afraid of leaning it out and overboosting it. i leave it capped b/c of the noise and torque loss (if there is any) and so i can go WOT and not have to worry about it. after i get a scantool or go tune at my friends house who has the DS i can play w/the dump some more

 

[Go For 1]

Thanks Jason (V8KILLR)! Mr. Tee, if you open the dump, you will want to start over as far as tuning goes. You can either turn down the boost about 2psi, or you can increase fuel pressure about 2psi. This is an estimated figure, and your car may respond differently than others.

However, the key is to watch the KR and O2 readouts if you go WOT. You definitely don't want to go lean with the dump open. This is especially true if your exhaust is restrictive, and you open the dump.

turbo buicks, you will realize a good gain if you open the dump, but you're playing it smart by making sure you don't go lean. You can go either way as I mentioned to Mr. Tee, but octane may be a problem when the boost increases with the dump open. So turning down the boost would be adviseable. HTH

 

[V8KILLR@msn.com]

turbo buicks,
Sounds like a plan!!!! I will say this, do not put your $$$ into any thing else before you get a scan tool. It is very easy to over boost our cars.

b4black,
I am not trying to be anal, but the backpressure is not zero, nor is it negligible.

Thanks,
Jason