sublimeracing

I was wondering if a pop off valve (not a BOV) would save me from boost creep? I have an 88T2 and am getting a downpipe, presilencer, and midpipe running to dual apex N1's. I am hoping on running between 10-12psi. I just spent $8,000 on all new engine parts. About everything got replaced.stupid pd Anyway I don't want to risk blowing my engine. I know I need to rewire or get a new fuel pump but was wondering if this will prevent boost creep with my stock waste gate?

Dyre

Pop-off vavles are a last step saftey measure, not a boost controller.

What year is your TII
If you spent $8k on a damn motor you should have at least taken the couple hours to port the **** out of your wastegate, or convereted the the seires 5 mani and turbo for $300 if you have a Series 4 TII.

sublimeracing

RETed

Pop off valves are very hard to set correctly (at least the HKS ones).&nbsp Or more accurately, the pop off valves do not trigger consistently at the same boost level.

As Dyre said, it's a last resort safety device.&nbsp Don't try and set it very close to your maximum boost levels.

Port your wastegate - this will minimize boost creep.


-Ted

Grizzly

How do you set them up? i know it sounds daft but how can you tell if its set correctly?

Is it a case of seting it to a level that is max for your car then run under it?

Do you have to hit the limit to test it?

What happens if its to high?

Freaky Monkey007

Isnt a pop off valve to keep the exact opposite of a BOV?? It keeps excess pressure from hittin the turbo right??

RETed

Adjust...pound your car, watch boost gauge...stop, adjust...do it all over.


Yes, basically.

No.&nbsp I would normally adjust it down till it triggers and back it off just a tad.

If it's set too high, it will never trigger...



-Ted

RETed

Think of a pop-off valve as a safety release valve.&nbsp Back in the day (even now), there were chances that a wastegate can get stuck close - this means instant stratosphere boost!&nbsp The pop-off valve is designed to blow off to prevent damage from such an event...



-Ted

RICE RACING

There is a company called NIZPRO in Melboure Australia that does not use wategates at all on their cars, they conrol boost via a pop off vale electronically controled via a MOTEC engine managment computer.

I have personally seen it on a few of their cars, It does work very very well and saves the worry of adding extra pipes etc to run a WG, only problem is you need a MOTEC to run it this way.

I believe if it was done in a mechanical (not via ECU) way that it would be inferior to a WG system.

RETed

That's almost like running a wastegate on the compressor side.&nbsp I've seen this done on a turbo'd Chevy Impala SS that popped up at the SEMA 99 show...

It made me cringe to think the turbo overspin it's going to attain when it does trigger!&nbsp I guess if you're running BB centers it should stau together, but 150,000+ RPM is not my idea of keeping everything safe!



-Ted

RICE RACING

Very good point !

She would be a "free spinner" at WOT @ 8000rpm with no bypass on the turbine !

I shudder to think what rpm's it would go to ?

Though they are a linked system....so if PR remains under contol, then rpm should be in check as well.

maxpesce

Using a POP-OFF valve alone to control boost is a good way to destroy your turbos - A wastgate reduces the amount of exhaust energy spinning the turbo, a BOV just releases charge air and nothing to reduce the exhaust energy reaching the turbine, thereby allowing the the turbo to overspeed.

RICE RACING

I agree with that theory as well, I wonder why some companies are doing it this way though?

Am I missing something ? I have to agree, on the face of it, as when a blow off valve opens PR goes to 0 but the turbo still spins at 50 000rpm or more for quite a while ...... Hence with a POP system the turbine will have to over speed if there is no reduction in mass flow rate to the turbine (which there is not).

I think I am right? , oh it's too early for me

peejay

What kind of turbine wheel/housing do they run?