pop-off valves
 

I was on Rotary Performance's site and was curious about the Greddy pop-off valves. Is anyone using this, and does it eliminate boost creep? I am still planning on porting my wastegate when the open exhaust goes on. Is it worth buying? Also, where does it mount? TID?

if your consern is boost creep, then port the waste gate, do not get a pop off valve to stop the boost creep, and this is the reason why- you can install the pop off valve to open and vent boost pressure to atmosphe so your motor is only seeing say 10psi of boost, however, your turbo is still boosting and will easily over boost.. so your motor might see 10psi, your turbo is boosting 16psi... and guess what, in a very short time your tubo will take a dump. I have my waste gate ported and with a full intake and rb full exhaust, the max boost I see is 7 psi without the aid of a boost controller.

Thanks for a quick reply. What year is your TII? What have you done for mods? Does it still creep even a little with the wastegate ported?

a pop off vavle is a safty feature like a fuse. you set if higher then you are running. and if your wastegate or boost controler fail causing your boost to skyrocket. the pop off valve will open and vent it all to the air.

welp its alot easier/cheaper to replace a turbo than a motor....

yes they work good.

you still can get overboost and boost creep with a Hugely ported wastegate. (Voice of experience)

Jason

I have a hugely ported wastegate on my 87TII w/ open exhaust and TID and it runs a bit over 7psi as John L says, but when the air is cold in 5th above 140mph it has hit 11psi- so I guess it can still creep (although I probably couldn't go much over that speed if it didn't!) You really have to try to get much over 7psi. Pop-off valve is great to protect against a freak overboost, but is not to be used as a bypass; its dumping metered air and allowing turbo to overspin (excessively heating the air charge and possibly damaging turbo.) Port that wastegate!

If you are running above stock levels of boost, get a POV!
I have gone through 3 engines because of creep, and wish I would have spent the extra $150 a long time ago!

Word of advice...these things are very hard to set very accurately; they do not always trigger at the same pressure under all conditions.&nbsp Mind you, this is strictly with experience with the HKS pop-off valve, and I have never messed with the GReddy unit (the GReddy unit has only been on the U.S. market for a few years now).

These things should not be set so close to your normal boost levels.&nbsp On a stock turbo FC, it really should be set as high as 14-15psi or so.&nbsp Remember, this is a safety device to trigger in cases of catestrophic failure.&nbsp Try not to use it as a band-aid to fix a slight creep condition.&nbsp Porting the wastegate should minimize boost creep.

I run a 1987 Turbo II with a ported wastegate - it's about 0.5mm of lip smaller than the single wastegate flapper.&nbsp I've got no problems with the turbo spooling to 0.7 kg/cm^2, which is about 10psi.&nbsp I run a 3" Racing Beat downpipe, 3" Racing Beat pre-silencer, single Walker Dynomax UltraFLO - so my exhaust flows very well.




-Ted

Thanks for all the replies. With an aftermarket turbo--lets say a T04E--and a huge wastegate--one that claims to handle 1000 hp--can you completely eliminate boost creep? And just for fun lets say I have a rewired fuel pump, 720 cc injectors, Apexi S-AFC, FMIC, and all neccesary upgrades to support a T04E. Hopefully soon this will be a reality.:D