boost creeping up...

[Joel W.]

ok , i have a custom boost controller, from an air regulator, and the dual port actuator with 7.5 lb spring. it worked very good with my old 2.5 in exhaust, super accurate, no overshoots, no creep.

I just swapped over to 3" turbo back system and now im experiencing boost creep. it hits 7,5 lbs then 8,9,10 slowly rises, makes me think i have a vacume hose leak but i dont see one. or hear one.

can anyone help explain to me what might be causing it and why it is happening after the new exhaust?

bit confused here...

 

[T34418L3ONE]

you have to readjust the mbc because you have less backpressure, i have to adjust my hk$ from night to day due to the change in intercooler effiecenty

 

[IHI-RHC7]

On most supras, intake, full downpipe and exahust = 10-11 psi...
with no boost controller.

 

[Joel W.]

On most supras, intake, full downpipe and exahust = 10-11 psi...
with no boost controller.

you have to readjust the mbc because you have less backpressure, i have to adjust my hk$ from night to day due to the change in intercooler effiecenty

hmmm. so what your saying is its normal to see creep with my setup, just due to the better flow? even if i was running the stock actuator without controller? i would still see this creep in boost...

i did see that i was at 12 psi before, then and after the exahust i was at 15 so i dialed the boost down a bit back to 12.

i do knowtice a difference in creep , last night it was cold and creep was worse, this am it was 30 degrees warmer and creep was less...

thank you both..

 

[Joel W.]

so does an electronic boost controller work better. any overshoots or creep with them?

 

[gixxer750]

occasionally...but you get the boost much faster with an EBC

 

[Joel W.]

hmmm,...why would it be faster spool with a ebc? the waistgate is closed on both mbc and ebc untill boost is achieved?

 

[GrimJack]

I'd be interested to know this as well.

Joel, I'd be willing to bet that if you ran a line straight from the turbo outlet into the wastegate, you'll be at 10-11psi. I wouldn't advise trying to set the boost controller lower than that, it's just going to be a PITA to get it working right.

 

[Joel W.]

ya its worth testing, i will try it and see..

 

[gixxer750]

I'm not sure why the boost comes on with a boost controller...

With no boost controller, and a dp, intake.....so on, you get boost creep up to about 11 psi by like 4k rpm.... with boost controller....when manifold pressure goes positive at 2500 rpm, I have a full 15 psi 200 rpm later at 2700....

 

[lagged]

4 washers got me ~10 psi which creeped to 15psi at higher RPMs.

 

[Joel W.]

cool guys thanks ... glad im not alone...