Boost Drops About 2psi Nearby Redline

[10MinuteCar]

i have a electronic boost controller (Greddy Profec B Spec 2), and the cars pretty much stock except a cat back exhaust. im having a top boost of 11psi but it drops to 8.7 nearby redline. what do you guys think the problem is?

I don't think i have any boost leak as i dynoed it to check and the unique auto sports guys says its normal for the stock turbo but they also said a cat back exhaust will help the boost drop less, but it didn't do that.

What do you guys think the problem is? i really want a full 11psi boost to redline.

by the way the car is GTT R34

Edited January 11, 2008 by 10MinuteCar

[10MinuteCar]

please help!

[r32woohoo]

sounds about right

get a split dump and front pipe to help the turbo breathe better in the upper rev range

[VB-]

yeah normal for stock turbo/dump arrangement

[10MinuteCar]

wait im so newbie that when you guys always say front pipe i don't get what it is. i know the dump pipe is the single pipe from turbo to the cat but wats a front pipe??

[eddieeeee-ro]

wait im so newbie that when you guys always say front pipe i don't get what it is. i know the dump pipe is the single pipe from turbo to the cat but wats a front pipe??

dump pipe is straight off the turbo, which leads into the front pipe which is just before the cat. aka dump/front pipe. u can get it in one peice.

[10MinuteCar]

so dump pipe will fix this problem of dropping boost?

[10MinuteCar]

also whats a downpipe? is that just a dump pipe?

[10MinuteCar]

do everyone drop 2 psi on higher than stock boost? even with a eletronic boost controller as well like myself?

[Dose Pipe Sutututu]

do everyone drop 2 psi on higher than stock boost? even with a eletronic boost controller as well like myself?

I use to have a case where my rubber intake collapsed causing the boost to drop once the engine bay was warm, and with the silicon intake pipe I purchased, IT MADE IT WORSE ended up going back to the stock intake, and reinforcing it with stainless steel off cuts. Problem solved.

I think the reason why your boost is dropping is due to your restrictive exhaust system. Invest in a dump & front pipe and a high flow catalytic.

[shnaped_second]

My 34 drops boost by around 4 pound on redline, i have the boost set to 14psi and by redline it drops to just below 10psi, get used to it mate if your going to keep the stock turbo

[tek_01]

It is normal, altho mine is dropping from 14psi to about 11psi

get a free flowing full exhaust system as suggested before to help it breathe better

i would of thought that standard turbs would be able to hold 11psi but i guess not

[R33Turbo]

is it possible to use a r32 actuator inconjunction with the EBC by any chance?

[R33Turbo]

just a question would a exhaust manifold leak cause the boost drop as mentioned before from about 11psi down to 9psi as well? or will it never even reach the 11psi in the first place?

[shnaped_second]

is it possible to use a r32 actuator inconjunction with the EBC by any chance?

Yes but you would be wasting your time, I have a adjustable hks actuator and it still drops off boost

just a question would a exhaust manifold leak cause the boost drop as mentioned before from about 11psi down to 9psi as well? or will it never even reach the 11psi in the first place?

Possible but it would need to be a big exhaust leak

[dmr]

even with upgrading to a bigger front/dump pipe, the stock turbo wouldn't hold anything over 10psi very well.

[R338OY]

just a question would a exhaust manifold leak cause the boost drop as mentioned before from about 11psi down to 9psi as well? or will it never even reach the 11psi in the first place?

I just had my leaking manifold repaired.

Problem was low boost from low rpms. Once i put the boot in it was hard to notice because there was lots of pressure and i made the 11psi my boost controller was set to.

Manifold leak (depending how severe) shouldn't cause high rpm boost loss. Like all the fellas said, it's normal for your setup to lose 2-3psi.

[jase-r34]

I run a GReddy profec on my GTT also and have found that just playin with the gain setting in particular can help stop the boost dropping off in the higher revs. Im only running 10psi hi boost and still playin round with the settings but have managed to get it pretty good and hold the 10.

I also have a 3" system off the back of the turbo that prob helps a bit too tho.

Good luck!

[R33Turbo]

I run a GReddy profec on my GTT also and have found that just playin with the gain setting in particular can help stop the boost dropping off in the higher revs. Im only running 10psi hi boost and still playin round with the settings but have managed to get it pretty good and hold the 10.

I also have a 3" system off the back of the turbo that prob helps a bit too tho.

Good luck!

oh great! since we're both using the same cool EBC could u gimme some advice on how to set the settings to hold 10psi boost please? from 1st step to last as ive never tried to touch the EBC myself but will do with the help of a pro

[jase-r34]

LOL i am hardly an expert!

Ive only had it on there for bout 2 or 3 weeks and been playing with it tryin to get it somewhere right.

just went and had a look at my settings and atm they are-

set: 40%

gain:27

set gain:6psi

its holding boost pretty well but needs more fine tuning. also been hard cause ive been trying to do it on my own...

My cars mods are just 3" turbo back and a K&N panel so pretty stock...

hope that was of some help to ya!

oh also just adding the peak boost with those settings was 10.3psi....not sure of the rpm(bit hard to drive and look at it lol)

Edited January 14, 2008 by jase-r34