Boost Issues, Help!

[dori34]

ok my car is getting tuned atm, the tuner told me that the boost opens at 10psi on low throttle but then it keeps climbing and climbing as the rev increase.

i believe the ext gate is running a 10psi spring but my tuner said if its changed to a lower psi spring, it won't help.

38mm turbosmrat ultra gate

turbonetics stage 2 T3 turbo 0.63/64 front i think

apparently my rear housing size is 0.48 and my tuner said this is causing it to have boost issues. (can anyone confirm?)

is there anyway to fix it apart from changing rear housings as the wastegate is welded onto the rear housing + finding another rear housing that matches my dump etc can take some time

any help much appreciated.

cheers

[Adriano]

Pull the spring out and see if it still overboosts

[dori34]

and if it does?

and if it doesnt?

trying all variables here before changing rear housing (which im pretty sure i wont be able to find one again so might have to change turbs )

[cheez]

if spring is removed car will show no boost cos the wastegate requires no pressure to open and thus u make no boost. if this is the case then the spring in the gate could be the issue so try that first.

some1 correct me if im wrong, but arent the ultra gates standard spring around the 15odd psi?

[dori34]

narh they are 7 i checked the turbosmart manual.

however the guy i bought it off had them upgraded to run 17psi

i took it apart and there were two springs (bigger - outter, and smaller - inner)

he got them from GCG so i will ring them tomorrow to confirm but im sure smaller is 7, bigger is 10

would a small rear housing like that cause this issue? (cause ive never heard of this problem b4)

[paulr33]

he left your car running unlimited boost?

[dori34]

no no

once he saw it hit past 15/16 he backed off

this is the type of rear housing that i have. there is smaller hole but my dump is just one piece from the main rear xhaust wheel, does it matter or should there be a small pipe going to the dump for this lil hole on the right off the exhaust wheel as well - split style dump?

[mad082]

now i'm not the most knowledgable person on this forum when it comes to turbos, but i would assume that the smaller rear housing should be limiting the boost as it would be choking more than a larger housing. i know that being smaller will make the gases flow faster but if the wastegate is going it's job then the gases shouldn't be getting to the turbine wheel to over boost.

my guess is that has to do with either the wastegate size (bigger wastegate will let you run lower boost as it can flow more air therefore letting less go to the turbo to raise boost), header design or something fouling in the dump pipe to block it or possibly something blocking the vaccum (boost) line from the cooler piping (or where ever you have it mounted) to the wastegate.

i agree with taking the springs out of the wastegate to effectively run no boost and see what happens

[cheez]

if there was 2 springs in the wastegate, actually in it, then ur pressure is higher to compress both, if ur saying its got 2 springs that come with it then run the smaller 1 only after u've tried runnin the car without a spring.

plus small rear housing isnt the issue, .48 tho it is small would limit your boost and effectively the amount of power your able to acheive.

then again it could be the wastegate flap fouling your dump pipe. first try the no spring method, then if that isnt working run it with a spring and no dump pipe and make sure the wastegate is opening and not ceased or anything like that. to check fouling, open the gate manually and place a rag in it to hold the gate fully opened, mount the dump and remove to see if the gate flap has moved after you remove the dump, its fouling your dump and there is your issue.

Edited June 19, 2009 by cheez

[mad082]

he has an external gate, so i highly doubt it is actually fouling as they work more like a bov.

just reading on the instructions for the wastegate, which spring are you using? the outer purple spring is a 7psi spring and the outher blue spring is 10 psi. the white inner spring is 7psi.

now for the obvious questions

and you have the hose from the cooling piping or where ever hooked up to the lower section?

have you actually tried to open the wastegate by pushing on it?

and finally, which of these best resemble your setup as far as the angle of your wastegate pipe is

[dori34]

thats what i was thinking, small housing won't do this, it would only restrict the top end & final power output

my gate is mounted like picture #2 but on less of an angle.

lower section nipple of the gate is hooked up to the turbo, thats how i left it when i dropped it off at the tuners but i dont know if he corrected it or moved it.

is this not the right spot & should it be best placed on the cooler pipe by tapping a nipple in?

i will try the smaller spring tonight, i have confirmed with GCG the smaller one is 7psi and the one currently in the wastegate is a 10psi one.

they arent turbosmart springs so they are different colour,

have you actually tried to open the wastegate by pushing on it?

no i haven't is it meant to budge or not budge at all?

if i take the spring out and try run it, what am i suppose to look for? is it suppose to boost or not boost?

if it boosts; what does that mean?

if it doesnt; what does that mean?

cheers for all the help guys, really appreciate it. sorry for all the noob questions, my first turbo car

[mad082]

well first i would take the wastegate off and try to push it open by hand (doesn't matter if the spring is in there or not). if it doesn't open then that is your problem. if you have the spring out of it it should move freely with little resistance. with the spring in it should take a pic of force (obviously).

with the spring out and the wastegate on the car, theoretically there should be no boost (or extremely little) when driving. this is because most or all of the exhaust gases should be exiting through the wastegate rather than spooling the turbo.

however because you only have a relatively small wastegate it may simply be that it cannot flow enough exhaust gas to not have the excess go through the turbo. and then the fact that the turbo is so small that the air going through it is travelling at high speed.

as odd as it sounds, to a certain extent the lower the boost you want to run, the bigger the wastegate you need, especially with a small exhaust housing. this is because it takes so little amount of exhaust gas to spin the turbo and create boost, but there is a lot of it coming out of the cylinders that the wastegate has to work much harder than a big turbo running high boost.

when you say your wastegate pipe is like diagram 2 but on less of an angle, do you mean more like pic 3, or less of an angle being more flat? if it is more like diagram 3 then that is probably also not helping the situation.

[dori34]

oh okay thanks for explaining that out to me.

so ive been test driving it ever since i got it back.

it holds 10psi fine until say 5500ish so it just climbs up top around 5500/6000 onwards which is near redline anyway in which i back off unless i flooring it each gear.

would this change anything or should i still check the wastegate still (by taking the spring out etc) ?

ill post up a pic of how its mounted on my housing.

cheers

[mad082]

ok well if it is holding boost up until 5500 then only rising after that, then it sounds like it is going to be a flow issue in the wastegate or dump pipe.

also how much is it actually rising by?

it may also be worth just moving the hose that goes to the wastegate to a different location just to make sure it isn't being caused by that. i have had issues with boost fluctuation because if it before.

[GT-RZ]

I would agree, The fact that it holds pressure up until 5500rpm and then after that the pressure creeps would point straight to the wastegate not being able to allow sufficient flow to hold lower pressure than 10psi. The wastegate is open but it still causes enough of a restriction to allow the pressure to increase.

Did you check to see if the wastegate can be fully opened with the spring not installed? If that's not the case then you will have to do some altering. could be a restriction anywhere, not just the wastegate.

Edited June 20, 2009 by GT-RZ

[dori34]

im going to test it without the spring tonight or tomorrow.

anthoer problem could be that the spring in there might be too long and cuasing it to have issues.

ill post back tomorrow of how it goes after i remove the spring a nd see how that goes.

boost rises to 15/16psi and looks to be still climbing but the tuner backed off and had around 1500rpm left