View Full Version : kill myself- die car. post your overboost probs

02-23-2006, 06:11 PM
so it's at a shop who's had it for awhile now and cannot figure it out. i'm probably gonna pick it up this tuesday and bring it to another shop who won't be able to figure it out.
car has sr with rebuilt bottom end. stock head. stock cams.
hks knock-off bov. apprently not leaking.
also has greddy profec b.
turbo is a gt2871r .64 ar
with actuator bypassed it craps itself. with flapper open same deal.
it'll boost to around 24-25 lbs before it starts to break up hard.
i cant figure it out.
this shop is baffled and they have seen tons of sr and 2871r equipped cars.
i really don't know what the fu(k else to do at this point and am WAY past frustrated. (i've been bumming rides for 3.5 weeks now as my daily driver s14 dies in storage...)
hoping someone went through something like this already and could post up about it.

02-23-2006, 09:36 PM

02-23-2006, 10:41 PM
arn't you boosting a little too much. I believe 18psi is near the top of its efficency. I did a setup for someone. Made 312hp 310tq @18psi. 740cc injectors, FPR, ROM tune, Greddy RSPL intercooler, HKS valve

02-23-2006, 10:42 PM
arn't you boosting a little too much

Welcome to the thread about overboosting.

02-24-2006, 11:06 AM
arn't you boosting a little too much

Welcome to the thread about overboosting.

thank you kookz, and damnit jon i dont wanna do that.
i want to know what is wrong.
and many people boost more than 18 on this turbo.

02-24-2006, 11:30 AM
ive boosted 19.5 psi on the 2871 . 86 and have meade 325 whp 319 tq with stock cams intake and exhaust mani's no over boosting problems. boost controller greddy profec b spec 2

ive also done a .64 which which oddly enough doesnt have a problem with over boosting but wont hold boost till rediline hits 19.5 psi then bleeds off to 17-17.5 by redline.

02-26-2006, 04:32 PM
any ideas whats wrong with mine then?
it doesnt just kinds sorta spike btw- it just builds boost unchecked until it breaks up hard. not enough spark to handle it im guessing.
ive considered vosko's solution, but don't want to unbless i have to.
a friend has told me i should add a cat and port the hole and go with a bigger flapper. that could work too, i guess, but i dont want to do that either. i want to know what's wrong and no one can figure it out.
totally stumped...

02-26-2006, 04:46 PM
tried something as easy as just another boost controller? im sure someone would let you throw one on real quick, or since its a shop they should have one. specially since they cant figure it out

all else fails just use vosko's idea. its the best

02-26-2006, 06:34 PM
Port the internal gate, easy to do and should solve your problems.

02-26-2006, 06:49 PM
Vosko was telling me about this situation the other day. Even running directly off the wastegate spring (no boost controller) the same spiking occurs. Even with the gate wide open it still builds boost? Very weird.

02-26-2006, 09:16 PM
Thsi may seem like a really stupid question, but is that the GT2871R in the picture you posted??

Cuz it looks like a T28, nowhere near lloking like a 2871 http://forums.freshalloy.com/images/graemlins/confused.gif

02-26-2006, 11:02 PM
That picture is from www.full-race.com (http://www.full-race.com) showing fitment of the manifold, it was Vosko's way of suggesting tubular manifold + external gate.

02-26-2006, 11:09 PM
Thsi may seem like a really stupid question, but is that the GT2871R in the picture you posted??

Cuz it looks like a T28, nowhere near lloking like a 2871 http://forums.freshalloy.com/images/graemlins/confused.gif

That's not his turbo, Vosko posted the pic with the intent of suggesting adding an external wastegate, lol... the 2871 does come in a t28-style compressor housing now tho...

EDIT: damn, beat me to it

02-26-2006, 11:10 PM
That picture is from www.full-race.com (http://www.full-race.com) showing fitment of the manifold, it was Vosko's way of suggesting tubular manifold + external gate.

you betcha! kooks is 100% correct, that is a picture borrowed from full race

i still say ex wg is the way to go..... i had nothing but problems with my old GT25R + hks actuator internal wg.....

02-26-2006, 11:36 PM
i have boost creep problem too. butim using the hks style turbo outlet and i had to smash the flapper pipe to clear the steering column, i think taht is my problem, im gonn upgrade to the greddy one.

02-26-2006, 11:52 PM
I had the same problem with my gt2871r .64, http://forums.freshalloy.com/images/graemlins/beatdeadhorse5.gif what the cause was for me was the actuator rod was to short so it clamped the flapper shut to tightly i couldn't loosen it anymore without it falling off. What I did was get a another rod and cut and welded them together for extra length.. It works ok now but does like to creep to .9bar with the boost controller turned off. It holds my low boost setting 1bar quite well it creeps to 1.1bar at high rpms the high boost setting 1.2bar it holds pretty flat haven't tested it on the road yet but was ok on the dyno.

Loosen up the rod if you can?

02-27-2006, 07:25 AM
Oops! Thought that was your pic!!

you can get the HKS actuator for the 2871R. Apparently the turbo is not fitted with an actuator from Garrett. So the vendors put the WG on themselves. I bought mine from Enjuku, who get them from Precision. You may be having a WG problem like he said. Look into it and price the HKS one if thats the issue. They are fairly cheap.

02-27-2006, 11:20 AM
flapper held WIDE OPEN this still happens. it doesnt creep- it just keeps building boost till it cant anymore. (breaks up nasty)
i actually had my old man make a slightly longer rod for the actuator so i should have no prob holding a lower boost. that's not even the issue though.
if anyone on the internet can figure this out i will paypal you $20.
this is retarded.
external wastegate would work i guess, but i shouldnt have to do that.
if all it did was spike or creep a little i wouldnt even care. at all.
ideally i want to run 17lbs low boost and 21lbs high boost. i have what i believe to be a goood working old profec b on teh car.
or if anyone wants to come to my house with a shotgun and blow my brains out i will give you $50 cash.
thanks guys.

02-27-2006, 02:03 PM
Maybe a torn vac line to the gate????
have you tried to replace the gate with a known working one???

i woudl also say that external is thew ay to go.. lots more room for the exhuast to move. lots more controll

02-27-2006, 02:04 PM
also, does it do it witht he boosty controller totally disconnected???? just running off the intake mani?

02-27-2006, 02:05 PM
it always does it.
vacuum lines were checked along with all the other possible parts.

02-27-2006, 02:17 PM
cracked wastegate flap. This sounds like that. Take the 02 housing off and look at the back of the wastegate flap. You may find some cracks.

02-27-2006, 02:38 PM
Who/where did you purchase the turbo from? I would definitely be giving them a call.

If the flap was cracked, it would be bleeding exhaust, not making any boost, which is the opposite of whats happening.

02-27-2006, 03:01 PM
What are your A/Fs and is your timing set correctly? Possibly your timing is off along w/ a rich condition causing combustion in the exhaust manifold?

You shouldnt have to, but porting the internal gate could solve the problem. Mabye it has a defect of too small an internal gate.

02-27-2006, 05:32 PM
or the gate itself is sticking, and the actuator cant pull it back.. or the actuator is bad

02-27-2006, 05:39 PM
There must be something blocking flow through the wastegate flapper.

Take your O2 housing off and open the flapper and make sure there is nothing in there, make sure your O2 housing doesnt have some bull**** on it that would stop exhaust from flowing through the wastegate opening

when you know for sure there is a clear path for the exhaust to go through teh wastegate before hitting the turbo and it still is spooling like crazy (which is a physical imposibility) then thank god because you must have gotten some sort of heavenly turbo or some [censored]

try it again with no wastegate just the flapper wide open

infact try it with the O2 sensor off and make sure there is a lot of air goign around the turbo. There def is not right now im going to guess something is clogging that opening somehow.

This is one [censored] up situation

02-27-2006, 08:49 PM
Yeah when I had the original rod unscrew itself allowing the flapper to open, all I could get was about 1psi if that.

02-28-2006, 12:13 AM
im over boosting hard. i thought i was making crazy power, 5.8psi spring. ive been beating on it for a week now and finally got a boost guage on it. my ka24de is spiking to 13 psi and i only have 370cc injectors in it. a wonder it didnt grenade...ssac manifolds suck i was happy cuz it didnt crack at all but the wastegate hole is so small no wonder im spiking.

02-28-2006, 01:15 PM
what kinda turbo outlet are u using?

02-28-2006, 07:04 PM
regular megan o2. not dented or f'd up in any way.
so get this- i picked up teh car today. when i arrived at the shop i was informed that it doesnt over boost any more. i asked what they did and was told nothing. i drove home 3 hours and it did not overboost. holds 12 lbs all day now. no idea why and the shop didnt know either. i tried to turn it up with the boost controller and that doesnt work. and the breaking up was something else apparently. they took out a little timing and it doesnt break up. for this turbo at 12 lbs the car seems pretty slow. (my roomate has a stock sr in an s13 with full open 3" exhaust and no boost control and his car seems significantly faster than mine. i drove his just a couple days ago.)
this car is a non-stop headache for me latley. dude at the shop also told me i probably need a new driveshaft carrier bearing. i was like, "huh? wtf" as it was fine when i dropped it off. sure enough i hear some weird clunking now sometimes. awesome.
thanks to anyone who attempted to figure this out for me.

02-28-2006, 07:15 PM
Probably a loose hose or something go to another shop next time i think? Turbo feels better once you get above 1bar tuning definitely help to. Goodluck