Boosting at 10 + lbs...WTF

[Tictakman]

I have no clue why im boosting above 8lbs. i have a 38mm tial wastegate w a 8lb spring. i really wasnt watching the boost gauge till the other day and when im in 3rd i can boost above 10lbs. i dont run a boost controller so the top nipple is not connected to anything. i have the side nipple on the wastegate connected to the compressor on the turbo. anyone have any ideas why or what i can do so that i dont blow the engine. could it be my boost gauge maybe? im watching my wideband and its not getting lean at all, i think the highest number i see when boosted is about 11.5 or so. anyone know? ill be at the detroit auto show this weekend so i dont know if ill have access to a puter.

Zak

[Structure240sx]

where is your boost guages source? are you positive you have the right spring in the wastegate? any leaks or cracks in any vaccum lines?

[klattr1]

typical if its really cold out.

[NX95240]

mine will creep alittle if it is cold outside.

[toki]

I can count the number of times i've heard of a tial 38 really creeping on a 7lb setup on... no hands. I definitly think there is another problem here, pinhole leak in the vac source to the wastegate would be my best bet.

[Tictakman]

my boost signal is at my fpr. ill change the line to the wastegate when i get back in town on sunday. hopefully that is it. the wastegate was bought brand new but i guess they could have made a mistake, what color is the 8lb spring.

Zak

[IvanAtSPRacing]

Your boost gauge may be off. Especially if its a cheap one.

[nissanfanatic]

I had the same thing happen one time. Turns out it was a kinked line.

Another thing you may want to check is the spring, like structure said. My turbonetics springs were painted the wrong color. How many did they send you? You should be able to tell by looking at it closely.

[rn240sx]

A lot colder than normal weather temps will do that..!! Like here in Florida its always HOT (80 deg or more)

In the winter it will drop down to the 30's for a week or two. Thats when my stock boost goes from 7.5 psi up to 11 psi..!!!

Cant stop that..!! Well unless u change out the wastegate spring...Just make sure ur fuel system can support 11 psi..

[daniel240]

do you have your wastegate dumppipe open or routed back into your exhaust system? if there is any restriction there, it will cause boost creep.

[toki]

alright dudes, I don't know where your wastegates are, but mine is on my manifold, and after my car has been sitting warming up for a couple minutes like any good ka-t should on a cold day, I personally wouldn't jump out and touch my wastegate. I somehow think latent heating might make it's way into that wastegate spring. The idea of the spring being colder and there for providing more tension is kind of...iffy at best to me.

[Projex240]

the temp of your wastegate doesnt matter.Colder air(as in the 20 degree weather here in columbia sc) hitting a FMIC will cause the air to be denser, thus raising the boost pressure in the manifold.

class dismissed...j/k

-Josh

[TrunkMonkey]

the temp of your wastegate doesnt matter.Colder air(as in the 20 degree weather here in columbia sc) hitting a FMIC will cause the air to be denser, thus raising the boost pressure in the manifold.

class dismissed...j/k

-Josh

what Josh said while i was typing....

colder air is much more dense. it gives the effect of having a larger compressor. same psi, but more air. if you're relying on just your wastegate to control your boost, it won't be able to keep up.

-demetrius

[toki]

.....

wastegate opens dependant on manifold pressure if it is hooked up right. Your arguement makes no sense unless the wastegate was hooked up to a source before the intercooler.

[toki]

meh, if you say so. I just don't think an air temp difference like that would be enough to make a 38 creep. I very well could be wrong here, but 1.5" can move some exhaust.

[TrunkMonkey]

.....

wastegate opens dependant on manifold pressure if it is hooked up right. Your arguement makes no sense unless the wastegate was hooked up to a source before the intercooler.

it's hooked up to his compressor...BUT

he can still experience boost creep with the cold weather if his signal came from the intake manifold. wastegates don't react very quickly by themselves. that's why the springs are designed to open BEFORE the desired psi.

-demetrius

[Tictakman]

ya the signal is coming from the compressor side of the turbo. i ran it tonight and it was doing the same thing(25 degrees). im running an autometer boost gauge so its not the cheapest. im running 370 cc injectors w a walbro and it seems to be keeping up fine from what the wideband is saying. i hit 11 lbs right at the end 3rd gear so it doesnt rise past that.

Zak

[TrunkMonkey]

i wouldn't worry about it if your AFR is 11.5:1.

-demetrius

[nissanfanatic]

If it still worries you, try getting the signal from the intake manifold. Good luck.

[virus77]

If it still worries you, try getting the signal from the intake manifold. Good luck.

That will raise the boost

[boostdesigns.com]

I can agree with that i live in panama city FL and when i go home to greenville SC to see family the colder air does mess with my 38MM by a pound or two the colder air will affect it. to compensate i took my wastegate feed from the turbo as short as possible with the largest vacume line possible i also use the hks evc pro and adjust it slightly and it brings it under control with no problems. when i return to florida i haft to change boost controller settings to put it back to normal but its dead on every time here. so yes if you have colder air it very well will affect the reaction of the wastegate.

[Tictakman]

ill try that out perry, if im reading it right i get the shortest line but with the largest inside diameter i can make work?

Zak

[Structure240sx]

yea the lowest i could boost on my .5 bar tial spring was 9psi