Boost Spikes!

[1sty]

Recently I have noticed a little boost creap.

From the start the car boosted to a steady 7.5 PSI, recently I has been hitting 8 PSI and Tonight it hit 10 PSI!!!!!!

I test ed some and found that the boost sits around the 7.5 in second and 3rd but can creep to 9-10 in 4th and shakes like a bastard around 8 PSI in 5th, I mean the needle on the guage shakes not the car.

Is there anything I can do about this or is there a mechanical failure?

I assumed I should just back down the waste gate?

 

[spoolinmp3]

cold weather will make your car boost spike.
You have to be careful because each higher gear produces more load subsequently raising the boost.
This is like a double negative on the motor since high boost is bad and its even worse in higher gears without accurate timing and fuel control.
Other things that will cause the boost to be higher is a big exhaust and downpipe.
Leaks will actually show a lower boost pressure....
Be careful 10 psi is very dangerous on a FMU setup......we dont want another PRO 5 incident

 

[1sty]

What might cuase a car to do it other then weather?
It is actualy 20 degrees warmer here then it has been.

Also my exhuast is only a 2.25" so nothing huge.

I was scard to death when I saw that guage reach 10 and I always watch it if I am on the throttle for more then 3 seconds.

 

[chdesign]

the colder the air the more dense and the more dense the more O2 content thus you are burning more effieceint and pushing more exhaust gasses. Another thing I know about is the small orifice that the intragal wastegate on the T3's use. The swing valve is right at 3/4" and the exhaust gasses are very turbulant in that area with that small a hole and as much gas is being pushed through sometimes it doesn't work as well as it should a external wastegate might solve that problem as a 35 mm valve such as a deltagate is almost twice the size of a T3 swing gate assembly opening allowing for more effiecient bypass of the exhaust gas.

 

[Kooldino]

I don't understand how overboost can happen...i mean the wastegate cracks open at X PSI, right???

 

[1sty]

It should but mine is messed up or something. Basicly was only boosting to 7.5 PSI in any gear and that was trhough 5 months where the temp was everywhere from 70 degress out to 0 degress out. Now the car will spike in 4th or 5th gear to 8.5 and if I stay on it to 10 PSI. 2nd and 3rd dont show this problem but I assume thats becuase i am not in them long enough for the boost to get that high.

 

[I-Am-Chris]

like he said the higher the gear the more load on the engine...more boost. Are you running a boost controller if so what kind. If it a blitz or a greedy or something like that, try turning the gain down if not then hum turn the boost down.

 

[1sty]

Just the waste gate that came with the kit. I know for a fact temperature has nothing to do with it, I think something is mechanicly messed up.

 

[LinuxRacr]

Since it has been colder down here, I have been spiking to 7 PSI. I just watch the gauge, and adjust my pedal pressing accordingly. When it warms up during the day, it doesn't do this. Be careful...10 PSI!

 

[1sty]

Is it possible that the Waste Gate wears itself out after a while and becomes less compliant cuasing it to stay closed longer, I would think it would work the opposite but with rusting up hear I hink this would be a possibility.

 

[I-Am-Chris]

Yeah but if he gao a new turo with his kit then it shouldnt be wearing out yet, not for a while

 

[1sty]

Yes, its a new turbo and waste gate

 

[spoolinmp3]

Sometimes things malfunction, see if you can get the turbo warrantied, if you think its your wastegate