# Boost creep / spiking



## CHRISSID6 (Apr 2, 2015)

Help needed.
I have a R33 Gtst RB25DET with a link g4 ecu and hybrid turbo. 
When at the mappers it was all getting setup on dyno and was getting a boost creep / spiking.
The mapper said that it could be cus the wastegate doesn't open enough and catching on my japspeed turbo elbow. Removed the elbow and put pressure into the actuator and the wastegate doesn't seem to open much more than before.
Contacted the mapper and explained. He said it could be the actuator isnt long enough to allow the wastegate to fully open so might need a new one like hks. After looking through the Internet and have found a few posts saying it creeps because the internal wastegate isn't big enough to allow the gasses out. So now I'm thinking of fitting a external wastegate. Anybody else done this? And did it solve the problem? 
Thanks in advance


----------



## Gojira-R32 (Jun 22, 2012)

boost creep internal wastegate not big enough OR actuator not opening internal wastegate not open enough.

i also whent frol internal wG to external WG, never regretted it.

Running also link wire in ECU, HKS GT-RS and external WG HKS standard one 35mm ported to 38mm with return pipe to exhaust system, no screamer


----------



## CHRISSID6 (Apr 2, 2015)

Well I'm sending my turbo back to be tested cus they said they never had a issue with all the other turbos they sold.
Where did you fit your external wastegate.


----------



## Gojira-R32 (Jun 22, 2012)

because i knew at front, the internal wasn't be able to get rid of enough exhaust gasses.

AND because no internal WG gives better flow in exhaust housing, thus faster spool, not much, but every little piece together gives a good end result


----------



## AlexJ (Apr 3, 2003)

Was boost creeping and spiking with the boost control turned off?

If not and if the hybrid turbo is fairly mild spec then it just sounds like they didn't know how to set up the boost control imo.


----------



## CHRISSID6 (Apr 2, 2015)

Your getting boost creep, turbo spools at 0.7 bar, which would be a good baseline if it stayed flat.
However boost climbs at a slow Rate as rpm rises and as it reaches 5500rpm it climbs aggressively to 1.4 bar.
This effect is replicated with boost control taken out of the equation by looping the comp cover feed to the actuator.

This is what the mapper sent me. He does seem clued up to be fair


----------



## AlexJ (Apr 3, 2003)

fair enough, if it is creeping that much with the wg actuator directly plumbed in then its probably a wg issue.


----------



## CHRISSID6 (Apr 2, 2015)

I've removed the turbo again tonight and looking at it again the wastegate orifice does look quite small. So sending turbo back to be tested and wastegate made bigger.
Fingers crossed that will cure it.


----------

