Fresh engine with drift motion 3" downpipe and exhaust and aftermarket intercooler, drift motion modified oil pump, oil thermostat, cooler and filter relocator, now makes so much boost I get 12lbs at about 5000 rpms and hit fuel cut. Running stock turbo and wastegate, what is the easy way to lower (or control) boost? Can I change where the waste gate gets its hose pressure, or somehow modify the internals? What's the cheapest/best way to do this?
How to decrease boost
- Thread starter rustfarmer
- Start date
I have a cheap dial type in line valve I could use, but I thought that would limit the pressure the wastegate gets and thus increase boost by adjustment. You must mean something else. I'm new to the turbo stuff, so could you point me to the right kind of controller?
You can't go lower boost than what the spring rate of the wastegate is. Need systems that can allow you around FC; VPC, REBIC LC, Lexus AFM/550, standalone EMS, etc... Or stay off the gas pedal
Staying off the gas pedal is no fun! Can the stock wastegate be opened up and the spring trimmed, or can I buy an adjustable waste gate to use with the stock turbo?
Had a Similar Thing going on This might help
The Thread
http://www.supramania.com/forums/sh...earing-Rebuild-progress-and-Q&highlight=turbo
Porting page
http://www.supramania.com/forums/sho...gate porting
The Thread
http://www.supramania.com/forums/sh...earing-Rebuild-progress-and-Q&highlight=turbo
Porting page
http://www.supramania.com/forums/sho...gate porting
Lowering boost is really simple, unless the turbo can outflow the wastegate opening (which happens on a modified CT26). For most CT26's, you just install a weaker spring into the wastegate actuator (or use a worn out one from a used turbo).
Boost controllers can only increase pressure, not decrease.
Try a weaker spring first and then explore more complicated options.
Boost controllers can only increase pressure, not decrease.
Try a weaker spring first and then explore more complicated options.
12 PSI sounds like either a major boost creep issue (Need bigger/better exhaust) or else a shimmed wastegate to me. Check for washers in between the wastegate actuator and the turbo housing. If there are any, remove them.
If there are not, then what's boost at about 3000 RPM? Does it just keep increasing as RPM goes up?
If there are not, then what's boost at about 3000 RPM? Does it just keep increasing as RPM goes up?
FIXED I think. Turns out the new intercooler pipe was hitting the wastegate linkage and had it blocked, or so it seems. Boost now climbs to about 10 or 11 at full revs (or as much as I plan to spin it without a good tach) and no fuel cut. Thanks to all for your help!