Lowering boost
06-18-06, 12:28 PM
#1
Lowering boost
Today I installed a Slowboy MBC that I won yesterday in a DSM club raffle. I followed the "Version 2" of the diagram below found on numerous threads here. The thing is, I am only using the MBC to LOWER my boost for now. My mods are:
K&N Intake
Stock Sequentials
eBay FMIC w/custom ducting
Downpipe
Catback
and some other reliability mods (koyo radiator, silicone hoses, new check valves hopefully this week, etc)
I plan to take the car to two weekend-long track events in July, and it's going to be hot. I have no fuel or engine management at this time, so I intend to make sure I'm not overboosting or running too hot by lowering the boost a few PSI. This is just temporary until I can get a PFC and have the car tuned properly. At this point I am more concerned with reliability than making power.
I installed the MBC, T'd to both wastegate and precontrol actuators, capped off the outlets of the actuators and set the MBC completely open. On the street the car pulls 7 or 8 PSI as expected which is great, but the transition pretty abrupt - it spiked a bit, but not over 10 psi. I figure using the "Version 2" setup to lower boost was never an intended use and by setting the MBC completely open I've made the boost spike worse. Any suggestions? Would increasing the boost a bit higher bring things into line? Should I just use the stock restrictor pill instead of the MBC for the PCA? Am I an idiot for even using an MBC when I could have just capped off the outlet of the WGA?
K&N Intake
Stock Sequentials
eBay FMIC w/custom ducting
Downpipe
Catback
and some other reliability mods (koyo radiator, silicone hoses, new check valves hopefully this week, etc)
I plan to take the car to two weekend-long track events in July, and it's going to be hot. I have no fuel or engine management at this time, so I intend to make sure I'm not overboosting or running too hot by lowering the boost a few PSI. This is just temporary until I can get a PFC and have the car tuned properly. At this point I am more concerned with reliability than making power.
I installed the MBC, T'd to both wastegate and precontrol actuators, capped off the outlets of the actuators and set the MBC completely open. On the street the car pulls 7 or 8 PSI as expected which is great, but the transition pretty abrupt - it spiked a bit, but not over 10 psi. I figure using the "Version 2" setup to lower boost was never an intended use and by setting the MBC completely open I've made the boost spike worse. Any suggestions? Would increasing the boost a bit higher bring things into line? Should I just use the stock restrictor pill instead of the MBC for the PCA? Am I an idiot for even using an MBC when I could have just capped off the outlet of the WGA?
06-18-06, 05:16 PM
#2
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If you just wanted to run 7 psi, all you had to do was remove the restrictor pill in the wastegate line. Or unplug the harness from the wastegate actuator at the front of the UIM. Don't cap anything off!
Either of the methods above will result in a smooth 7 psi with no transition spiking. KISS
Either of the methods above will result in a smooth 7 psi with no transition spiking. KISS
06-18-06, 08:05 PM
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Originally Posted by rynberg
If you just wanted to run 7 psi, all you had to do was remove the restrictor pill in the wastegate line. Or unplug the harness from the wastegate actuator at the front of the UIM. Don't cap anything off!
Either of the methods above will result in a smooth 7 psi with no transition spiking. KISS
Either of the methods above will result in a smooth 7 psi with no transition spiking. KISS
hey, remember i had a similar problem, u said dont boost over 10psi rite? my turbos are non sequential meaning bigger boost rite? how do i reduce the boost to under 10 psi? do i use a mbc or what?
06-18-06, 08:17 PM
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Originally Posted by 2xrx7
hey, remember i had a similar problem, u said dont boost over 10psi rite? my turbos are non sequential meaning bigger boost rite? how do i reduce the boost to under 10 psi? do i use a mbc or what?
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