Boost Reduction

[jjm86m]

How do you reduce boost? Running 7psi on a Disco Potato and I need to reduce the psi to around 3-4 before I blow something up. I've already been advised to get the right equipment for a tune but I need a stop gap in between. My understanding is that a MBC wide open will only keep you running stock or +1psi due to the restriction in the line. Anything that will reduce the pressure and let me start low and increase slowly?

Thanks

 

[JasonBourne]

i sugest that you buy the MBC i think that will help you

 

[StealthWyvern]

i sugest that you buy the MBC i think that will help you

Just how is he going to reduce/lower boost with a MBC? I'm really curious on that....

 

[notme]

^ yes me too.

 

[JasonBourne]

with the MBC can you reduce and increse the boost? or not?

 

[StealthWyvern]

with the MBC can you reduce and increse the boost? or not?

you can only raise the boost above what the spring int he wastegate is set to. Only way to lower boost is to change out the waste gate. Yes you can raise and lower it but you cant go lower then what the wastegate is set to.

 

[HKPRO5]

You could probably get something to keep the wastegate open....

 

[StealthWyvern]

You could probably get something to keep the wastegate open....

like a check valve.. tha will keep it open all the time i would assume

 

[Carlinator]

Or just zip tie the wastgate actuator arm open.

 

[CHIQLES]

to lower boost on the stock wastegate you want the most minimal tension on the arm.
for the other waste gates with the internal springs same theory minimal tension spring would be the best. if you are useing the lightest spring already my thought would be to cut the spring a little so that you have even less tension on the flap. but thats the theory.

 

[CHIQLES]

if you zip the arm open youl have no boost

 

[codex]

7 PSI is 7 PSI, if anything the gt28 is safer since it takes longer to build boost. Cutting the spring will make it stiffer and increase boost.

 

[jjm86m]

If you have a closed face waste gate you wouldn't have access to cut the spring....

I have a forge wastegate that the mechanic couldn't use because the nipple was interfering with the turbo housing. Has anyone ever "clocked" a forge wastegate since the spring is replaceable to lower psi?

 

[CHIQLES]

waste gate with the threaded arm you can adjust the tension to the flap. the forge i thought came with 3 different springs so you could adjust the tension there.

 

[jjm86m]

Used the method below so the tension wouldn't be that adjustable since it's already cut. Used a different wastegate though since the stock gt2860rs is rated 12-14psi.

http://www.mazdas247.com/forum/showthread.php?123736940-How-to-Swap-MSP-Stock-Turbo-For-gt2860rs

Forge comes with the spring you specify. I'm wondering if anyone has replaced that spring by themselves.

7psi isn't really 7psi because while you are spooling up more slowly it is because there the A/R number is higher (62 vs 76) which would mean that you are pushing more air into your engine at the same pressure.

 

[SeR_Cyclops]

7 PSI is 7 PSI, if anything the gt28 is safer since it takes longer to build boost. Cutting the spring will make it stiffer and increase boost.

This is correct but wrong. It is the same PSI but their is more flow with the GT28rs so you are more likely to blow up your engine. I have read countless and countless arguments on this one. The fact is I wouldnt run anything more than 6psi stock on a 28rs because it equates to about 10psi on the stock turbo.

OH and BTW the 28rs spools slower but the time is not really noticeable. I hear it is about the same in all honesty.

 

[jjm86m]

Its pretty well documented that Zuku was running a GT2860RS at ~4psi. He recently sold his car, does anybody remember how he was running that low?

 

[2.0t03speed]

he had a forge wastegate. What mods do you have your aren't going to blow your s*** up at 7psi on a 28rs. I was running 10psi on a 28rs w/ a 505 intake mani no tune just stock ecu. The stock ecu was built for that setup tip into boost was low 11's with top end afr's being 12.3. I'm going to run 10psi again with a slightly smaller turbo (gt28r) proabably with even richer afr's then my gt28rs.

 

[jjm86m]

Hard Pipes w. HKS BOV, Bypass valve, CustomMSP SMIC, AEM CAI, Previous owner claims an upgraded intake mani.

 

[2.0t03speed]

replace your exhaust and you should be fine