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Discussion Starter · #1 ·
My car see’s 18psi in 2nd gear, is this normal. What are you other BPU guys seeing? I get poor traction shifting from even 2nd to 3rd.

My mods:
6-speed
Apexi Power FC Standalone/ still on MAF
HKS Exhaust Titanium
HKS Intake
Greddy 4 row Intercooler
Down Pipe 3 1/2 inch
MBC set at 18-19psi
 

· Boost4fun
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Well, 18psi is what BPU should see, right? I set my AVC-R slightly lower in 2nd to avoid the rear brake loose.. But basically: Why not?
Gerd
 

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When most say they are hitting XXpsi @ BPU levels they are referring to peak boost in higher gears, i.e. under maximum load. So 18psi in 2nd gear will result in 20+ for you in 3rd and above. That is too much, so you should turn it down a few psi.
 

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Discussion Starter · #4 ·
crossways said:
When most say they are hitting XXpsi @ BPU levels they are referring to peak boost in higher gears, i.e. under maximum load. So 18psi in 2nd gear will result in 20+ for you in 3rd and above. That is too much, so you should turn it down a few psi.
Thank you, I understand now. I will lower my boost.
 

· Will work for Supra parts
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If you're BPU and you have your boost set at 18 psi, I am just wondering if you have an a/f gauge yet? Probably a real good idea before you start turning up the boost beyond stock. You never know how safe you are till then. Even if the general agreement is that a stock fuel system will handle 18 psi safely, that doesn't guarantee your fuel system is 100% healthy.
 

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But bear in mind, with an aftermarket intercooler you can see boost beyond what you have your boost controller set to. This happens usually in cooler weather. We had a discussion on this recently, and many people, myself included with an aftermarket FMIC often see 20+psi with our controllers OFF in ideal weather conditions.
 

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Discussion Starter · #7 ·
Espeefan said:
If you're BPU and you have your boost set at 18 psi, I am just wondering if you have an a/f gauge yet? Probably a real good idea before you start turning up the boost beyond stock. You never know how safe you are till then. Even if the general agreement is that a stock fuel system will handle 18 psi safely, that doesn't guarantee your fuel system is 100% healthy.
My car was tuned on 18psi, with a/f reading mid 11s all the way across. Very conservative tune.

RRocket said:
But bear in mind, with an aftermarket intercooler you can see boost beyond what you have your boost controller set to. This happens usually in cooler weather. We had a discussion on this recently, and many people, myself included with an aftermarket FMIC often see 20+psi with our controllers OFF in ideal weather conditions.
Very true, I had this problem in the winter. My large exhaust piping with my large 4row piping made the small stock wastegate spike to 20+psi sometimes. There are way to fix this though.
 

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7THSIGN said:
There are way to fix this though.
How do we fix this? I'd be curious to hear....
 

· Stock Twins King
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RRocket said:
How do we fix this? I'd be curious to hear....
Try moving the BC pressure source from the IM to the "Y" pipe nipple on the turbo outlet area. This eliminates spiking I've heard. Now keep in mind that I havn't tried it as yet, but as soon as my new #2 gets here next week I am definately going to switch mine. This was a big discussion awhile back and at that time is was proven to eliminate spikes and "bucking" when rapid "lifting" off throttle. This is due to huge pressure drops when the throttle plate closes, yet there is still high pressure in the pipes. Creating spikes and back pressues.
 
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