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Discussion Starter · #1 ·
Ok, I need to reduce my boost from 3000 - 3500 rpms, in 5th gear because I think I'm hitting the surge line on my turbo at full tilt above 20 psi. As far as I can tell the Apexi AVC-R is about the only thing out there that will do RPM based boost.

I could probably do it with a bleed system connected to one of the GPO's, but I'd also like something that didn't fluctuate with air temps.

Any thoughts/alternatives?
 

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audifreakjim said:
Ok, I need to reduce my boost from 3000 - 3500 rpms, in 5th gear because I think I'm hitting the surge line on my turbo at full tilt above 20 psi. As far as I can tell the Apexi AVC-R is about the only thing out there that will do RPM based boost.

I could probably do it with a bleed system connected to one of the GPO's, but I'd also like something that didn't fluctuate with air temps.

Any thoughts/alternatives?
Either use the 034 or one of the Megasquirts you have along with one of the many WGFVs around. Should be able to map boost for all conditions. Javad messed around with this a bit IIRC, maybe he's got some more info.
HTH
Mike
'88 VW "R22"
 

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audifreakjim said:
I'm not sure where the MS stands on boost control thing, I'll probably try the 034 EFI GPO first. Now that I think of it I may not want closed Loop just yet, your boost gauge is a real easy way to see if you running to much retard in certain areas since it will make the boost go up.
Since you'd be using the MS only for boost control, it doesn't really matter what progress anyone has made WRT boost control. Simply hook a WGFV up to an injector driver. Scale the VE map something like this...
Low RPM-Low VE %s to keep out of surge
Higher RPM/ low load- Very high %s to ramp up boost fast
Maximum load(say 20psi)- set the VE %s to zero, turning off the valve, when boost drops below 20psi it'll get the valve going again. This'll all happen instantaneously, and since the MS interpolates between points, it should be pretty easy, and smooth. I'll be playing with this in the near future.
OTOH, since I'm pretty sure you can make the 034 control it, you might as well us it :)
Mike
'88 VW "R22"
 

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Hey Jim, yes, like Mike says, you can basically do the same thing with the 034 GPO, IME controlling max boost with a bleed valve is the best way to do it, that way your max boost is set and cannot spike past what you want it to, then you use a frequency valve to bleed the signal line beneath that, and using the diode trick, you actually can get very good resolution.

I agree with Mike, get it working via the 034, the best way to do it =)
 

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Discussion Starter · #8 ·
I think I'm going to give Eric F. closed loop Boost control on the MS a try. I've been running around town at around 2.44 bar absolute (~21 psi
) when it's warm, this morning in the cold, I was seeing 26, 27 psi of boost. The car handled it fine, but that's just way to much change for me. The goal is to get the car tunned for ~2.6 bar on the dyno, and then leave it there. I hope it's possible, my egt's shot past 1700 on a few pulls at this boost level, so I may be limited to small overboost times, or get a larger more efficient turbo.

On another note, I piped in another BPV, and the turbo response is much better, and my strange surging problem has been almost elimilated. I honestly think there's room for a third valve, even with two, if I don't shift really quick at redline, the amount of air coming out is just crazy!
 
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