Why do I boost in Neutral after dp install?
02-11-2005, 12:22 PM
#1
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Car Info: AWD TURBO wagon
Why do I boost in Neutral after dp install?
I have an 02 wrx with a stromung catback, gutted uppipe, and a stromung shorty downpipe with the divorced wastegate. Before I had the downpipe, when I was in neutral or had the clutch in, I could rev the engine and my boost guage (autometer if it matters) would never show any boost. Now after the install, I can get about 7-8 psi before getting to redline while in neutral. Is this normal?
02-13-2005, 01:00 AM
#3
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Well I doubt that I am getting a false reading from my boost guage. It is a simple mechanical gauge with just a single vacuum line going to a brass tee off of the bov. If there was some sort of a problem with the gauge (like a kink or leak) then I would be seeing less indicated boost than before, but the gauge is reading true because while in gear I still hit peak boost at about 14-14.5psi.
I didn't think that I would be able to boost out of gear or with the clutch in because there is almost no load on the engine, but it is doing it anyway. In fact, when I checked more carefully today, I saw that I was making almost 10psi before redline, when before the dp when I did the same thing it would just show less and less vacume, but never any boost.
Anyone else, maybe someone with an engineering degree, want to tell my why this is happening? I don't really mind that I can boost like this, but I thought that I understood the turbo system in my car, and this is pissing me off that there is something that I don't understand.
I didn't think that I would be able to boost out of gear or with the clutch in because there is almost no load on the engine, but it is doing it anyway. In fact, when I checked more carefully today, I saw that I was making almost 10psi before redline, when before the dp when I did the same thing it would just show less and less vacume, but never any boost.
Anyone else, maybe someone with an engineering degree, want to tell my why this is happening? I don't really mind that I can boost like this, but I thought that I understood the turbo system in my car, and this is pissing me off that there is something that I don't understand.
02-13-2005, 08:22 PM
#7
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Yeah, I am getting around 20" at idle, but when I rev my engine (aka "make the neighbors nervous" now that I have a downpipe) I can boost. I will check to see if I have a vacuum hose loose somewhere, but I think that it has something to do with how the wastegate is affected by the divorced tube on the downpipe.
Someone must know why it does this. Maybe Shiv or someone at Cobb knows?
Someone must know why it does this. Maybe Shiv or someone at Cobb knows?
02-14-2005, 04:58 AM
#8
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Car Info: 2002 Impreza WRX
So you are worried you boost when you rev it while you're in neutral? I'm not sure why this would be a problem.. I have to admit I don't have a boost gauge so I dunno if this is normal.. Remember that video with the WRX and the duck call strapped to its BOV.. it had to have boosted at idle too since they were just revving it to get the BOV to vent.
02-18-2005, 12:34 AM
#10
I'm assuming your putting the gas pedal close to the floor when you rev it? If so, seeing boost in this situation is normal. The reason that it didn't happen before the downpipe is because the stock downpipe was not allowing the turbo to spool as quickly and under such low load. You removed the restriction, so now you're seeing boost. No worries.... and BTW, that's the best way to get a good launch for a strip run.... rev to ~3000RPM, then before you're ready to go, floor it and quickly slip the clutch once the tach reaches 5k RPM. This way you build a bit of boost before you leave the line. Be careful as this can also be a good way to snap that tranny if you're not smooth with the clutch 
-- Ed
Equilibrium Tuning
-- Ed
Equilibrium Tuning
02-23-2005, 11:30 AM
#15
Originally Posted by AzN121184
hrm, i get max 1-3 psi's while just revving in neutral.
Is 7-8 psi's on the gauge normal Vaus? THanks
Is 7-8 psi's on the gauge normal Vaus? THanks
-- Ed
EQ Tuning