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| Boost issues http://forums.ctzcc.com/viewtopic.php?f=4&t=6229 |
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| Author: | ZjustinZ [ Sun Aug 07, 2011 1:23 pm ] |
| Post subject: | Boost issues |
So yesterday I installed a manual boost controller on my Z, had it set to 8psi. Today I took her out for a spin and had a boost spike up to 10. Now I thought the B.O.V. was supposed to prevent it from boosting over 8psi. Any ideas?? Also no matter what psi I'm running it makes that blow off valve pssssh sound. Is that normal? Its my first running turbo Z31 so just curious. |
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| Author: | Frank T [ Sun Aug 07, 2011 1:33 pm ] |
| Post subject: | |
Doesn't sound right, but I'm not a Turbo guy. Anybody? |
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| Author: | Mike_G [ Sun Aug 07, 2011 2:30 pm ] |
| Post subject: | |
The blow off is typical.. Is the boost control electronic or manual ? |
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| Author: | ZjustinZ [ Sun Aug 07, 2011 2:35 pm ] |
| Post subject: | |
Its a manual boost controller. |
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| Author: | Mike_G [ Sun Aug 07, 2011 5:17 pm ] |
| Post subject: | |
A 2 psi spike isnt all that bad. Check all your vacuum lines If any are old or deteriorating It can create a spike. Remember adding boost requires more fuel so dont go too crazy  I would turn it down and see If you still have it. Determine If its between shifts or on the top end.
The bov releases pressure from the intake and prevents compressor surge. When you let off when in boost the bov allows the compressed air out instead of bouncing off the closed throttle or surging the turbos. |
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| Author: | ZjustinZ [ Sun Aug 07, 2011 6:41 pm ] |
| Post subject: | |
I think for now I'm gonna turn it down and leave it at 7psi until I get a fancy electronic boost controller..looking for an old Greddy profec-b spec 1. I dont have a b.o.v. on my z...I heard it makes the car run rich unless you convert to map or use a blow-thru setup. Thats why I'm confused when my car makes the noise. |
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| Author: | Mark C [ Sun Aug 07, 2011 8:16 pm ] |
| Post subject: | |
Boost controller opens the wastegate, not the BOV. BOV releases accumulated pressure in the intake system when you let up on the throttle suddenly, so that pressure doesn't slow the spinning compressor down. If you are having boost spikes it can be because the wastegate is not large enough or not opening completely. If so, an electronic boost control won't solve your problem. If you have a mechanical boost control, your problem may simply be that it's not properly calibrated....you set it at 8 but it really is off calibration and allowing 10. Mechanical boost controls are basically just a spring, and they open gradually as pressure rises, instead of going straight from fully closed to fully open wastegate. A BOV should not have any effect on your mixture control, not sure where you heard it would.It keeps the turbine spooled up between shifts so you don't drop below the boost threshhold each time you shift, and you definitely want one. The simplest electronic boost controls let you set your wastegate spring for low boost but then you put the control valve in the pressure line that goes to the wastegate. The electronically controlled valve doesn't open till whatever pressure you set it at is reached, and the wastegate fully opens all at once. |
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