Why do I have boost before throttle body but not after and into the manifold
11-15-2006, 01:24 PM
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Why do I have boost before throttle body but not after and into the manifold I have a 98 camaro with a procharger and I am getting boost into the supercharger plenum and all the way up to the throttle body. There is a vacuum port with a nipple sticking out the top of the throttle body that appears to be just before the throttle body butterfly plate. The map sensor at the back of the manifold or the brake booster vacuum lines all show no boost once you measure past the throttle body like in the manifold. Anyone have any ideas? I have heard that there may be some type of anti backfire ports in the manifold and if that is true will it affect boost going into the engine.
11-15-2006, 06:16 PM
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we are measuring the boost on the dyno with two boost gauges (one in the supercharger plenum and one connected to the brake booster vacuum line). At 25% load on the dyno and half throttle we see 6psi in the supercharger plenum and no boost at all on the manifold gauge. At WOT we see 9psi (advertised psi from procharger) and only about 2psi from the map sensor or the gauge tee'd into the manifold. Is the manifold bleeding off boost. I checked for leaks and can't find any. We have a smoke machine and everything is sealed up nicely. Can you get the burst panels to install in the stock manifold and would this solve the problem? This is definately weird and have not yet experienced anything quite like this.
11-15-2006, 06:33 PM
#6
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Originally Posted by CTP Racing
There is a vacuum port with a nipple sticking out the top of the throttle body that appears to be just before the throttle body butterfly plate.
Intake manifold pressure MUST be measured on the engine side of the TB. otherwise, the "pressure" you are seeing, is simply the air being forced against the closed throttle blade.
It would be interesting to see how high that gets when you shut the throttle at high rpm's !!!!!
Where is the supercharger plenum ??? What car is this ??
Some cars will have a one way valve in their brake booster line, so the servo does not see boost, only vacuum.
09-08-2007, 03:58 PM
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what cars would have a one way valve on the brake booster line? i have a 01 ws6 im referencing my bpv pressure from the booster line i'll build 5-6psi at wot then it drops to 0.
