Rear turbo bleeding boost... bad cam?
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From: Murrieta
Rear turbo bleeding boost... bad cam? I've got an LS1 F-car with an STS kit. Only other mod is an off-the-shelf Comp 224/224 114 cam with XE lobes. The car feels kinda funny: it doesn't spool up until late (after 3000) and the boost builds really fast. The problem is at the top end the boost bleeds off, it starts trailing at about 4800 and by 6500 it's down to about 3psi. I'm pretty new to turbos here but all the hardware looks good, plumbing is nice and tight.
Has my cam got too much overlap, causing me to lose pressure on the top end, or am I troubleshooting in the wrong place? Should I switch it out for a Z06 cam and see what happens?
Throw me some ideas.
Has my cam got too much overlap, causing me to lose pressure on the top end, or am I troubleshooting in the wrong place? Should I switch it out for a Z06 cam and see what happens?
Throw me some ideas.
Thread Starter
Moderator
Joined: Apr 2002
Posts: 814
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From: Murrieta
Originally Posted by NYSS Guy
What size turbo are you running? How much boost?
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Verdad Gallardo I would guess the standard 60 trim is choking up top. I only say that because I experienced the same thing. But, I think valve float was contributing to mine. With the cam (and heads?) you are pushing more air, and it is making the 60-1 even more inefficient.
One other thing to check is leaks, like mentioned above. You can make something to check this using pvc pipe with a pvc cap from home depot. Drill a hole in the cap, put a valve on it, and seal it. Attach that to the pipe right after the turbo (heading to the intake), hook up a compressor and pump some air in there. It should hold, and if not you should hear the air escaping. Oh, don't forget to cap the side right at the throttle body. HTH.
One other thing to check is leaks, like mentioned above. You can make something to check this using pvc pipe with a pvc cap from home depot. Drill a hole in the cap, put a valve on it, and seal it. Attach that to the pipe right after the turbo (heading to the intake), hook up a compressor and pump some air in there. It should hold, and if not you should hear the air escaping. Oh, don't forget to cap the side right at the throttle body. HTH.
sounds like a leak to me, i have a 228/228 on a 115, so you arent that much "lopier" than me. and my car holds the boost all day long........ provided i get a better clutch, the stock one doesnt like 500rwhp 
