turbo issue
08-15-2010, 12:45 PM
#11
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thanks
08-16-2010, 04:41 PM
#12
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If the rings haven't sealed yet they never will and it's a bad build. Not sure how your PCV system is setup but you may have a bad check valve allowing excess pressure into the crankcase. I personally will not run a closed PCV system on a performance turbo build.
Not sure what kind of cubes your motor is but an 02+ LS6 cam should spin up to 6400 rpm and peak around 6000 rpm on a 5.7. If it's peaking way earlier than that than your turbo is too small.
Not sure what kind of cubes your motor is but an 02+ LS6 cam should spin up to 6400 rpm and peak around 6000 rpm on a 5.7. If it's peaking way earlier than that than your turbo is too small.
08-16-2010, 06:30 PM
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If the rings haven't sealed yet they never will and it's a bad build. Not sure how your PCV system is setup but you may have a bad check valve allowing excess pressure into the crankcase. I personally will not run a closed PCV system on a performance turbo build.
Not sure what kind of cubes your motor is but an 02+ LS6 cam should spin up to 6400 rpm and peak around 6000 rpm on a 5.7. If it's peaking way earlier than that than your turbo is too small.
Not sure what kind of cubes your motor is but an 02+ LS6 cam should spin up to 6400 rpm and peak around 6000 rpm on a 5.7. If it's peaking way earlier than that than your turbo is too small.
thats with a gt4202 with a 1.15 ar
08-16-2010, 07:03 PM
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Not sure what to tell you other than I can't remember how many LS6 cammed 5.7 turbo cars I have tuned and every one of them has peaked around 5900-6100 rpms with an appropriately sized turbo. That graph you posted shows peak HP at 5100-5300 rpm which I have never seen with a 5.7 and an LS6 cam.
08-16-2010, 07:11 PM
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Not sure what that dyno graph has to do with his problem but OK. 
53RUSSELL, I would start with a leakdown test to see if anything looks amiss and go from there.
53RUSSELL, I would start with a leakdown test to see if anything looks amiss and go from there.
Last edited by NicD; 08-16-2010 at 07:17 PM.
08-16-2010, 07:20 PM
#17
just showin quick and the OP that the LS6 cam spins just fine up to 5600-6100 with very minimal drop off lol.
here is another https://www.performancetrucks.net/fo...9&postcount=32
If the engine is vented correctly and there is nothing wrong with the tube itself, then considering the engine was just built, id assume something is wrong there. like said, compression test and go from there.
here is another https://www.performancetrucks.net/fo...9&postcount=32
If the engine is vented correctly and there is nothing wrong with the tube itself, then considering the engine was just built, id assume something is wrong there. like said, compression test and go from there.
08-16-2010, 07:44 PM
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just showin quick and the OP that the LS6 cam spins just fine up to 5600-6100 with very minimal drop off lol.
If the engine is vented correctly and there is nothing wrong with the tube itself, then considering the engine was just built, id assume something is wrong there. like said, compression test and go from there.
If the engine is vented correctly and there is nothing wrong with the tube itself, then considering the engine was just built, id assume something is wrong there. like said, compression test and go from there.
Either way yes it needs a leakdown to see what's going on with vents and popping dipsticks.
08-16-2010, 10:36 PM
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Not sure what to tell you other than I can't remember how many LS6 cammed 5.7 turbo cars I have tuned and every one of them has peaked around 5900-6100 rpms with an appropriately sized turbo. That graph you posted shows peak HP at 5100-5300 rpm which I have never seen with a 5.7 and an LS6 cam.
that ls1 above had 4" all the way back, and is truck manifold setup
unless the cars you tuned were different then others that have had bad luck
also foose truck is a 4.8. a cam that is designed for a larger motor will carry further then it does in the larger motor in a smaller motor. thats why my cam pulled close to 8k.
08-17-2010, 06:17 AM
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I agree with quick. Block everything off and vent it. I would also vent the oil fill cap. I was blowing the dipstick out until i closed the pvc and vented everything. I might have $30 invested in vent filters. Thats my .02. Good luck!