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Thread: Procharger boost issues

  1. #1
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    Procharger boost issues

    See if someone may stumble on a eureka moment that Im missing. 5th Gen SS M6, cam longtubes and procharger. Didnt realize at first how small of a pulley customer had on D1SC boost would peak around 4800 and then fall which wasnt right. Put a very heavy spring in bypass valve to make sure that was staying shut, no change. Did the math and realized the 3.55/7.65 pulley combo at 7K would be near maxing this blower out and should make 15psi+, not the 8 and then fall down we are seeing.
    Attached Files Attached Files
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere

  2. #2
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    Depending on cam - a cam and longtube setup can cause up to a 6psi loss... Otherwise if procharger is functioning correctly - can only be a leak (intake, intake gaskets, restricted inlet, intercooler leak) - recommend smoke checking...
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

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  3. #3
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    So I capped the charge pipe into TB, and the inlet of the blower, and pressurized it up to 20-25 psi, only found two minor leaks, around the circumference of the blower hat (they always leak a little there but just the faintest amount) and the MAF card slot into the one endtank on the intercooler, checked the gasket to make sure it was in place its fine, just a very slight leak. Not enough to lose a pound much less the almost 10 we are missing.

    Next thinking was belt slip (although didnt seem to be dusting that belt much at all) so i grabbed a 4.38 pulley from another project and a smaller belt. Set tension according to ATIs instructions again. Obviously less boost but still hit a peak (5.6 at 5400) and then fell off - not right for anything centrifugal??? Makes less boost at 6100 than it does at 4100 rpm. On the motor a couple months prior the thing peaked at 6400 on motor and carried clean to 7100. This pulley combo with a cam I think most people see 8-9 psi

    Also, tried pressure testing intake, pinched off the brake booster hose in the back, and pressurized from the front of the TB back. Could hear air leaking but nothing major - in that when I pulled off a 3/16 vacuum cap the air that came out of the was 10s of times more and leaving that vacuum cap off wouldnt barely affect boost. A cracked intake would show up in the way of unusually low idle airflow readings needed for the thing to idle which I dont have
    Attached Files Attached Files
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere

  4. #4
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    I still haven't had the ability to look at a log in detail, but one thing did come to mind - boost is a resistance in airflow - are you somehow possibly floating valves? Just wondering with the new cam... Were springs installed, pushrods checked? Just some out there thinking...
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  5. #5
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    Lobe spring combo I've used before. Clean to 7k prior to blower with the setup

  6. #6
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    Quote Originally Posted by GHuggins View Post
    I still haven't had the ability to look at a log in detail, but one thing did come to mind - boost is a resistance in airflow - are you somehow possibly floating valves? Just wondering with the new cam... Were springs installed, pushrods checked? Just some out there thinking...
    Thats exactly what i was thinking. Had that issue late last year with a vortech blown foxbody...valves would start floating at around 5000 rpm and that was it. Put new springs in and viola probpem solved.

    The boost has to be going somewhere and i would assume straight out of the exhaust
    2010 CTS-V A6, Airaid CAI, 2.4 pulley, ported ls7 throttle body, ID850s, ARH 1-7/8" headers and X pipe, TR7IX plugs, MSD wires, Elite catch can, ZL1 lid and Track Attack HX

  7. #7
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    Had this problem on a challenger srt8 f1 procharger. the boost went away after I did a pulley change for 18 psi from 8 psi. The car ran great at 8 psi. I had a silicone 90 degree elbow on the intake side of the blower and it was sucking up tight against the inlet under wot. just a thought. I couldn't get anyone to stand right next to it on the dyne to see if that was actually happening so I pulled the elbow off and it had marks from the impeller. good luck!

  8. #8
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    That's what I meant by inlet restriction. Just not in so much detail ; )

  9. #9
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    when i first had my blower fitted i had 15psi at low rpm and then it fell off like a wave to 10psi at redline, all i done was a better w2a intercooler lowered iat bout 5 deg and 160 deg stat and i now keep 15psi all the way, could be a heat issue maby ?

  10. #10
    Senior Tuner mowton's Avatar
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    Quote Originally Posted by 07GTS View Post
    when i first had my blower fitted i had 15psi at low rpm and then it fell off like a wave to 10psi at redline, all i done was a better w2a intercooler lowered iat bout 5 deg and 160 deg stat and i now keep 15psi all the way, could be a heat issue maby ?
    Could have also decreased the pressure drop across the IC.

    Ed M
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

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  11. #11
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    Its the intercooler. We did one with their "race" inter cooler upgrade and was still seeing almost 30 psi in front of the cooler vs 15 after.
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  12. #12
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    BTW. it was a 2010 Camaro kit. We had to make a blower mount brace for it too. Just tightening the belt you could see almost .100 deflection in the blower bracket.
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  13. #13
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    Oh you mean procharger isn't perfect? Obviously it was the customers fault, someway, somehow..

  14. #14
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    Did this ever get resolved? I am having the same exact problems. 2700cfm Treadstone intercooler. Red race valve tick performance spec'd cam for my 408 with the f1a. Cannot for the life of me find the issue. No leaks. Was worried valve float.