05-07-2016, 03:19 PM | #1 |
Drives: 2009 Pontiac G8 GXP Join Date: Jun 2012
Location: Lodi, CA
Posts: 22
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loosing boost above 3500 rpm
Just got back from the dyno shop for the first run with the 2300 Maggie. Ran into a odd issue the car holds 10 psi boost until around 3500 rpm then drops off to 6 psi by 6000 rpm. Running a cog drive in rear 3.8 front pulley with super damper didnt see any signs of belt slip or the bypass opening? Was going to ask Magnuson on Monday just thought I would ask here as well.
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05-07-2016, 03:47 PM | #2 |
Drives: camaro ss\rs Join Date: Jun 2014
Location: Italia
Posts: 755
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are you sure that the bypass is not opening?
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2014 camaro SS Whipple powered ,3.750 pulley,ID850, CAI,Flowmaster American Thunder exhaust,MGW racing shifter,Bo White ported tb,MightyMouse Catch Can,Vitesse throttle controller,GM 3.91 rear end, Dynatech longtube haders, BTR Pd cam,Fluidampr stock pulley,ZL1 fuel pump and ADM fpcm, Phastek scoop and fluid thank relocation Bmr Motor mount . Tuned by Mastuning
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05-07-2016, 04:42 PM | #3 |
Drives: 2011 Camaro 2Ss M6 Join Date: Dec 2011
Location: Southern California
Posts: 4,013
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Take it to a better shop
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05-08-2016, 10:47 AM | #4 |
Drives: 2010 ss/rs Join Date: Jun 2013
Location: kansas city missouri
Posts: 247
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if you find the issue would like to know. having similar issue with mine. bypass valve has been replaced.
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rotofab cai
ported throttle body sp headers with cats loud mouth axle back no mufflers tuned by steve williams 6l80etuning.com bmr split springs cam motion custom camshaft btr 660 spring kit maggie 2300 id850 injectors livernois fuel pump |
05-08-2016, 02:43 PM | #5 |
Drives: 2013 Camaro SS 1LE Join Date: Oct 2014
Location: earth
Posts: 288
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what cam? what other mods do you have?
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05-08-2016, 02:50 PM | #6 |
Drives: Maggie blown LS3 vette Join Date: Aug 2009
Location: SE TX
Posts: 1,490
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Belt slip. Once you start making boost, the belt stretches. If the belt isn't the shortest one you can wrestle on there, the tensioner will run out of travel and lose the ability to keep the belt tight.
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05-08-2016, 06:42 PM | #7 |
Drives: 2010 ss/rs Join Date: Jun 2013
Location: kansas city missouri
Posts: 247
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I'm running the supplied belt with the 3.8 pulley and overdrive cogs.
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rotofab cai
ported throttle body sp headers with cats loud mouth axle back no mufflers tuned by steve williams 6l80etuning.com bmr split springs cam motion custom camshaft btr 660 spring kit maggie 2300 id850 injectors livernois fuel pump |
05-08-2016, 08:53 PM | #8 |
Drives: 2009 Pontiac G8 GXP Join Date: Jun 2012
Location: Lodi, CA
Posts: 22
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I found the smallest belt I could barly get on and its tension is super tight. Slid the adjuster pulley as close as possible to the tensioner
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05-08-2016, 11:28 PM | #9 |
Drives: 2015 C7 Z06 M7 Join Date: Dec 2012
Location: So-Cal
Posts: 651
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Could be belt slip, but a 3.8" pulley doesn't seem that small. How about calibration, have you logged throttle position? Torque management isn't closing the throttle is it? Just a thought.
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05-09-2016, 12:20 AM | #10 |
Drives: 2009 Pontiac G8 GXP Join Date: Jun 2012
Location: Lodi, CA
Posts: 22
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No pretty sure torque management is turned off even tired it without the air cleaner it ran worse.
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05-09-2016, 05:41 PM | #11 |
Drives: 2009 Pontiac G8 GXP Join Date: Jun 2012
Location: Lodi, CA
Posts: 22
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Well I have full boost!!! When I called magnuson and asked how to set the vacuum actuator after I removed it to install injectors they said to push it down half way. So I just pushed it down all the way and reset the set screw and now I have full boost. Thinking that the mid point might be a preset setting to keep it at its stock 6 psi boost.
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05-09-2016, 05:59 PM | #12 |
Drives: 2010 ss/rs Join Date: Jun 2013
Location: kansas city missouri
Posts: 247
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Great info! Glad you got it figured out
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rotofab cai
ported throttle body sp headers with cats loud mouth axle back no mufflers tuned by steve williams 6l80etuning.com bmr split springs cam motion custom camshaft btr 660 spring kit maggie 2300 id850 injectors livernois fuel pump |
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