Low RWHP????
04-28-2013, 01:46 PM
#1
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Low RWHP???? I really need some help here!!!
I have a 2004 GTO with a LS1
I have a stock bottom end other than ARP bolts, Fast 92/92 4" CAI
Stock 07 5.3 Tahoe 243 heads with dual lunati .670 springs and a 231/231 .605/.605 lift cam Texas Speed 7.40 pushrods
Blue demon 42# injectors and OBX long tube headers
Fuel pressure at idle 63# at WOT it drops to 58#
Problem I have is this combo is only putting 340 RWHP
I know this is exceptionally low.
Any ideas! I know the cam is installed dot to dot.
My tuner said it was off a tooth.
I have a 2004 GTO with a LS1
I have a stock bottom end other than ARP bolts, Fast 92/92 4" CAI
Stock 07 5.3 Tahoe 243 heads with dual lunati .670 springs and a 231/231 .605/.605 lift cam Texas Speed 7.40 pushrods
Blue demon 42# injectors and OBX long tube headers
Fuel pressure at idle 63# at WOT it drops to 58#
Problem I have is this combo is only putting 340 RWHP
I know this is exceptionally low.
Any ideas! I know the cam is installed dot to dot.
My tuner said it was off a tooth.
Last edited by 2004yjgto; 04-29-2013 at 06:28 AM.
04-28-2013, 01:55 PM
#3
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I did another gto with stock 241 heads .650 springs a fast 90/90 same CAI
And exhaust with a hot cam 2 and it made 400RWHP
So with that thought process this should be right there or better
Right?
The initial tune was changed several times due to being told we need this that and the other but as it went further down the line of other parts needed the RWHP actually dropped. The first tune made 389 but said fuel pump was bad then next was it needs injectors so put them in then MAF then it went SD now it's at 340RWHP.
Thanks in advance for any and all responses
And exhaust with a hot cam 2 and it made 400RWHP
So with that thought process this should be right there or better
Right?
The initial tune was changed several times due to being told we need this that and the other but as it went further down the line of other parts needed the RWHP actually dropped. The first tune made 389 but said fuel pump was bad then next was it needs injectors so put them in then MAF then it went SD now it's at 340RWHP.
Thanks in advance for any and all responses
Last edited by 2004yjgto; 04-28-2013 at 02:04 PM.
04-28-2013, 06:01 PM
#6
I don't think power is that far off. I would not expect a regular gas 5.3 to make the same power as a premium fuel 5.7L LS1, with a truck rear end and big heavier tires & wheels as a GTO with a smaller rear end and smaller, lighter tires & wheels. The GTO is not stellar, but the truck is not that far off from what I have seen.
04-29-2013, 12:58 AM
#7
I think hes saying the heads are from an 07 5.3
So stock 799s
It should be closer to 410-415 wheel in a 5.7 through a fairly light drivetrain
If it kept dropping after tuning changes thats where i would look first.
So stock 799s
It should be closer to 410-415 wheel in a 5.7 through a fairly light drivetrain
If it kept dropping after tuning changes thats where i would look first.
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04-29-2013, 07:46 AM
#10
What kind of dyno?
What's the A/F and spark?
Is it down a cylinder?
Does it have CATS? If so it is possible one or both are collapsing.
Too many unanswered questions. Too many variables. Need to find someone with a good diagnostic mind. Fuel pump, injectors won't make you low on power, unless an injector is working, or the fuel pump is so weak the A/F is so lean it noses over. Even if the pressure is somewhat low, and the injectors are at 100%, won't cause loss of power as long as you can achieve the correct A/F ratio.
What's the A/F and spark?
Is it down a cylinder?
Does it have CATS? If so it is possible one or both are collapsing.
Too many unanswered questions. Too many variables. Need to find someone with a good diagnostic mind. Fuel pump, injectors won't make you low on power, unless an injector is working, or the fuel pump is so weak the A/F is so lean it noses over. Even if the pressure is somewhat low, and the injectors are at 100%, won't cause loss of power as long as you can achieve the correct A/F ratio.
04-29-2013, 05:26 PM
#15
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Sorry A4 with a vigilante 3600 one piece aluminum shaft the high end BMR axles stage whatever. Built transmission. This isn't a race car by any means but it should be able to put better numbers down. I was talking to someone earlier that suggested many possibilities and we talked about maybe changing the cam.
04-29-2013, 09:07 PM
#16
Unless the cam has some serious damage its not the reason for the low hp. A stock cam should make more power than that.
Before you start throwing money on new parts and taking stuff apart, id find the problem
Before you start throwing money on new parts and taking stuff apart, id find the problem
04-30-2013, 09:56 AM
#17
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Make sure your not losing spark on one of the cylinders. I had a weak coil give me fits for a month before i figured it out. Could also be in the tune. How does it run on the street? Don't always go by dyno #'s. Are you sure your pushrods are the right length?
