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I’m really just looking for some ideas on why power is so low. I have some thoughts, but I’m curious what some others think. The plot below was on the stock GTO plugs, but I got the same results later with the BR7EF plugs.
I do believe the dyno curve as I post-processed it from several 3rd gear pulls on the street – so this is based off the real thrust required to generate the measured g’s.
There are 2 ‘knees’ in the torque curve. The first at 5200 RPM keeps power from rising (i.e. peak power is extremely low at 5200 RPM). The second, at 6200 RPM has the tq really nose dive. I’m somewhat inclined to think I have two separate phenomenon occurring.
Details:
Car is an 05 GTO with a manual 4l80e and 3.73 gears.
L33 bored to 5.7L with F1A Procharger
Ported 243 heads with larger stainless valves
9.5 CR
Cam: Custom FTI - 214/228 .600/.600 with 113 LSA
PAC 1218 valvesprings w/15,000 miles
1-7/8 Kooks headers w/ 3” dual exhaust
Stock LS2 intake
Tune Details:
Fuel: 93 octane at 11.0 average AFR
Timing: 20* start falling to 14* at peak boost
Air Temp: 85*F – 110*F during the pull
I have some upgrade plans this year, but I'd like to get some thoughts on this first and sort out any potential issues and/or help guide my future decisions based on any discussion here.
Any thoughts/comments/suggestions?
Give me a call this afternoon if you get a chance, perhaps I can help you to figure out why it is falling flat on it's face. Bob
__________________ ATI ProCharger and Moser Sales 260 672-2076
Nobody has mentioned the fact that there is a 2.65" restrictor at the blower inlet.
Im not a blower guy, but it seems like this would be a problem or is it a normal way to limit blowers without pulley changes?
Take a look at this dyno graph. 12.4 psi of boost from an F-1A ProCharger using the ProCharger GTO bracket assembly, and it made 864 rwhp. This is with my Brute Speed blower cam in a CTS-V. Back at the old EPP shop we built this engine starting with a new LS2 block. 9.5/1 compression ratio using a Calles Compstar 4.0 stroke crank, Compstar rods and Diamond pistons. We installed AFR 225 heads on it and a FAST 92 intake. Nothing exotic, but it has been together since 2008 and is still running strong. We initially had an LS2 intake manifold on it, and it was at 809 rwhp with 14.4 psi of boost. We lost two psi of boost when we swapped intakes but picked up a lot of hp.
You're running a spring that is rated for a maximum of .600 lift on a cam with .600 lift. If those lobes are even slightly aggressive, its going to float them.
That is not true. Just because he's close to the max lift rating of the spring doesn't mean he doesn't have enough spring.
As long as it is .050 from coil bind at max lift and if it has the right pressures it would be fine. "IF" being the key word.
And for god's sakes before you change any parts, put it on a real dyno. That is the easiest thing to do from hear instead of changing a bunch of parts you might not even need to change.
03-28-2017, 06:34 AM
