Help me figure out my setup?
03-10-2014, 12:59 PM
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Help me figure out my setup? Alright, my engine setup in my 2005 GTO is not ideal but I'm wondering what kind of input I can get from some of the expert LS experts. Here is my current combo.
stock CI brand new LS2 block
forged Weisco stock bore pistons with -3.2CC valve reliefs (setup to 0 deck)
.030 Cometics to help regain compression from the 0 deck setup since stock is raised)
ported 243s with 360* valve job, PRC .650 springs and milled to 61 cc.
approximate compression ratio is 11:4.1
226/230 EPS cam with 117+2 LSA. So around -6 overlap
FAST 102 and the ports matched up well to the heads
90 mm ported stock TB
10% UD crank pulley
forged stock length rods.
Vararam intake
Mantic Single disc clutch
1 piece aluminum DS
billet stubs
I originally had a stock 70k ls2 and specced the cam for a FAST 90 and stock manifolds and catless mids (why it has lots of negative overlap.
After having the rebuild because my POS clutch blew apart and took out the engine I upgraded to Kooks 1 7/8 headers and the FAST 102. I still have the stock cat back with a stolen Fox H and magnaflow mufflers.
The car had been 115.89 on one run in the past (DA was over 1000 ft so it was magic air) on the stock motor with stock manifolds and UD pulley but was mostly in the 113-114 range (i attributed the variables to the stock clutch slipping. )
Now the car has been 113-113.75. This is all on street tires with poor 2.0-2.1 60s so I know that's a variable but I consistently get walked by a buddies 117-118 maggied G8.
I tune the car myself and have no knock and WB readings in the 12.8 range.
Am I expecting too much for this smallish cam and mismatched exhaust to trap 115-116 consistently? With this much negative overlap should I adjust my spark timing differently than most people have theirs set up? I did a compression check and they were all 180+-5# and the leak down showed less than 10% on all cylinders so I am assuming the engine is healthy. Thanks for taking the time and replying. I do plan on upgrading cams later to take advantage of the headers (2* overlap to avoid the gas smell) but would like to optimize this setup.
stock CI brand new LS2 block
forged Weisco stock bore pistons with -3.2CC valve reliefs (setup to 0 deck)
.030 Cometics to help regain compression from the 0 deck setup since stock is raised)
ported 243s with 360* valve job, PRC .650 springs and milled to 61 cc.
approximate compression ratio is 11:4.1
226/230 EPS cam with 117+2 LSA. So around -6 overlap
FAST 102 and the ports matched up well to the heads
90 mm ported stock TB
10% UD crank pulley
forged stock length rods.
Vararam intake
Mantic Single disc clutch
1 piece aluminum DS
billet stubs
I originally had a stock 70k ls2 and specced the cam for a FAST 90 and stock manifolds and catless mids (why it has lots of negative overlap.
After having the rebuild because my POS clutch blew apart and took out the engine I upgraded to Kooks 1 7/8 headers and the FAST 102. I still have the stock cat back with a stolen Fox H and magnaflow mufflers.
The car had been 115.89 on one run in the past (DA was over 1000 ft so it was magic air) on the stock motor with stock manifolds and UD pulley but was mostly in the 113-114 range (i attributed the variables to the stock clutch slipping. )
Now the car has been 113-113.75. This is all on street tires with poor 2.0-2.1 60s so I know that's a variable but I consistently get walked by a buddies 117-118 maggied G8.
I tune the car myself and have no knock and WB readings in the 12.8 range.
Am I expecting too much for this smallish cam and mismatched exhaust to trap 115-116 consistently? With this much negative overlap should I adjust my spark timing differently than most people have theirs set up? I did a compression check and they were all 180+-5# and the leak down showed less than 10% on all cylinders so I am assuming the engine is healthy. Thanks for taking the time and replying. I do plan on upgrading cams later to take advantage of the headers (2* overlap to avoid the gas smell) but would like to optimize this setup.
03-10-2014, 11:37 PM
#3
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I had considered this but was not sure how it would react. I don't feel like the car lacks much in the mid range but I guess it can be hard for the butt meter to tell. with the LSA as high as it is I know I must be losing a bit of mid range where it spends a lot of time in 4th gear. Honestly If I'm going as far as buying a new chain (currently a non adjustable new stock) and removing the timing cover I would probably get a cam more optimized for the combo. Thank you for the reply. W