Hey guys,
Have you had this problem?
I’m having a little trouble with spark knock. I can’t seem to get past the 4000 RPM range without getting some sort of knock.
Mods: 03 Vette, LS2 Block stroked to 402. Forged rotating assy. Vortec V3 Supercharger with 60LB injectors running 10.2 pounds of boost. Blower cam, aftermarket heads. LT Headers. Spark plugs are 2 steps colder and gapped at .028. Plug wires are new GM Performance wires. Fuel system is a dual fuel pump setup and the AFR is a constant 11.2/1 throughout our pulls. Trust me it’s not a fueling issue. Since we were having knock issues I removed the normal dyno pids I use and concentrated on all the timing pids. I’ve done the normally aspirated 402’s and the supercharged LS1’s but this is the first suspercharged 402 I have done.
We are running COS3 02030003 The tables have been scaled so we don’t hit the 2.3 GPS wall. Car runs great except for this spark knock problem. It seems the more pulls we made the more knock we got. We were very careful to make sure the Coolant and Oil temps were the same for every pull. Things we are going to check are: PCV system, oil in the intake, clearance issues with headers ect.
I’ve attached our first pulls data log and the accompanying tune and our last pulls data log and the associated tune. Our first dyno pull had an extremely conservative timing table with no knock and around 530 RWHP. As we worked our way up with the timing our RWHP went to 615. It didn’t matter what I did to the boost retard timing tables we still got knock.
I’m looking for all the ideas you guys can give me.
Thanks for your time.
Randy
DYNO PDF.pdfEFI LIVE POST_0006.tunEFI LIVE POST_0000.tunEFI LIVE Post Log 0006.efiEFI LIVE Post Log 0000.efi