Boyes50
June 28th, 2017, 10:01 AM
Hey Guys, Looking for some insight on a tuning issue I'm having with my LS Powered Sled Pulling Truck. First, background on the truck.
2004 Silverado 2500HD, Stripped and Cut Down Competition Truck and Chassis. 4L80E Manual Valve Body. FTI 5,500 9.5" Non Lockup Converter. Pulls in 1st Gear and 4LO in the Transfer Case.
Engine is a LQ4, 230s and .625 Lift Cam, 799 Heads, NNBS Intake, OEM Exhaust Manifolds for Rules. Engine dynode 430HP @ the wheels on a Non-Load Dyno. EFI Live Tuned. VP MS109 Fuel, 50# Delphi Injectors.
Engine runs amazing without load. Running it in the driveway and even hooked to a backhoe in a field, truck redlines to 7,500 and sounds perfect. Zero knock, Zero hesitation. Engine just flat out runs.
Hook it to the sled, and apply engine load, and you can watch the timing curve drop. Without any recorded knock, as soon as the tires get a hold of traction and feel the weight of the sled, the timing automatically drops to 10 Degrees. We have the Knock Sensors and Knock Retard tables turned down and set to 0, but still see this drop in timing.
Any ideas or anyone else ever seen an LS Based Vehicle drop to a constant 10 Degrees of timing under severe load? And, how do I post an attachment so I can share my EFI Log and Current Tune from the last pull.
Thanks for looking!
2004 Silverado 2500HD, Stripped and Cut Down Competition Truck and Chassis. 4L80E Manual Valve Body. FTI 5,500 9.5" Non Lockup Converter. Pulls in 1st Gear and 4LO in the Transfer Case.
Engine is a LQ4, 230s and .625 Lift Cam, 799 Heads, NNBS Intake, OEM Exhaust Manifolds for Rules. Engine dynode 430HP @ the wheels on a Non-Load Dyno. EFI Live Tuned. VP MS109 Fuel, 50# Delphi Injectors.
Engine runs amazing without load. Running it in the driveway and even hooked to a backhoe in a field, truck redlines to 7,500 and sounds perfect. Zero knock, Zero hesitation. Engine just flat out runs.
Hook it to the sled, and apply engine load, and you can watch the timing curve drop. Without any recorded knock, as soon as the tires get a hold of traction and feel the weight of the sled, the timing automatically drops to 10 Degrees. We have the Knock Sensors and Knock Retard tables turned down and set to 0, but still see this drop in timing.
Any ideas or anyone else ever seen an LS Based Vehicle drop to a constant 10 Degrees of timing under severe load? And, how do I post an attachment so I can share my EFI Log and Current Tune from the last pull.
Thanks for looking!