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Have a project nearly ready for tuning under load (have it starting well, idling ok at 800-850, and running fine under no load). It is a crate LS3 with ITBs, headers, cam/springs (228/236 on 113 LSA). I'm using a Holley HP ECU which I hope will learn the fuel side of things pretty well once I get out on the road, but I need to manually build the timing table. I'm familiar with speed density tuning.
Ignition is about right at idle and no-load (TPS values between 2% at idle and 5% at 3-4k rpm, 28 degrees at idle rising pretty quickly to a flat 45) and I've used the top line of typical speed density table for this engine for TPS >90%. The thing I'm unsure about is how to ramp between the two bookends.
I have **assumed** that by about 25% throttle at very low RPM all timing should be pulled and I should be at or very close to my WOT timing by then, and I have tapered that approach across and up so that by 3k it is more like a speed density spark table from there to 7k. Am I on the right track? And better yet, anyone got an alpha-N example for an atmo LS they could share?
Screen shot attached of my draft table.
Cheers, Andrew Robertson, Wellington NZ
Hi Andrew that is a pretty good draft table, I would remove a couple of degrees to start with but the shape is fine,