Pump timing October 08, 2021 06:18AM
I understand the basics and how to change the timing and that it will alter torque and egts, but why? How does advancing or retarding injection timing do so? Earlier injection resulting in better fuel air mix and a bigger boom? I realize that it has to be changed to match the rpms so to speak, but I’m curious about the performance role it plays.
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Re: Pump timing October 08, 2021 07:48AM
Advancing the timing more heat stays in the cylinder. May hurt low rpm performance if you pull the rpm real low, 1600 to1800 rpm or so. Retarding timing will increase exhaust temps, flame out the stack, because the mixture won't have time to burn in the cylinder at higher rpm's, will typically improve low rpm lugging performance.
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Re: Pump timing October 08, 2021 08:52AM
Advanced timing: injects fuel when piston is lower in bore. Typically ignites sooner causing more cylinder psi before tdc. This causes hp and torque losses at lower rpm’s as it tries to stall the piston.

Retarded timing: piston is higher in bore upon injection so kills higher rpm power due to time lost to ignite before tdc. Helps low end at low rpm due to pressure pushing on top of piston longer improving torque.

This is a fairly simplistic explanation but it should help you understand what’s going on a little better
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