how to get initial tune and timing for 383 stroker lm7
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how to get initial tune and timing for 383 stroker lm7 Title says it all really. What are the steps to get the ECU/PCM ready for a 383 stroker LM7 (goin in a 99 silverado)? I understand you can tell the computer about the new bore/stroke but how do you tell it about the timing change from stroker crank?
For the initial fire up, just change the cylinder volume to match the new displacement. The rest can be dialed in while running. Just go slow and resist the urge to hit WOT until you are close to a good tune.
Thread Starter
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thank you. I guess the timing is really the mystery part to me. Is timing not different with a stroker crank?
As mentioned, you should update the new cylinder volume in the tune so the PCM can accurately calculate air mass and subsequently the correct fueling. The timing will be a result of how efficient your new build is, not necessarily the stroke of the stroker crank. As long as you have the correct tooth reluctor wheel on the crank and the correct crank sensor, that’s all the PCM needs as for as crank data. Timing will need to be tuned same as any other new build.
Teching In
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The only timing change due to the stroke will be minor and will not affect start up. Going to a stroker increases your piston speed so you may have to advance the timing more at higher rpms to compensate. 3.622 stroke runs about 65 feet per second at 6.500 rpm and a 4.000 stroker has a piston speed of about 76 feet per second. In the real world not a huge difference but something to think about as you refine your higher rpm tune. Of course there will be differences due to compression, fuel, cam etc changes in your new motor but for startup they will be fine with stock tables for the most part as long as you are not pulling a load or WOT until you have adjusted everything.
