What timming should I be targeting?
04-28-2009, 01:45 PM
#1
What timming should I be targeting? I am trying to decide on to start tuning my timing at WOT. I have a 408 iron block, 230/240 600/600 114 cam, 9.5:1 compression, and L92 heads. I would like to know what timing everyone with a set up close to mine is running? I have been told these heads like 22 degrees and a reputable build shop told me to shoot for 32 degrees total timing due to my lower compression. I know I can probably get away with running higher timing but how much is usless and starts to cut power?
04-28-2009, 01:51 PM
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Yeah, I say 30-32* should be good for your motor. L92's like more timing than the cathedral port heads. With the lower compression as well as the the L92 heads I'd say 30 is probably a very good place to start, then work your way to 32 and see if you see any gains. I run 30 in our L92 headed motor, but its 12:1. Hell, it might can stand 32 degrees but I'm gonna have to do some more testing on the track to see if i get anything from 32*, if not I'm keeping it as low as I can get away with.
04-28-2009, 11:13 PM
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Trust me, he will want much more than 22* with that motor and those heads. At a minimum, 28*. With 93 it should be able to take 32* assuming it isn't running hot or something. I doubt it would need much past 32 though. I'd start at 28 and go up from there. L92's are not like standard cathedral port heads, they like more timing.
04-29-2009, 12:49 PM
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The best thing to do is get on a load bearing dyno that allows you to do steady state tuning to find MBT for part throttle.
For WOT timing you can do the same, but doing several sweeps with different timing but not changing air fuel will be "good enough" for most people.
What I typically do is prepare several tunes each with the only thing different is the timing. I then load each tune, dyno, and then compare the dyno graphs to see where I made and lost power.
You could also take it to the track but driver error and other variables really aren't as scientific as getting an actual power measurement.
The guys are right though, the L92 setups do take a bit more timing due to the combustion chambers, but most people have seen success with 25-32 degrees of timing.
For WOT timing you can do the same, but doing several sweeps with different timing but not changing air fuel will be "good enough" for most people.
What I typically do is prepare several tunes each with the only thing different is the timing. I then load each tune, dyno, and then compare the dyno graphs to see where I made and lost power.
You could also take it to the track but driver error and other variables really aren't as scientific as getting an actual power measurement.
The guys are right though, the L92 setups do take a bit more timing due to the combustion chambers, but most people have seen success with 25-32 degrees of timing.
