Patrick G

iTrader: (14)

I've got a 400+ rwhp heads/cam LS1. The cc size is 61cc's giving me a compression ratio of 10.90 to 1. My current tuning starts my WOT timing at 24 degrees at 3000 rpms, goes to 25 degrees over 5000 rpms and is at 26 degrees by 6000 rpms. The motor does not knock on 93 octane.

In past LS1s, I used to run a lot of timing (30-32 degrees w/0 kr), but none had this high of compression. Is there any benefit to bumping it up 2 degrees across the board? That means the timing would start at 26 degrees and climb to 28 degrees. Another possible scenario would be for the timing to start at 26 degrees and then just stay there. I think the car would pick up some mid-range torque with more timing, but I'm not sure about the top-end increase.

I've seen countless dynos showing minimal gains above 28 degrees of timing, but is there anything to be gained by going from 26 to 28? Also what about my 24 degrees of timing in the mid-range?

Pro Stock John

iTrader: (34)

I have always run 28 degrees of timing at WOT and no more.

I am running 11.25:1 compression.

Patrick G

iTrader: (14)

Thanks for the statement John. I know that 28 degrees works well for most combos. Question is, how much power and tq am I leaving on the table with a timing curve that starts at 24 and ends at 26? 2 hp? 5 hp? 10 tq at low rpm? No difference?

Terry Burger

iTrader: (4)

Some cars pick up power with less timing than you have now, others pick up power with more timing. I'd say you'll see little to no gain, but it can't hurt to try. <img src="gr_images/icons/wink.gif" border="0">

ChrisB

It really depends on the chamber configuration, the fuel type, the camshaft (amount of overlap/intake charge contamination), compression and cylinder head temp. It is going to vary from configuration to configuration.

I would say you are pretty close to where you want to be.

Chris