Thread: Timing Maps for Tuning

I'm having a hard time interpreting your timing map. On the left side it says 'kpa' according to that at 18psi (125kpa) you'd be over 20* of timing from 2k rpm to redline?! Something doesn't seem right about that. What am I missing?

Have to figure in atmospheric pressure. @ around 22psi would be 255kpa.

kPa for these purposes is almost always used as an "absolute" measurement. 0 kPa is perfect vacuum. ~100 kPa is atmospheric pressure at sea level. 200 kPa is one atmosphere positive pressure relative to atmospheric, or "14.5 psi of boost".

Fixed for you.

Ahhh! That makes more sense. So you'd be around 225 kpa @ 18psi.

So now your timing would be under 14*. Is your timing so low because of the ported heads, cams, and intake manifold?

That's why I had the ~ there, dick. =P

Glad I could 'help'

That's why I put "safely tuned" in the description. Map has LOTS of room for improvement. TBH I'll probably just throw some 112 in it and bump it a couple degrees if I'm trying to pick up some top end at the track. Like if the car goes 11.10 and I want to get in the 10's.

hmmm, ya 14* seems quite 'safe'. I was thinking maybe it was that low because that's where it was most efficient due to your very free flowing head, cams, and intake manifold. Supposedly the more you allow the engine to breath the lower the advance you need. I'm guessing because there's a greater quantity of air in the cylinder per stroke? So essentially you wouldn't need to start the firing process so early as there'd be enough oxygen in the cylinder to combust at a more retarded point.

Oddly enough, the timing map from Jack Warrior Tuning at the most extreme point of the map for DET is 19*. For how safe we think their tunes are you'd assume 19* would be the lowest you'd ever need.

-G

All other things being equal, a more dense mixture (more air, and more fuel to go with it) will burn faster than a less dense mixture. That is why "the more you allow the engine to breath the lower the advance you need".