Discussion and questions related to the course EFI Tuning Fundamentals
I have a NA LS2 putting out 600hp on the dyno and my EGTs read around 1300-1500 during normal street driving. My wideband shows around 14-15 afr under load but I’m concerned with the egt temps. With the wideband not showing a lean condition are my egts still hot enough to cause damage?
hello don't be too concerned with that egt while cruising it is fine just to try something try adding a couple of deg of timing and see if that helps but keep an eye on knock under snap acceleration
As Ross said, under part throttle there's less air-fuel charge density and this burns more slowly, sometimes by a surprising margin. If the timing is less than optimum, the charge can still be burning as it passes into the exhaust and not only does that add direct heat, but the cooling affect of the expansion as the piston passes down the bore is also reduced. By optimising the ignition point, not only is the charged burned in the cylinder, reducing exhaust temperatures, but you will usually gain a significant amount of fuel economy and, with the price of fuel, that can be a big saving over a year*.
An AFR of 14-15:1 under load is a little lean, I'd be looking at running it a little richer, around 13:1 for petrol/gasoline should be around the figure, maybe a bit richer for forced induction, but that will depend on the engine characteristics. Light throttle cruise, I'd consider around 16-16.5:1 to give best lean power - but, again, will depend on engine characteristics.
*get it right, and you could gain 10-50% in economy over a bad tune - if you spend $1000 on fuel a year that could be an extra $100-500 in your pocket.
Also, a dollar saved is better than a dollar earned, as you're not paying taxes on it.