[THUNDERA]

Originally Posted by thumbster

A/F ratios of 15.1:1 are no problem at all on a modern aluminum headed engine like the 5.7 Tundra engine. In fact it wouldn't surprise me if you'd see A/F ratios of 16:1 or higher under light cruise conditions. This is how you get better fuel economy and as long as you have a knock sensor in the loop and look at your EGTs, you're ok. If this engine can run on 87 octane with 10.5:1 compression, it can deal with leaner A/F ratios with slightly higher octane fuel and likely have quite a bit more part throttle economy to begin with.

I don't know about that, man....

15:1 is lean. Lean is hot - especially under WOT. You run up a mountain burning 15:1 by the time you get to the top, who knows what you will have burnt, melted or fried...Not to mention the higher compression is already making things hot. Yes, during part-throttle cruising you may see AFR's as high as 16:1, but you are putting in less air and fuel - less heat.

I'm not disagreeing with you - But if it were my truck running 15:1, I'd be afraid to floor it up Wolf Creek in the middle of summer with my boat behind me. Personally I think 13-14:1 is the safest WOT AFR.

My .02...