If your 10% lean across the board about how much power would that hurt?

 

Lean compared to what?

Rich

 

What do you consider 10%, after my rocker swap mine went to 13.9 at wot. I was told it wouldn't gain any power but make it alot safer at 13.1. It will be corrected asap.

 

I don't think you will gain much unless it was pinging and you were getting a lot of spark retard.

 

Again, we don't know what he means by 10% lean. But variations from max power AF ratio work like this - as you lean it out from optimum there is power loss pretty much in proportion to how lean you make it. The EGT will also get hotter and eventually you can melt things. A little richer than the max power mixture results in less power loss than going to the lean side. That is one reason stock tunes are a bit rich.There is a safety factor built in so that if the air is very good, you get gas with a low specific gravity, etc. it will not be too lean and risk engine damage and there is very little power loss being a little rich anyway. One of the reason people who can run alcohol like it so much is that it is quite forgiving of a rich mixture. The tune is more forgiving than gas.

Regardless of the fuel, they all must be richer than stoichiometric for max power. NA cars on gas like low 13:1 AF ratios. Blower cars need richer mixtures.

Rich

 

I dont have the sheet in front of me but I think it was high 14's to mid 15's