Rotary Air Fuel Ratio what shoudl it be?

[CraigN]

What sort of AFR should i be seeing on my FD ? i have a wideband in the car and i know what sort of readings i should be seeing on a 4pot piston engine but im not sure about rotaries.

anyone advise ? whats richwhats stoich and whats lean ?

[A7NTY]

under full boost I dont like seeing numbers higher than 11. To be ultra safe 10.5.

[CraigN]

Lower safer ? higher means richer i cant see how lower is safer lol

my cosworth was mapped to 11.7 on full boost my geague starts to read lean at about 10:1

if yours is about 10-11 on ful lchat mines about the same

[Jit]

no the lower the number, the richer.... 14.7 is stoich and you run about 10.5s to 11s to keep things cooler

[A7NTY]

The large number eg 10 is the number of parts air to 1 part fuel.

[Prof]

In theory Stoich is best, as all the fuel is burned, but depending on other factors, this could lead to heat problems and possible detonation. Under higher boost, extra fuel is usually added, making the mixture rich, lowering the AFR, but the additional fuel cools the combustion chamber and staves off the bad things happening !
 
If you can keep the intake temperatures low, and have WI, then you can run a leaner mixture before running into problems. Running too lean will rob you of power, and cause excessive heat build up.
 
10-12 should be good for WOT with boost, under normal conditions I think.

[CraigN]

in that case i can see were all my fuel has gone !

cheers ladies