Cruisin down the road my a/f's are reading around the mid 13's no boost just cruisin does this seem a lil rich?

 

whats your setup?

 

pt-67 50 mm w/g hks mani.....etc

 

porting? i would say that is a lil rich for sure search a bit. id say mid 14-15.0 afr is what you should shoot for however ive seen others talking about even 16's

 

under high high vac ive had my car crusing at low 16's, however if you have a cat i have been told this is too hot, my egt's were around 700*C 4" post turbine

 

Damn that is pretty hot!! Yea iam running in the neighborhood of high15's low 16's right now. With 720cc all around

 

some of you might think this is crazy, but i have actually had more success getting better fuel mileage by tuning the car to where it drives the best at "X" amount of throttle/ vaccum when cruising. sometimes this is in the high 14's and sometimes the mid 13's but wherever i end up usually produces the best fuel mileage while still having some grunt.

i guess my point is that you can't just say "tune for high 15's for best fuel mileage". doesn't always work and egt's can become a major threat if your cruising so hot and then get in to boost real quick.

 

Yea i hear what your saying i retarded my timing a lil as per ari yallon at rp. But damn it just worries me thats the big deal of it all.

 

You're not crazy and 100% correct. That's what tuning is all about.
People believe it's the actual AFR's that gives economy and power.
Just like ignition timing there's no set value that gives the best results.

 

Um its a universal well known fact that for steady low vacum sub 110kph curuising on the flat lands an excees air ratio of 5% or more will yield best fuel efficiency, EGT is controled by appropriate amounts of ignition timing......

14.9 to 15.3:1 is what I set always, the only deviation to this is when I am using a bullsit excuse for a computer such as a microwreck that you need to be more towards 1 lambda as they vary so much and any leaner on a non CDI or enhanced ignition system on a rotary will result in a lean surge !

Any other condition is just that ANOTHER CONDITION and its a balance between power OR maximum fuel efficency dont confuse the two as they are different aims and achieved differently.

I apply the logic that at certain amounts of TPS or load its tuned for maximum fuel efficency 1 lambda or leaner even up to a few PSI of positive boost, IF the driver wants more than this then he is usually demanding 5 psi or more and thus the fueling curve reflects his demands, YOU CANNOT HAVE BOTH, this is why top end ECU's not available to us generaly (like bosch motorsport range, pectel and others) have switchable maps that let you choose between efficiency OR power.

I apply maximum fuel efficency below 2psi boost towards maximum power up to 15psi boost then maximum reliability from 15psi onwards