Need help quick!! A/F ratio and EGT for NA 13B! (Formula Mazda)
 

Hey guys,

I have an NA 13B in a Formula Mazda and would like some input on air/fuel ratios and EGTs as well.

The car is equipped with EGT sensor in each exhaust runner about 4" from the head. It has a wideband oxygen sensor in the collector after the runners come together.

It's running a a Weber DCOE carb. and I have a wide selection of jets to choose from. Right now it's PIG rich but my team won't listen to me and lean it out because they are scared of the 18.0:1 air/fuel ratio when the driver lifted off the gas (they won't believe me that it's normal to spike under no load...). :rlaugh:

I'm trying to gather as much data as I can... I'm used to turbo Toyotas but the rules in the rotary game are slightly different... I heard "through the grapevine" that rotaries can run as much as 200-300 degrees (F) hotter than a piston engine for EGTs.

Max performance is key. Reliability and longevity are secondary :) (it is a racecar after all...)

My team is real conservative and thinks I'm too aggressive... I tried to tune for 13:1 air/fuel and 1700 degrees EGT and EVERYONE else balked at that. Noone has experience tuning rotaries on the team so I'd appreciate all the info I can get!! Next race is tomorrow morning at 7:30 am so quick replies are appreciated :) I'll check it later tonight and tomorrow morning before 7:30! (that's a practice session).

Thanks guys.

-Greg

P.S. Any additional info like "it's hard to run an NA rotary overly lean" is also appreciated!

check this out
 

visit thisweb site, lots of good information on mixtures, and proper egt for rotories
http://www.yawpower.com/

Your numbers are reasonable.
But, to prove you are right, get that thing on a dyno.
Dyno doesn't lie if you're making power or not.


-Ted