Air/Fuel guage install

[kflyer]

It's been a little slow here so I thought I'd post a few pic's of the Air/Fuel gauge kit I installed last night. It's mad by Inovative and purchased on Ebay for $156 shipped. Can anyone tell me what number range it should be in and why? I was told previously around 12-13. First race this weekend. Thanks! -Kevin

http://www.innovatemotorsports.com/products/MTXL.php

[sflaten]

What you are looking for is a stiochiometric ratio. If I remember 12.6:1 is ideal.

EPA wants more in the 13:1. remember that the lower the number the richer the mix.

Not sure how this will work with our rich running cars or how it will read when bealching flames out of the tail pipe. Hopefully someone out there has more specific info for these cars.

Steve

[David Ferguson]

Normally maximum power is found with a Lambda value between .88 and .92. Multiply this by the stiochiometric ratio for gasoline (14.7), and you will arrive at Air/Fuel ratios of 12.9 - 13.5.

[kflyer]

Normally maximum power is found with a Lambda value between .88 and .92. Multiply this by the stiochiometric ratio for gasoline (14.7), and you will arrive at Air/Fuel ratios of 12.9 - 13.5.

Thanks! I wonder if this holds true for a Rotary engine as well?

[driver68]

You will only see the number you tune to at the end of the longest straight when you have the motor as wound as it will get. Hopefully that gauge records as number will be all over the place. Many opinions on this subject and a fair amount of tribal knowledge so be very conservative and keep it plenty rich until you really feel you understand the jetting. Rebuilds are expensive. We typically run below David's range except for big races.

[sracing]

Having lots of experience with wide band o2's and hundreds of engines from ACVW through Viper V12's, I have to say I have not messed with one on a rotary.

However on all normally asperated engines you want the a/f to be 12.8 to 13.2 at WOT from peak Torque RPM through max RPM. As pointed out ~.88 if using lambda figures.

12.5 won't hurt much, and at 13.5 you may get a bit more HP, but you are pushing temps and potential knock issues.

The gauge is only practical at WOT from peak torque RPM through max RPM. It is alway nice to see a flat 13.2 up to max RPM wiith a slight richening (12.8) at max RPM.

The innovate unit works fine, but I have used it and the AEM units with the exact same readings on the engine and chassis dynos.

Keep in mind that leaded fuel will eventually destroy the wide band sensor. Expect 50 hours or so out of one with leaded fuels. Your throttle enrichment and run mixtures will cause this to vary greatly. The good thing is that when they go bad, they may read a bit slow or just stop reading at all. I have never seen one read WRONG.

FYI, they (sensors) are basically a battery that use free oxygen as the electrolyte. Most compare the free oxygen in the air (21%) and compare that to the free Ox in the exhaust.

In theory if you have 14.7 to 1. (Lambda 1), you have the most efficient ratio for your engine. But this is only safely doable at idle and light cruise. Under high loads you need it to be richer.

[Dakar318]

on NA rotary your looking for 12.5-13 under a load/ dyno pull.

highway cruise is more like 14.7-15.

i like the innovates as the o2 sensor is a stock bosch unit for some VW that every parts house has for $50.

i need to install one on mine, but i need to do the exhaust system update on my FM as i still have the presilencer/ supertrap setup from way back when.