DragStuff

My new 408 has 13.5:1 compression and I need to run 110 racing fuel. The racing fuel that is available around here is all 110 leaded Sunoco which will ruin my O2 sensor (I think). What are you guys with O2 sensors runing for race fuel?
Thanks

The leaded fuel will take a toll on the 02 sensors but there not that expensive and I have seen them last more that a season and some heavy racing....

I use blue Sunoco and have a duel 02 system with 8 egts...there is no better way to tune your motor.....

bracketracer wrote:The leaded fuel will take a toll on the 02 sensors but there not that expensive and I have seen them last more that a season and some heavy racing....

Thanks for the reply, bracketracer.

Humm, no one uses unleaded racing fuel? Is there such a thing???

Randy, what type of fuel do you suggest when runing O2 sensors??? Are the sensors just "expendable"?

bracketracer wrote:I use blue Sunoco and have a duel 02 system with 8 egts...there is no better way to tune your motor.....

Bracketracer / Randy: How much cyl-to-cyl variation do you see on the EGTs for a typical run? Do you tune for a specific temp or just consistency?

Your AFR should be abound 12.5 with a carb...And your EGT's should be 1350ish reading them at the finishline...But you have to careful as cyd's 1,2,7,8 are going to be hotter as that's just the way it is. You can adjust for that but that's another chapter.......Remember no body said you have to put the same jet on both sides in the front or the back of the carb

The O2 sensors are good for several hours of run time with leaded fuel, which is a lot of passes. Do the free air calibration regularly, as the sensor will drift with use. If the sensor is too contaminated with lead, it won't free air cal correctly.

Target EGT temps will vary with combustion chamber design, timing and fuel type. Target temps for a typical racing gas, normally aspirated engine will be between 1250 and 1400 max temp. When running 1/8 mile, max temp will be lower (heat continues to build throughout the run).

The EGT temperature spread of all cylinders is dependant on how well fuel and air is delivered. For example, a typical aftermarket intake manifold is not very well balanced, and EGT spread between all cylinders will be about 200 degrees. A typical "Comp" sheet metal manifold will have about 100 degrees spread, while a Prostock manifold that has been fine tuned on the dyno will have about 25 degrees spread.

More racers are going to O2s instead of EGTs, but the cost is still the biggest factor.

Randy

Randy & bracketracer: thanks for the info!

You can get a good AFR reading os say 12.5 and still have 1,2 & 7,8 be above 1400*.........To proper tune you really need 8 EGT's......I can also show you how to balance out those hot cyd with out any manifold work.....Not real hard just need some track time...

Another option that will save your wallet in the long haul is E85. Won't hurt the sensors and much easier on the wallet. $2.66 a gallon here last I checked. I have an 1150 I built on a 13.2 to 1 427 SBC using E85. It will more than offset the cost of a carb in the long run, as well as a pump and regulator if they are not up to par. And if you get one that is set up well you should pick up some ET in the process. Any questions, let me know.

I've got 6 years of use on the RPM wide band O2 using leaded race fuel.