why dont we use leaded gasoline? i mean, a lot of the guys have gutted cats, and the fact that leaded gasonline destroys cats is WHY leaded gasoline was banned, but that's the only reason (to the best of my knowledge). if we use leaded gasoline, we'd have hella-high compression cars.

just a thought...

 

Leaded gasoline will also coat the O2 sensors....rendering them less accurate and eventually making them useless.

 

Ditto on the 02's. I run Sunoco 104 unleaded when I need added octane.

 

I like to keep my cats happy, but even if you don't care much about clean air, closed loop is a great thing for part throttle driving. So keeping the O2 sensors happy, by running unleaded, is a good thing as well.

Rich Krause

 

hmm, but arent 02s for clean air anyway? and if ya gotz no catz, why bother?

if ya have 02 sims, would you really need to worry?

i think that the higgest n/a compression a stock motor had like 13.XX:1. now, that's rather high...and it was achieved cause they used leaded gasoline back then.

 

No.... the O2 sensors are not just for "emissions". They help the PCM provide the correct A/F ratio. The only reason LT1's get great gas mileage, at least the way they came from the factory, is the fact that the closed loop A/F ratio is carefully controlled at 14.7:1 to get the best balance of emissions AND fuel economy. It is this closed loop control that allows the PCM to adjust to moderate changes, including mod's and changing environmental conditions. IT is this closed loop control that eliminated the issues that carb's caused with fouled plugs, etc.

"Sims" are only for the "after-cat" sensors, used to monitor the cat convertor efficiency. But the pre-cat sensors can not be eliminated, unless you convert your PCM programming to run constantly in open loop and tune it VERY carefully.

I run C16 leaded racing fuel, and can not run O2 sensors, so I run open loop on a MoTeC M48Pro engine management computer. But I've got more than 40 engine and chassis dyno pulls to verify the tuning.

 

Do you pull the O2 sensors before going to the track or do you run open loop all the time? Just wondering about the part throttle/varying load tuning that would be difficult to nail down on a dyno...

 

I do not use the O2 sensor for control at all. They are still connected to my stock PCM, and I can read them on my ScanMaster. One still seems to be working fine, after a lot of leaded fuel. The other one has been showing lower and lower readings as time goes by, even though the tune has been verified periodically. I suspect it is "lead poisoning". I just keep them there to plug the bungs, and the bungs are necessary for wide-band tuning.

I really don't drive the car on the street much any more... NJ emissions and the DMV "roadside emissions checks" have scared me off the streets. But the MoTeC has a much larger capacity for fuel maps than a stock PCM, and it is set up for speed-density. When I ran it alpha-N, looking only at RPM and TPS, it generally ran too rich at low loads. But with the speed-density tuning, it runs fine. In effect, I have eliminated the O2 sensors, the MAF sensor and the knock sensor (doesn't work to well with a solid roller ).

 

you nerd.

 

lmao...thats what I was thinking. I wish I was that smart. Or had the money