Leaded Fuel vs. O2 Sensors.

**BLOWNDFIZ** · 05-15-2009, 11:35 AM

OK race gas guys give me all of your opinions on leaded fuel. Typically I run 94 octane Sunoco unleaded with 15 psi. I have the tune extremely safe, and the knock sensor has yet to show any true detonation on a log. Car made 559 RWHP @ 9psi and 22 degrees timing. Now I'm at 15 psi still @ 22 degrees timing. I hear I'm leaving quite a bit of power on the table and should be able to up the timing to near 26.

Last year I bought 15 gallons of VP MS103 unleaded and mixed that with the 94. Well we have a gas station right down the road from me that sells 110 leaded out of the pump. I'd still probably mix it with the 94 but my question is how will this really affect my O2 sensors? My DFI wideband is an NTK which are supposed to be leaded fuel resistant. However the Autometer wideband on the car is a Bosch, which I hear are not as resistant. Then on the nitrous car I'm running stock O2's and I'm pretty sure these don't like lead at all.

Let me hear your stories....

TIA!

**ksmyss** · 05-15-2009, 01:18 PM

i used to mix leaded and unleaded alot when i would go to the track with no problems and a few of my buddies did the same.

why not go to e85 on the blown car?

**BLOWNDFIZ** · 05-15-2009, 01:30 PM

Originally Posted by ksmyss

why not go to e85 on the blown car?

I seriously considered it. I even remapped a tune that I think would be a good starting point for E85. The problem I run into is the duty cycle on the injectors. I run 75 lb injetors and in order to keep the DC in line with E85 I'd have to bump base FP up a considerable amount. With the increased pressure would come a decrease in volume so I'd then be concerned with the capacity of my -6 feed lines???

If I just stick to pump/race gas I could basically keep the same tune and just bump timing at the track. Then no matter what was in the tank the tune and fuel pressure I could just leave alone. It's not hard to load a complete new tune in DFI but if I had a 1/2 tank of E85 and 1/2 tank of pump my tune would be off. With pump/race my tune would be fine regardless of the mix.

I've also considered going 1/2 pump, 1/2 E85. Seems some turbo Buick guys do this with good success. Bump the VE and Timing table at the track and the rest of the tune could most likely stay the same.

**ksmyss** · 05-15-2009, 01:36 PM

what about upgrading the injectors to run 100% e85 all the time? boosted peps are making very very good power on e85 and might be worth the injector upgrade to get all out of it that you can.

i plan on running e85 if mine ever gets back on the road. its not boosted but nitrous loves it too.

but like i said i ran alot of leaded gas with no problems. if i ran it all the time then there might have been a problem but every weekend or every other weekend didn't hurt anthing with a tank or 2 between leaded cycles.

**1FASTSS** · 05-21-2009, 01:53 PM

I run it all the time. Mostly just when I'm heading out to the track. According to Speed my 02's are shut off unless they are tuning my car. I have to check on the wideband I just installed but I ran some race gas thru it this past weekend without any issue except I have a pressure problem right now that I hope is the filter. God only knows how old the race gas i got was since its just warmed up here.

Not sure on the ODB1 if you can completely shut them off or not.

I would say your pretty safe running a mixture of the 2. Worst case is replacing the 02 more often but since you work for NAPA I'm sure you can get them pretty cheap.

**Speed Inc.** · 06-09-2009, 10:06 AM

I know this is a bit older, but as Chris noted we run the larger cam cars in open loops. This helps with drivability and the fact you can run any fuel.

Denso 02's have proven to be less sensitive to leaded fuels as well.

**z28rob18** · 06-09-2009, 10:11 AM

when runnin the car in open loop you dont really need an maf right? wat about the o2 sensors does it still read them?

**jakesz28** · 06-10-2009, 07:14 PM

If your car isn't running rich you can get by quite a while with leaded gas but in time you will have to replace the o2's. If any one is running an inovative wide band you can actually get a replacement sensor from carquest for about $40. So if you have to replace it once a year it won't kill the wallet to bad.