nelsons 93 octane tune. Is it bad on the sensors?? I dont know how much he advanced the timing on the comp and i was just wondering. I wouldnt think he wouldve advanced it enough but who knows?

Thanks,
derek

 

I've ran 100 octane unleaded before, but not on a "Nelson" tune. It ran great. I like the added octane when spraying, since I leave the Hypertech 93 in. Just make sure you run the unleaded, as leaded fuel is hard on the O2 sensors.

 

Leaded fuel???? LoL That has been gone for a long time. You have to by lead additived to add to todays gas for old engines that need the lead in the gas.

Jim

 

Actually.. most race fuels are leaded.

Stick with 100, or 104 unleaded, and youll be ok!

 

octane is a good thing and doesnt have to be tuned for, you need octane to ammend for a tune but not tune for the octane. stick with unleaded for sure

 

There is a station not far from my place that sells leaded race gas.

 

I can get 100 octane low-lead AND 100 octane unleaded here at our airport...I gotta be REAL careful which pump I pull up to !!

 

Octane doesn't have to be tuned for? Sure it does.
Actually, Octane has no bearing on the energy content of the fuel. Octane is ONLY a measure of the fuel's ability to resist detonation. Higher octane gives no advantage at all to an engine that does not detonate on a lower octane grade. There are other factors of the fuel that have to be taken into consideration.

Oxygenation.

Both VP and Sunoco 100 and 104 octane unleaded fuels are oxygenated. Moreso the 104. Typically the 104 octane grade can be obtained at a lower price per gallon than the 100 because the 100 is marketed and sold as a street-legal fuel and therefore has all the road taxes associated with it. Oxygenation in fuel allows a lower air to fuel ratio to burn as efficiently as the ratios for conventional fuels. This means you can richen up the mixture and get power instead of choke.

Races fuels have different specific gravites than "pump gas" does. Your PCM has a constant for fuel density.

Back to the original statement that Octane does not have to be tuned for....
Since all octane does is resist detonation, there is simply no point to put higher octane fuel into an engine that doesn't ping on lower octane. If you're going to spend the extra money on a fuel with superior detonation resistance, add timing or add boost! Use it! That is what you are paying for!

And another thing, lead isn't just bad for oxygen sensors, it RUINS THEM! Cats too if you have them.

 

How much is the 100 unleaded?

 

What he said.
I've got a 11.5-1 iron headed small block in my '57 that really should run on Cam II (or some kinda race gas). I usually keep the timing back a bit just because I mostly just "cruise" the car on Saturday nights. Cam II around here is $4.50 a gallon, so since 93 octane has went up so high it really isn't "that bad" (did I really say that?) I usually run a mix of 93 and Cam II. The motor has updated guides and so on so I really don't need the lead, but it definately runs better w/ higher octane. It might be in my head, but it even sounds different @ idle.