Is it safe to run pure 106 Octane gas? I'm gonna pick some up tonight for ****s and giggles.

 

Is it leaded?

 

I don't believe so. I understand that if it is I have to remove my CATS and O2 sensors. If it were I wouldn't try and use it.

 

Im not sure on this one where it is 13 pts higher than premium. I have run 100 in mine without a problem though.

Dan

 

i ran 105 at the track. only because I didn't expect to get that many runs in and was running out of gas. car was fine.

I dont have cats though

 

Just got back. It was 100 octane actually. Runs great. Nice bit of power boost. Not worth the $5 a gallon though.

 

The only reason you would see a power boost with higher octane fuel is if you have spark retard problems with the fuel you normally run. Higher octane does not correlate to increased energy content - some higher octane components actually have less BTU/# or are lower in density and reduce the amount of energy deleivered by what is essentially a "fixed volume" fuel injection system. You can't generalize, but in actual dyno tests, going from 94 octane to VP C-16 (117.5 octane) on my engine only showed a 6HP gain (490 -> 496), not something you would feel. And C-16 is an extremely dense fuel (= more #/Gal = more BTU/volume) intended for nitrous applications.

 

So will running the higher octane fuel 100+, will it do damage to a stock LT1?

 

No... it will only damage your wallet.


That's assuming you are talking about "unleaded" fuel. Running fuel with lead will destroy the O2 sensors and the cats.

 

So if you are not running cats and are running o2 simms, you can get away with leaded fuel?

 

you still regular o2 sensors in ODII
you use o2 sims for the o2 sensors after the cat

 

Then you are able to run leaded fuel correct?

 

Frank.... let's try this one step at a time......

If you run leaded fuel, and you have a cat, the lead will destroy the cat. If you remove the cat, you have no problem as far as the cat is concerned. But you still need to consider the O2 sensors.

If you have an OBD-II setup (96/96) and are using O2 sims to eliminate the two after cat O2 sensors, you still can NOT use leaded fuel. There are still two pre-cat O2 sensors (just like in the OBD-I cars), that are vital to the engine A/F management system. If you run leaded fuel, you will destroy the O2 sensors, and this will throw your tuning totally out of whack.

If you want to run leaded fuel, you need to reprogram your PCM to operate in open loop. This means the PCM will calculate what it thinks are the correct fuel injector pulse widths, but there will be no feedback from the O2 sensors to correct any error. Entirely possible to operate in open loop, but it requires some very careful tuning to keep gas mileage decent, and to avoid mixtures that foul you plugs.

 

I understand now, just read this post and curious,
Thanks

 

And sometimes you actually slow down with the higher octane fuel. I think alot of it has to do with having the "right" burn rate and the higher octane stuff just burns a bit slower (less volatile).

What we used to do is get about 5 gallons of 92-93 octane in the tank and take 2, 5 gallon containers of 108 with us. Make a run and get your mph (ET don't count here). Then run the car with 3 gallons of the 108 added. If the car picks up mph then you're headed in the right direction. Keep adding 3 gallons of 108 until you slow down or stagnate. Mind you that you need to keep everything very consistent from one run til the next... same coolant temps, everything as close as possible.

Of course we do this on carb motors where we'd also advance the timing. So there are some other things that play into the process but it does give you an indication of what octane the engine really wants. Sometimes the lower octane stuff burns at just the right speed for a given advance. I'm not sure of a way to determine the actual octane increase with this method though. Anyone know??

-Mindgame