Switching between race gas and pump gas

[Unchained]

In my quest to achieve Stoichiometric combustion I have found there to be some variables involved when switching between leaded race gas and unleaded pump gas.
I've had my turbo engine tuned and running real strong on pump gas and then found that when I switched to leaded racing gas the engine ran too rich. So much that it didn't want to clean out at high rpm.
Come to find out leaded racing gas is a higher specific gravity than pump gas so the two require a different mix.
Does any one else run both types of fuel?
Maybe this will only apply to a Turbocharged application where you can adjust your boost easily.

[RACER52]

my engine definately runs richer when on straight 110. but the egts fall down to 1200 max. So its a toss up. If I'm gonna run it real hard for a long run than rich and low egt's is where I wanna be. But for short bursts and regtular use pump gas actually feels stronger.
right now at 12lbs boost pump gas barely does it. I can see the idle change when on race gas. But it loves 20% mix.
bbc quad rotor whipple efi.
Racer

[don johnson]

Hi,
I have used all fuels in my 33 Daytona with 1070 HP Supercharged motors, running 11 lbs of boost. Usually I run 50/50 pump to av gas. For Poker Runs, sustained high speed, I run straight av gas or straight Unocal leaded racing depending on availabliity. This is done only as a precaution...
There is no difference in how my engines run/perform with any of these fuels. The motors idle, run and perform at all RPM's identical.
The only thing I can tell you is the Unocal sure smells good!

[5th Horseman]

I've herd that 02 sensors shouldn't be used with leaded fuels, something about contaminating the sensor. Could this be an issue here? I wonder how much lead it takes to make a sensor read bad?
Just a thought,
Paul
.

[bajaboater502]

Octane does not make horsepower only an engine with enough compression to utilize the octane will increase performance, if your engine is not detonating then the fuel your running is fine. Leaded fuel has a heavier mass to it and will run diffrently. The lead in racing fuel is a lubricant and will help prevent wear on you engine especially at high temps and hard runs when your oil gets hot and thins. In 2 stroke applications such as dirt bikes and atv's the lead lubricant lets you reduce the amount of oil you need to add to the fuel for engine lubrication thus increasing its performance. Yes it will make the o2 sensor go screwy, we put 3 gallons of vp c 12 in one of the tow vehicles (all we had in the middle of no where) when it ran out of gas in Utah and with in a few miles the truck was not happy and would barely run because the computer picked up the lead. I have a few racing atv's we take to the dunes in dumont and glamis and while they are not big block chev's there are still high performance engines and they all require a little different mix, my completly worked to the hilt quadzilla (2 stroke) runs best on straight vp c-12 leaded fuel mix with 2 stroke oil at a 50 to 1 ratio And yes it does smell good. my sisters polaris 400 scrambler (2 stroke)which is not quite as worked as my zilla (still vey impressive for a polaris in the sand) runs best on a 50/50 c12 to pump gas mix while my brothers warrior (4 stroke)which has quite a bit of work done to it runs best with only 25% c-12 and 75% 93 octane and if i take it much higher will run rich and not run as smooth or hard. Unless you are getting detonation then high test pump gas should be fine and it is the lead not the octane in racing fuels that is helping to protect your engine. Lead is a great thing for an engine and that is why it was added to fuel years ago, but it does pollute the enviroment, although I have only ever seen one boater get a ticket for it a few years ago in florida because the coast guard smelled it and dipped his tank.

[Unchained]

I understand about the race gas not making any more power. I use race gas if I've dialed the boost to over 15 lbs. and 93 octane pump gas on 14 lbs boost.
I just read an article in Turbo and Hi tech performance mag and they were able to run 91 octane up to 22 lbs boost in a 2004 Mitsubishi Lancer.
They ran race gas and boosted it up to 35 psi.
When I bought the wide band O2 sensor from Innovate Motorsports they mentioned about the reduced life of the sensor on leaded fuel.
I asked them how long it would last and they said in a street car it may only go 10,000 miles.
I figured that is about 20 years in a boat so I have been running it on leaded for many hours and it seems to work real good.