Using 100 LL as additive to XJR

I am new to this forum. I have owned a 1999 XJR. It has run flawlessly over the last 6 years and 70,000 Miles. I have access to AV GAS. I wonder whether the onboard computer will advance the timing with the increase of octane associated with addition of 100LL (as a mix)? Will this destroy the converter? Or will the addition of enhanced octane, increase the power of the motor?

I am new to this forum. I have owned a 1999 XJR. It has run flawlessly over the last 6 years and 70,000 Miles. I have access to AV GAS. I wonder whether the onboard computer will advance the timing with the increase of octane associated with addition of 100LL (as a mix)? Will this destroy the converter? Or will the addition of enhanced octane, increase the power of the motor?


If you haven't....DON'T. There is no reason to use any fuel other than what is recommended. Your computer will go nuts trying to adjust timing, etc. I realize this is an old post, but I see this question a lot. Modern engine management systems will just compensate when the fuel gets out of normal ranges. I mix 100 (unleaded and 91 in my '91 ZR-1 Corvette because the 91 we get is well below the minimum 93 that was available when the car was built. The 100-105 Avgas did great in my modified '65 coupe years ago, but that was purely carb/water injection...and no electronics other than MDS spark. 93 octane should be plenty for the XJR unless you plan on racing it at the strip (which will kill your drivetrain).

I would spend your money on a Throttle body cleaning + MAF,you
will find any lost HP!

MCGIVER

I would spend your money on a Throttle body cleaning + MAF,you
will find any lost HP!

MCGIVER

Sorry but please check the date and do not resurrect old threads. This one is too old to be replying in. Your future cooperation is appreciated. This thread is closed.


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