DRMC911

I was wondering if anybody knows if it would be okay to bump up the fuel octane in my Boxster from 93 to 110, going to the track and was wondering if it would improve the power or no difference other than going from $3.00 a gallon to $6.50 a gallon

Macster

If you're using a name brand 93 octane gas going to 110 octane is overkill.

IIRC 93 octane gas is very close to what Porsche recommends. Here's a snippet from my 03 Turbo's manual: 98 RON or 93 CLC or AKI.

Track driving is mostly if not all full throttle driving so the engine controller under full throttle acceleration go open loop and increase the fueling running the engine a bit richer than it would otherwise. A richer mixture is one less prone to detonation.

Now if you want some extra piece of mind add a few gallons of a racing gas (of course NO LEADED GAS!) to a few gallons of 93 gasoline which will bump the octane up a few points. As engines age their octane requirements can go up some and running say 95 octane (by the blending of 93 and 100+ octane racing gas in the proper amounts) buys you and the engine a bit more protection against detonation.

The engine won't make any more power but what power it does make will be a bit further away from the detonation danger point.

Or you can just dump in 6 to 8 gallons of 100+ gasoline and avoid the math. A few extra dollars in high octane gas won't break the bank and you can think about your lines instead of the gas tank's contents.

Just don't go to the track with too little fuel either. All that hard braking, high speed cornering can interrupt the flow of fuel if the tank's level too low.

A few extra gallons of gasoline and the weight it represents won't make any difference to your track times.

Sincerely,

Macster.

Pat

Personally, i'd shoot for a ~95 oct blend.

DRMC911

Thank you, i was thinking of going with about 5-6 gl. and fill the tank up so i would have a mixture in there. i just wanted to make sure it was okay. this will be my first trip to the track and just trying to get as much info as i can. Thank you alot for you help.

GTA_G20

Do not fill the tank! Full tank = more weight. Lots of people make this mistake

Macster

No need to top tank to the brim but not a good idea to start with too low a gas tank level.

The stock factory alignment guidelines have the tank full so the alignment's best (I guess) when the tank's full. The car's f/r weight ratio a bit better balanced and the front end may grip a bit better with a little extra weight from gas being over the front tires.

IIRC the owners manual advises against hard cornering when tank level low.

The fuel pump can enhale air.

I remember not too long ago someone posted of having his car's engine cut out in some places on the track due to low fuel and air getting sucked in by the pump.

While one may be slower with a few extra gallons of gas in the tank (approx. 7.6lbs per gallon) he won't be nearly as slow if the engine cuts a few times every lap.

Sincerely,

Macster.