Quantity and Quality

[racerone]

I have read in many publications coincidental with the release of the GT3 the fuel tank's capacity is anything from 16.9 gallons (USA DOT STD), to 18.4 gallons (from whatever source), to finally as much as 23+ gallons. Obviously all GT3's here have the capacity at the mandated 16.9 gallons. The question which begs an answer is: What is the true maximum volume of the fuel tank installed on GT3s?

If, and this is a speculatitive conclusion only, the build capacity is indeed greater than 16.9 gallons by what means has the capacity been reduced-----and can possible unused capacity be restored? Second item: Though the GT3 engine will run effectively enough on 91 octance pump gas I would hazard a guess the driveability would be improved and performance increased (marginally) if the octane could be brought to say 95 or 96 ROM. Now comes the conundrum, how does one get there from 91? As mentioned in previous forums the store additives are for naught. True toluene or xylene will raise the octane, but wouldn't they cook-off the sensors (to say nothing of their total illegality)? Anyone having any success on this front?

[mds]

According to the 911 GT3 Product Information booklet, tank capacity is LHD: 23.5; RHD: 16.9; USA: 16.6. I understand the smaller USA tank is due to USA safety requirements.

The 98 RON super unleaded factory fuel specification is roughly equivalent to 93 AKI (average of MON + RON). My local 76 gas station sells 100 AKI at $4.20 per gallon. I run a mix of 1 part 100 with 3 parts 91. The car will run on 91 at slightly reduced performance. I suggest avoiding additives. Check around, you may be able to find 96 or 100 locally.

[gt3Steve]

There's 2 issues with the US GT3 gas tank. The safety aspect is placement relative to the front axle and regulations prohibit the gas tank extending forward or below it (I forget which). You can't simply swap out the 23.5 gallon tank as the US tank has a different vapor recovery configuration/parts and you'd get a fault on the OBDII system.