My Evolution Motorsports GT 660 tuned 2001 996TT seems to finally be through the teething problems and error codes (leaking checkvalves in the intake system were causing CEL's at idle).

Evolution Motorsport recommends 100LL for driving at the race track. Power on 93 octane is certainly adequate. Is there any risk for engine damage if using 93 octane on the track?

 

100ll is av gas and contains lead. it will kill your cats if you have them and run it on a regular basis

not sure why anyone would run 100ll when 103 ,105, and 110 unleaded race gas is sold at most high performance shops

 

And kill your O2 sensors eventually.

 

Sorry - 100LL comes from my old piloting background. I meant unleaded.

The best unleaded they have here at Sebring is 98 octane. Like I stated above: There is plenty of power with 93 octane as I use on the street. Should I use 98 rather than 93 on the track to protect the engine as Evo suggests, or will the ECU protect the engine? Since installing the 74 lb injectors I do not seem to have any detonation problems anymore.

 

How many pennies are saved by using 93 at the track?

 

Though it may be relatively cheap insurance it is not insignificant.
I think I pay $9/gl for 98 octane. At 6 mpg I use appr. 35 gl/day. 98 octane then costs me appr. $175 more per day.

 

If Evolution recommends 100 octane for the track that's what I'd use. It is not necessarily power that you lose with running too low an octane of gasoline, it is the engine that stands at risk, at risk from detonation.

The tune may not have the ability to dial back the timing far enough quick enough to avoid detonation if you run too low an octane of gasoline.

Can't understand someone spending all that money on a tune would then balk at the expense of running some 100 octane gasoline once in a while, in order -- I might add -- to enjoy the full benefit of the tune. Why buy a tune to add horsepower if you are then going to turn around and leave that horsepower at home by your selection of gasoline? Why attempt to "save" a few dollars for fuel costs when a very very expensive engine is potentially at risk?

 

.. AGREED.. Well said.

 

I'm going to disagree with the posts above. If your car is tuned properly for 93, then I see no issue with running that at the track. I've tried 100 and 110 (I think, can't remember exactly how much over 100 it was?) and honestly didn't really notice any difference, but then again anything over 600 HP/TQ is a waste at most tracks since you can't really put it down anywhere other than on long straights. I already can't use second gear at 91 octane here at altitude on the track because the car just spins the rears on corner exit, so I only shift down to third gear even on hairpins unless I'm behind a slow car and have to go below my normal speeds.

Track days are already expensive and you can easily spend a couple hundred extra bucks a day by using 100 instead of 93 ($9+/gallon instead of $4/gallon), so it saves you money too. Again if somebody says "Sure, short-term it saves you $ but long-term it'll cost you because you'll damage your engine." then I have to question your build/tune/shop.....

 

I did some analysis on what I will use in a year as far as gasoline and costs etc

You can BUY a 55 gallon drum of Torco 108 octane race gas at about $10 a gallon and mix 7 gallons of that with 8 or so of 93 pump gas to get around 100 octane..... buy the little pumper gadget to avoid spills.... a teensy bit more work but if you are racing you have a lot more work anyway

Costs/Yr Octane

$1,454.55 93
$2,363.64 108/93
$2,012.22 Accelerator/93 - not worth the risk of damage
$1,454.55 Water/Meth + 93
$1,432.50 Ethanol - brilliant power but conversion and on sell costs
$3,487.50 100 oct pump - getting ripped off
$4,590.91 MS 109 / 93 - 5 gallon drums at $88 including tax for 104 octane


This is based on 20 mpg average and 7500 miles a year or so... only $900 a year more to run 108/93

 

what your not calculating though is the degradation of the octane by keeping high octane fuel in a large container for a full yr

 

I pay $8 a gallon for 110 Sunoco leaded in 55 gallon drums here in Chicago.

 

how do your cats and O2 sensors feel about running leaded fuel thru them?

 

It's for my built motorcycle.
But it wouldn't be good for those items but occasionally I will mix few gallons in on a hot night when I want to play.

 

aha the bike! one of my good friends just 2 screaming eagle cvo ultra classics!