20HP Gain With Race Gas.

[Vincent]

I was recently told by VF Engineering/GIAC that our cars gain up to 20hp when dyno with 101+ octane gas. Evidently the ECU in the R8 automatically detects the fuel and change it's mapping for more output.
I am planning to do some butt dyno with 101 octane this weekend.We'll see.

[09R8]

do share your butt's experience

[Vincent]

do share your butt's experience

Been driving around in race seats and high hp cars for so long my buttocks might not be all that accurate.

[desperado]

Evidently the ECU in the R8 automatically detects the fuel and change it's mapping for more output.

Seems at odds with what I was told by an APR dealer while discussing ECU flashing; that, conversely, poor quality fuel doesn't trigger a gradual reduction in engine output (for example, by gradually retarding the timing). Instead, if octane is low enough (i.e. detonation is detected) he claimed the engine will go directly into 'limp-home' mode, limiting power output to 50% of normal.

Hmmm... if what you say is true, that the engine will "turn up the performance wick" so to speak, I wonder whether it might also address my random misfire problems. My research so far leads me to believe the random misfire may be due to Audi's conservatively programmed (rich) fuel-air ratio, done to allow for the wide range of gasoline quality likely to be found out there in the real world.

Of course 100 octane fuel, while having a higher antiknock rating, typically also has a lower energy content (BTU/kg) as it is more highly refined (contains lighter fractions). [someone please correct me if I have this backwards] So, even if the ECU doesn't make any adjustment, using 100 should inherently lead to a leaner-running engine and therefore cleaner spark plugs.

There is a gas station near my area that, besides the normal grades, sells 100 octane (R+M/2) unleaded racing fuel from one of their pumps. Its a VP Racing Fuel branded station, the only one I've ever seen outside a race track! Only problem is, last time I was in there the 100 octane was selling for $7.99 per US Gallon! (for comparison, I paid $1.92 yesterday for 91 unleaded premium). I'll try a couple of tanks and report back on the results of my "bum test".

[desperado]

I was recently told by VF Engineering/GIAC that our cars gain up to 20hp when dyno with 101+ octane gas.

Could one of the tuners monitoring this forum that is doing dyno testing perhaps do a run on racing gas to test this hypothesis? I'm thinking of Jason at STaSIS for example, as they have an ongoing R8 program at the moment.

[R84ME]

If you want to experiment and have a low-security, General Aviation airport near you - and can get on the ramp - you can go pump 100LL at about $4.00+/gal. US. It MAY be against the law (a Felony?) but I see muscle cars filling up all the time. FUN FUN! ! !

[4ringer]

Union 76 Stations in SoCal @ Cheseboro & 101 in Agoura and on San Vicente in Brentwood both sell 100 octane; been using it for years to keep the exotic pipes clean... when mere premium was $4.00 a couple of months ago it seemed like a good deal @ $6.99...

[MikeB]

I believe a BP station in Edinburgh is the only one in Scotland to offer 102 octane petrol??

[desperado]

If you have a General Aviation airport near, you can go pump 100LL

Well, I wouldn't suggest doing that. 100LL (blue dye) is NOT unleaded fuel, it is aviation Low Lead (hence the LL designation). The problem is that it's only "low" in relation to 100/130 aviation gasoline (green dye) which had a VERY LARGE amount of lead (for use in your granddaddy's supercharged Merlin ).

If you use 100LL you will ruin the catalytic converters. Even if you have installed an aftermarket exhaust, there are pre-cats on the headers which are usually retained in the exhaust system.

[R84ME]

If you use 100LL you will ruin the catalytic converters. Even if you have installed an aftermarket exhaust, there are pre-cats on the headers which are usually retained in the exhaust system.

I don't even think 130 is available anymore, it's 100LL or JetA - but that's probably why the Muscle cars are filling up, no cats to worry about!