Audi R8 Forums banner
1 - 20 of 40 Posts

·
Premium Member
Joined
·
351 Posts
Discussion Starter · #1 ·
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.:cool:
 

·
Registered
Joined
·
482 Posts
do share your butt's experience
 

·
Super Moderator
Joined
·
3,615 Posts
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".
 

·
Super Moderator
Joined
·
3,615 Posts
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.
 

·
Premium Member
Joined
·
1,244 Posts
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! ! !
 

·
Registered
Joined
·
13 Posts
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...
 

·
Super Moderator
Joined
·
3,615 Posts
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.
 

·
Premium Member
Joined
·
1,244 Posts
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! :)
 

·
Premium Member
Joined
·
1,244 Posts

·
Super Moderator
Joined
·
3,615 Posts
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! :)
Yes, 100LL has effectively replaced 100/130. Does anyone remember back when they used to sell purple 115/145(!) aviation fuel ?

If you are still interested in aviation gasoline for your performance car, start your reading here:
http://www.osbornauto.com/racing/race2avgas.htm
 

·
Super Moderator
Joined
·
3,615 Posts

·
Registered
Joined
·
482 Posts

·
Premium Member
Joined
·
351 Posts
Discussion Starter · #15 ·
Most ECU pull back timing or go to limp mode to allow cars to run with wide range fuel without detonation. Tuners do after market flashes on the ECU to narrow the range of fuel to just premium high octane thereby limiting the timing and increase output.

From what I was told the new generation ECU such as R8 has all the above safety features. Plus the ability to detect high octane fuel and automatically increase output by switching between maps without tuner flash.

The EvomSit flash I had on my Porsche 996 Turbo also had that capability and worked very well.


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".
 

·
Super Moderator
Joined
·
3,615 Posts
100 octane fuel, while having a higher antiknock rating, typically also has a lower energy content (BTU/kg) as it is more highly refined
I had lunch today with a high performance engine builder (700 - 1200HP big block chevy engines), and he believes that the BTU content of the various gasolines is intentionally kept constant as part of the blending process. Can anyone point me to the definitive answer?
 

·
Super Moderator
Joined
·
3,615 Posts
Race Fuel from VP Racing ... Apparently it's awesome stuff. But very expensive.
I just filled up with VP Racing's 100UL "Streetblaze" Racing Fuel from the pump at the VP Racing Station on Euclid Avenue, one block north of the 60 freeway in Ontario, California.

wait for it.........drumroll....... $8.99 / US gallon! (91UL was well under $2 at the same station.) All I can say is, it had better be awesome! ;)

They also sell 101UL, 103UL, & 109UL in 5 gallon containers. They are all priced at $12/gallon.


Oxygenated with ethanol, this CARB-legal fuel is specifically engineered for high-performance street cars including sport compacts, muscle cars, street rods and more. It's environmentally friendly and street legal throughout the U.S. In applications with anything from 4- to 12-cyclinders or engines equipped with a turbocharger, supercharger or nitrous oxide system (NOS), StreetBlaze 100 will generate optimum power and performance. In turbocharged or supercharged applications, it allows an increase in boost without fear of detonation. NOS users can also leverage their higher octane ratings to step up to a more powerful nitrous oxide system. Dyno tests with a turbocharged application proved StreetBlaze100 generates up to 14% more horsepower compared to premium grade 91 octane unleaded gasoline. Designed for use in cast-iron head engines with CRs up to 13:1 and aluminum head engines up to 14:1. Works well on the latest generation of electronically-controlled turbo engines. Contains no metal compounds and won't harm catalytic converters or oxygen sensors.
Color: Orange
Oxygenated: Yes
Motor Octane 96
R+M/2: 100
Specific Gravity: .746 at 60° F
 

·
Premium Member
Joined
·
351 Posts
Discussion Starter · #20 ·
I just filled up with VP Racing's 100UL "Streetblaze" Racing Fuel from the pump at the VP Racing Station on Euclid Avenue, one block north of the 60 freeway in Ontario, California.

wait for it.........drumroll....... $8.99 / US gallon! (91UL was well under $2 at the same station.) All I can say is, it had better be awesome! ;)

They also sell 101UL, 103UL, & 109UL in 5 gallon containers. They are all priced at $12/gallon.

It'll probably take half a tank before you will notice anything.
 
1 - 20 of 40 Posts
Top