101 Octane question
09-19-2009, 10:04 PM
#31
Burning Brakes
When I put 100 octane in the GT 3 there is a noticeable difference in the acceleration and feel of the throttle response. At 8.95 a gallon and only one location in Pasadena it becomes a treat instead of a daily thing. I have to think the ECU allows the timing to be pushed because of the lack of pre-detonation. For me it is a seat of the pants experience and not the mathematical calculations we just read.
09-20-2009, 12:25 AM
#32
Race Director
When I put 100 octane in the GT 3 there is a noticeable difference in the acceleration and feel of the throttle response. At 8.95 a gallon and only one location in Pasadena it becomes a treat instead of a daily thing. I have to think the ECU allows the timing to be pushed because of the lack of pre-detonation. For me it is a seat of the pants experience and not the mathematical calculations we just read.
High compression one of the "cheapest" ways to get more HP and by running the proper octane of gas the engine controller can advance ignition to take full advantage of the high compression with no danger from detonation.
Sincerely,
Macster.
09-20-2009, 01:35 AM
#34
I have to disagree with this - anyone could easily be wrong. The discussion has been way over my head, so I'm a guy with an opinion - which may or may not be right. If I were an automotive engineer, engine tuner, etc., then I'd have the knowledge to know what I was talking about - at least, that's my opinion 
A good technical explanation followed compelling tests (dyno for example) would seem to weed out opinion from useful information.
The most compelling test would be done under controlled conditions with the same car and would be repeatable for anyone with the right equipment - and I have to believe while most of us don't have that setup, gasoline companies, race car tuners, and car makers such as PAG certainly do.
A good technical explanation followed compelling tests (dyno for example) would seem to weed out opinion from useful information.
The most compelling test would be done under controlled conditions with the same car and would be repeatable for anyone with the right equipment - and I have to believe while most of us don't have that setup, gasoline companies, race car tuners, and car makers such as PAG certainly do.
Dave
09-20-2009, 01:36 AM
#35
You have to be careful. Evo (UK published car mag) did an gas/octane test a few years back -- I have the article somewhere -- and found considerable differences between gasolines and considerable differences in engine output (turbo-charged VW GTi). Considerable. IIRC between best and worst was 40ftlbs of torque.
Same test run with BMW M6 and there was very little difference. The testers believe that in order to protect the BWM's drivetrain from the output of the engine the engine controller dialed back timing to soften the load the engine subjected the drivetrain to and thus there were no notable differences between the tested gasolines.
But with the VW the results clearly indicate there is power and torque to be had by running a quality gasoline that has the engine maker's octane rating.
Running a higher octane rated gasoline does not help, though some experimentation is needed cause of engine deposits and the possibility the engine's octane requirements have gone up.
However if one runs a quality premium grade of gasoline this will tend to keep deposits from building up. There is more to premium gasoline than just a higher octane rating.
Also, variations were noted between different fills of the same brand and octane of gasoline. This was attributed to staleness. Premium gasoline can go stale and lose some of its *punch*.
The advice was to fill the car's tank with the proper grade and octane rating of gasoline. This gasoline best bought from a name brand gas station and should be bought from a busy station, one that is least likely to have stale gasoline its underground storage tanks.
This last bit of advice can actually be an arqument against running racing fuel cause the racing gasoline may be stale given the turnover is light. Even so I find it hard to believe the gas would go so stale as to be no better than 91/93/94 gasoline, though 100 gasoline may not be 100, but a bit less if it is stale.
Sincerely,
Macster.
Same test run with BMW M6 and there was very little difference. The testers believe that in order to protect the BWM's drivetrain from the output of the engine the engine controller dialed back timing to soften the load the engine subjected the drivetrain to and thus there were no notable differences between the tested gasolines.
But with the VW the results clearly indicate there is power and torque to be had by running a quality gasoline that has the engine maker's octane rating.
Running a higher octane rated gasoline does not help, though some experimentation is needed cause of engine deposits and the possibility the engine's octane requirements have gone up.
However if one runs a quality premium grade of gasoline this will tend to keep deposits from building up. There is more to premium gasoline than just a higher octane rating.
Also, variations were noted between different fills of the same brand and octane of gasoline. This was attributed to staleness. Premium gasoline can go stale and lose some of its *punch*.
The advice was to fill the car's tank with the proper grade and octane rating of gasoline. This gasoline best bought from a name brand gas station and should be bought from a busy station, one that is least likely to have stale gasoline its underground storage tanks.
This last bit of advice can actually be an arqument against running racing fuel cause the racing gasoline may be stale given the turnover is light. Even so I find it hard to believe the gas would go so stale as to be no better than 91/93/94 gasoline, though 100 gasoline may not be 100, but a bit less if it is stale.
Sincerely,
Macster.
Dave
09-20-2009, 12:32 PM
#36
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Marc, I'd love to see that EVO article if you find it.
I've asked about the "freshness" of gas several times. Most feel it's not an issue with the way the EPA now controls tanks and ventilation of same. Gas typically doesn't have issues until it gets 6 months old or older. I have seen advice stating it shouldn't be held in translucent containers, use metal or opaque if it's going to be in there longer than a week. A race weekend is okay for translucent plastic.
Now mistakes in storage are another matter. I read, though can't find, a piece about BMW Minis in the NE US a couple of years ago having trouble because of the heavy rains they received, and perhaps because a few station tank caps weren't properly secured, water got in (standing water in the parking lot), and it was an E10 ethanol blend. A number of fuel pumps went bad when the water separated out. BMW said this wasn't a warranty item, it was bad fuel, leaving the owners to try and recover from stations. Not good.
I've asked about the "freshness" of gas several times. Most feel it's not an issue with the way the EPA now controls tanks and ventilation of same. Gas typically doesn't have issues until it gets 6 months old or older. I have seen advice stating it shouldn't be held in translucent containers, use metal or opaque if it's going to be in there longer than a week. A race weekend is okay for translucent plastic.
Now mistakes in storage are another matter. I read, though can't find, a piece about BMW Minis in the NE US a couple of years ago having trouble because of the heavy rains they received, and perhaps because a few station tank caps weren't properly secured, water got in (standing water in the parking lot), and it was an E10 ethanol blend. A number of fuel pumps went bad when the water separated out. BMW said this wasn't a warranty item, it was bad fuel, leaving the owners to try and recover from stations. Not good.
09-20-2009, 07:42 PM
#37
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Speaking of marketing
This is Shell Germany, not Shell U.S., FWIW. Speaking of Shell and marketing, one thing that's puzzled me is that V-Power varies all over the place. Within 5 miles of me, I have V-Power that's a) 91 E0, b) 93 E10, and c) 93 E0. Now if I went in them and bought a Coke, it would be all the same. So why spend all of the money on marketing V-Power if it's just what the retailer felt like buying?
Also, got any sources inside Shell or recently retired? I'm afraid if I call the press office it'll just give them a mind-boggle to ask tech questions.
Thanks!
Also, got any sources inside Shell or recently retired? I'm afraid if I call the press office it'll just give them a mind-boggle to ask tech questions.
Thanks!
09-20-2009, 10:40 PM
#38
Race Director
Marc, I'd love to see that EVO article if you find it.
I've asked about the "freshness" of gas several times. Most feel it's not an issue with the way the EPA now controls tanks and ventilation of same. Gas typically doesn't have issues until it gets 6 months old or older. I have seen advice stating it shouldn't be held in translucent containers, use metal or opaque if it's going to be in there longer than a week. A race weekend is okay for translucent plastic.
Now mistakes in storage are another matter. I read, though can't find, a piece about BMW Minis in the NE US a couple of years ago having trouble because of the heavy rains they received, and perhaps because a few station tank caps weren't properly secured, water got in (standing water in the parking lot), and it was an E10 ethanol blend. A number of fuel pumps went bad when the water separated out. BMW said this wasn't a warranty item, it was bad fuel, leaving the owners to try and recover from stations. Not good.
I've asked about the "freshness" of gas several times. Most feel it's not an issue with the way the EPA now controls tanks and ventilation of same. Gas typically doesn't have issues until it gets 6 months old or older. I have seen advice stating it shouldn't be held in translucent containers, use metal or opaque if it's going to be in there longer than a week. A race weekend is okay for translucent plastic.
Now mistakes in storage are another matter. I read, though can't find, a piece about BMW Minis in the NE US a couple of years ago having trouble because of the heavy rains they received, and perhaps because a few station tank caps weren't properly secured, water got in (standing water in the parking lot), and it was an E10 ethanol blend. A number of fuel pumps went bad when the water separated out. BMW said this wasn't a warranty item, it was bad fuel, leaving the owners to try and recover from stations. Not good.
As for staleness I think the likelihood is greater in areas where the ground temperature is high(er). There is already a problem in at least the USA with the station pumps measuring fuel by volume and not by weight and this results in the customer receiving warm gas but less gas due to the gas being warm and thus occupying more space but having its energy content diminished some because of it.
Gas suppliers claim it is not a problem but in areas where ground temperatures are low -- which works to the deteriment of the gas stations and their owners and their suppliers of gasolines -- stations are fitted with dispensing pumps that dispense by weight not volume.
My point is that becauset the gasoline is stored at an elevated temperature the more volatile compounds leave the gasoline (and are caught by the ground tank's vapor traps) and these more volatile compounds leaving results in the gasoline going "stale".
Sincerely,
Macster.
09-21-2009, 07:33 AM
#39
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When I put 100 octane in the GT 3 there is a noticeable difference in the acceleration and feel of the throttle response. At 8.95 a gallon and only one location in Pasadena it becomes a treat instead of a daily thing. I have to think the ECU allows the timing to be pushed because of the lack of pre-detonation. For me it is a seat of the pants experience and not the mathematical calculations we just read.
09-21-2009, 08:05 PM
#40
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This turned out to be an awsome thread. For me, like many others, this technical stuff is too much. But I just got back from the track. And, BOY DOES IT MOVE! Another 997.2 on the track was running hotter (a bit). His average fuel consumption was 26.5L/100km (no idea what it is in normal terms) and mine was 24.5. And on the back straight I was pulling away from him. I understand there are too many variables in this case, but I will definitely continue mixing on track days only. I the city it's a waste of $$$. Too bad a Viper, a Vette and a S2000 went home on flatbeds, though. Safe motoring, everyone.
