Fuel choices
#31
Three Wheelin'
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And true to a degree what someone else said run the lowest octane you can get away with where the engine doesn't knock. However, on more sophiticated vehciles that have the ability to retard timing to eliminate knock you will loose performance. You wont here it knock but the vehicle will retard timing so you don't hear knocking, and for performance reasons you want as much advanced time as you can get without problems - generally speaking.
#32
Three Wheelin'
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When speaking of fuel density as related to performance...would filling up in the early morning when the outside air is at its coldest be beneficial? Fuel is denser when cool, correct?
Just on a side note. This PhD was doing research on how much Ethanol you can mix with gasoline before they seperated out, which is about 15% effectively. 17% in a lab perfect world. He got a grant to by a nameless company who was trying to make a 20 or 25% fuel. Not possible according to this guy. That also led to many discussions about gasoline and ethanol but that is another discussion. What I can say there isn't any thing good about putting ethanol in gasoline when it comes to performance. It reduced density, reduces volumetric effciency, and perfromance. It does help economy very slightly, mainly it reduces emissions, and that is its main purpose for mixing it with gasloine.
#33
Nordschleife Master
If you want to say that denser gas of lower octane will put out more btus then thinner gas with a higher octane , then I will say you might be correct but when you do a real world test you will find that the thinner high octane will get you down the road quicker in a 964 .
Ethanol fuel (E100) 76,100 btu/gal
Gasoline (conventional, summer) 114,500 btu/gal
Gasoline (conventional, winter) 112,500 btu/gal
Gasoline (reformulated gasoline, ethanol) 111,836 btu/gal
Gasoline (reformulated gasoline, ETBE) 111,811 btu/gal
Gasoline (reformulated gasoline, MTBE) 111,745 btu/gal
Gasoline (10% MBTE) 112,000 btu/gal
Gasoline (regular unleaded) 114,100 btu/gal
Diesel is denser than gasoline , its "Specific gravity" is greater than and it has more btu/gal .
E85
http://en.wikipedia.org/wiki/E85
http://www.topspeed.com/cars/ethanol-cars/ke327.html
Ethanol = 22.27 kWh/gal
http://www.carmagazine.co.uk/Green-C...enigsegg-CCXR/
"A green Koenigsegg? Surely some mistake?
For those who find themselves a little underwhelmed by the 806bhp power output of the Koenigsegg CCX, check out the new CCXR. Unveiled to a stunned Geneva audience, the CCXR packs a barely believable 1018bhp and - get this - it runs on environmentally friendly E85 biofuel. 'Our engineers couldn't quite believe the figures when we tested the car,' Christian von Koenigsegg told CAR Online when he showed us the car. 'Apart from a few minor changes to the fuel injection system, fuel lines, upping the supercharger boost pressure from 1.2 to 1.5 bar and changing the piston rings, the engine is the same as that in the CCX,' he explained."
"The engine tune in the CCXR is more powerful than that of the CCX, putting out 759 kilowatts (1004 bhp) at 7200 rpm and 1060 Newton metres of torque at 6100 rpm, 25% more power than the CCX.[2][3] Christian von Koenigsegg said that "Our engineers couldn't quite believe the figures when we tested the car".[4] The increased power is a result of the cooling properties of ethanol in the engine's combustion chambers allowing for a higher pressure in the cylinder and the biofuel having a higher octane rating of 113 RON compared to 95 RON for petrol in North America and 100 RON for petrol in Europe..."
Less kWh/gal than gasoline , Ethanol = 22.27 kWh/gal / Gasoline = 33.41 kWh/gal , and the fuel gives higher performance ? That does not line up with what you are saying , in fact it shows that what you are saying is not real world .
http://www.buyrealgas.com/
Ethanol fuel (E100) 76,100 btu/gal
Gasoline (conventional, summer) 114,500 btu/gal
Gasoline (conventional, winter) 112,500 btu/gal
Gasoline (reformulated gasoline, ethanol) 111,836 btu/gal
Gasoline (reformulated gasoline, ETBE) 111,811 btu/gal
Gasoline (reformulated gasoline, MTBE) 111,745 btu/gal
Gasoline (10% MBTE) 112,000 btu/gal
Gasoline (regular unleaded) 114,100 btu/gal
Diesel is denser than gasoline , its "Specific gravity" is greater than and it has more btu/gal .
Just on a side note. This PhD was doing research on how much Ethanol you can mix with gasoline before they seperated out, which is about 15% effectively. 17% in a lab perfect world. He got a grant to by a nameless company who was trying to make a 20 or 25% fuel. Not possible according to this guy.
http://en.wikipedia.org/wiki/E85
http://www.topspeed.com/cars/ethanol-cars/ke327.html
Example
33 kW and 29 kW for gasoline and CNG fuelled engine at 3500 rpm at full load, respectively. The octane rating of the CNG fuel is 120-130, but has a much lower density vs. the 93 octane gasoline that it was tested against.
A 4 kW difference from a fuel with a significantly higher octane number, which is 5 and half horse power.
33 kW and 29 kW for gasoline and CNG fuelled engine at 3500 rpm at full load, respectively. The octane rating of the CNG fuel is 120-130, but has a much lower density vs. the 93 octane gasoline that it was tested against.
A 4 kW difference from a fuel with a significantly higher octane number, which is 5 and half horse power.
http://www.carmagazine.co.uk/Green-C...enigsegg-CCXR/
"A green Koenigsegg? Surely some mistake?
For those who find themselves a little underwhelmed by the 806bhp power output of the Koenigsegg CCX, check out the new CCXR. Unveiled to a stunned Geneva audience, the CCXR packs a barely believable 1018bhp and - get this - it runs on environmentally friendly E85 biofuel. 'Our engineers couldn't quite believe the figures when we tested the car,' Christian von Koenigsegg told CAR Online when he showed us the car. 'Apart from a few minor changes to the fuel injection system, fuel lines, upping the supercharger boost pressure from 1.2 to 1.5 bar and changing the piston rings, the engine is the same as that in the CCX,' he explained."
"The engine tune in the CCXR is more powerful than that of the CCX, putting out 759 kilowatts (1004 bhp) at 7200 rpm and 1060 Newton metres of torque at 6100 rpm, 25% more power than the CCX.[2][3] Christian von Koenigsegg said that "Our engineers couldn't quite believe the figures when we tested the car".[4] The increased power is a result of the cooling properties of ethanol in the engine's combustion chambers allowing for a higher pressure in the cylinder and the biofuel having a higher octane rating of 113 RON compared to 95 RON for petrol in North America and 100 RON for petrol in Europe..."
Less kWh/gal than gasoline , Ethanol = 22.27 kWh/gal / Gasoline = 33.41 kWh/gal , and the fuel gives higher performance ? That does not line up with what you are saying , in fact it shows that what you are saying is not real world .
#34
If you want to say that denser gas of lower octane will put out more btus then thinner gas with a higher octane , then I will say you might be correct but when you do a real world test you will find that the thinner high octane will get you down the road quicker in a 964 .
Ethanol fuel (E100) 76,100 btu/gal
Gasoline (conventional, summer) 114,500 btu/gal
Gasoline (conventional, winter) 112,500 btu/gal
Gasoline (reformulated gasoline, ethanol) 111,836 btu/gal
Gasoline (reformulated gasoline, ETBE) 111,811 btu/gal
Gasoline (reformulated gasoline, MTBE) 111,745 btu/gal
Gasoline (10% MBTE) 112,000 btu/gal
Gasoline (regular unleaded) 114,100 btu/gal
Diesel is denser than gasoline , its "Specific gravity" is greater than and it has more btu/gal .
E85
http://en.wikipedia.org/wiki/E85
http://www.topspeed.com/cars/ethanol-cars/ke327.html
Ethanol = 22.27 kWh/gal
http://www.carmagazine.co.uk/Green-C...enigsegg-CCXR/
"A green Koenigsegg? Surely some mistake?
For those who find themselves a little underwhelmed by the 806bhp power output of the Koenigsegg CCX, check out the new CCXR. Unveiled to a stunned Geneva audience, the CCXR packs a barely believable 1018bhp and - get this - it runs on environmentally friendly E85 biofuel. 'Our engineers couldn't quite believe the figures when we tested the car,' Christian von Koenigsegg told CAR Online when he showed us the car. 'Apart from a few minor changes to the fuel injection system, fuel lines, upping the supercharger boost pressure from 1.2 to 1.5 bar and changing the piston rings, the engine is the same as that in the CCX,' he explained."
"The engine tune in the CCXR is more powerful than that of the CCX, putting out 759 kilowatts (1004 bhp) at 7200 rpm and 1060 Newton metres of torque at 6100 rpm, 25% more power than the CCX.[2][3] Christian von Koenigsegg said that "Our engineers couldn't quite believe the figures when we tested the car".[4] The increased power is a result of the cooling properties of ethanol in the engine's combustion chambers allowing for a higher pressure in the cylinder and the biofuel having a higher octane rating of 113 RON compared to 95 RON for petrol in North America and 100 RON for petrol in Europe..."
Less kWh/gal than gasoline , Ethanol = 22.27 kWh/gal / Gasoline = 33.41 kWh/gal , and the fuel gives higher performance ? That does not line up with what you are saying , in fact it shows that what you are saying is not real world .
http://www.buyrealgas.com/
Ethanol fuel (E100) 76,100 btu/gal
Gasoline (conventional, summer) 114,500 btu/gal
Gasoline (conventional, winter) 112,500 btu/gal
Gasoline (reformulated gasoline, ethanol) 111,836 btu/gal
Gasoline (reformulated gasoline, ETBE) 111,811 btu/gal
Gasoline (reformulated gasoline, MTBE) 111,745 btu/gal
Gasoline (10% MBTE) 112,000 btu/gal
Gasoline (regular unleaded) 114,100 btu/gal
Diesel is denser than gasoline , its "Specific gravity" is greater than and it has more btu/gal .
E85
http://en.wikipedia.org/wiki/E85
http://www.topspeed.com/cars/ethanol-cars/ke327.html
Ethanol = 22.27 kWh/gal
http://www.carmagazine.co.uk/Green-C...enigsegg-CCXR/
"A green Koenigsegg? Surely some mistake?
For those who find themselves a little underwhelmed by the 806bhp power output of the Koenigsegg CCX, check out the new CCXR. Unveiled to a stunned Geneva audience, the CCXR packs a barely believable 1018bhp and - get this - it runs on environmentally friendly E85 biofuel. 'Our engineers couldn't quite believe the figures when we tested the car,' Christian von Koenigsegg told CAR Online when he showed us the car. 'Apart from a few minor changes to the fuel injection system, fuel lines, upping the supercharger boost pressure from 1.2 to 1.5 bar and changing the piston rings, the engine is the same as that in the CCX,' he explained."
"The engine tune in the CCXR is more powerful than that of the CCX, putting out 759 kilowatts (1004 bhp) at 7200 rpm and 1060 Newton metres of torque at 6100 rpm, 25% more power than the CCX.[2][3] Christian von Koenigsegg said that "Our engineers couldn't quite believe the figures when we tested the car".[4] The increased power is a result of the cooling properties of ethanol in the engine's combustion chambers allowing for a higher pressure in the cylinder and the biofuel having a higher octane rating of 113 RON compared to 95 RON for petrol in North America and 100 RON for petrol in Europe..."
Less kWh/gal than gasoline , Ethanol = 22.27 kWh/gal / Gasoline = 33.41 kWh/gal , and the fuel gives higher performance ? That does not line up with what you are saying , in fact it shows that what you are saying is not real world .
http://www.buyrealgas.com/
Remember octane rating is the number that the fuel will detonate at x cylinder pressure.
On a standard 964 you do not have that ability the cylinder pressure is fixed. It's not a apples to apples comparison.
#35
"If your car isn't knocking, then higher octane will basically yield little to no power increase."
Actually, in most cases one will never become aware of knocking, given the
knock control system used in the 964 DME ECM. What really happens is that
the ECM will retard the spark and eliminate the knock immediately and on
a singular cylinder if that's the case. The retard remains until the knock is
eliminated, e.g. less engine load. With a retarded timing the torque is reduced
and thus performance.
So when using lower octane fuels the engine will produce lower torque,
i.e. It results in a higher probability of the knocks and the knock control
system retarding the timing. Furthermore, when using the so-called 'performance'
chips, the probability of knocks (because of the 'pushed' timing) is increased
resulting in actually reduced torque (performance) under some driving conditions.
So using a 'performance' chip could be considered another zero-sum-game.
Actually, in most cases one will never become aware of knocking, given the
knock control system used in the 964 DME ECM. What really happens is that
the ECM will retard the spark and eliminate the knock immediately and on
a singular cylinder if that's the case. The retard remains until the knock is
eliminated, e.g. less engine load. With a retarded timing the torque is reduced
and thus performance.
So when using lower octane fuels the engine will produce lower torque,
i.e. It results in a higher probability of the knocks and the knock control
system retarding the timing. Furthermore, when using the so-called 'performance'
chips, the probability of knocks (because of the 'pushed' timing) is increased
resulting in actually reduced torque (performance) under some driving conditions.
So using a 'performance' chip could be considered another zero-sum-game.
#36
"If your car isn't knocking, then higher octane will basically yield little to no power increase."
Actually, in most cases one will never become aware of knocking, given the
knock control system used in the 964 DME ECM. What really happens is that
the ECM will retard the spark and eliminate the knock immediately and on
a singular cylinder if that's the case. The retard remains until the knock is
eliminated, e.g. less engine load. With a retarded timing the torque is reduced
and thus performance.
So when using lower octane fuels the engine will produce lower torque,
which results in a higher probability of the knocks and the knock control
system retarding the timing. When using the so-called 'performance' chips,
the probability of knocks is increased resulting in actually reduced torque
(performance) under some driving condition. So using a 'performance' chip
could be considered a zero-sum-game.
Actually, in most cases one will never become aware of knocking, given the
knock control system used in the 964 DME ECM. What really happens is that
the ECM will retard the spark and eliminate the knock immediately and on
a singular cylinder if that's the case. The retard remains until the knock is
eliminated, e.g. less engine load. With a retarded timing the torque is reduced
and thus performance.
So when using lower octane fuels the engine will produce lower torque,
which results in a higher probability of the knocks and the knock control
system retarding the timing. When using the so-called 'performance' chips,
the probability of knocks is increased resulting in actually reduced torque
(performance) under some driving condition. So using a 'performance' chip
could be considered a zero-sum-game.
#37
"but it seems to me that a sufficiently advanced EFI system (Motronic would seem to fit the bill) would detect that leaner mixture, and now introduce Z (a higher volume) amount of fuel to combine with X amount of air, in order to sufficiently enrichen the mixture to stoich or whatever AFR it looks for - Thus, in my admittedly non-qualified brain, producing the same amount of power, but increasing fuel consumption thereby reducing efficiency?"
The Porsche 964 DME ECM does not use power (HP) as a feedback element to tweak its output.
It's only feedbacks are; RPM, O2, load (AFM), cam timing (Hall sensor), temp (air/head), and
knock signals. So the the ECM never knows it actual power output. Although the O2 sensor
does help it maintain close to the ideal AFR for peak torque.
The Porsche 964 DME ECM does not use power (HP) as a feedback element to tweak its output.
It's only feedbacks are; RPM, O2, load (AFM), cam timing (Hall sensor), temp (air/head), and
knock signals. So the the ECM never knows it actual power output. Although the O2 sensor
does help it maintain close to the ideal AFR for peak torque.
#38
Nordschleife Master
This is another subject that you don't quite get .
"A little knowledge is a dangerous thing"
Your "advice" is "funny" and dangerous .
Anybody who follows your advice will put their engine at risk of great damage .
#39
Nordschleife Master
The Porsche 964 DME ECM does not use power (HP) as a feedback element to tweak its output.
It's only feedbacks are; RPM, O2, load (AFM), cam timing (Hall sensor), temp (air/head), and
knock signals. So the the ECM never knows it actual power output. Although the O2 sensor
does help it maintain close to the ideal AFR for peak torque.
It's only feedbacks are; RPM, O2, load (AFM), cam timing (Hall sensor), temp (air/head), and
knock signals. So the the ECM never knows it actual power output. Although the O2 sensor
does help it maintain close to the ideal AFR for peak torque.
I've been meaning to contact you , I picked up a auto force efi 8400 .
Have you ever used one ?
#40
"Is there any system on any car that looks at HP ?
I've been meaning to contact you , I picked up a auto force efi 8400 .
Have you ever used one ?"
Please call sometime. The number is on my website.
I've been meaning to contact you , I picked up a auto force efi 8400 .
Have you ever used one ?"
Please call sometime. The number is on my website.
#41
So you fail to address that a lower fuel density fuel can produce more hp and torque than a higher density fuel . You dodged it by pointing to the boost .
That's not the whole story , it's much more interesting if you look into the reality .
The pressure is constantly changing . And is changeable .
This is another subject that you don't quite get .
"A little knowledge is a dangerous thing"
Your "advice" is "funny" and dangerous .
Anybody who follows your advice will put their engine at risk of great damage .
That's not the whole story , it's much more interesting if you look into the reality .
The pressure is constantly changing . And is changeable .
This is another subject that you don't quite get .
"A little knowledge is a dangerous thing"
Your "advice" is "funny" and dangerous .
Anybody who follows your advice will put their engine at risk of great damage .
It is NOT the fuel that is making the increased hp and torque. The fuel is allowing the engine to make increased hp and torque by increasing boost in this case. The fuel is just allowing them to do it.
And actually no, there is not a whole lot more that needs to be said about octane.
Tell me exactly how the cylinder pressure at detonation is changing in a 3.6 964 motor. The only way to effectively do that is variable valve timing and or boost, which this particular engine has neither. So tell me smarty pants how is that happening.
Lastly I have not given anyone advice on what fuel to put into their car. I only pointed out that octane is somewhat meaningless in assessing fuel quality, and an explination of fuel density in relation to performance.
Show me where I said you need to run this fuel or else. The closest thing was a suggestion to use the best quality fuel which would likely come from a name brand supplier. How is that putting anyone's engine a great risk, moron.
Last edited by Makmov; 05-18-2012 at 02:51 PM.
#42
"If your car isn't knocking, then higher octane will basically yield little to no power increase."
Actually, in most cases one will never become aware of knocking, given the
knock control system used in the 964 DME ECM. What really happens is that
the ECM will retard the spark and eliminate the knock immediately and on
a singular cylinder if that's the case. The retard remains until the knock is
eliminated, e.g. less engine load. With a retarded timing the torque is reduced
and thus performance.
So when using lower octane fuels the engine will produce lower torque,
i.e. It results in a higher probability of the knocks and the knock control
system retarding the timing. Furthermore, when using the so-called 'performance'
chips, the probability of knocks (because of the 'pushed' timing) is increased
resulting in actually reduced torque (performance) under some driving conditions.
So using a 'performance' chip could be considered another zero-sum-game.
Actually, in most cases one will never become aware of knocking, given the
knock control system used in the 964 DME ECM. What really happens is that
the ECM will retard the spark and eliminate the knock immediately and on
a singular cylinder if that's the case. The retard remains until the knock is
eliminated, e.g. less engine load. With a retarded timing the torque is reduced
and thus performance.
So when using lower octane fuels the engine will produce lower torque,
i.e. It results in a higher probability of the knocks and the knock control
system retarding the timing. Furthermore, when using the so-called 'performance'
chips, the probability of knocks (because of the 'pushed' timing) is increased
resulting in actually reduced torque (performance) under some driving conditions.
So using a 'performance' chip could be considered another zero-sum-game.
So a good performance chip remaps the fuel trims increasing power and performance.
#43
"Not really the case at all. In the case of the 964 the mapping of the factory chip was intentionally lean for better fuel economy and emissions."
The AFRs are so close to the ideal range (within a 2 point range) that tweaking the fuel maps
yields basically NOTHING for a stock engine. That's the TOTAL hyperbole (and snake oil) of those
that sell the so-called 'performance' chips. It's all about how much the timing can be 'pushed'
that yields a torque change. There's no real knowledge required. It's simple; for every one degree
change of timing, a three to four ft-lbs change in torque results at the peak torque point.
"So a good performance chip remaps the fuel trims increasing power and performance."
Sure? Let's see the data where JUST a fuel map change has yielded a torque gain of any significance
without tweaking the timing for a stock engine!
Bottom line: Another one that 'bought' into the tuning B.S.!
The AFRs are so close to the ideal range (within a 2 point range) that tweaking the fuel maps
yields basically NOTHING for a stock engine. That's the TOTAL hyperbole (and snake oil) of those
that sell the so-called 'performance' chips. It's all about how much the timing can be 'pushed'
that yields a torque change. There's no real knowledge required. It's simple; for every one degree
change of timing, a three to four ft-lbs change in torque results at the peak torque point.
"So a good performance chip remaps the fuel trims increasing power and performance."
Sure? Let's see the data where JUST a fuel map change has yielded a torque gain of any significance
without tweaking the timing for a stock engine!
Bottom line: Another one that 'bought' into the tuning B.S.!
#44
I think you will find all the data you need here http://www.911chips.com/index.html.
And sure there might be some ing timming envolved but your argument was a chip was net zero.
And sure there might be some ing timming envolved but your argument was a chip was net zero.
#45
"I think you will find all the data you need here"
Please! How about some REAL and UNBIASED data?
Doubt that there are any or if so won't provide any because it indicates the ZERO effect of AFR tweaking.
Please! How about some REAL and UNBIASED data?
Doubt that there are any or if so won't provide any because it indicates the ZERO effect of AFR tweaking.