Which octane gas rating do you put in your F?
03-31-15, 08:00 AM
#16
I would dare to say your car will run better filling up at a station that only sells E10. Why is that? Because all the big name top tier brands sell nothing but E10 now (Shell, Chevron, BP, etc.). Their fuel has the best additives which help keep your engine clean.
The only stations I've seen selling ethanol free gas are small no name stations with unknown or no additives at all. Obviously, the best of both worlds would be a top tier brand with good additives still selling ethanol free gas, but that is not the case at least in my area.
The only stations I've seen selling ethanol free gas are small no name stations with unknown or no additives at all. Obviously, the best of both worlds would be a top tier brand with good additives still selling ethanol free gas, but that is not the case at least in my area.
03-31-15, 09:04 AM
#17
Pure ethanol has an octane rating of 114
They say your typical 91 octane gas mixed with 10% ethanol has an octane rating of about 95. The downside is ethanol burns faster and you may see a drop in mpg.
a higher octane rating means the fuel is more stable and is less susceptible to detonation. Your ECU is probably seeing less detonation (knock) and is not pulling as much timing, which would make the car feel like it's running better.
They say your typical 91 octane gas mixed with 10% ethanol has an octane rating of about 95. The downside is ethanol burns faster and you may see a drop in mpg.
a higher octane rating means the fuel is more stable and is less susceptible to detonation. Your ECU is probably seeing less detonation (knock) and is not pulling as much timing, which would make the car feel like it's running better.
03-31-15, 01:51 PM
#18
Tech Info Resource
iTrader: (2)
Wow. Lots of bad speculation. Ethanol is less energy dense than gasoline so your MPG will suffer no matter how little ethanol is in the fuel. Ethanol is about 60% of the energy content of gasoline by volume (but not by weight). There is no way on God's green earth that ethanol will ever turn to water without being through some kind of combustion process. The real problem is alcohol is hygroscopic (just like brake fluid) so it has a tendency to attract and retain water. This is why the gasoline "dryer" in a bottle is just alcohol. It mixes with the water and allows it to get burned by the engine without any major issues (as long as you don't have a tight tune and run at WOT - if your tune is very close and you're running under full load, you'd better be very sure you have no water in your fuel. You can spray it in the intake all day long, but don't let it get in the fuel.) Last but not least, the seals in your fuel system are resistant to certain chemical cocktails, and when alcohol was introduced to gasoline, many of the o-rings used by the manufacturers were not ready for it and deteriorated rapidly. So now you see in your owner's manual, specific fuel recommendations based on the OEM's knowledge of what seal materials they used and how they perform with different fuels.
Ethanol is not what made your car run better. Fuel additive packages across brands tend to be antagonistic, so if you want to clean up your injectors, the easiest thing to do is buy a different brand of fuel. The different additive profile will make the previous build up go away and a different build up start. So bouncing between brands is the best (and cheapest) way to keep your fuel system clean.
E15 is not the norm anywhere, and Lexus says specifically do not run the IS-F on anything with more than 10% ethanol. Check the owner's manual...
If you are feeding your 2UR-GSE any gasoline of 91 octane or higher using (R+M)/2, then it is not retarding timing and it should not be detonating. If it were detonating and the timing being retarded to compensate, the engine would run hot and feel very slow.
Ethanol is not what made your car run better. Fuel additive packages across brands tend to be antagonistic, so if you want to clean up your injectors, the easiest thing to do is buy a different brand of fuel. The different additive profile will make the previous build up go away and a different build up start. So bouncing between brands is the best (and cheapest) way to keep your fuel system clean.
E15 is not the norm anywhere, and Lexus says specifically do not run the IS-F on anything with more than 10% ethanol. Check the owner's manual...
If you are feeding your 2UR-GSE any gasoline of 91 octane or higher using (R+M)/2, then it is not retarding timing and it should not be detonating. If it were detonating and the timing being retarded to compensate, the engine would run hot and feel very slow.
03-31-15, 04:00 PM
#19
Well, I guess I was all wet. I just checked my owner's manual and could find no reference to ethanol. I also checked the Lexus Knowledge Center, and Nada there too.
The only thing I could find is the attached chart from the Renewable Fuels Association. And, yup, it looks like E10 is the recommendation.
Lou
The only thing I could find is the attached chart from the Renewable Fuels Association. And, yup, it looks like E10 is the recommendation.
Lou
03-31-15, 05:43 PM
#20
Tech Info Resource
iTrader: (2)
Page 410 of the 2008 owner's manual:
Page 411
n Gasoline quality standards
l Automotive manufacturers in the US, Europe and Japan have developed a specification for fuel quality called World-Wide Fuel Charter (WWFC) that is expected to be applied worldwide.
l The WWFC consists of four categories that are based on required emission levels. In the US, category 4 has been adopted.
l The WWFC improves air quality by lowering emissions in vehicle fleets, and customer satisfaction through better performance.
n Lexus recommends the use of gasoline containing detergent additives l Lexus recommends the use of gasoline that contains detergent additives to avoid build-up of engine deposits.
l All gasoline sold in the US contains detergent additives to clean and/or keep clean intake systems.
n Lexus recommends the use of cleaner burning gasoline Cleaner burning gasoline, including reformulated gasoline that contains oxygenates such as ethanol or MTBE (Methyl Tertiary Butyl Ether) is available in many areas.
Lexus recommends the use of cleaner burning gasoline and appropriately blended reformulated gasoline. These types of gasoline provide excellent vehicle performance, reduce vehicle emissions and improve air quality.
n Lexus does not recommend blended gasoline
l Lexus allows the use of oxygenate blended gasoline where the oxygenate content is up to 10% ethanol or 15% MTBE.
l If you use gasohol in your Lexus, be sure that it has an octane rating no lower than 87.
l Lexus DOES NOT recommend the use of gasoline containing methanol.
n Lexus does not recommend gasoline containing MMT
Some gasoline contains octane enhancing additive called MMT (Methylcyclopentadienyl Manganese Tricarbonyl).
Lexus DOES NOT recommend the use of gasoline that contains MMT. If fuel containing MMT is used, your emission control system may be adversely affected.
The malfunction indicator lamp on the instrument cluster may come on. If this happens, contact your Lexus dealer for service.
l Automotive manufacturers in the US, Europe and Japan have developed a specification for fuel quality called World-Wide Fuel Charter (WWFC) that is expected to be applied worldwide.
l The WWFC consists of four categories that are based on required emission levels. In the US, category 4 has been adopted.
l The WWFC improves air quality by lowering emissions in vehicle fleets, and customer satisfaction through better performance.
n Lexus recommends the use of gasoline containing detergent additives l Lexus recommends the use of gasoline that contains detergent additives to avoid build-up of engine deposits.
l All gasoline sold in the US contains detergent additives to clean and/or keep clean intake systems.
n Lexus recommends the use of cleaner burning gasoline Cleaner burning gasoline, including reformulated gasoline that contains oxygenates such as ethanol or MTBE (Methyl Tertiary Butyl Ether) is available in many areas.
Lexus recommends the use of cleaner burning gasoline and appropriately blended reformulated gasoline. These types of gasoline provide excellent vehicle performance, reduce vehicle emissions and improve air quality.
n Lexus does not recommend blended gasoline
l Lexus allows the use of oxygenate blended gasoline where the oxygenate content is up to 10% ethanol or 15% MTBE.
l If you use gasohol in your Lexus, be sure that it has an octane rating no lower than 87.
l Lexus DOES NOT recommend the use of gasoline containing methanol.
n Lexus does not recommend gasoline containing MMT
Some gasoline contains octane enhancing additive called MMT (Methylcyclopentadienyl Manganese Tricarbonyl).
Lexus DOES NOT recommend the use of gasoline that contains MMT. If fuel containing MMT is used, your emission control system may be adversely affected.
The malfunction indicator lamp on the instrument cluster may come on. If this happens, contact your Lexus dealer for service.
NOTICE
Notice on gasoline quality
l Do not use leaded gasoline.
Leaded gasoline can cause damage to your vehicle’s three-way catalytic converters causing the emission control system to malfunction.
l Do not use gasohol other than that stated here.
Other gasohol may cause fuel system damage or vehicle performance problems.
l Use of unleaded gasoline with an octane rating lower than 91 may result in engine knocking. Persistent knocking can lead to engine damage and should be corrected by refueling with higher octane unleaded gasoline.
Fuel-related poor driveability
If after using a different type of fuel, poor driveability is encountered (poor hot starting, vaporization, engine knocking, etc.), discontinue the use of that type of fuel.
When refueling with gasohol
Take care not to spill gasohol. It can damage your vehicle's paint.
Notice on gasoline quality
l Do not use leaded gasoline.
Leaded gasoline can cause damage to your vehicle’s three-way catalytic converters causing the emission control system to malfunction.
l Do not use gasohol other than that stated here.
Other gasohol may cause fuel system damage or vehicle performance problems.
l Use of unleaded gasoline with an octane rating lower than 91 may result in engine knocking. Persistent knocking can lead to engine damage and should be corrected by refueling with higher octane unleaded gasoline.
Fuel-related poor driveability
If after using a different type of fuel, poor driveability is encountered (poor hot starting, vaporization, engine knocking, etc.), discontinue the use of that type of fuel.
When refueling with gasohol
Take care not to spill gasohol. It can damage your vehicle's paint.
03-31-15, 05:52 PM
#21
Tech Info Resource
iTrader: (2)
Oh, yeah, on page 409 it says:
Fuel tank opening for unleaded gasoline
To help prevent incorrect fueling, your Lexus has a fuel tank opening that only accommodates the special nozzle on unleaded fuel pumps.
n If premium gasoline is not available
If 91 rating gasoline cannot be obtained, you may use unleaded gasoline with an octane rating as low as 87 (Research Octane Rating 91).
n If your engine knocks
l Consult your Lexus dealer.
l You may occasionally notice light knocking for a short time while accelerating or driving uphill. This is normal and there is no need for concern.
n Gasoline quality
In very few cases, driveability problems may be caused by the brand of gasoline you are using. If driveability problems persist, try changing the brand of gasoline. If this
does not correct the problem, consult your Lexus dealer.
To help prevent incorrect fueling, your Lexus has a fuel tank opening that only accommodates the special nozzle on unleaded fuel pumps.
n If premium gasoline is not available
If 91 rating gasoline cannot be obtained, you may use unleaded gasoline with an octane rating as low as 87 (Research Octane Rating 91).
n If your engine knocks
l Consult your Lexus dealer.
l You may occasionally notice light knocking for a short time while accelerating or driving uphill. This is normal and there is no need for concern.
n Gasoline quality
In very few cases, driveability problems may be caused by the brand of gasoline you are using. If driveability problems persist, try changing the brand of gasoline. If this
does not correct the problem, consult your Lexus dealer.
03-31-15, 06:12 PM
#22
OK, you are correct - I found it
However, it referenced MTBE, so I had to look that up:
http://toxics.usgs.gov/definitions/mtbe_def.html
Thanks for setting me straight
Lou
However, it referenced MTBE, so I had to look that up:http://toxics.usgs.gov/definitions/mtbe_def.html
Thanks for setting me straight
Lou
03-31-15, 09:33 PM
#23
Wow. Lots of bad speculation. Ethanol is less energy dense than gasoline so your MPG will suffer no matter how little ethanol is in the fuel. Ethanol is about 60% of the energy content of gasoline by volume (but not by weight). There is no way on God's green earth that ethanol will ever turn to water without being through some kind of combustion process. The real problem is alcohol is hygroscopic (just like brake fluid) so it has a tendency to attract and retain water. This is why the gasoline "dryer" in a bottle is just alcohol. It mixes with the water and allows it to get burned by the engine without any major issues (as long as you don't have a tight tune and run at WOT - if your tune is very close and you're running under full load, you'd better be very sure you have no water in your fuel. You can spray it in the intake all day long, but don't let it get in the fuel.) Last but not least, the seals in your fuel system are resistant to certain chemical cocktails, and when alcohol was introduced to gasoline, many of the o-rings used by the manufacturers were not ready for it and deteriorated rapidly. So now you see in your owner's manual, specific fuel recommendations based on the OEM's knowledge of what seal materials they used and how they perform with different fuels.
Ethanol is not what made your car run better. Fuel additive packages across brands tend to be antagonistic, so if you want to clean up your injectors, the easiest thing to do is buy a different brand of fuel. The different additive profile will make the previous build up go away and a different build up start. So bouncing between brands is the best (and cheapest) way to keep your fuel system clean.
E15 is not the norm anywhere, and Lexus says specifically do not run the IS-F on anything with more than 10% ethanol. Check the owner's manual...
If you are feeding your 2UR-GSE any gasoline of 91 octane or higher using (R+M)/2, then it is not retarding timing and it should not be detonating. If it were detonating and the timing being retarded to compensate, the engine would run hot and feel very slow.
Ethanol is not what made your car run better. Fuel additive packages across brands tend to be antagonistic, so if you want to clean up your injectors, the easiest thing to do is buy a different brand of fuel. The different additive profile will make the previous build up go away and a different build up start. So bouncing between brands is the best (and cheapest) way to keep your fuel system clean.
E15 is not the norm anywhere, and Lexus says specifically do not run the IS-F on anything with more than 10% ethanol. Check the owner's manual...
If you are feeding your 2UR-GSE any gasoline of 91 octane or higher using (R+M)/2, then it is not retarding timing and it should not be detonating. If it were detonating and the timing being retarded to compensate, the engine would run hot and feel very slow.
Bingo. I'll add that ethanol does attract water, but after the E10 blend reaches its saturation point, additional water introduced to the fuel will cause the ethanol to separate out, leaving you with a layer of wet ethanol, and a layer of ~87 octane gasoline (the octane of the fuel without ethanol). This would likely take many months of sitting, or water poured into your tank to happen though.
09-20-15, 09:24 AM
#25
Which octane gas rating do you put in your F?
I've been always curious to see what octane rating others had put in their F. For me, I've tried 87 (accidentally and engine pulled timing pretty bad), 91 and a mix of 100/91 octane. It could be the placebo effect but i do notice that when I mixed the two, the car pulls off the line smoother. I actually want to know what's the highest octane rating our ecu can take without pulling timing. Is 91 octane the best performance rating or 93? Or maybe 94 octane? I know e9x m3 runs a lot better on 93 octane. Will our F will run even better with a little higher octane then 91? I would love more opinions and data if you do have it.
09-20-15, 10:11 AM
#26
I haven't been able to find a lot of places in SoCal that go above 91, but when I fill up, I've exclusively pumped 91. I don't know if there's a huge benefit, but the difference in the wallet is enough to not want to consider it unless I really was gearing for something race-worthy.'
If you're looking for 100 octane unleaded, there's one in Pasadena on Arroyo Parkway. As for 93, I've seen some in DTLA, Pomona, and Fullerton. They're there, but definitely not as common as one might prefer.
If you're looking for 100 octane unleaded, there's one in Pasadena on Arroyo Parkway. As for 93, I've seen some in DTLA, Pomona, and Fullerton. They're there, but definitely not as common as one might prefer.
09-20-15, 10:23 AM
#27
Octane is control not power. The higher the octane the more resistant it is to pre-ignition/detonation/knock. There will be a point where a higher octane becomes useless.
The ECU pulls timing when it senses knock. Higher octane protects against knock thus allowing the computer the full amount of timing the engineers designed the engine to run. It does not give the engine more power, it just keeps it from losing power due to undesired circumstances.
The ECU pulls timing when it senses knock. Higher octane protects against knock thus allowing the computer the full amount of timing the engineers designed the engine to run. It does not give the engine more power, it just keeps it from losing power due to undesired circumstances.
09-20-15, 11:33 AM
#28
Tech Info Resource
iTrader: (2)
Lexus tuned the engine to run well on 91 because their biggest market is California and there is no 93 in Cali anymore. IME, Cali 91 is no better than 89, and I did a lot of experiments with my Supra to get it to run well after the transition to 92 then to 91. Cali fuel is crap pretty much. Georgia only has 93. Just another small reason I left California after 24 years of fighting the CARB.
The other thing to keep in mind is altitude. The higher up you are, the less octane you need because the guiding principles are based in Charle's law regarding pressure and temperature. Any change in pressure is accompanied by a change in temperature. This is an immutable law. When atmospheric pressure is lower, you need less octane because the temperature of the gas in the cylinder at full compression will be less. It all comes down to this anytime you are considering appropriate octane, and it gets a lot more complicated with forced induction, because you have to look at dynamic compression ratio, not static. Cam selection will also impact this even in NA engines so if your tuning is close to the edge for the fuel you are running, changing lift and duration can be the kiss of death.
The other thing to keep in mind is altitude. The higher up you are, the less octane you need because the guiding principles are based in Charle's law regarding pressure and temperature. Any change in pressure is accompanied by a change in temperature. This is an immutable law. When atmospheric pressure is lower, you need less octane because the temperature of the gas in the cylinder at full compression will be less. It all comes down to this anytime you are considering appropriate octane, and it gets a lot more complicated with forced induction, because you have to look at dynamic compression ratio, not static. Cam selection will also impact this even in NA engines so if your tuning is close to the edge for the fuel you are running, changing lift and duration can be the kiss of death.
Last edited by lobuxracer; 09-20-15 at 11:36 AM.
09-20-15, 11:35 AM
#29
Beside at the track, can't recall the last 20+ yrs I saw a station has Octane above 91 here in California.
I haven't been able to find a lot of places in SoCal that go above 91, but when I fill up, I've exclusively pumped 91. I don't know if there's a huge benefit, but the difference in the wallet is enough to not want to consider it unless I really was gearing for something race-worthy.'
If you're looking for 100 octane unleaded, there's one in Pasadena on Arroyo Parkway. As for 93, I've seen some in DTLA, Pomona, and Fullerton. They're there, but definitely not as common as one might prefer.
If you're looking for 100 octane unleaded, there's one in Pasadena on Arroyo Parkway. As for 93, I've seen some in DTLA, Pomona, and Fullerton. They're there, but definitely not as common as one might prefer.
09-20-15, 12:31 PM
#30
