What octane do these run on, 87,89,91?
11-27-2004, 07:23 PM
#41
Senior Member
SL Member
Scion Evolution
Join Date: Jan 2004
Location: In the Hot Tub
Posts: 5,736
Originally Posted by empleh
i think i'll stick with my 87. just make sure you fill up at chevron or 76 
I prefer to save the buck or more per fillup and then buying an occasional fuel system cleaner.
11-29-2004, 07:42 AM
#43
Senior Member
SL Member
Join Date: Jul 2004
Posts: 109
Well, from reading this you can tell me 93 oct is a waste, but after running 87 ever since I bought my box back in June and recently switching to 93, I can say that the engine definitely runs smoother now than it did before, and doesn't seem to struggle or work nearly as hard going up the steep-___ hills here in PA as it did with 87.
On a side note, the gas in Japan avgs about 96 oct so mechanically the engine will handle higher octane no problem, although they may be using a different ECU special for America to handle our crappy gas. If it's one universal ECU for Japan and America though, I can't imagine that it would not adjust to benefit from using higher oct gas. Anyone know if the ECU is special for here? Just curious.
On a side note, the gas in Japan avgs about 96 oct so mechanically the engine will handle higher octane no problem, although they may be using a different ECU special for America to handle our crappy gas. If it's one universal ECU for Japan and America though, I can't imagine that it would not adjust to benefit from using higher oct gas. Anyone know if the ECU is special for here? Just curious.
11-29-2004, 10:27 AM
#44
Member
SL Member
Join Date: Nov 2004
Location: Southeast of Disorder
Posts: 94
More than you ever wanted to know about gasoline. I'm with Old Punk, btw. My supercharged Miata has to run 93 octane, and I run an MSD ignition retard as well, but the xB is designed for 87. Anything more than that and you're wasting your money. These cars weren't meant to put out horsepower. They were meant to be economical.
11-29-2004, 05:32 PM
#45
Senior Member
SL Member
Scion Evolution
Join Date: Jan 2004
Location: In the Hot Tub
Posts: 5,736
The ECU doesn't change the compression ratio and that is what can take advantage of the higher octane. If you're NOT getting pre-ignition with 87, the higher octane WON'T do you any good.
11-29-2004, 06:15 PM
#46
Senior Member
SL Member
Join Date: Jul 2004
Posts: 109
But the ECU does control timing, which can be advanced/retarded by the ECU to get optimum performance from the fuel being used. Within limits, the higher the octane fuel being used, the further you should be able to advance the timing before you get pinging etc., thus better performance. Mechanically, the xB engine was designed not for 87 oct, but for as high as 96 oct to also be used in the JDM market where gas is much higher quality. It may run on 87 here and do fine, but it runs smoother with less effort on higher.
11-29-2004, 07:03 PM
#47
Member
SL Member
Join Date: Nov 2004
Location: Southeast of Disorder
Posts: 94
But if the ECU runs a *standard* such as 10* BTDC with 87 octane, and isn't programmed to continue running the timing up until knock occurs, then backing off, then it will *not* advance the timing. Just because the timing *can* be advanced past spec doesn't mean it *will* unless you fool the computer.
The ECU on my OBDII 1996 Miata must be fooled into allowing higher timing. You have to jump 10-gnd and then manually advance the timing with the CAS. The Miata was tuned for 87 octane and that's what OBDII knows is best for it.
The ECU on these cars was tuned for 87 octane. The base timing for the ECU is such that it runs well on 87 octane. I have a hard time believing that ECU is going to advance the timing until it gets knock. It's just going to go "Hey, no knock. They must be running 87 octane or better."
The ECU on my OBDII 1996 Miata must be fooled into allowing higher timing. You have to jump 10-gnd and then manually advance the timing with the CAS. The Miata was tuned for 87 octane and that's what OBDII knows is best for it.
The ECU on these cars was tuned for 87 octane. The base timing for the ECU is such that it runs well on 87 octane. I have a hard time believing that ECU is going to advance the timing until it gets knock. It's just going to go "Hey, no knock. They must be running 87 octane or better."
11-29-2004, 10:56 PM
#49
Senior Member
SL Member
Scion Evolution
Join Date: Jan 2004
Location: In the Hot Tub
Posts: 5,736
Originally Posted by phinz
But if the ECU runs a *standard* such as 10* BTDC with 87 octane, and isn't programmed to continue running the timing up until knock occurs, then backing off, then it will *not* advance the timing. Just because the timing *can* be advanced past spec doesn't mean it *will* unless you fool the computer.
The ECU on my OBDII 1996 Miata must be fooled into allowing higher timing. You have to jump 10-gnd and then manually advance the timing with the CAS. The Miata was tuned for 87 octane and that's what OBDII knows is best for it.
The ECU on these cars was tuned for 87 octane. The base timing for the ECU is such that it runs well on 87 octane. I have a hard time believing that ECU is going to advance the timing until it gets knock. It's just going to go "Hey, no knock. They must be running 87 octane or better."
The ECU on my OBDII 1996 Miata must be fooled into allowing higher timing. You have to jump 10-gnd and then manually advance the timing with the CAS. The Miata was tuned for 87 octane and that's what OBDII knows is best for it.
The ECU on these cars was tuned for 87 octane. The base timing for the ECU is such that it runs well on 87 octane. I have a hard time believing that ECU is going to advance the timing until it gets knock. It's just going to go "Hey, no knock. They must be running 87 octane or better."
The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.
The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.
The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.
It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.
http://auto.howstuffworks.com/question90.htm
The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.
The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.
It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.
http://auto.howstuffworks.com/question90.htm
11-29-2004, 11:24 PM
#50
Senior Member
DeepSouth Scions
SL Member
Join Date: Feb 2004
Location: North West Arkansas
Posts: 586
Originally Posted by TheScionicMan
Originally Posted by phinz
But if the ECU runs a *standard* such as 10* BTDC with 87 octane, and isn't programmed to continue running the timing up until knock occurs, then backing off, then it will *not* advance the timing. Just because the timing *can* be advanced past spec doesn't mean it *will* unless you fool the computer.
The ECU on my OBDII 1996 Miata must be fooled into allowing higher timing. You have to jump 10-gnd and then manually advance the timing with the CAS. The Miata was tuned for 87 octane and that's what OBDII knows is best for it.
The ECU on these cars was tuned for 87 octane. The base timing for the ECU is such that it runs well on 87 octane. I have a hard time believing that ECU is going to advance the timing until it gets knock. It's just going to go "Hey, no knock. They must be running 87 octane or better."
The ECU on my OBDII 1996 Miata must be fooled into allowing higher timing. You have to jump 10-gnd and then manually advance the timing with the CAS. The Miata was tuned for 87 octane and that's what OBDII knows is best for it.
The ECU on these cars was tuned for 87 octane. The base timing for the ECU is such that it runs well on 87 octane. I have a hard time believing that ECU is going to advance the timing until it gets knock. It's just going to go "Hey, no knock. They must be running 87 octane or better."
The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.
The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.
The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.
It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.
http://auto.howstuffworks.com/question90.htm
The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.
The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.
It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.
http://auto.howstuffworks.com/question90.htm
IMO the people who buy 92 octane gas, buy it for peace at mind, it probably does not do a dam thing, but, why not, it will not hurt anything. I maybe wrong, but that is my take on it.
-nt
11-29-2004, 11:36 PM
#51
Member
Join Date: Jul 2004
Posts: 34
Higher octane gas equals less work for the engine in the long run and less work under heavy acceration. Also with a Cold Air Induction System that experiences a "Ram" effect you will build higher HP and TQ numbers than with a lower octane.
11-29-2004, 11:43 PM
#52
Senior Member
DeepSouth Scions
SL Member
Join Date: Feb 2004
Location: North West Arkansas
Posts: 586
Originally Posted by Eski628
Higher octane gas equals less work for the engine in the long run and less work under heavy acceration. Also with a Cold Air Induction System that experiences a "Ram" effect you will build higher HP and TQ numbers than with a lower octane.
.-nt
11-30-2004, 12:22 AM
#53
Senior Member
SL Member
Scion Evolution
Join Date: Jan 2004
Location: In the Hot Tub
Posts: 5,736
Originally Posted by Eski628
Higher octane gas equals less work for the engine in the long run and less work under heavy acceration. Also with a Cold Air Induction System that experiences a "Ram" effect you will build higher HP and TQ numbers than with a lower octane.
It's not a subjective thing, "Who is to say"? The compression ratio is to say, That's who. With our comression ratio, higher octane WILL DO NO GOOD! PLAIN AND SIMPLE! Shouldn't even be a debate...
Nobody said that these cars WOULDN"T run fine on higher octane. The fact of the matter is they will not be able to gain any advantage out of it. It's money you're thowing away - worse, giving it to the Big Oil companies...
11-30-2004, 12:24 AM
#54
Senior Member
SL Member
Scinergy
Join Date: May 2004
Location: Denver, CO
Posts: 307
Originally Posted by Eski628
Higher octane gas equals less work for the engine in the long run and less work under heavy acceration. Also with a Cold Air Induction System that experiences a "Ram" effect you will build higher HP and TQ numbers than with a lower octane.
seriously people, go read the GAS FAQ
http://www.cs.uu.nl/wais/html/na-dir...line-faq/.html
Thread
Thread Starter
Forum
Replies
Last Post
DDonovan
Regional - Canada
0
03-23-2015 08:51 PM
cid_mcdp
Maintenance & Car Care
4
01-05-2015 02:45 PM
