Octane Rating?
#2
RE: Octane Rating?
Can o' worms question. The manufacturerspecifies premium, which is 91 octane or higher (at least in N. America). Different countries use differnt methods to determine octane ratines (RON and so forth). Bottom line is that 91 or higher is what Jaguar says to use. It doesn't "recommend" premium, it specifies it. There is a difference.
That being said, you will find plenty of X type owners who run 87 or 89 octane all the time with no ill effects, myself included. Some say the only penalty is the loss of a few hp at the top end of the curve, while others will swear that you're gonna blow the whole thing up.
I run 3 tanks of 87 to 1 tank of 93.
That being said, you will find plenty of X type owners who run 87 or 89 octane all the time with no ill effects, myself included. Some say the only penalty is the loss of a few hp at the top end of the curve, while others will swear that you're gonna blow the whole thing up.
I run 3 tanks of 87 to 1 tank of 93.
#3
RE: Octane Rating?
What I've read is that the computers in cars these days will compensate timing-wise for the different fuel grade used. So you won't get that popping noise in the engine. What I read is that it shouldn't hurt the engine. Like you said, the HP loss is minimal and might not be quite as fuel efficient. I might try it and see if the MPG suffers. If it doesn't, saving 30¢ per gallon might be worth it.
#4
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#6
RE: Octane Rating?
Since fuel prices went up, I've been interested in the possible differences between octane ratings vs. mpg. I've done multi-tank tests with both 87 and 93 and have found no significant difference in fuel economy. Biggest factor is still the judicious use of your right foot. Have not felt any "seat of the pants" difference in power either. That being said, I believe that a higher octane has a better detergent quality than lower octanes, and a tankful on a regular basis is a good thing. Just my opinion.
The motors in the X typesare not forced induction - therefore detonation (pinging)should not be that big of an issue.
The motors in the X typesare not forced induction - therefore detonation (pinging)should not be that big of an issue.
#7
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#8
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RE: Octane Rating?
remember that the computer is not "instant" in its adjustments. It will take a few tanks for the car to adapt to a different octane.
Same issue going up in grade vs going down in grade.
THe worst thing you can do is switch back and forth.
THe engine and programming is designed for premium fuel. Dont be confused by numbers in different countries.. premium is premium.
There are 2 different methods to measure octane, and they give different results.
Europe reports the higher number, while the reported number in North america is an average of the two methods.
Either way... premium is premium.
I think a light footed driver could probably switch to regular fuel for the winter season with little effect. If you dont have winter, or are not light footed, Keep with the premium. the 10% cost premium will take you 10% further down the road.
bear in mind also that a light footed driver is more likely to have "buildup" in the engine. (back side of the vales especially) and lower grade fuel will lead to more buildups, so there is potential for harm there.
Same issue going up in grade vs going down in grade.
THe worst thing you can do is switch back and forth.
THe engine and programming is designed for premium fuel. Dont be confused by numbers in different countries.. premium is premium.
There are 2 different methods to measure octane, and they give different results.
Europe reports the higher number, while the reported number in North america is an average of the two methods.
Either way... premium is premium.
I think a light footed driver could probably switch to regular fuel for the winter season with little effect. If you dont have winter, or are not light footed, Keep with the premium. the 10% cost premium will take you 10% further down the road.
bear in mind also that a light footed driver is more likely to have "buildup" in the engine. (back side of the vales especially) and lower grade fuel will lead to more buildups, so there is potential for harm there.
#9
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RE: Octane Rating?
Please stop me when I am wrong here as I am no OBD-II expert, but it is my understanding that when a computer for a car is installed that is recommending premium fuel, the program for the timing assumes this grade of fuel and from the start has the timing advanced a few degrees with the intent of getting more power and preventing pre-detonation. Loss of power is not a big deal for most people, but the pre-detonation can be a big issue as this can lead to engine failure. I don't recall the compression ratio of our cars, but you get up near 10.0 or so, running a higher grade gas (ie, higher octane) is required to prevent pre-detonation. With the installation of a knock sensor (sensing the pre-detonation), the computer can retard the timing/fuel back to prevent this from happening. But, the computer can only compensate so much. I don't know if it is truely worth it. The price a month is minimal in my opinion for the added assurance that the motor will work as it was designed and not fail on me. Not to bring back an older topic, but look at the car and treat it accordingly.
#10
RE: Octane Rating?
Pull fuse 32 to erase the timing settings and force it to relearn the timing settings immediately (with Super+ in the tank) thus avoiding having to wait for a few tankfuls.
Ive tried Regular (95Ron here in UK) and Super+ (98 Ron) and cannot tell any difference apart from what Chris X said...worse MPG from Super+ due to putting foot down to see if it works.
Over here regular has come down from £1.19p/ltr (£5.40 per UK Gallon equivalent to about $10.26 per UK Gallon at $1.9:£1) )to 95.9p/ltr over the last week or two.Yes, thats right over $10 a gallon over here thanks to the govt 79% tax + VAT on fuel (I believe)!!!
Super+ is still over £1.10/ltr in some places so the extra paid over here wont warrant any savings claimed by the fuel companies.
When I had my MR2 Turbo it was imported from Japan where their std fuel is 102Ron (if I remember).
It would 'pink' like mad using 95Ron so had it mapped to take super+ (98 Ron).On that car using 95 Ron would wreck the engine due to the pre detonation ('pinking'), not an issue with the X Type.
Ive tried Regular (95Ron here in UK) and Super+ (98 Ron) and cannot tell any difference apart from what Chris X said...worse MPG from Super+ due to putting foot down to see if it works.
Over here regular has come down from £1.19p/ltr (£5.40 per UK Gallon equivalent to about $10.26 per UK Gallon at $1.9:£1) )to 95.9p/ltr over the last week or two.Yes, thats right over $10 a gallon over here thanks to the govt 79% tax + VAT on fuel (I believe)!!!
Super+ is still over £1.10/ltr in some places so the extra paid over here wont warrant any savings claimed by the fuel companies.
When I had my MR2 Turbo it was imported from Japan where their std fuel is 102Ron (if I remember).
It would 'pink' like mad using 95Ron so had it mapped to take super+ (98 Ron).On that car using 95 Ron would wreck the engine due to the pre detonation ('pinking'), not an issue with the X Type.
#14
#17
#20
RE: Octane Rating?
well, just 'cuz I can't keep my big mouth shut... I'll throw-in my $.02
Years ago, I was racing a 2-valve, air-cooled Ducati. On the Dyno, this bike made as much as 4hp more with a mid-grade (88 octane) fuel, versus a 91, or even the 110 race fuel readily available at the racetracks. Even with the high compression. It seems the higher octane slowed the ignition / burn rate so much that it reduced cylinder pressure.
Now, when we added another spark-plug to the head, we ended-up with two flame fronts that solved that issue, and we were able to make more power with the higher octane fuels.
How does that translate to your Jag-oo-R?
It doesn't. But it's interesting anyways.
what DOES translate to your Jag though, is the fact that the QUALITY of the fuel you use is as important (or more so) than the octane rating.
Don't buy fuel at places that didn't START by selling fuel... like 7-11, or Grocery Stores... or WalMart. Buy fuel from a reputable refiner. My personla preference runs to Chevron, with the Techroline (or whatever they call it now) additive that maintains injector health.
Years ago, I was racing a 2-valve, air-cooled Ducati. On the Dyno, this bike made as much as 4hp more with a mid-grade (88 octane) fuel, versus a 91, or even the 110 race fuel readily available at the racetracks. Even with the high compression. It seems the higher octane slowed the ignition / burn rate so much that it reduced cylinder pressure.
Now, when we added another spark-plug to the head, we ended-up with two flame fronts that solved that issue, and we were able to make more power with the higher octane fuels.
How does that translate to your Jag-oo-R?
It doesn't. But it's interesting anyways.
what DOES translate to your Jag though, is the fact that the QUALITY of the fuel you use is as important (or more so) than the octane rating.
Don't buy fuel at places that didn't START by selling fuel... like 7-11, or Grocery Stores... or WalMart. Buy fuel from a reputable refiner. My personla preference runs to Chevron, with the Techroline (or whatever they call it now) additive that maintains injector health.