ANOTHER NAIL IN THE OCTANE COFFIN -- BUT . . .

[BillGargan]

From the November 2009 Consumer Reports Page 45 regarding Car Myths

MYTH: If regular-grade fuel is good, premium must be better.
REALITY: Most vehicles run just fine on regular-grade (87 octane) fuel. Using premium in these cars won't hurt, but it won't improve performance, either. A higher-octane number simply means that the fuel is less prone to pre-ignition problems, so it's often specified for hotter running, high-compression engines. So if your car is designed for 87-octane fuel, don't waste money on premium.

CHECK: While I am a strong proponent of the statement above, they do mention "hotter running high-compression" . . . I suspect that some of you that have the opinion that premium fuel makes your engine run better -- and who live in climates where your engine almost always runs hotter -- may have a reason for your suspicion. But, all available expertise says no.

[BLACK WIDOW]

From the November 2009 Consumer Reports Page 45 regarding Car Myths

MYTH: If regular-grade fuel is good, premium must be better.
REALITY: Most vehicles run just fine on regular-grade (87 octane) fuel. Using premium in these cars won't hurt, but it won't improve performance, either. A higher-octane number simply means that the fuel is less prone to pre-ignition problems, so it's often specified for hotter running, high-compression engines. So if your car is designed for 87-octane fuel, don't waste money on premium.

CHECK: While I am a strong proponent of the statement above, they do mention "hotter running high-compression" . . . I suspect that some of you that have the opinion that premium fuel makes your engine run better -- and who live in climates where your engine almost always runs hotter -- may have a reason for your suspicion. But, all available expertise says no.

Think that is the correct advice for most autos that run lower compression.
I also think that 10.8/1 is high compression in my book, so I guess that is why I run 87 in the autos and 91 in the Spyder.:D


Michael:doorag:

[NancysToy]

Compression doesn't mean what it did back in the days of carbureted engines. With today's arrays of sensors, electronic fuel injection, electronic ignition, and sophisticated computerized engine management systems, plus some vehicles that even have electronically adjustable valve timing, compression is much higher than it used to be, with no problems. We can now run compression ratios that required aviation fuel when I was young, and ratios that would have been scoffed at by engineers in our grandfathers' day. Don't go by the numbers alone.

[ataDude]

Compression doesn't mean what it did back in the days of carbureted engines. With today's arrays of sensors, electronic fuel injection, electronic ignition, and sophisticated computerized engine management systems, plus some vehicles that even have electronically adjustable valve timing, compression is much higher than it used to be, with no problems. We can now run compression ratios that required aviation fuel when I was young, and ratios that would have been scoffed at by engineers in our grandfathers' day. Don't go by the numbers alone.

.
They had aviation back then, Scotty? :D

.

[RYDRS]

Ya...lets try some of that aviation fuel !!!!

[j45p3r]

Someone should do a dyno test with 87 and 91/93 and just see what happens.

[BLACK WIDOW]

Compression doesn't mean what it did back in the days of carbureted engines. With today's arrays of sensors, electronic fuel injection, electronic ignition, and sophisticated computerized engine management systems, plus some vehicles that even have electronically adjustable valve timing, compression is much higher than it used to be, with no problems. We can now run compression ratios that required aviation fuel when I was young, and ratios that would have been scoffed at by engineers in our grandfathers' day. Don't go by the numbers alone.


Yes, you are exactly right, and from the Spyder perspective it is the knock sensors that communicate with the ECU and retards the timing until any pre-ignition is quieted. This will save the engine from damage, but doesn't do much for performance or economy.nojokeIMHO.


Michael:doorag:


























,

[Smylinacha]

Not sure why since I'm no gearhead (hdx is my gearhead) but mine runs better on premium - I get better mileage, it runs cooler, doesn't pop. Maybe because of my magic man juice box and the work HDX did to the Spyder. But I remember filling it w/ regular when it was stock and it ran ok but not as good as it does now.

My Charger hemi will not take regular but I don't have to put 93 in, i use the mid grade and it seems to run just fine.

[Magic Man]

Someone should do a dyno test with 87 and 91/93 and just see what happens.


When you find the Dyno that can run a Spyder let us know, I'll be all over getting one on there for sure! :clap: :thumbup:

MM

[j45p3r]

When you find the Dyno that can run a Spyder let us know, I'll be all over getting one on there for sure! :clap: :thumbup:

MM
I thought you had done this already by disconnecting the rear wheel sensors?

[wyliec]

For every study that says 'A' is better than 'B' you'll find a study that says 'B' is better than 'A'; fill in A and B with whatever you want. The bottom line is, who cares. Use whatever works for you.

And for those that say save the extra money you spend on the higher octane and buy some mods, yeah right. In my area the difference in price between 87 and 93 is a dime and you save a whopping 60 cents per tankful at the most. I'd say most people spend more on snacks, coffee, and cigarettes each day. So, if you really want to save some money for mods..............

[BLACK WIDOW]

:gaah:

If you or anyone else using 87 octane is satisfied with their Spyder's performance and MPG's, then that is exactly the product you should use. BRP says that it is the minimum acceptable octane rating, so all is good.

Some of us, however, are interested in maximizing the Spyder's powerplant potential, and 87 just doesn't cut it....Higher octane is required to take full advantage of ignition timing advance under load in higher throttle positions, otherwise knock control will retard ignition timing, reducing engine power.....

The sage advice that you and others quote on the 'neverendingongoingdoesn'tgoawayoctanedebate' is great for the family truckster, but it really doesn't apply to high performance bike engines. There's a bunch of engine performance forums out there, and maybe I missed it, but I've yet to see anyone tout the benifits of 87 octane fuel in any of them:dontknow:........

:agree:When I bought the Spyder I ran nothing but 87 octane for about the first 3000 miles. Then I tried the 91 octane and noticed the spyder ran much better with improved acceleration and better response in 5th gear at highway speeds.. The Spyder will definately run on 87 octane (there is no question about that) but it runs much better with the 91. I am sure that some will say they noticed no difference, so for them the 87 should be good to go but for me it's 91 octane.

Michael:doorag:

[BajaRon]

Does your Spyder run better in cold or cool weather (once at operating temp) but start to sputter or seem to lose some power and zip when it gets to 5 or 6 bars?

Don't blame it on your Spyder, it is protecting itself and your investment from the low octane fuel you put in it.

Sure, it runs on 87 octane, and it won't hurt itself. But to do this it must retard ignition timing (in some situations) until it can function safely on the low octane fuel. So it lives up to the statement in the manual that says "Minimum Octane - 87".

Kind of like minimum wage. If your employer pays you M/W then they meet the letter of the law. But I think we can all agree that "Minimum" is not necessarily the same as "Optimal".

Sputtering and degraded performance at higher operating temperatures has convinced riders that their Spyder is overheating. When, in fact, 5 or even 6 bars is not really too hot. It used to worry me some as well. I'd be sitting in traffic and my Spyder would start sputtering, I could feel lack of performance and the heat coming off the engine compartment. I'd look down and see 5 or 6 bars on the temp gauge and was convinced my Spyder was just overheated.

But with more information I have changed my mind. Even 6 bars is not all that hot. My Honda Valkyie used to run at 220-225 at times and it didn't bother it a bit. Modern engines are designed to run at these temps.

It is the Spyder's computer that is deliberately causing the engine to run that way to keep it from knocking (which will do real damage in a hurry if not prevented). Higher operating temps require a higher octane to prevent knock. If the octane isn't there then the Spyder compensates with ignition timing adjustment.

So this is the trade-off using 87 Octane in the Spyder.

If you don't mind the retarded ignition timing then you're good to go. If you would rather keep the ignition timing at optimum then you need to provide an octane high enough so your Spyder doesn't have to reduce performance to make it all work.

The article sighted is for general automotive applications with lower compression and a lower performance engine design. If an engine is designed to run regular fuel without having to resort to any performance robbing, anti-knock adjustments, it is not compromising engine performance to use 87 octane. In these cases it is a waste of money to use premium as the engine will give you all it's got with regular fuel.

While this is a good, general rule of thumb, it is not a universal truth. There are some applications where this rule does not fit.

I use Premium and my Spyder runs better and gets better fuel mileage. Did it work with regular? Sure, but it didn't work as well.

It all depends on what you want.

[Firefly]

I've yet to see any proof that there is more power or MPG by running higher octane. Seat of the pants is not proof of fact.

On one hand you have the octane keeping things in check - on the other it's the ECU and sensors---- same way of getting the same results.

Any *possible* gains in performance or MPG would be minimal at best.

Now - if you're doing some extra tuning with the higher octane--that would certainly be a step in the right direction. Not sure if the JB can do enough to take advantage or not... but I doubt it.

Until I see a dyno or controlled lab results showing increased MPG---- I make this offer-----

I'll run my Spyder on 87 against anyone running 93 and buy em' lunch and a tank of high octane if they can take me in the 1/4 mile..... :D

Better sign up before I go Super or Turbo--- and/or new pistons & cams.....;) Of course then I would actually NEED to run high octane....:yikes:

I sure don't want to be around when some folks find out about the tooth fairy or Santa----- :roflblack:

[Firefly]

.
They had aviation back then, Scotty? :D

.


:roflblack::roflblack::roflblack:

Cold man--- reallllly cold!

[BajaRon]

.
They had aviation back then, Scotty? :D

.

Sure, birds have been around for a LONG TIME! So, what birds eat could be considered "Aviation Fuel" couln't it? :ohyea:

[Pogo]

For the past month I've been keeping a log of the fuel that I use and the distance I get between fills. I'm interested because next March the Ulysses Club is having its AGM in Albany, Western Australia, 3900 km from me in Sydney.:2excited: While there is a fuel stop every 200 km or so, when 3000 Ulysseans cross the Nullarbor (http://maps.google.com/maps?f=d&source=s_d&saddr=Sydney,+NSW&daddr=Albany,+WA&hl=en&geocode=&mra=ls&sll=-33.675447,151.115076&sspn=0.012089,0.012896&ie=UTF8&t=h&z=4) ahead of me, premium fuel may be at, um, a premium. :roflblack:

So far, I'm finding that on our 10% ethanol blend (which is displacing 91 (RON) octane fuel in Sydney), I get about 12 km/l. On 95 octane or on 98, I get about 13 km/l. I've done 4 tankfulls on each, and the figures are just beginning to stop bouncing around from variables like ride type and weather.

I know that the engine management system is doing the right thing, but it doesn't know how far I have to go to the next stop. With a pillion, a trailer and a prevailing westerly wind, I could end up well short. I don't fancy pushing my Spyder the last 25 km to the next roadhouse, even if the road is flat and featureless.:pray:

Cheers;

Pogo.

[bone crusher]

I've been saying this for some time and even put on the board some links to studies on this...yet, there are those that swear by higher octane...so be it...





From the November 2009 Consumer Reports Page 45 regarding Car Myths

MYTH: If regular-grade fuel is good, premium must be better.
REALITY: Most vehicles run just fine on regular-grade (87 octane) fuel. Using premium in these cars won't hurt, but it won't improve performance, either. A higher-octane number simply means that the fuel is less prone to pre-ignition problems, so it's often specified for hotter running, high-compression engines. So if your car is designed for 87-octane fuel, don't waste money on premium.

CHECK: While I am a strong proponent of the statement above, they do mention "hotter running high-compression" . . . I suspect that some of you that have the opinion that premium fuel makes your engine run better -- and who live in climates where your engine almost always runs hotter -- may have a reason for your suspicion. But, all available expertise says no.

[BLACK WIDOW]

I've yet to see any proof that there is more power or MPG by running higher octane. Seat of the pants is not proof of fact.

On one hand you have the octane keeping things in check - on the other it's the ECU and sensors---- same way of getting the same results.

Any *possible* gains in performance or MPG would be minimal at best.

Now - if you're doing some extra tuning with the higher octane--that would certainly be a step in the right direction. Not sure if the JB can do enough to take advantage or not... but I doubt it.

Until I see a dyno or controlled lab results showing increased MPG---- I make this offer-----

I'll run my Spyder on 87 against anyone running 93 and buy em' lunch and a tank of high octane if they can take me in the 1/4 mile..... :D

Better sign up before I go Super or Turbo--- and/or new pistons & cams.....;) Of course then I would actually NEED to run high octane....:yikes:

I sure don't want to be around when some folks find out about the tooth fairy or Santa----- :roflblack:

When it's my seat and my pants it's good enough for me:D

Michael:doorag:

[BLACK WIDOW]

:doorag:


:agree:

Michael;)

[NancysToy]

As usual, we have a great many differing opinions here. All actually have some merit. For some people, their riding style and the climate can make the Spyder (or another vehicle) run worse when the engine heats, or at higher ambient temperatures. The engine management system can compensate for the tendency to knock under these conditions, but performance can be degraded to the point where it is horribly noticeable. My wife's HHR is a case in point. Never knocks on regular, but has no zip and runs poorly sometimes. Has plenty of go at all times on premium, and actually gets far better mileage.

One of the confusing factors is that everyone rides differently, and lives in a different area. That means that not only is the climate different, but the fuel supplies vary both regionally and seasonally. What is good for one rider may not work for another. To complicate matters, the Spyder has a relatively limited ability to compensate for higher or lower octane. While it may not knock as octane drops and temperatures rise, it may reach a point where it runs out of ability to compensate and acts up horribly. On the other side of the coin, it has little built in compensation to allow more ignition advance if the engine doesn't knock, so increased performance is less than what it might be. It is not capable of pushing your eyeballs to the back of your helmet just because you ran high octane fuel. As a result, we are all quite confused.

Run whatever kind of fuel seems to make both you and the Spyder happy. If you put 15,000 miles on your Spyder in a year, the difference between regular and premium fuel costs will only be $200. That won't buy many mods...and it won't put you in the poorhouse, either. You are the only one you need to please. No sense in trying to convince everyone else.

[dave01]

While in NC a few weeks ago, I came across fuel with no ethanol crap in it. I filled the spyder up at the same station 4 times, running regular grade and the spyder was a little quicker and had better throttle response. To get the same results with ethanol diluted fuel, I have to run 92-93 octane. I know this isnt proven/scientific/documented/controlled testing, but it works for me. I have one bike that wont run on anything less than 116 octane VP C-16 fuel with only 8:1 compression........till the turbo spools up. My quad manual says ONLY regular grade fuel since it is factory tuned t run on it and doesnt have all of the computers/fuel management stuff the spyder does.
Whatever works for each person should be good enough...IMHO:banghead:

[BLACK WIDOW]

As usual, we have a great many differing opinions here. All actually have some merit. For some people, their riding style and the climate can make the Spyder (or another vehicle) run worse when the engine heats, or at higher ambient temperatures. The engine management system can compensate for the tendency to knock under these conditions, but performance can be degraded to the point where it is horribly noticeable. My wife's HHR is a case in point. Never knocks on regular, but has no zip and runs poorly sometimes. Has plenty of go at all times on premium, and actually gets far better mileage.

One of the confusing factors is that everyone rides differently, and lives in a different area. That means that not only is the climate different, but the fuel supplies vary both regionally and seasonally. What is good for one rider may not work for another. To complicate matters, the Spyder has a relatively limited ability to compensate for higher or lower octane. While it may not knock as octane drops and temperatures rise, it may reach a point where it runs out of ability to compensate and acts up horribly. On the other side of the coin, it has little built in compensation to allow more ignition advance if the engine doesn't knock, so increased performance is less than what it might be. It is not capable of pushing your eyeballs to the back of your helmet just because you ran high octane fuel. As a result, we are all quite confused.

Run whatever kind of fuel seems to make both you and the Spyder happy. If you put 15,000 miles on your Spyder in a year, the difference between regular and premium fuel costs will only be $200. That won't buy many mods...and it won't put you in the poorhouse, either. You are the only one you need to please. No sense in trying to convince everyone else.

You are totally right about that. I knew a fellow once that was totally convinced that it was a waste of money to change oil in his car because he rationalized that the filter would clean his oil and that was all he changed. It didn't matter what he read or what he was told that is what he thought:D.

[bjt]

.
They had aviation back then, Scotty? :D

.

He had a few options... :D

[Firefly]

As usual, we have a great many differing opinions here. All actually have some merit. For some people, their riding style and the climate can make the Spyder (or another vehicle) run worse when the engine heats, or at higher ambient temperatures. The engine management system can compensate for the tendency to knock under these conditions, but performance can be degraded to the point where it is horribly noticeable. My wife's HHR is a case in point. Never knocks on regular, but has no zip and runs poorly sometimes. Has plenty of go at all times on premium, and actually gets far better mileage.

One of the confusing factors is that everyone rides differently, and lives in a different area. That means that not only is the climate different, but the fuel supplies vary both regionally and seasonally. What is good for one rider may not work for another. To complicate matters, the Spyder has a relatively limited ability to compensate for higher or lower octane. While it may not knock as octane drops and temperatures rise, it may reach a point where it runs out of ability to compensate and acts up horribly. On the other side of the coin, it has little built in compensation to allow more ignition advance if the engine doesn't knock, so increased performance is less than what it might be. It is not capable of pushing your eyeballs to the back of your helmet just because you ran high octane fuel. As a result, we are all quite confused.

Run whatever kind of fuel seems to make both you and the Spyder happy. If you put 15,000 miles on your Spyder in a year, the difference between regular and premium fuel costs will only be $200. That won't buy many mods...and it won't put you in the poorhouse, either. You are the only one you need to please. No sense in trying to convince everyone else.

Very well put indeed.

The problem I see with end-user MPG ratings is that there are too many variables for anyone to get accurate results. You would have to fill the tank exactly each time, ride the same roads - in the same weather - with the same shifting and throttle each time. These variables in riding can easily make a 5 mpg shift--- something 'premium' fuel isn't going to do -- at least not on the Spyder. This is evidenced by the well-known difference between highway and city mpg ratings--- and we all know what a difference there is between those two.

[BLACK WIDOW]

Very well put indeed.

The problem I see with end-user MPG ratings is that there are too many variables for anyone to get accurate results. You would have to fill the tank exactly each time, ride the same roads - in the same weather - with the same shifting and throttle each time. These variables in riding can easily make a 5 mpg shift--- something 'premium' fuel isn't going to do -- at least not on the Spyder. This is evidenced by the well-known difference between highway and city mpg ratings--- and we all know what a difference there is between those two.

As you have correctly stated the comparison of fuel economy is very subjective at best, and almost impossible to do any direct comparisons because of the variables you mentioned. I am really not concerned with any difference in the fuel economy, for me that is a moot point. The performance is my issue more than anything else. I for one am very willing to pay a few more cents per gallon for what I believe is better performance. If I didn't think performance was better I certainly wouldn't spend that extra dime. This is just my opinion and observations, others may vary.:thumbup:


Michael:doorag:

[kman]

:popcorn:

[3wheeldemon]

http://thm-a01.yimg.com/image/4bd0ea52d44b4668 (http://rds.yahoo.com/_ylt=A0geu7dsGJJK6S4AATtXNyoA;_ylu=X3oDMTBscWN2ZnB jBHNlYwNzYwRjb2xvA2FjMgR2dGlkAw--/SIG=1oh47qcoc/EXP=1251174892/**http%3a//images.search.yahoo.com/images/view%3fback=http%253A%252F%252Fsearch.yahoo.com%25 2Fsearch%253Fei%253DUTF-8%2526p%253Dexxon%252Blogos%26w=250%26h=76%26imgur l=www.raymondloewy.com%252Fbusiness%252Fassetphoto s%252Ficons%252Fimages%252FLogos%252C%252520BP-Sheel-Exxon.jpg%26size=12.2kB%26name=Logos%2b%2bBP%2bShe el%2bExxon%2bjpg%26rcurl=http%253A%252F%252Fwww.ra ymondloewy.com%252Fbusiness%252Fassetphotos%252Fic ons%252Fpages%252FLogos%252C%252520BP-Sheel-Exxon.htm%26rurl=http%253A%252F%252Fwww.raymondloe wy.com%252Fbusiness%252Fassetphotos%252Ficons%252F pages%252FLogos%252C%252520BP-Sheel-Exxon.htm%26p=exxon%2blogos%26type=jpeg%26no=1%26t t=60%26oid=4bd0ea52d44b4668%26tit=Logos%2b%2bBP%2b Sheel%2bExxon%2bjpg%26sigr=12ovespqi%26sigi=12ia0h 2bj%26sigb=11lto9vbu):roflblack: :roflblack::roflblack:

[BajaRon]

http://thm-a01.yimg.com/image/4bd0ea52d44b4668 (http://rds.yahoo.com/_ylt=A0geu7dsGJJK6S4AATtXNyoA;_ylu=X3oDMTBscWN2ZnB jBHNlYwNzYwRjb2xvA2FjMgR2dGlkAw--/SIG=1oh47qcoc/EXP=1251174892/**http%3a//images.search.yahoo.com/images/view%3fback=http%253A%252F%252Fsearch.yahoo.com%25 2Fsearch%253Fei%253DUTF-8%2526p%253Dexxon%252Blogos%26w=250%26h=76%26imgur l=www.raymondloewy.com%252Fbusiness%252Fassetphoto s%252Ficons%252Fimages%252FLogos%252C%252520BP-Sheel-Exxon.jpg%26size=12.2kB%26name=Logos%2b%2bBP%2bShe el%2bExxon%2bjpg%26rcurl=http%253A%252F%252Fwww.ra ymondloewy.com%252Fbusiness%252Fassetphotos%252Fic ons%252Fpages%252FLogos%252C%252520BP-Sheel-Exxon.htm%26rurl=http%253A%252F%252Fwww.raymondloe wy.com%252Fbusiness%252Fassetphotos%252Ficons%252F pages%252FLogos%252C%252520BP-Sheel-Exxon.htm%26p=exxon%2blogos%26type=jpeg%26no=1%26t t=60%26oid=4bd0ea52d44b4668%26tit=Logos%2b%2bBP%2b Sheel%2bExxon%2bjpg%26sigr=12ovespqi%26sigi=12ia0h 2bj%26sigb=11lto9vbu):roflblack: :roflblack::roflblack:

Uh... It's raining here in East Tennessee. So on days like this it's more fun to :bdh:

[NancysToy]

...and for those of you who have made carefully (or not so carefully) disguised remarks about my age......if you think that's bad, you should see the odometer! :roflblack:

Pterodactyl Airlines Welcomes you aboard for you flight. Please fasten your seatbelts.

[Firefly]

As you have correctly stated the comparison of fuel economy is very subjective at best, and almost impossible to do any direct comparisons because of the variables you mentioned. I am really not concerned with any difference in the fuel economy, for me that is a moot point. The performance is my issue more than anything else. I for one am very willing to pay a few more cents per gallon for what I believe is better performance. If I didn't think performance was better I certainly wouldn't spend that extra dime. This is just my opinion and observations, others may vary.:thumbup:


Michael:doorag:

:agree:

I'm all about wanting performance--- and if I find out there is a benefit of running higher octane in the Spyder---- I could be converted. Thus far - I've just not seen any extra benefit --- mine runs the same no matter what.

If I dive into the engine and do some performance upgrades---- I'll have no choice but to switch gas.....

[Star Cruiser]

:agree:When I bought the Spyder I ran nothing but 87 octane for about the first 3000 miles. Then I tried the 91 octane and noticed the spyder ran much better with improved acceleration and better response in 5th gear at highway speeds.. The Spyder will definately run on 87 octane (there is no question about that) but it runs much better with the 91. I am sure that some will say they noticed no difference, so for them the 87 should be good to go but for me it's 91 octane.

Michael:doorag:
Interesting - I didn't realize that sensors would prevent the knocking (perhaps at the expense of some power). I have always been a proponent of not using higher octane if there was no knock. I think I would try a tank or two of higher octane and see if there is a percievable difference. It is quite a bit more expensive in Canada for higher Octane. (62¢ per US gal more). $3.34 for regular $3.96 for Premium), so I'd only switch for a noticable difference. BUT it is worth a try,. Thanks for the education

[BLACK WIDOW]

Interesting - I didn't realize that sensors would prevent the knocking (perhaps at the expense of some power). I have always been a proponent of not using higher octane if there was no knock. I think I would try a tank or two of higher octane and see if there is a percievable difference. It is quite a bit more expensive in Canada for higher Octane. (62¢ per US gal more). $3.34 for regular $3.96 for Premium), so I'd only switch for a noticable difference. BUT it is worth a try,. Thanks for the education

Try it you may like it----I did.:D

Michael:doorag:

[ataDude]

...and for those of you who have made carefully (or not so carefully) disguised remarks about my age......if you think that's bad, you should see the odometer! :roflblack:

Pterodactyl Airlines Welcomes you aboard for you flight. Please fasten your seatbelts.

http://images.icanhascheezburger.com/completestore/2009/4/29/128855028774340668.jpg
.

[BajaRon]

Interesting - I didn't realize that sensors would prevent the knocking (perhaps at the expense of some power). I have always been a proponent of not using higher octane if there was no knock. I think I would try a tank or two of higher octane and see if there is a percievable difference. It is quite a bit more expensive in Canada for higher Octane. (62¢ per US gal more). $3.34 for regular $3.96 for Premium), so I'd only switch for a noticable difference. BUT it is worth a try,. Thanks for the education

That is a tough call at $.62 per gallon more for premium. Here it's around $.20 more a gallon.

I seem to be getting about 10% better fuel mileage with Premium on the freeway. Around town it's probably not that much different. For long distance driving the additional mileage pretty much pays for the additional cost of premium.

But at your prices it would take a much bigger improvement to make a dollars and cents reason to switch.

[Star Cruiser]

Think that is the correct advice for most autos that run lower compression.
I also think that 10.8/1 is high compression in my book, so I guess that is why I run 87 in the autos and 91 in the Spyder.:D


Michael:doorag:
Mike,
I wanted to get back to you. As you might know I have been a proponent of "if it ain't knocking, stick with regular grade". You mentioned about the computer retarding the timing to prevent knock, and that made sense. I have read that if the compression is greater than 10.5 to 1 it is considered "High Compression".
I've run a couple of tanks of Premium (91 octane) and it might be psychological, but it feels like more performance to me. No difference in milage or anything. There is still no "knock", but I seem to feel better acceleration. For the extra $2.50 or $3.00 a tank I think I'll stick with premium, at least for awhile to get some more comparisons back and forth with different octane ratings. "Almost" converted

[BLACK WIDOW]

Mike,
I wanted to get back to you. As you might know I have been a proponent of "if it ain't knocking, stick with regular grade". You mentioned about the computer retarding the timing to prevent knock, and that made sense. I have read that if the compression is greater than 10.5 to 1 it is considered "High Compression".
I've run a couple of tanks of Premium (91 octane) and it might be psychological, but it feels like more performance to me. No difference in milage or anything. There is still no "knock", but I seem to feel better acceleration. For the extra $2.50 or $3.00 a tank I think I'll stick with premium, at least for awhile to get some more comparisons back and forth with different octane ratings. "Almost" converted

Yes, that is also my experience and won't use anything but 91 octane. I certainly wouldn't use it if I couldn't tell the difference.nojoke

Michael:doorag:

[boborgera]

Yes, that is also my experience and won't use anything but 91 octane. I certainly wouldn't use it if I couldn't tell the difference.nojoke

Michael:doorag:


:agree::clap: That's all i use [91/93]. It's for better performance, At least in my humble opinion. And better performance = better MPG. That is With every thing else being equal.