1400 runs better on low octane?

[JohninVT]

I’ve religiously used 91 octane in my Touring since I bought it.  Last week I wasn’t paying attention and pumped 87.  The popping on deceleration was less and it seemed to smooth the abrupt flat spot letting off the throttle at 2800rpm.  I thought maybe I was imagining things since I haven’t ridden much lately but I put a second tank of 87 through it this weekend and it’s real.  It’s not a night and day difference and I still want a Beetle map but it really does run slightly better with lower octane gas.  It is not a fig newton of my imagination(as my six year old says). 

Why?  The manual says use high test.  All else being equal; temperature, air density, etc. it seems counterintuitive.  I’m still going to use 91 when it’s 90 degrees or I’m hammering on the bike but I ride pretty fast and was two up, in the mountains and it never pinged.  Why would it run better with lower octane gas?  Does it ever so slightly retard the ignition? 

[Ncdan]

I thought you were suppose to be Beetles  Guinea pig with the new 1400 map for our 1400’s?

[JohninVT]

I thought you were suppose to be Beetles  Guinea pig with the new 1400 map for our 1400’s?

Just sent him a PM.   

[twowheeladdict]

My thoughts are the call for premium is in case you get caught in traffic and the engine heats up enough to cause pre-ignition with 87.

On my other bikes that required premium I could run 87 if I knew I was going to be rolling down the highway with no ill effect.  I would only do that if the country gas station either didn't have premium or it didn't look like many people used premium.

I also prefer to get fuel where the premium has its own hose.  Especially if I am just topping the bike off. 

[Bud]

     The couple of times I used it the mgg seemed better.

[bad Chad]

Don’t think what you’re saying makes sense.   Did you get the regular from the same station both times?  If so I would go to another station and try their regular. 

[Penderic]

I would get one of those ethanol measuring kits for yer pump gas and check for any differences in ethanol content between the 87 and 91 octane .....

 

 

[TN Mark]

I’ve religiously used 91 octane in my Touring since I bought it.  Last week I wasn’t paying attention and pumped 87.  The popping on deceleration was less and it seemed to smooth the abrupt flat spot letting off the throttle at 2800rpm.  I thought maybe I was imagining things since I haven’t ridden much lately but I put a second tank of 87 through it this weekend and it’s real.  It’s not a night and day difference and I still want a Beetle map but it really does run slightly better with lower octane gas.  It is not a fig newton of my imagination(as my six year old says). 

Why?  The manual says use high test.  All else being equal; temperature, air density, etc. it seems counterintuitive.  I’m still going to use 91 when it’s 90 degrees or I’m hammering on the bike but I ride pretty fast and was two up, in the mountains and it never pinged.  Why would it run better with lower octane gas?  Does it ever so slightly retard the ignition?

It works like that with my bike as well. Premium is called for but Regular feels snappier. Todays Premium is mostly to slow the burn of the fuel to prevent detonation. The premium burns slower and therefore produces less felt power.
 

[Ncdan]

It works like that with my bike as well. Premium is called for but Regular feels snappier. Todays Premium is mostly to slow the burn of the fuel to prevent detonation. The premium burns slower and therefore produces less felt power.

That’s interesting Mark. So that being a fact, except in the heat of summer, the lower octane fuel is a better option, right?

[Rough Edge racing]

It works like that with my bike as well. Premium is called for but Regular feels snappier. Todays Premium is mostly to slow the burn of the fuel to prevent detonation. The premium burns slower and therefore produces less felt power.

  Looking for more power on my Triumph 650 land speed race to stay ahead of the competition I looked at the dozens of types of racing fuels to see if one on them could make a touch more power than the racing fuel I am using...I got into a lot of research on fuel burn rates , how octane and evaportion rate controls detonation and what is detonation or pinging...I have posted tech articles here from Kevin Cameron and a leading automotive engineer on the theories of detonation...None of this supports that higher octane pump gas burn slower to control detonation...In fact the opposite is true, a faster burn limits detonation...Detona tion take time to occur...
  I would like to see actual technical proof and not articles without references  that higher octane burns slower to control detonation...Detona tion and octane is very interesting to me for some reason.

[Kev m]

It works like that with my bike as well. Premium is called for but Regular feels snappier. Todays Premium is mostly to slow the burn of the fuel to prevent detonation. The premium burns slower and therefore produces less felt power.

That's all accurate except the last sentence. The answer is "it depends" - on timing advance and compression. If there isn't enough of one of those factors yes, the slower burn will produce a little less power and a little more emissions. However, if there is enough of one or both, then the premium will produce slightly more power and a little less emissions.

I can't say which is true for the Cali 1400. But since it's also ambient condition dependent it may also just depend on the day.

[TN Mark]

We're talking pump gas, not racing fuel right? And street vehicles, not racing vehicles right?

My bike, a Victory Cross Country Tour 106" engine producing 115Hp and 116 Ft/Lbs Torque to the rear wheel with mild cams, a better flowing intake, a better flowing exhaust, mild (+4) timing advance, a PCV and dyno tuning, according to my butt dyno, seems to run more powerful on regular than it does on premium. I'm sure I had premium in the tank when it was on the dyno earlier this year. I made an exhaust change which is why I had it dyno tuned a second time.

I suspect the freshness of todays (ethanol) pump gas could a big factor. Few people run premium compared to regular in their vehicles regardless of what the owners manual may call out. People tend to buy pump gas based on cost, not octane rating. Gas stations, on average, sell a lot more regular than premium. My daughter schedules gas deliveries to stations and says regular outsells premium by about 3 to 1. Regular gas is typically a lot fresher than premium. Todays ethanol based gas will reduce its efficiency and significantly degrade within days compared to months or more from just a decade ago. And yes, temperature and humidity also play a role in your vehicles performance as well as in the gas degradation.

Of course there are several factors that contribute to the end result. Any of the most knowledgeable engine tuners, when they take a look inside your combustion chamber, are able to see if you've been using regular or wasting your money on premium gas. Using premium when you don't 'need to' will result in excessive buildup of carbon in your combustion chambers. The general rule of thumb, for your street ridden vehicle is to use the lower octane rating whenever possible without causing pinging etc.

Sometimes a simple downshift and therefore running at a higher rpm will eliminate pinging. 

So, JohninVT, I'm not at all surprised to read your CA1400 runs better on regular than on premium.

[twowheeladdict]

We're talking pump gas, not racing fuel right? And street vehicles, not racing vehicles right?

My bike, a Victory Cross Country Tour 106" engine producing 115Hp and 116 Ft/Lbs Torque to the rear wheel with mild cams, a better flowing intake, a better flowing exhaust, mild (+4) timing advance, a PCV and dyno tuning, according to my butt dyno, seems to run more powerful on regular than it does on premium. I'm sure I had premium in the tank when it was on the dyno earlier this year. I made an exhaust change which is why I had it dyno tuned a second time.

I suspect the freshness of todays (ethanol) pump gas could a big factor. Few people run premium compared to regular in their vehicles regardless of what the owners manual may call out. People tend to buy pump gas based on cost, not octane rating. Gas stations, on average, sell a lot more regular than premium. My daughter schedules gas deliveries to stations and says regular outsells premium by about 3 to 1. Regular gas is typically a lot fresher than premium. Todays ethanol based gas will reduce its efficiency and significantly degrade within days compared to months or more from just a decade ago. And yes, temperature and humidity also play a role in your vehicles performance as well as in the gas degradation.

Of course there are several factors that contribute to the end result. Any of the most knowledgeable engine tuners, when they take a look inside your combustion chamber, are able to see if you've been using regular or wasting your money on premium gas. Using premium when you don't 'need to' will result in excessive buildup of carbon in your combustion chambers. The general rule of thumb, for your street ridden vehicle is to use the lower octane rating whenever possible without causing pinging etc.

Sometimes a simple downshift and therefore running at a higher rpm will eliminate pinging. 

So, JohninVT, I'm not at all surprised to read your CA1400 runs better on regular than on premium.

Some modern cars will run both 87 and 93 octane.  The manual will usually say something like the performance will be lower when using 87 so if you want to get the most out of the vehicle run 93 octane.  They must be monitoring something and adjusting for the fuel mix. 

[Rough Edge racing]

 I asked this engine devolopment engineer the question about fuel octane and power...   David Redszus...http://www.precisionautoresearch.com/general%20info/WhoWeAre/PAR3.htm


     

 David Redszus » Mon Aug 26, 2019 12:11 pm


Not true. Fuel octane has nothing to do with burn rate...nothing. Two fuels with the same octane ratings can easily burn at different rates. Burn rate is principally a function of inlet air temperature, compression temperature, squish velocity and engine rpm. Suppose we use a 100 octane, unleaded fuel on the dyno optimally tuned, and then add some TEL or TML to the fuel while it is running. There will be no difference in performance. The two fuels are identical except for octane.

Of course, using the higher octane fuel would allow the engine to be tweake to a higher performance level without destruction due to detonation.


If we are speaking about pump gas, then all bets are off since we do not know what the actual octane values, RON and MON, actually are. Neither do we have any idea regarding the actual composition and properties of the fuels.

There is a reason why OEMs use very expensive certification fuels when performing engine tests; consistency.

[TN Mark]

I asked this engine devolopment engineer the question about fuel octane and power...   David Redszus...http://www.precisionautoresearch.com/general%20info/WhoWeAre/PAR3.htm


     

 David Redszus » Mon Aug 26, 2019 12:11 p

If we are speaking about pump gas, then all bets are off since we do not know what the actual octane values, RON and MON, actually are. Neither do we have any idea regarding the actual composition and properties of the fuels.

There is a reason why OEMs use very expensive certification fuels when performing engine tests; consistency.

Yes, we're talking pump gas therefore this is David's (and our) real world scenario. Pump gas that's purchased primarily due to its price at the pump versus the brand or the octane rating.

When I was on a long trip this Summer I ran regular a few times and noticed a performance difference. The bike seemed to run better and felt snappier. Likely similar to what JohninVT experienced. I tried regular a few more times and sometimes I noticed a difference and sometimes I didn't. Again, in the real world, not the theoretical world, not in the controlled environment of an engine building/testing laboratory, pump gas varies in freshness and performance.

It should come as no surprise that regular gas 'can' run better than premium as it simply could have been much fresher than the premium used recently. The basic difference between fuel brands that all come from the same refinery is primarily in the additive package. The sophistication of the vehicles fuel management system can also play a big part in the real world results.

I don't know anything about David who was referenced above. But I suspect he's torn down a few customers everyday, not race built engines, and can quickly determine if a higher than needed octane gas was used as well as if the oil was correct and changed at the proper intervals. 

[bad Chad]

I believe all modern autos, not so sure about M/C, that recommend running High test, will indeed run regular safely, the computer adjust, and the engine will run at a reduced level of performance.   You're daft if you believe a properly set up vehicle designed to run on premium, will run better and stronger on lower octane gas.

Mark's claim that most people who have a vehicle designed to run on premium choose to run regular, is most likely completely upside down.   In my experience, and that's all I have to go on as I have yet to see any evidence concerning the subject, people willing to dish out the extra bones to buy a vehicle designed for premium, don't start pinching pennies at the pump by running regular.

[TN Mark]

Sorry Chad, in my real world, regular outsells premium at least 3 to 1. Next tine you’re at the gas station filling up, take a look around to see what gas is going in to what vehicles. As I mentioned above, the more sophisticated the fuel management system the less that vehicle ‘needs’ to run premium. Even if it says so in the owners manual. Will said vehicle run differently on regular versus premium, maybe. Will the driver notice, not likely with most vehicles.

You can do whatever you wish so if you feel so inclined, try a tank of fresh regular in your vehicle that calls for premium. Let your own real world butt dyno be the arbiter and leave arguing theory to the theorists.

My real world butt dyno told me that regular pump gas ‘can’ out perform premium pump gas.

[Mike Tashjian]

In the mountains means less dense air to me and lower octane fuel would be appropriate.  So question is, how far up are the mountains you are riding?   I bought fuel in Colorado and the pump indicated the fuel was a couple of points lower to compensate for the thinner air.  Mike

[Rough Edge racing]

I don't know anything about David who was referenced above. But I suspect he's torn down a few customers everyday, not race built engines, and can quickly determine if a higher than needed octane gas was used as well as if the oil was correct and changed at the proper intervals.

  That's why I included his references , click on the blue highlighted link... His point is pump gas is so variable it's difficult to make comparisons...
   At the track I open a fresh 5 gallon pail of VP C12 leaded race fuel, 112 octane. I may only use a few gallons and it really doesn't stay fresh very long when opened so I use it my street bikes, 79 Triumph , 96 Monster 900, blended about 30 percent with 91 octane non ethanol pump gas...My butt dyno notices no difference...

[bad Chad]

Of course regular outsells premium, the vast majority of cars are designed for it!   You said most people with cars designed for premium run regular.   I don’t believe that’s so, and I suspect you have no evidence to support your claim.

I have run regular on several occasions in three different Guzzi, I didn’t feel any performance gain on any of them.

[oldbike54]

 It isn't about burn rate , which can be manipulated by chemistry . Lower octane ignites easier , and some dyno testing shows that an engine capable of running on 87 will make more power on lower octane than on higher octane . We have this discussion about every year or so , lots of confusion about what octane actually does , in the simplest definition , higher octane is more resistant to ignition , meaning higher compression ratios , usually meaning in modern engines CR ratios above 10.5 to 1 need a bit more octane to prevent pre-ignition . Older designs like a hemi-head Triumph run hotter than a modern design with more effective cooling . Gasoline will flash at 536 degrees F under zero pressure , ethanol at higher temps . Increasing pressure effectively lowers the flash point , as does the distance between the ignition source and the fuel mixture . The closer the ignition source , the lower the flash point . What this all means , octane requirements are dependent on several factors beyond just compression ratio .

 Dusty

[TN Mark]

I not clear on exactly what your point is a Chad. If you want to use premium, go for it. If you choose to use regular, go for it. If your vehicles run the same, great! Use the lowest octane rating you can without noticing a decrease in performance or an increase in pinging. It’s your money and your vehicles, do what you want with them.

[TN Mark]

  That's why I included his references , click on the blue highlighted link... His point is pump gas is so variable it's difficult to make comparisons...
   At the track I open a fresh 5 gallon pail of VP C12 leaded race fuel, 112 octane. I may only use a few gallons and it really doesn't stay fresh very long when opened so I use it my street bikes, 79 Triumph , 96 Monster 900, blended about 30 percent with 91 octane non ethanol pump gas...My butt dyno notices no difference...

Excellent data and information, thank you for your posts.

[TN Mark]

It isn't about burn rate , which can be manipulated by chemistry . Lower octane ignites easier , and some dyno testing shows that an engine capable of running on 87 will make more power on lower octane than on higher octane . We have this discussion about every year or so , lots of confusion about what octane actually does , in the simplest definition , higher octane is more resistant to ignition , meaning higher compression ratios , usually meaning in modern engines CR ratios above 10.5 to 1 need a bit more octane to prevent pre-ignition . Older designs like a hemi-head Triumph run hotter than a modern design with more effective cooling . Gasoline will flash at 536 degrees F under zero pressure , ethanol at higher temps . Increasing pressure effectively lowers the flash point , as does the distance between the ignition source and the fuel mixture . The closer the ignition source , the lower the flash point . What this all means , octane requirements are dependent on several factors beyond just compression ratio .

 Dusty

This, yes sir!

[bad Chad]

My point is not obscure, I don’t know why you would have trouble understanding?

[Ncdan]

4 gallons of 87 octane 10.00 dollars
4 gallons of 93 octane 10.40 dollars
These numbers are appropriate in my area.
Therefore personally I just run what the factory requirements or recommended fuel.
That said,  I will say at times Ive had to run the lesser octane and can’t tell much, if any, difference from one tank to the other, other than a little pinging if the  ambient temps are higher.

[Huzo]

Hmmm..
I’ve determined over the time I’ve had my Norge, how far I can get under similar conditions with 98 at my local Shell.
Just for the sheer sake of it , I tried to get 500 k from Creswick to Tarcutta on a tank once and made it, I filled up and it took 21.8 litres of a 23 litre tank.
I will try again next time and see what happens with 95 if the conditions are the same.
Of course the problems will be that temp. will not be identical, wind will vary and load will not be the same weight wise or aerodynamically, but I will be interested to see how it works out.
If the power figure is better, I should have the throttle open very slightly less to achieve the same trip in the same time.
That’ll be the best “butt dyno” I know of..

[bad Chad]

The seat of the pants argument is absurd in this context.    For the sake of argument, even if regular gas some how managed to produce 5% more power, practically no one would be able to notice from the saddle.

[TN Mark]

My point is not obscure, I don’t know why you would have trouble understanding?

Critiques and challenges isn’t necessarily making a point. If one person can’t tell the difference in how their bike runs from one type of gas to the next, that doesn’t negate the experience of ones who can tell a difference. The mere fact that some notice their bike running different on different gas types emphasizes the point. Your experience is yours and others have theirs.

[Tom H]

FWIW:

A few years ago, one of my loops started pinging on the freeway. Quick acceleration at about 60-70mph. Running premium gas from the station that I had been using for a few years.

Gave the bike a quick tune up to make sure all was in order. Back to my commute and still had a ping. Rode the other loop and all was fine, then it needed gas. Same station and now that bike started pinging. WTH??? Yes I checked it out as well. Hummm????

Rode the EVT and then needed gas. Again same station and it started pinging. All of this is over about a 10 or so day period.

Gotta be the gas. Filled up at a different station and that helped alot. I only fill about 3 gallons at a time, just before reserve kicks in. Next fill and they were running fine as normal.

I had never noticed it before, but there was a ummm new label about ethanol on the pump at the old station. The new station did not have an ethanol label.

Whats actually in the gas at both stations, I don't know. But unless I have to, I won't use the first station again. BTW, both are brand name stations.

Tom