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 Post subject: Fuel Octane
PostPosted: Wed Jun 14, 2017 4:07 am 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7699
Location: Hope, B.C Canada
Here is a little something I pulled off the net a few weeks ago. Unfortunately I can't remember which site but I must of figured it was important when I saved it.
Octane Index:
The evaluation of the octane number by the two laboratory methods requires a standard Engine, and the test procedure can be both expensive and time-consuming. The standard Engine required for the test may not always be available, especially in out-of-the-way places or in small or mobile laboratories. These and other considerations led to the search for a rapid method for the evaluation of the anti-knock quality of gasoline. Such methods include FTIR, near infrared on-line analyzers (ASTM D-2885) and others. Deriving an equation that can be used for calculating the octane quality would also serve the same purpose with added advantages. The term Octane Index is often used to refer to the calculated octane quality in contradistinction to the (measured) research or motor (( Internal Combustion Engine ? )) octane numbers. The octane index can be of great service in the blending of gasoline. motor (( Internal Combustion Engine ? )) gasoline, as marketed, is usually a blend of several types of refinery grades that are derived from different processes such as straight-run gasoline, reformate, cracked gasoline etc. These different grades are considered as one group when blending to meet final product specifications. Most refiners produce and market more than one grade of motor (( Internal Combustion Engine ? )) gasoline, differing principally in their anti-knock quality. The ability to predict the octane quality of the blends prior to blending is essential, something for which the calculated octane index is specially suited.

In other words they're FKN guessing.
The standard Engine used is to much of a hassle to have handy.
Anybody trust the oil companies ?? It's all about the maximum profit model right ?? If you can take a short cut it would make big bucks right ?? It's the capitalist way. Anybody buy a chocolate bar lately ?? When I was a kid they were twice the size they are now and they charge us four times as much for less. You can compare any product you like, laundry soap, any food product and even Wiseco pistons (they don't machine them anymore to save weight). It's the capitalist way. Now lets pretend our oddy Engine, which was made just after the stone age (the 1970's) is on the edge of major detonation due to Engine design and/or your lack of maintenance. I wonder what would happen ?? I read a piece where they found that the Pilot ignition allowed a variance in rpm from 7400 to 8000 rpm. Would that make a difference ?? How accurate is the ignition module ?? I wonder if the ignition module also floats a degree ?? Detonation is a fact of life now with this crap fuel they sell us and deto is deadly to an oddy, or any other vintage bike. Read the stuff from Klemm.


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 Post subject: Re: Fuel Octane
PostPosted: Wed Jun 14, 2017 9:04 am 
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Joined: Thu Jan 14, 2016 2:36 pm
Posts: 313
Location: Wilmington NC
And this

Attachment:
Race Gas Pump.jpg
Race Gas Pump.jpg [ 30.27 KiB | Viewed 454 times ]


Is cheaper than this

Attachment:
Pistons 3.jpg
Pistons 3.jpg [ 75.62 KiB | Viewed 454 times ]


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 Post subject: Re: Fuel Octane
PostPosted: Thu Jun 15, 2017 3:59 pm 
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Joined: Thu Apr 29, 2010 12:53 am
Posts: 1430
Location: Norco, CA
This is why I always run Av-gas, 100LL, had a friend that used to do octane testing for shell, gave him some of the Av Gas, I don't recall the exact numbers but I'm thinking the octane was 104 or 106 and it contained good old lead to get there, I think if you check 100LL, it will always be at least 100, there's no pulling to the side of the road after getting crap gas when your in a plane.

the part about the candy bars, that's just modern market strategy, you know when you hire some grad kids and expect them to make improvements, how easy is it to make a 20% smaller portion then claim now with 20% fewer calories!
Gas hikes are the same, they inflate the prices 20 or 30% for a while, people bitch and complain a bit, finally the price drops by 10 or 15% and people are happy, people you are still getting screwed.
rant over


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 Post subject: Re: Fuel Octane
PostPosted: Thu Jun 15, 2017 10:27 pm 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7699
Location: Hope, B.C Canada
Kuma wrote:
This is why I always run Av-gas, 100LL, had a friend that used to do octane testing for shell, gave him some of the Av Gas, I don't recall the exact numbers but I'm thinking the octane was 104 or 106 and it contained good old lead to get there, I think if you check 100LL, it will always be at least 100, there's no pulling to the side of the road after getting crap gas when your in a plane.

the part about the candy bars, that's just modern market strategy, you know when you hire some grad kids and expect them to make improvements, how easy is it to make a 20% smaller portion then claim now with 20% fewer calories!
Gas hikes are the same, they inflate the prices 20 or 30% for a while, people bitch and complain a bit, finally the price drops by 10 or 15% and people are happy, people you are still getting screwed.
rant over


Hey Kuma did he ever comment on how close the octane was when he tested pump gas with regards to what is posted ??
Was there any deviation and if so how much ?? Now that would be interesting to me.
Then there are always the scammers -- a long time ago now, a "New Canadian" was scamming customers with regular fuel in the premium tank and then another "New Canadian" had a rig on the pumps so that it did not pump the correct amount of fuel. The pump may have said 10 gallons but it wasn't. They got busted by random testing.


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 Post subject: Re: Fuel Octane
PostPosted: Sat Jun 17, 2017 2:39 pm 
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Joined: Fri Jan 12, 2007 2:17 pm
Posts: 3620
Location: Wichita ks
I wonder what would happen?? I read a piece where they found that the Pilot ignition allowed a variance in rpm from 7400 to 8000 rpm.

If your referring to rev limiter I do believe it was from 7400 to 7600. I also believe that came from Lee. Don't "quote" me on that until i find the post. As far as floating a degree or two Ummmmm. I would say first you would need to look at the book (Service Manual) and then understand how the trigger coil fires, again book as far as timing goes it does state +/- as a base line. The books shows (+/- 1.2 degrees, pilot). The ody manual should also state information. Now since you like the net for find cool facts find how does the trigger coil fire. Then find how the CDI (Capacitor Discharge Ignition) function in relation to rpm. as far as the pilot goes the Manual says "F (Mark)=19.5 degree +/- 1.2 degrees @2000 rpm". Once that is done you can go back to manual for ody or pilot and find the relationship to LPP and octane. Then run your port map numbers against and other Engine numbers and then have a great understanding on if higher octane fuel in required for a given rpm and then factor in +/- degrees. There is a math relation ship to the whole thing. By the way if your looking for even more fun find out how a pipe is set to port timing in degrees and the wrong one with a set up can be fatal to the Engine.

One other item to mention here is a way to monitor or understand Engine temperature as it plays a big part in the whole thing. There is a reason pilots went water cooled and most with odys using an aftermarket setup use a cooling fan or water cooling set up of some type using pump gas or a fuel or fuel mixture. Yes back in the day i had ody's and learned real quick there limits I had a nice piston collection as well,most with holes in them. Once I got a handle on them (using pump gas) never bought another piston.

Since there was no rev limiter on the ody and then they put one on the pilot, I would think they figured that one out. It wasn't until we started over boring, pipe and clutching them that we ran into issues. Yes, higher octane is a crutch and sometimes a necessity. Higher octane fuels is a safe bet, however not always the thing to do. Yes a quality fuel is important with a static setting machine (NON EFI). Then we tend to go fat (richer) to offset the variables in air quality.


You can go to my project page and look for the heading fun times in garage for some examples of set up. You can do the same with your spare parts and post up some fun stuff of your own on the ody. I would enjoy seeing and reading your fun times at camp CO.


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 Post subject: Re: Fuel Octane
PostPosted: Sat Jun 17, 2017 3:05 pm 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7699
Location: Hope, B.C Canada
adnoh wrote:
I wonder what would happen?? I read a piece where they found that the Pilot ignition allowed a variance in rpm from 7400 to 8000 rpm.

If your referring to rev limiter I do believe it was from 7400 to 7600. I also believe that came from Lee. Don't "quote" me on that until i find the post. As far as floating a degree or two Ummmmm. I would say first you would need to look at the book (Service Manual) and then understand how the trigger coil fires, again book as far as timing goes it does state +/- as a base line. The books shows (+/- 1.2 degrees, pilot). The ody manual should also state information. Now since you like the net for find cool facts find how does the trigger coil fire. Then find how the CDI (Capacitor Discharge Ignition) (Capacitor Discharge Ignition) function in relation to rpm. as far as the pilot goes the Manual says "F (Mark)=19.5 degree +/- 1.2 degrees @2000 rpm". Once that is done you can go back to manual for ody or pilot and find the relationship to LPP and octane. Then run your port map numbers against and other Engine numbers and then have a great understanding on if higher octane fuel in required for a given rpm and then factor in +/- degrees. There is a math relation ship to the whole thing. By the way if your looking for even more fun find out how a pipe is set to port timing in degrees and the wrong one with a set up can be fatal to the Engine.

One other item to mention here is a way to monitor or understand Engine temperature as it plays a big part in the whole thing. There is a reason pilots went water cooled and most with odys using an aftermarket setup use a cooling fan or water cooling set up of some type using pump gas or a fuel or fuel mixture. Yes back in the day i had ody's and learned real quick there limits I had a nice piston collection as well,most with holes in them. Once I got a handle on them (using pump gas) never bought another piston.

Since there was no rev limiter on the ody and then they put one on the pilot, I would think they figured that one out. It wasn't until we started over boring, pipe and clutching them that we ran into issues. Yes, higher octane is a crutch and sometimes a necessity. Higher octane fuels is a safe bet, however not always the thing to do. Yes a quality fuel is important with a static setting machine (NON EFI). Then we tend to go fat (richer) to offset the variables in air quality.


You can go to my project page and look for the heading fun times in garage for some examples of set up. You can do the same with your spare parts and post up some fun stuff of your own on the ody. I would enjoy seeing and reading your fun times at camp CO.


Well you confirmed some of my personal beliefs and theories.
I like the part where you said: "Yes, higher octane is a crutch and sometimes a necessity."
That's what I have been doing all along. I realized there were issues but others like Randman actually ran pump gas successfully at higher altitudes than what I was running at. The only difference was the humidity. It averages at over 60% here on the coastal mountains but it's 15% around Randman's ride area. There are other issues I am sure but don't know how to find them. Avgas was a dragon slayer for me. It's just gas n go now. I am not an Engine theory guy like you. Doubt there is anyone on this site that can match your Engine theories. At the end of the day I believe Honda has done all the engineering and we just need to keep the oddys in tip top shape. Even engineers F up. You said: " There is a reason pilots went water cooled and most with odys using an aftermarket setup use a cooling fan or water cooling set up of some type using pump gas or a fuel or fuel mixture." That's right they did F up. One small issue and poofkaboom hole in piston. I believe as you do that the heat is a big issue. I believe that heat is detonating the fuel prematurely. I can't prove it through theory though.
Dragon slayer: AVGAS


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 Post subject: Re: Fuel Octane
PostPosted: Sat Jun 17, 2017 4:08 pm 
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Joined: Fri Jan 12, 2007 2:17 pm
Posts: 3620
Location: Wichita ks
here is a pic of the ody book on timing. should help answer some questions


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 Post subject: Re: Fuel Octane
PostPosted: Sat Jun 17, 2017 4:29 pm 
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Joined: Fri Jan 12, 2007 2:17 pm
Posts: 3620
Location: Wichita ks
you can see that the ody and pilot are few degrees apart. now we look at Engine temp take water cooled jackets. Lower water temps lower octane number required. so air cooled and lowering there head and jacket ( cylinder) temp lower octane required. In a water cooled application or pilot case 1 point for 10 to 15 degrees of water temp. I use max water temp for this. I run different set ups use 170 180 and 200. I have even ran a low compression Engine on pump gas at 240 to 260. Not recommended just playing around to find limits. I prefer 175 to 180 for pump gas with a margin of error of one point.

Now look at he effect the higher temp has on intake strength or fuel density. Again higher temp need cooler fuel. The primary compression ratio or case ratio has an effect on this. If we reduce cylinder and head temps in way of cooling than the fuel density stays in check.

There is a direct relation to UCCR and exhaust port duration to static compression as a base line for octane for a given timing of LPP. Than we adjust the number based off of temp and port velocity's. You can quickly see why one may use a high octane and one can live of a lower. The UCCR increases with over bore as the exhaust duration gets smaller if not corrected at time of over bore which has an effect not only on static but octane required.


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