Mixing 91 with 95 together

[Yung360]

Hello everyone!

So I had recently acquired a 2003 Honda CB900 from a private sale (in the a very clean condition for it's age I might add =P).
At the moment, I am using 95 since the previous owner used it as well. However, I would like to make the switch to 91 just to save a few extra dollars.

The only thing stopping me is that I'm not too sure if it's a good idea to mix 95 and 91 in the same tank. Is this a good idea?

Additionally, does anyone have links to resources where I can learn more about the mechanics behind motorcycles?

Cheers

[onearmedbandit]

Mixing the two shouldn't cause any issue at all. I don't use 91 in anything, based on my own experience and listening to those that have worked in the petrol industry here. My suggestion would be to run a few tanks on 95, record your fuel consumption, then repeat with 91 and compare.

[Akzle]

as long as you get the portions right it wont be a issue. you always want whole octane numbers or you're firing order will be out by half (or whatever degrees the decimal is)

ie if you mix 50% of 95 and 50% of 91 you end up with 93 - which is good, but if you got say 60% of 91 and 40% of 95 you'd be left with 92.5 octane which will cause irreversable engine damage cos your cam timing will be out by 5 degrees, and 5 degrees on a four stroke (5*4=20!!!) is going to lock up your rear wheel and basically kill you.

[Gremlin]

Mixing the two shouldn't cause any issue at all. I don't use 91 in anything, based on my own experience and listening to those that have worked in the petrol industry here. My suggestion would be to run a few tanks on 95, record your fuel consumption, then repeat with 91 and compare.
It's a Hornet. Mine has only done 140k on 91, but I think it's fine?

Ignore Azkle, he's off the meds again...

[Mike.Gayner]

Don't mix 91 and 95 together, it becomes flammable.

[Mike.Gayner]

as long as you get the portions right it wont be a issue. you always want whole octane numbers or you're firing order will be out by half (or whatever degrees the decimal is)

ie if you mix 50% of 95 and 50% of 91 you end up with 93 - which is good, but if you got say 60% of 91 and 40% of 95 you'd be left with 92.5 octane which will cause irreversable engine damage cos your cam timing will be out by 5 degrees, and 5 degrees on a four stroke (5*4=20!!!) is going to lock up your rear wheel and basically kill you.

The maths checks out.

[Runty]

However octane rating refers to octagonal engines (8 strokes) 8*5=40 so you'll die twice as quickly

Sent from my D6503 using Tapatalk

[FJRider]

It's a honda ... the bloody thing will probably run (ok-ish) on diesel ... :niceone:


Try it ... let us know how you got on ... :innocent:

[FJRider]

The maths checks out.

So would his daughter .... if you're ok with beards ... ;)

[AllanB]

The Hornet 900 manual states 91 or higher.


I owned one for 8 years from new.

I ran it for lengthy periods on both recording MPG's,

Performance wise there was zero difference, no spluttering, pinging, or any adverse mechanical reaction.

Mileage was likewise indistinguishable between the two.

I ended up filing up at whatever pump was closest and free - mixing made no difference.

My conclusion for that specific bike:

91 & 95 differ in colour and price.

Otherwise zero difference.

It's a peach of a engine that will last forever if you treat it to regular fresh oil.

PS - don't add a K&N air filter - they are noted on this specific bike to bugger up fueling unless you have a custom tune Power Commander fitted.

Do consider talking to KSS regarding replacement front fork springs - cheapest handling improvement you can do.

[husaberg]

Hello everyone!

So I had recently acquired a 2003 Honda CB900 from a private sale (in the a very clean condition for it's age I might add =P).
At the moment, I am using 95 since the previous owner used it as well. However, I would like to make the switch to 91 just to save a few extra dollars.

The only thing stopping me is that I'm not too sure if it's a good idea to mix 95 and 91 in the same tank. Is this a good idea?

Additionally, does anyone have links to resources where I can learn more about the mechanics behind motorcycles?

Cheers

Honda asks for a minimum of 91 Ron.
91 will be fine its generally written under the filler on a honda.
Take special attention to the coolent/antifreeze used only use the recomeded types and proportions Hondas are a bit suceptable to the warm fuzzies/furries

[sidecar bob]

Honda asks for a minimum of 91 Ron.
91 will be fine its generally written under the filler on a honda.

What if you can't get 91 Ron, & can only get 91 Darren or 91 Colin? Will that work too?

[husaberg]

What if you can't get 91 Ron, & can only get 91 Darren or 91 Colin? Will that work too?
shut up or i will tell your Mon:2thumbsup
Ron measures all NZ pump fuels he must be a busy buggar
Ps Bmw service agents shouldn't make jokes about fuel or emissions.:innocent:

[sidecar bob]

shut up or i will tell your Mon:2thumbsup
Bmw service agents shouldn't make jokes about fuel or emissions.:innocent:

VW service agents even less so. :facepalm:

[husaberg]

VW service agents even less so. :facepalm:

Zee other germans are not so squeaky
http://www.dw.com/en/german-emissions-scandal-threatens-to-engulf-mercedes-bmw/a-18937447

The results appeared to show that Mercedes and BMW models are also cheating on emissions tests

[JimO]

What if you can't get 91 Ron, & can only get 91 Darren or 91 Colin? Will that work too?

straight to the pool room

[caspernz]

Just fill with 91. No fancy procedure.

[Yung360]

Sweet as!

Cheers guys

[skippa1]

as long as you get the portions right it wont be a issue. you always want whole octane numbers or you're firing order will be out by half (or whatever degrees the decimal is)

ie if you mix 50% of 95 and 50% of 91 you end up with 93 - which is good, but if you got say 60% of 91 and 40% of 95 you'd be left with 92.5 octane which will cause irreversable engine damage cos your cam timing will be out by 5 degrees, and 5 degrees on a four stroke (5*4=20!!!) is going to lock up your rear wheel and basically kill you.
Yet again.....Akzle is right

[HenryDorsetCase]

The Hornet 900 manual states 91 or higher.


I owned one for 8 years from new.

I ran it for lengthy periods on both recording MPG's,

Performance wise there was zero difference, no spluttering, pinging, or any adverse mechanical reaction.

Mileage was likewise indistinguishable between the two.

I ended up filing up at whatever pump was closest and free - mixing made no difference.

My conclusion for that specific bike:

91 & 95 differ in colour and price.

Otherwise zero difference.

It's a peach of a engine that will last forever if you treat it to regular fresh oil.

PS - don't add a K&N air filter - they are noted on this specific bike to bugger up fueling unless you have a custom tune Power Commander fitted.

Do consider talking to KSS regarding replacement front fork springs - cheapest handling improvement you can do.

I also owned one and rated it. Best money I spent on mine was Ohlins shock and fork revalve/rebuild.

I use 91 because 95 made no difference I could tell.

[caseye]

Yet again.....Akzle is right

Jeez Skip! Don't do it! His heads big enough already.
LOL, 91 or 98, ethanlo etc, it all works, it's the degree to which it works that is important.
I've used Gulls 90 lately and the ol bandit loves it, you know you've put it in there for sure, milegae, well, who cares, I get there with more Omph! and no pinging or huge backfires when I decelerate.

[madbikeboy]

Points to OAB and Gremlin. 91 and 98, basically interchangeable for a bike that is specified minimum 91. In theory, you should see better MPG with 98 because it has more oomph for each cycle. This isn't usually proven in practice because you don't run exactly the same route, temperature, wind direction, weight, etc etc - and you're usually riding on the street at part throttle.

Octane ratings are basically guidelines, and they're measured differently across the world (we use RON, the USA uses an average of RON and MON); it's a measure that allows you to match the compression ratio and state of tune before detonation with the appropriate fuel. It's basically a measure of knock index.

Here's kind of how it works. A softly tuned motor (sensible compression ratio and no boost) of perhaps 10:1 compression ratio will happily work on 91 all day with no problems so long as the timing is set correctly. With a Hornet, this is probably the situation. So, you can run 91, 95, or 98 with no real issue.

If you ran 105 octane, you'd essentially be wasting your time, there would be no using the extra "bang" in the fuel.

So, take one of my recently built motors. It runs huge boost due to a small 8/71 GMC supercharger with a lot of overdrive into 572 cubic inches. If I ran that with 91 octane at idle, or just off idle, there would likely be no real issue. But, open the throttle and bring on boost and you'd have detonation. With a effective compression ratio of way higher than 14:1, low octane gas would create much damage, very expensive damage if no timing was pulled. In modern cars, they have a knock sensor which detects detonation and retards timing. For each pound of boost, the rule of thumb is usually near on 3 degrees of timing retardation. This high performance motor needs 105+ octane, some people run Methanol in this type of set up instead because it allows a degree of safety.

On my old GSXR1000, I ran 98 plus octane booster because it was normally aspirated, but higher compression ratio to make more power. Same point, the correct octane for the correct compression ratio with the correct timing map.


Some simple rules:
Diesel in a petrol motor = bad. Drain the tank and start again.
Petrol in a diesel = very. very bad. The car needs to be taken to a good mechanic, tank drained, fuel lines drained, injector pumps cleaned. Common rail diesels with petrol in them literally blow the injector pumps apart, this can be a $15,000 repair on late model CRD's.

91 octane in an average motor = fine (listen for pinking, if no pinking, no problem).
91 octane in a performance motor, or turbo or supercharged motor = bad. Detonation = broken motor.

98 octane in an average motor = fine, but a 20 cent per litre waste.
98 in a performance motor = fine.

91 + 98 is fine in an average motor. 91 + 98 in a performance motor, less good.

Disclaimer. Yes I know I'm massively over simplifying it and missing a bunch of information, but it's almost 1 am and I don't give a fuck.

[caspernz]

Points to OAB and Gremlin. 91 and 98, basically interchangeable for a bike that is specified minimum 91. In theory, you should see better MPG with 98 because it has more oomph for each cycle. This isn't usually proven in practice because you don't run exactly the same route, temperature, wind direction, weight, etc etc - and you're usually riding on the street at part throttle.

Octane ratings are basically guidelines, and they're measured differently across the world (we use RON, the USA uses an average of RON and MON); it's a measure that allows you to match the compression ratio and state of tune before detonation with the appropriate fuel. It's basically a measure of knock index.

Here's kind of how it works. A softly tuned motor (sensible compression ratio and no boost) of perhaps 10:1 compression ratio will happily work on 91 all day with no problems so long as the timing is set correctly. With a Hornet, this is probably the situation. So, you can run 91, 95, or 98 with no real issue.

If you ran 105 octane, you'd essentially be wasting your time, there would be no using the extra "bang" in the fuel.

So, take one of my recently built motors. It runs huge boost due to a small 8/71 GMC supercharger with a lot of overdrive into 572 cubic inches. If I ran that with 91 octane at idle, or just off idle, there would likely be no real issue. But, open the throttle and bring on boost and you'd have detonation. With a effective compression ratio of way higher than 14:1, low octane gas would create much damage, very expensive damage if no timing was pulled. In modern cars, they have a knock sensor which detects detonation and retards timing. For each pound of boost, the rule of thumb is usually near on 3 degrees of timing retardation. This high performance motor needs 105+ octane, some people run Methanol in this type of set up instead because it allows a degree of safety.

On my old GSXR1000, I ran 98 plus octane booster because it was normally aspirated, but higher compression ratio to make more power. Same point, the correct octane for the correct compression ratio with the correct timing map.


Some simple rules:
Diesel in a petrol motor = bad. Drain the tank and start again.
Petrol in a diesel = very. very bad. The car needs to be taken to a good mechanic, tank drained, fuel lines drained, injector pumps cleaned. Common rail diesels with petrol in them literally blow the injector pumps apart, this can be a $15,000 repair on late model CRD's.

91 octane in an average motor = fine (listen for pinking, if no pinking, no problem).
91 octane in a performance motor, or turbo or supercharged motor = bad. Detonation = broken motor.

98 octane in an average motor = fine, but a 20 cent per litre waste.
98 in a performance motor = fine.

91 + 98 is fine in an average motor. 91 + 98 in a performance motor, less good.

Disclaimer. Yes I know I'm massively over simplifying it and missing a bunch of information, but it's almost 1 am and I don't give a fuck.

Given the OP asked what is a very basic question...most of the above just sailed straight over his head :woohoo:

[YellowDog]

Ahemmm.....

You need to check your set up & tune. My bike is tuned for a minimum 95RON only. It was fine for 91RON before, however I found it a little snatchy on the throttle.

If your bike is stock, then 91 is fine, but there must be a reason why the previous owner decided to use 95? Perhaps it was retuned for 95RON OR perhaps he just found it ran a little better?

[madbikeboy]

Given the OP asked what is a very basic question...most of the above just sailed straight over his head :woohoo:

Basic question was met with a mix of right and sort of right answers. Thought adding a better answer would help others who see this post.

[Autech]

Basic question was met with a mix of right and sort of right answers. Thought adding a better answer would help others who see this post.

My eyes glazed over after the 3rd word and I skimmed the rest...

[Gremlin]

Given the OP asked what is a very basic question...most of the above just sailed straight over his head :woohoo:
Well, he talked about both octane ratings, but didn't say if you could mix them... and did mention about blowing stuff up :confused:

[madbikeboy]

Well, he talked about both octane ratings, but didn't say if you could mix them... and did mention about blowing stuff up :confused:

Read the last line before the disclaimer. And the first line. And a few lines in the middle.

[Dave-]

Basic question was met with a mix of right and sort of right answers. Thought adding a better answer would help others who see this post.

It's funny how people offered advice then admitted they couldn't follow your post. :brick:

Just wait till they start asking about e85....

[malcy25]

Octane ratings are basically guidelines, and they're measured differently across the world (we use RON, the USA uses an average of RON and MON); it's a measure that allows you to match the compression ratio and state of tune before detonation with the appropriate fuel. It's basically a measure of knock index.

Here's kind of how it works. A softly tuned motor (sensible compression ratio and no boost) of perhaps 10:1 compression ratio will happily work on 91 all day with no problems so long as the timing is set correctly. With a Hornet, this is probably the situation. So, you can run 91, 95, or 98 with no real issue.

If you ran 105 octane, you'd essentially be wasting your time, there would be no using the extra "bang" in the fuel.

So, take one of my recently built motors. It runs huge boost due to a small 8/71 GMC supercharger with a lot of overdrive into 572 cubic inches. If I ran that with 91 octane at idle, or just off idle, there would likely be no real issue. But, open the throttle and bring on boost and you'd have detonation. With a effective compression ratio of way higher than 14:1, low octane gas would create much damage, very expensive damage if no timing was pulled. In modern cars, they have a knock sensor which detects detonation and retards timing. For each pound of boost, the rule of thumb is usually near on 3 degrees of timing retardation. This high performance motor needs 105+ octane, some people run Methanol in this type of set up instead because it allows a degree of safety.

On my old GSXR1000, I ran 98 plus octane booster because it was normally aspirated, but higher compression ratio to make more power. Same point, the correct octane for the correct compression ratio with the correct timing map.


.

"If you ran 105 octane, you'd essentially be wasting your time, there would be no using the extra "bang" in the fuel." Wrong. As you say right above that, it's a measure of it's ability to resist detonation. Octane is not a measure of energy value of the fuel. It just allows the engine and tuner/builder to do the things that create the power and not eat itself. Things can get funky above 100 octane. The original SAE testing only could test to 100. Once you start looking at specialist fuels the range is massive and fining the right one can be fun, just looking at the, Sunoco, VP or Elf range makes my head explode, let alone the wallet....there's a whole world out there. The good old regular Avgas works fine in a lot of older bike situations where they have been leaned upon, but it is set for low rpm engines at high altitude. Modern high rpm engines don't like it and I've heard of guys with R1's and the like thinking they'll get a bonus, but actually get less power than PULP and shittier running.

Octane boosters.....hmmm, I've had a play with those, including one that is arguably the best. I've heard of independent testing that could not detect an effect. I used tetraboost out of the UK which gave good results in a 98 unleaded in the UK (specific dyno testing and real world results, better than Avgas for total performance due to good octane AND high burn speed, more like an ELF) and shit result for me here. I suspect the octane booster was okay, but the underlying fuel was the let down. Pre-ignition anyone.....that cost me a lot of money.

[Dave-]

Wrong. As you say right above that, it's a measure of it's ability to resist detonation. Octane is not a measure of energy value of the fuel. It just allows the engine and tuner/builder to do the things that create the power and not eat itself.

He goes on to say "Disclaimer. Yes I know I'm massively over simplifying it and missing a bunch of information, but it's almost 1 am and I don't give a fuck.".

I'd count this comment as a massive over simplification. I think we all agree the extra energy isn't "in" the fuel.

[husaberg]

"If you ran 105 octane, you'd essentially be wasting your time, there would be no using the extra "bang" in the fuel." Wrong. As you say right above that, it's a measure of it's ability to resist detonation. Octane is not a measure of energy value of the fuel. It just allows the engine and tuner/builder to do the things that create the power and not eat itself. Things can get funky above 100 octane. The original SAE testing only could test to 100. Once you start looking at specialist fuels the range is massive and fining the right one can be fun, just looking at the, Sunoco, VP or Elf range makes my head explode, let alone the wallet....there's a whole world out there. The good old regular Avgas works fine in a lot of older bike situations where they have been leaned upon, but it is set for low rpm engines at high altitude. Modern high rpm engines don't like it and I've heard of guys with R1's and the like thinking they'll get a bonus, but actually get less power than PULP and shittier running.

Octane boosters.....hmmm, I've had a play with those, including one that is arguably the best. I've heard of independent testing that could not detect an effect. I used tetraboost out of the UK which gave good results in a 98 unleaded in the UK (specific dyno testing and real world results, better than Avgas for total performance due to good octane AND high burn speed, more like an ELF) and shit result for me here. I suspect the octane booster was okay, but the underlying fuel was the let down. Pre-ignition anyone.....that cost me a lot of money.

Intersting thing is Honda did a load of reaserch and proved high octane was actually irelevent at high revs.
329468
also fuels also used to have a supercharger rating such as 100/110 Avgas.

[madbikeboy]

He goes on to say "Disclaimer. Yes I know I'm massively over simplifying it and missing a bunch of information, but it's almost 1 am and I don't give a fuck.".

I'd count this comment as a massive over simplification. I think we all agree the extra energy isn't "in" the fuel.

Precisely.

1234567890.

[madbikeboy]

Intersting thing is Honda did a load of reaserch and proved high octane was actually irelevent at high revs.
329468
also fuels also used to have a supercharger rating such as 100/110 Avgas.

MSD ignitions spark multiple times under about 3,000 RPM. Then it's a single spark. The critical bit for engines is the bit before the torque and HP lines intersect. I'd write a full response on this, but no one would read it, and everyone would disagree anyhow, based on their backgrounds of huge engine building experience they don't have...

As for the supercharger rating - it's a complex balance of the fuel, the type of blower (roots / centrifugal), carb'd or injected. If injected, then how big the intercooler is... etc etc...

[Akzle]

MSD ignitions spark multiple times under about 3,000 RPM. Then it's a single spark. The critical bit for engines is the bit before the torque and HP lines intersect. I'd write a full response on this, but no one would read it, and everyone would disagree anyhow, based on their backgrounds of huge engine building experience they don't have...

As for the supercharger rating - it's a complex balance of the fuel, the type of blower (roots / centrifugal), carb'd or injected. If injected, then how big the intercooler is... etc etc...

https://i.imgflip.com/lti1z.jpg

your so kewl.

[Moise]

Hate to spoil the party, but all the op asked was whether he could put 91 in a tank that had 95 in it.

The answer is yes.

Sent from somewhere using Tapatalk

[madbikeboy]

It's funny how people offered advice then admitted they couldn't follow your post. :brick:

Just wait till they start asking about e85....

I'm totally green with E85. I know a few hot rodders who have attempted to make power on it, but the really gifted work is the young guys with Japanese cars with lots of boost. I'm heading back to Aus in a very short amount of time, one of my mates is building a E85 Barra turbo set up in a '66 Mustang, he's going to be doing the tuning work on it around the middle of the year and I've asked to tag along during the dyno stage. White man's magic.

[cods4]

I'm totally green with E85. I know a few hot rodders who have attempted to make power on it, but the really gifted work is the young guys with Japanese cars with lots of boost. I'm heading back to Aus in a very short amount of time, one of my mates is building a E85 Barra turbo set up in a '66 Mustang, he's going to be doing the tuning work on it around the middle of the year and I've asked to tag along during the dyno stage. White man's magic.

I've just converted my subaru hillclimb/track car to E85. It is great stuff for turbo engines. The tuner can pretty much advance the ignition timing as much as he wants without seeing detonation. They can generally get to the point when any further advance results in less torque (there's probably a good name for it) and then wind it back just a bit. When I got back into bikes I looked briefly at doing an E85 conversion but I don't think its worth while without a turbo.

[Dave-]

They can generally get to the point when any further advance results in less torque (there's probably a good name for it)

https://en.wikipedia.org/wiki/Maximum_brake_torque

"Typically" 13-14 deg after TDC (so say -13 BTDC)

Anyone interested in this guff ought to check out https://www.hpacademy.com/

USD$99 for the tuning basics package ought to enlighten 99% of people to the basic principles of engine tuning.

[malcy25]

Intersting thing is Honda did a load of reaserch and proved high octane was actually irelevent at high revs.
329468
also fuels also used to have a supercharger rating such as 100/110 Avgas.

Husa

is 100/130 octane rating for avgas we get here (and for the old purple 115/145 as I am lead to believe, but we don't see that here anymore).

I've survived on 100LL blue in Aussie at various times, but was glad to find some 100 Green this year, same as what we usually get here. In past years the 100LL "race fuel" we have received at various times might as well have been turps....

[husaberg]

Husa

is 100/130 octane rating for avgas we get here (and for the old purple 115/145 as I am lead to believe, but we don't see that here anymore).

I've survived on 100LL blue in Aussie at various times, but was glad to find some 100 Green this year, same as what we usually get here. In past years the 100LL "race fuel" we have received at various times might as well have been turps....

I'd have to check, it will be on the Mobil website etc i guess.
I couldn't remember myself i was quoting of the cuff.
How the ratings work is well covered in the Bell 2 stroke book.
Pg 117 on
http://iheartstella.com/resources/manuals/tuning/Graham-Bell-Two-Stroke-Performance-Tuning.pdf

[husaberg]

I'd have to check, it will be on the Mobil website etc i guess.
I couldn't remember myself i was quoting of the cuff.
How the ratings work is well covered in the Bell 2 stroke book.
Pg 117 on
http://iheartstella.com/resources/manuals/tuning/Graham-Bell-Two-Stroke-Performance-Tuning.pdf

I had a look at mobil came up empty
Shell had this on their international website
http://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/the-aeroshell-book/_jcr_content/par/textimage_1433441235.stream/1445040706292/dc509e15cde99b11ddb6ed7e50c61e2e427a0f512435718921 ed79028ed25048/aeroshell-book-2fuels.pdf

Avgas 100 This was the standard high octane fuel for aviation piston engines and has a high lead content. There are two major specifications for Avgas 100. The ASTM D 910 and UK DEF STAN 91-90. These two specifications are essentially the same, but differ over antioxidant content, oxidation stability requirements and max lead content.
Avgas 100 is dyed green and is now only produced in a few refineries in the world.
Avgas 100LL This grade is the lower lead version of Avgas 100. Low lead is a relative term. There is still up to 0.56 g/litre of lead in Avgas 100LL. This grade is listed in the same specifications as Avgas 100, namely ASTM D 910 and UK DEF STAN 91-90.
Avgas 100LL is dyed blue and is the main grade of Avgas used worldwide.
Avgas 100VLL This grade is the very low lead version of Avgas 100LL, containing a maximum lead concentration of 0.45 g/litre. It is effectively a variant of Avgas 100LL with a restraint on the max lead content. It could be made available as an interim measure prior to the introduction of an unleaded high octane fuel, should it be necessary to address environmental concerns about leaded fuels. This grade is listed in ASTM D 910 and, other than the lower lead content, is constrained by the same specification requirements as Avgas 100LL. It therefore meets the same aircraft approvals and operating limitation requirements as Avgas 100LL meeting ASTM D910.
Avgas 100VLL is dyed blue.
AVIATION FUELS

2.72.6
Avgas UL82 This grade is intended to comply with the same aircraft approvals as the original motor gasoline (mogas) Supplementary Type Certificate (STC) approvals, but with better compositional and performance control. It is aimed at the low compression ratio engines which do not need the high octane of Avgas 100 and could be designed to run on unleaded fuel. Avgas UL82 is specified in ASTM D 6227. Unlike other Avgas specifications, ASTM D6227 allows the use of some non-hydrocarbon components used in mogas, such as ethers, but, unlike mogas specifications, alcohols are not permitted.
Avgas UL82 is dyed purple.
Avgas UL87 This is a relatively new grade added to ASTM D6227, driven by the need for some light sport engines to have a higher octane fuel than Avgas UL82.
Avgas UL82 is dyed yellow.
Avgas UL91 Compositionally this grade is somewhat comparable with Avgas 100LL but with a zero lead content, which results in a lower octane rating of 91MON. Avgas UL91 is specified in ASTM D7547. Avgas UL91 differs principally from both Avgas UL87 and UL82 not only in the higher octane rating, but in lower vapour pressure (49kPa max compared with 60kPa max in ASTM D6227) and that oxygenates such as ethers are not permitted. In common with all other current Avgas specifications, ASTM D7547 does not permit the use of alcohols such as ethanol.
Avgas UL91 is dyed orange.
History of Avgas Grades Avgas is gasoline fuel for reciprocating piston engined aircraft. As with all gasolines, avgas is very volatile and is extremely flammable at normal operating temperatures. Procedures and equipment for safe handling of this product must therefore be of the highest order.
Avgas grades are defined primarily by their octane rating. Two ratings are applied to aviation gasolines (the lean mixture rating and the rich mixture rating) which results in a multiple numbering system e.g. Avgas 100/130 (in this case the lean mixture performance rating is 100 and the rich mixture rating is 130).
In the past, there were many different grades of aviation gasoline in general use e.g. 80/87, 91/96, 100/130, 108/135 and 115/145. However, with decreasing demand these were rationalised down to one principle grade, Avgas 100/130. (To avoid confusion and to minimise errors in handling aviation gasoline, it is now common practice to designate the grade by just the lean mixture performance rating; thus Avgas 100/130 becomes Avgas 100).
Some years ago, an additional grade was introduced to allow a common fuel to be used in engines originally designed for grades with lower lead contents as well as in those engines certified for higher lead contents. This grade is called Avgas 100LL, the LL standing for ‘low lead’.
All equipment and facilities handling avgas are colour coded and display prominently the API markings denoting the actual grade carried. Currently, the two major grades in use internationally are Avgas 100LL and Avgas 100. To ease identification the fuels are dyed: Avgas 100LL is coloured blue, while Avgas 100 is coloured green.
In 1999 a new Avgas grade UL82 (UL standing for unleaded) was introduced as a low octane grade suitable for low compression engines. It has a higher vapour pressure than conventional Avgas and can be manufactured from motor gasoline components, but, notably, the specification does not allow alcohols such as ethanol to be used. It is particularly applicable to those aircraft which have STCs to use automotive gasoline.
An extension of this has been the grade Avgas UL87, which was created in response to the higher octane demand of some light sport engines; notably the turbocharged Rotax® engines. UL87 is otherwise similar to UL82, using similar components, but again expressly excluding alcohols.
The relatively high vapour pressure of the ASTM D6227 specification makes UL82 and UL87 somewhat unsuitable for high altitude flight as engine failure from vapour lock can be an issue. In order to meet the demands from the military for an unleaded Avgas for use in high flying, unmanned aerial vehicles (UAVs), a new low vapour pressure UL91 grade was introduced, resulting in the requirement for a new specification, ASTM D7547. At the time of writing, this specification is approved for light sport engines, such as Rotax®, and is in the process of being considered for approval in a wider range of general aviation engines of low to mid-octane demand. However, it is clear that this will not be of high enough octane rating to be used safely in all general aviation engines and work continues in trying to find a true unleaded alternative to the almost ubiquitous Avgas 100LL.

pretty sure just the first two apply to us.

[madbikeboy]

I've just converted my subaru hillclimb/track car to E85. It is great stuff for turbo engines. The tuner can pretty much advance the ignition timing as much as he wants without seeing detonation. They can generally get to the point when any further advance results in less torque (there's probably a good name for it) and then wind it back just a bit. When I got back into bikes I looked briefly at doing an E85 conversion but I don't think its worth while without a turbo.

What are you using as an ECU? Are you using a pair of maps for E85 and for 98?

[madbikeboy]

https://en.wikipedia.org/wiki/Maximum_brake_torque

"Typically" 13-14 deg after TDC (so say -13 BTDC)

Anyone interested in this guff ought to check out https://www.hpacademy.com/

USD$99 for the tuning basics package ought to enlighten 99% of people to the basic principles of engine tuning.

Wow. That's neat. Wish there had of been this sort of resource available when I was a pup.

[husaberg]

https://en.wikipedia.org/wiki/Maximum_brake_torque

"Typically" 13-14 deg after TDC (so say -13 BTDC)

Anyone interested in this guff ought to check out https://www.hpacademy.com/

USD$99 for the tuning basics package ought to enlighten 99% of people to the basic principles of engine tuning.

They should also read up about the famous Harley engine that powered Lucifiers Hammer.
329485
Then read up on FZ and FZR racing engines plus how much advance the 60's Honda GP bikes needed compared to a 70's Cosworth for the other end of the spectrum.
329487

[madbikeboy]

They should also read up about the famous Harley engine that powered Lucifiers Hammer.
329485
Then read up on FZ and FZR racing engines plus how much advance the 60's Honda GP bikes needed compared to a 70's Cosworth for the other end of the spectrum.
329487

Why can't KB be like this more often?

Ever read the stories about the shift from the 392 to the 426 Hemi's? No one could make power out of the things, no one wanted to shift from racing the 392's. One day Big Daddy Garlits, pissed off that Chrysler were forcing him to run a 426 that couldn't keep up with the 392's - he decided to blow the thing up buy giving it almost 60 degrees of ignition timing. Then he dropped a half second off his best ET. He had a lead for most of that summer until one of his opponents watched him wring the neck of his distributor.

The mighty 426 Hemi - supposedly great, but many, many flaws for the real word. Give me a worked 440 any day of the week, and twice on Sundays. Ford's cammer 427 was even worse. The timing chain was long enough to need two different post codes.

[husaberg]

Why can't KB be like this more often?

Ever read the stories about the shift from the 392 to the 426 Hemi's? No one could make power out of the things, no one wanted to shift from racing the 392's. One day Big Daddy Garlits, pissed off that Chrysler were forcing him to run a 426 that couldn't keep up with the 392's - he decided to blow the thing up buy giving it almost 60 degrees of ignition timing. Then he dropped a half second off his best ET. He had a lead for most of that summer until one of his opponents watched him wring the neck of his distributor.

The mighty 426 Hemi - supposedly great, but many, many flaws for the real word. Give me a worked 440 any day of the week, and twice on Sundays. Ford's cammer 427 was even worse. The timing chain was long enough to need two different post codes.

Have you ever seen a baby Hemi AKA Toyota V engine
329488
The yanks often subscribe to the biggers better theory.
Hence why this thing exists
http://www.aaenperformance.com/v4_racing_engine.asp
329489

Propylene Oxide is what they use to speed up the slow combustion of Nitro methane it could well have its use with poor head designs san the nitro.
329491
To be fair the mods do seem to do a decent job of keeping the trolls out of the technical threads now, well better than they were over the last couple of years.

[cods4]

What are you using as an ECU? Are you using a pair of maps for E85 and for 98?

It uses a Link G4. It's only tuned on E85 but I have a map for 98 which I roadtuned myself with the wideband sensor so it is no good for boosting. I need to plug in the laptop to change it over.

[Dave-]

It uses a Link G4. It's only tuned on E85 but I have a map for 98 which I roadtuned myself with the wideband sensor so it is no good for boosting. I need to plug in the laptop to change it over.

Good choice.

I hear they're really great, and the best and awesome.

I may be biased

[madbikeboy]

It uses a Link G4. It's only tuned on E85 but I have a map for 98 which I roadtuned myself with the wideband sensor so it is no good for boosting. I need to plug in the laptop to change it over.

I've been using self learning EFI on some muscle cars, had some very good results with the Holley EFI self learning, Edelbrock set up, not so much. Neither seems to support E85 as a realistic option. Japanese cars with turbo's are light years ahead of old American cars even with more modern TBI set ups - TBI is God's way of telling you to buy an LS.