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a little help- octane v flame front

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Posted by: 2strok4fun---------------------

I was involved in a discussion on a watercraft BB regarding squish clearance and octane requirement. The discussion evolved into a discussion of a fuel's octane rating and flame front speed. I had made the comment that a higher octane rating doesent equal a slower flame front speed. I was jumped on even by the tuner "Guru's" of the site saying that I was incorrect.

Where can I find info regarding this topic? I have found info on TEL as it relates to octane and flame front rate but not octane rating in general.

If I am wrong somebody please correct me or help me find some useful information to support or disprove my statement.

thanx

chris


Posted by: Rich Rohrich---------------------

You are correct. Flame speed of a fuel is pretty much a function of the carbon/hydrogen makeup and the bonding of the fuels components. Octane doesn't enter into it.

Some of the fastest burning commercial fuels are the 118 octane "Pro stock" blends from VP and Phillips, which are essentially just iso-octane and a few other components.

Depending on the component make up of a fuel you can make fast or slow burning fuels with anything from 80 to 118 octane. FWIW, in the past 30 odd years I haven't met but a handful of "tuners" who knew diddly about how fuels work. Of course that rarely seems to keep them from spouting ignorant drivel on the subject. :D

Good sources for info on the subject include:

Hydrocarbon Chemistry - Author George A. Olah - ISBN 0-471-11359-x

Automotive Fuels Reference Book - Authors Keith Owen & Trevor Coley - ISBN 1-56091-589-7

The Chemistry of Hydrocarbon Fuels - Author Harold H. Shobert - ISBN 0-7506-0384-4


Posted by: 2strok4fun---------------------

Thank you,

I dont think I can convince any of these "tuners" without some footnotes, well maybe not even then.

chris


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by 2strok4fun
I dont think I can convince any of these "tuners" without some footnotes, well maybe not even then.



Don't bother, let the idiots wallow in their own ineptitude. You know the truth, and that's all that really matters. :D

The funny part is, the difference in laminar flame speeds between the fastest and slowest hydrocarbon fuels is pretty small. In cylinder turbulence, mixture density, air/fuel ratio and combustion chamber temperatures have a far greater effect than the burning speed of the fuel.


Posted by: bclapham---------------------

its kind of ironic, seeing all the name dropping that goes on in a dirtbike bike forum...yeh ricky lives next door, MC rides with me every wednesday....

well get this, George A. Olah reguarly attends many of the chemistry lectures that my department puts on! i've even showed up late and managed to snag a seat up front next to george himself, and he is THE MAN!!!.....maybe he might sign my helmet or side panels or something!

chemistry is life.

later

BC


Posted by: Kav---------------------

Quote:
Originally posted by some one far smarter then I.
which are essentially just iso-octane


I thought octane wan't a "thing" it was a measurement.

<--- kind of lost now.


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by Kav
I thought octane wan't a "thing" it was a measurement.


2,2,4-TRIMETHYLPENTANE or Iso-octane (C8 H18) is the standard hydrocarbon for fuel octane testing (octane rating of 100), and n-heptane is the component used as octane rating of zero. Percentages of iso-octane and n-heptane are used to determine pump octane numbers in special test engines.
Adding tetraethyl lead (TEL) to pure iso-octane can raise the the overall octane rating of a fuel well above 100, which is basically what they do to blend some of the narrow focus Pro-Stock type fuels.


Posted by: SFO---------------------

Quote:
Originally posted by Rich Rohrich


Adding tetraethyl lead (TEL) to pure iso-octane can raise the the overall octane rating of a fuel well above 100, which is basically what they do to blend some of the narrow focus Pro-Stock type fuels.


Like B37? :silly: :silly:


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by SFO
Like B37?


Yep, basically just like that. :D


Posted by: DEANSFASTWAY---------------------

How about propylene oxideas an additive?


Posted by: DEANSFASTWAY---------------------

Hi Rich; How about Nitromethane and Nitropropane why is nitropropane better mixed with gasolines than Nitromethane and does nitropropane carry oxygen to fortify burn. ? Is the current trend in racing fuels leaning towards oxygenated fuels ? Power Mist is a Busch supplier and they have done extensive testing with the oxy fuels and promising big gains. I would like to find out a bit more myself . Thanks DEAN


Posted by: 2strok4fun---------------------

Not to answer for Rich, but this is what I understand.

Nitromethane dosent mix with gas but Nitropropane does. And I believe the oxegen charge *is* what gain is. I could be wrong though.


Posted by: jmics19067---------------------

2stroke is right, Nitro methane will not homogenize< heh I like that big word> with gasoline. The more oxygen you can get in the cyinder the more fuel you can burn the more power you can get.Hopefully all the factors that make an engine well tuned are there to appreciate and harness the power.

as for a trend to use oxygenated fuel for racing you have to check with your racing sanction to see what fuels are allowed. Certain fuel blends and additives are illegal in most racing sanctions. With different sanctions not wanting different fuels/additives.


Posted by: DEANSFASTWAY---------------------

Nitromethane mixes up but it seems to separate so we keep sloshing the tank , but people were starting to ask questions. So were gonna start using N/P around 15% .


Posted by: nephron---------------------

Some words about Nitromethane (then forget about it):

It’s NOT a “powerful” fuel

It’s NOT even a very “flammable” fuel—it takes heating it to 96 F temp before flammable vapors even appear. Take a few degrees away from its desire to spontaneously ignite, and it wouldn’t even be considered a flammable! (don’t remember the numbers)

The reason it makes power is that it requires relatively little O2 to break a majority of its high energy bonds in the combustion process (to put it simply) . I think Top Fuel dragsters run 70-80% fuel to air ratios (vs. approx. 14:1 reverse air/fuel for our bikes/cars). So if you can imagine, a top fuel or model airplane motor at TDC on compression before firing is going to have about 70% of the cylinder literally filled with liquid nitromethane and combust almost all of it.

Using the Top Fuel as an example, since nitromethane needs horrendous spark energy, prolific fuel injection and compression ratios approximating 25:1 to ignite—I don’t think it’ll work too well in our bikes.

But by all means, feel free to go down to your local model airplane store, grab some up, fill her up and mix it 32:1 with some MX2T. I’ll stand there and watch you kick it over until you’re blue in the face, then throw a match in the tank for giggles.

I think Rich said once that you’d have better luck firing off some peanut butter with a match than nitromethane


Posted by: DEANSFASTWAY---------------------

Thanks for the info nephron but were not using it in our bikes were using it in a dirt modified big block with @ 850 hp and in a IHRA Corvetee funny car on alky with a Keith Black Hemi and a big big blower .We use about 6 gallons on the burnout and the quarter mile. were running 6.60.s right now but were considering the newest whipple blower, but our problem is getting the car to launch quick without smoking the tires . Some clutch work is in order. I sometimes like to ask questions on this forum that dont apply directly to dirt bikes , I hope noone feels that is inapropriate as we are or most of us are all engine and performance enthusiasts. But what I cannot Understand is why the attack by nephron? I never really stated that I was using it in a stock 2 stroke bike so my bad. Hes right in his respect as to why run it as I have seen people waste big money on buying racegas for some stock motored bikes thatwould probably run just as well if not better on pump premium.


Posted by: DEANSFASTWAY---------------------

Guess I did the same thing to Jaybird when Jaybird posted something about optimal fuel/oil mix ratio @ 16/1 and I replied to him that he didnt need all that oil . I didnt know he was as experienced as he was and Jaybird and Rich stated (you can swing a dead cat in the pits without hitting some weedwacker rider smoking running on 66/1 outboard lube ) or something like that . I just thought Jaybird was some kid just starting to ride and trying his best to foul his plugs or whatever and didnt have a manual . History was made since now Jaybird uses that as his quote , and I feel as though I contributed something in a humurous sort of way . CHEERS DEAN


Posted by: SFO---------------------

Congratulations Dean.
The internet is huge and there are some very clever dudes hanging out here.


Posted by: jmics19067---------------------

Quote:
It’s NOT a “powerful” fuel


Well that would depend on how you would look at it, I am looking at engines as an air pump perspective. If you are talking about the amount of energy released per pound of air consumed then it has the ability to produce more power at WOT high rpm but I am not sure how it would do in part throttle response.

Although since Dean asked a question that very easily could be mistaken for a dirt bike application and your answer would be mostly more than correct for this site. I dont feel your answer is being totally right.

after all there has been a few bench racing discussions/BS sessions that involve hydrozene, iso octane ,other strange forms of rocket fuel,and using straight bottle oxygen instead of nitrous oxide.

Now what Iwant to do is convert my bike over to home heating oil/diesal fuel
think of the benefits under a dollar a gallon and no fouled spark plugs ever and tons of low end torque plus better mileage


Posted by: DEANSFASTWAY---------------------

French Fry oil!


Posted by: SFO---------------------

I have a friend who gets free used corn chip oil, usualy in 6 55gal drum lots.
He runs it in his diesels.
Hasn't bought gas in two years...


Posted by: jmics19067---------------------

heheh we are on the Atkins diet over here in my household so anything to do with grains or starches is out .

unless of course it is distilled


Posted by: nephron---------------------

Quote:
what I cannot Understand is why the attack by nephron?


I'm sorry, I didn't know your app. :o
Had I known...by the way, nice app. I'd like to hear more about what you're doing and what you're trying to accomplish.


Posted by: DEANSFASTWAY---------------------

Its kool nephron you probably thought I was just some kid trying to blow up his dirt bike. I made that mistake a while back myself. How do you like your KX5 they are great bikes I had about 5 of them a while back?


Posted by: SFO---------------------

this ones for you nephron...

http://www.flbusa.com/images/munch_mamut_01.jpg


Posted by: DEANSFASTWAY---------------------

Thats a cool bike ! How about that three cylinder Harley ?


Posted by: nephron---------------------

DEANSFASTWAY---what class? Brackets? If so, for consistency's sake, why not pick a fuel and a dial-in and stick with it?

SFO--am I supposed to know what we're lookin' at there? You got me.


Posted by: SFO---------------------

Quote:
Originally posted by nephron
SFO--am I supposed to know what we're lookin' at there? You got me.

A modern Munch Mamoth.
The original car motor bike.
Used to be an nsu prince motor I believe.
It just made me think of you though, and your car guy stuff.



Posted by: SFO---------------------

Quote:
Originally posted by DEANSFASTWAY
Thats a cool bike ! How about that three cylinder Harley ?


do you have a picture?
I worked on some of the prototype stuff for the 3cyl fueling/h-d motor but lost track of it.


Posted by: DEANSFASTWAY---------------------

Nephron : We are always testing andlooking for more or easier power or easier/smarter/cheaper ways to accomplish things. Some of the questions I might ask really are just for mindsake or personal knowledge and I might never really apply them I feel its good to get to converse with people of diverse backgrounds and different areas of interest .As you can tell Im no scientist or engineer but I am interested in technical things . As for the cars,Its an IHRA Alcohol Funny Car and My other friend has a Dirt Modified with the latest big block assy you can get . Dirt Mods are run primarily in the Northeast US . I could link you to a site but I dont know how but you could check out www.SouthJerseyDirtRacing.com
and take a look .SFO: yeah I could swear I heard of moss machine somewhere in like sportrider or something or maybe with the fueling motor but it was you guys who did the original 3 cyl setup protos , that was pretty cool stuff . Did that Harley 3 cyl run smooth ? Take care you guys . DEAN


Posted by: mike perry---------------------

Dean,

Be werrrry caweful when using prop oxide with nitromethane.

Check out the nitronic research site, you can post questions on the "header flames" section.

Mike Perry
www.championspeedshop.com


Posted by: DEANSFASTWAY---------------------

Thanks Mike. I was thinking of using it only in gasoline on the car or maybe in bikes or on some real modified quad motors. Ill be sure to check out your site though. Thanks DEAN


Posted by: 2strok4fun---------------------

Deansfastway-

if you like different set-ups check out what this guy is doing to a sea-doo
http://www.sea-doo.net/board/thread...id=30627#263280
hmm not sure I did that right but hope it works


Posted by: DEANSFASTWAY---------------------

wow thats sick ! Did you see where Honda is making a $cyl 750 turbo jet ski ?


Posted by: 2strok4fun---------------------

BTW- If anyone is interested.

I was riding (sea-doo's) this last weekend with the guy I was having the online discussion with, the one that prompted me to start this thread. After about 1/4 mile of full throttle, he stuck a piston, for the third time this season. I was gracious and didnt gloat, but I laughed on the inside a little............................................... well alot


Posted by: jmics19067---------------------

a little poetic justice?


Posted by: Hogwylde---------------------

Everything you ever wanted to know about racing fuels....or so the site says. Actually, it covers fuels OTHER than gasoline primarily....but pretty good reading in case you're interested in gasoline alternatives>>>WWW.TURBOFAST.COM.AU/RACEFUEL.HTML



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