phazerrd

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Dec 16, 2001
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just had a friend offer me 15 gallons of sunoco blue race fuel for free,(his car season is over) however it is leaded, is that bad for my new honda??? thanks guys!!!!!!
 

Rich Rohrich

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It will work fine in your CRF but it will run a richer than premium pump fuel.
 

slodsm

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Jul 20, 2004
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It will actually slow the bike down because the fuel is a slower burning fuel to resist detonation in high compression cars. It will fire with the piston further from the combustion chamber on it's way down actually decreasing the amount of power stroke you have due to the late fire.
 

Rich Rohrich

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slodsm said:
It will actually slow the bike down because the fuel is a slower burning fuel to resist detonation in high compression cars. It will fire with the piston further from the combustion chamber on it's way down actually decreasing the amount of power stroke you have due to the late fire.

The octane rating has nothing to do with the laminar flame speed of the fuel, and running high octane fuel WILL NOT REDUCE POWER. The hydrogen/carbon bonding of the fuel's components will determine how easily and quickly the fuel can be reacted and it's ultimate heat release. The fastest burning hydrocarbon based fuels you'll find will be the 118 octane Pro Stock fuels. You can have fast burning high octane fuels as well as slow burning high octane fuels but the difference between the two is negligible and will NEVER be noticed by a rider.

Once you meet the engine's basic octane requirement, which in the case of the CRF is pretty much met by premium pump, the fuel's distillation (aka vaporization) curve is the single most important spec you should be looking at. The specific energy of the fuel is important as well, but if you can't vaporize the fuel the energy can never be released so it takes a back seat.

In other words you should be looking for a fuel that has a reasonably low front end temperature range (for good throttle response) and 90% vaporization and end point temperatures low enough to allow complete vporization of the fuel at high rpm. Basic rule of thumb for high speed single cylinder engines is, any fuel with a 90% vaporization temperature greater than about 240F will make less power above 7000 rpm than a fuel with a lower 90% temp all else being equal. For the record the 90% temperature of summer gas in Illinois is in the 340-370F range. It's similar in other places.

Choose your fuel wisely boys, there is more power in good combustion and proper tuning than those most of the shiny pipes people sell.

Here's what a curve for a proper high rpm four-stroke MX race fuel looks like (blue line on graph) and how it compares to pump fuel. (Special thanks to Dave Redszus from Firepower Fuels / Precision Automotive Research for the graph data)

distillation%20curve%20graph.jpg
 

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Okiewan

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The octane rating has nothing to do with the laminar flame speed of the fuel. The hydrogen/carbon bonding of the fuel's components will determine how easily and quickly the fuel can be reacted and it's ultimate heat release. The fastest burning hydrocarbon based fuels you'll find will be the 118 octane Pro Stock fuels. You can have fast burning high octane fuels as well as slow burning high octane fuels but the difference between the two is negligible and will NEVER be noticed by a rider.

Once you meet the engine's basic octane requirement, which in the case of the CRF is pretty much met by premium pump, the fuel's distillation (aka vaporization) curve is the single most important spec you should be looking at. The specific energy of the fuel is important as well, but if you can't vaporize the fuel the energy can never be released so it takes a back seat.

In other words you should be looking for a fuel that has a reasonably low front end temperature range (for good throttle response) and 90% vaporization and end point temperatures low enough to allow complete vporization of the fuel at high rpm. Basic rule of thumb for high speed single cylinder engines is, any fuel with a 90% vaporization temperature greater than about 240F will make less power above 7000 rpm than a fuel with a lower 90% temp all else being equal. For the record the 90% temperature of summer gas in Illinois is in the 340-370F range. It's similar in other places.

Choose your fuel wisely boys, there is more power in good combustion and proper tuning than those most of the shiny pipes people sell.
 

Rich Rohrich

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Wise guy - but you don't have the graph :)
 

slodsm

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Jul 20, 2004
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OK, I will not try to get technical with you for the simple fact, apparantly you two have spent some time reading on the net to find something you wanted to read. Do not take this as a flame whatsoever but simply as a word of advice.

You can read all of the technobabble you want on the internet and possibly from some college professor who read it somewhere else about linear burn rates and optimum max release and so on.

From 10 years of building hot rods and dyno tuning, I can tell you, right now, beyond the shadow of a doubt, the lowest grade fuel you can run without detonation will make you the most power, period!

It will have the most volatile explosion and less of a controlled burn rate and will result in quicker ET's and faster reving as long as you are still on the ragged edge of preignition. If you run 118 in an engine designed to run 93, you are simply paying much more for less power. It is up to you but the numbers don't lie and I have seen and built them time and time again since 1994.
 

Okiewan

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OK, I will not try to get technical with you for the simple fact, apparantly you two have spent some time reading on the net to find something you wanted to read.

LOL!!! Dude.

Uhh... I'll be nice here. You apparently haven't followed Mr. Rohrich's career, nor realize he is probably one of the most studied, respected "fuel" guys out there. He wrote the book on this stuff. My post, was in jest obviously.

You might want to do a little research before accusing Rich of "reading tecnobabble on the internet".
 

Rich Rohrich

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slodsm said:
OK, I will not try to get technical with you for the simple fact, apparantly you two have spent some time reading on the net to find something you wanted to read. Do not take this as a flame whatsoever but simply as a word of advice.

You can read all of the technobabble you want on the internet and possibly from some college professor who read it somewhere else about linear burn rates and optimum max release and so on.

.


I always enjoy when some newbie pops in here and tries to deal with people in a patronizingly superior manner, when it's clear you need to brush up on your combustion chemistry. :)

Rather than descend to your level, I'll suggest a few things you might want to read before you spout anymore nonsense in this forum. These books contain a real wealth of useful information that can be quite helpful for anyone who is interested in high performance engines and how hydrocarbon combustion actually works. Understanding how the chemistry works is one of the keys to making real horsepower.

References and further reading :

Harold H. Schobert - The Chemistry of Hydrocarbon Fuels - Butterworth-Heinemann Ltd.

Keith Owen, Trevor Coley - Automotive Fuels Reference Book - SAE - R151

H.P. Lenz - Mixture Formation in Spark-Ignition Engines - Springer-Verlag

Jeff Hartman - Fuel Injection - Motorbooks International

Germane, Wood, Hess - Lean Combustion in Spark-Ignited Internal Combustion Engines - A Review - SAE paper 831694

Z. Warhaft - An Introduction to Thermal Fluid Engineering - Cambridge University Press
 
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Okiewan

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So it doesn't seem so negitive...
We are open to new ways of thinking here... but we are NOT open to bad info. Please be sure you aren't over your head when posting something as fact... and be prepared to back it up. The internet is FULL of CRAP info and bad information. This is NOT the place for it.

This wasn't directed at slodsm .. it's meant as a general statement.
 

slodsm

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Rich Rohrich said:
I always enjoy when some newbie pops in here and tries to deal with people in a patronizingly superior manner, when it's clear you need to brush up on your combustion chemistry. :)

It always amazes me when an internet "Non Noob" such as yourself who seems to be a person of obviously superior intellect than those of us who only found the internet last week when we discovered hooking phone lines into our computers in our trailers one night after drinking Millwalkee's best for three days straight tries to seem so superior simply because of an earlier joined date or larger post count.


Now that we both have our insults out of the way, let's have a real discussion. Yes, I am a noob to DRN, big deal. I made my first 11 second pass in Jan of 1994, I didn't even have a full drivers license yet. I am far from a noob at the internal combustion engine, thank you. As for my credentials, I have few compared to you I am sure but let me add what I do have, I have been a full time body and paint man which was my introduction to auto's from jsut stepping on the gas. From there I went to a tech school in the Marine corps, I have been a mechanic, a collateral duty inspector, a fully quallified quality assurance rep for engines, transmissions, rotors, avionics, radios, and hydraulics and servos. I am FAR from a noob at mechanical knowledge.

Now, before you reply to this post, I beg you to put out the flame thrower you are getting ready to use and think about the following, for you to even care, you are bound to be doing some form of technical job for a career or if not, have a keen interest in it. In having that interest, I am sure you have discovered that not all things written are bible so to speak. Now, take into acct that yes, you can engineer your fuel to burn at a certain rate BUT, we are talking about plain old sunoco 118 leaded race fuel.

Lets see where we can go here. The car this fuel was intended to be run in (being a race car, I have owned many) will most likely be a very high compression setup creating massive heat in the combustion chamber which will heat the valves enough to actually ignite pump gas upon entry into the chamber vice when the plug fires. If not, it is a forced induction motor which is already operating at probably 300% VE (volumetric efficiency) simply because the vacuum of the motor no matter how strong only has 14.7 lbs to draw from because that is the atmospheric pressure (on average). Race cars with blowers once again although low compression are usually pushing around 30+ PSI of boost, they also need a slower burning fuel to avoid pre ignition and catastrophic failure of the engine.

I have seen in my own cars running only 22 PSI of boost as much as .5 seconds in the 1/4 mile from running a car tuned for 93 octane to VP 110, and the VP was slower because it effectively lowers the static compression ratio of the engine due to what? If you said slower burn rate, you won a cookie.

Now lets take into factor how these bikes were designed. Someone making a lot more money than we are has on paper the exact volumetric efficiency, the cam timing, spark timing, static and dynamic compression ratios, and averaged the expected heat index the bike will be running in to give you the proper grade of fuel to run with it. Are you saying you are smarter than him? Maybe, maybe not but the fact remains you didn't design it, he did and it's meant to work the way he wanted. If you were to completely remapp the ignition timing and add an adjustable cam gear to adjust valve timing, yes, you could see gains from the high octane fuel. Otherwise, simply a loss.


I have now stated my points as clear and concisely as possible without gettign rediculous. Take into acct that when you remain disbelievers, it will not come as a shock to me because I have another friend with an 03 Cobra on 18 lbs who has witnessed the loss of 19 HP on the dyno from using 110 leaded. He still believes it was a fluke and runs the race gas at the track and is consitently slower than on 93 octane.


In closing, all I can say is OPEC must love you guys. :cool:
 

Okiewan

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While I am not stupid enough to enter this conversation on a technical basis, I will comment on this;
It always amazes me when an internet "Non Noob" such as yourself
Really, Rich was doing this stuff long before the web was... well.. the web. When the Internet was called something else and AlGore invented it.

Jan of 1994, I didn't even have a full drivers license yet.
Meaning at most you were 15 at the time? 16 and lazy? I assume then you are what.. 24? 25? While I'm sure there have been advances in the science over the years, I know for a fact (assuming your age) Rich was messing with fuel mixtures well before you were born. I suppose I should post up a couple of the pics of him on drag bikes a full decade before your mommy and daddy contemplated your existence.

The point? An "Internet" *anything... is not the guy you're trying to get going here. He was about this stuff a LONG, LONG time ago.
 

Rich Rohrich

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slodsm said:
Now, before you reply to this post, I beg you to put out the flame thrower you are getting ready to use

No need to worry about that.. It's clear I have nothing I can teach you ( science be damned :) ) so I won't waste any more of your time or mine responding to your posts. :bang:
 
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phazerrd

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Dec 16, 2001
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I did not mean to start a war guys, I simply wanted to know if this donation of race fuel was ok for by little f's belly, did not want to give it "lead poisining"
 

Rich Rohrich

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phazerrd said:
I did not mean to start a war guys,

Don't worry about it. This stuff happens all the time, it comes with the territory. :cool:

If you look back through the thread I think you'll find the answer to your question. ;)
 

SFO

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Where is hardhat when you need him?
Rich, you must be mellowing with age.
I think young guns rock, BTW.
Bend a knee and pass the hymnal, we all gotta find the right key for our parts.
Tossing eggs at the resident brougham as an entrance is often considered poor taste by the locals.
This is not personal.
 

slideways11

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This thread reminds me of a conversation I had awhile back with a friend of mine who has been drag racing motorcycles for about 30 years. He said he was probably the worst person to be talking to about making HP for the application I was looking at. He said basically I build bombs that only have to last for a handful of seconds, he said I could probably get you the holeshot at every race you ever went to, but after the first turn you would be pushing back to the pits for a new motor.
 

slodsm

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Jul 20, 2004
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Personally, I am simply stating my opinion from what I have experienced. I would honestly love to hear Riches version because I am all for learning something new. If what I learned from testing everything from pump gas to C12 is different in motocross app's, I would love to know why. I am not hard headed to say the least. I just like to learn. If I typed it wrong, then I apologize because the lack of inflection, emotion, and tone in words on the net tend to leave the conveyance of conversation up to the reader and can be interpreted in many ways. I am all ofr learning new things but personally, the things I stated are from my own experience and if I can be taught otherwise, I will know for the next time.
 

ironworker

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slodsm said:
I am not hard headed to say the least. I just like to learn. If I typed it wrong, then I apologize because the lack of inflection, emotion, and tone in words on the net tend to leave the conveyance of conversation up to the reader and can be interpreted in many ways.

I think I interpreted it correctly, ROFL :laugh:
 

phazerrd

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Dec 16, 2001
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I guess i asked a really great question. I also hope others can learn from this thread. I see is has good ratings on the thumper menu, and this is all owed to Eric Gorr, if had not purchased an awesome cr144 a couple years ago kit from him i no doubt would not have seen the link to drn on his website. THANKS ERIC for the fast 144 and the link that started this great thread.
 

CaptainObvious

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I like 100LL AvGas mixed with diesel. That's right, but before you think of me as a crazy man, let me explain. Aircraft fuels are designed to operate at a steady throttle setting...and that is how I ride my bike...WOT. From the moment the gate drops to the end of the race, I just hold it open. Heck I even hold open for the trip through the pits too. I'm so damn fast it's scarry.

So why do I mix my 100LL with Diesel you may ask. Well have you checked prices of 100LL and diesel? With such a mixture, I can get my composite cost pr gallon down to $1.867393345. Talk about chemistry!

And before you all flame me, saying that I'm full of 80 Green fuel (a little fuel joke there - damn, I'm funny too), let me tell you that I'm a graduate of Harvard with a degree in Fuel, I have a Masters in methane and I'm very old, so I must know what I'm talking about.....but I'm not old enough to know that riding at WOT though the pits is bad.

I can get so much horsepower from a single gallon of fuel, you would that that I must be full of it ;)
 

ironworker

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RV !!!! Buhahaha your funny as hell dood :cool:
 
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