Fuels

[Motorrad]

Well the KX needs a rebuild so Im trying to figure out how much to let Stewart loose on it.... Price of fuel is a key factor as It will be raced in the desert. (want to be able to afford to race)..

Was looking at different fuels... and found this.... Need to find the actuall breakdown, but avgas 100LL and C12 seem to be simmilar in gravity (everyone seems to say avgas is lighter than others)....  but they are .001 within eachother....

http://kennystrickland.com/pdf_spec_c12.pdf

(breakdown at bottom of page)
http://www.shell.com/static/au-en/downloads/aviation/avgas_100ll_pds.pdf

EDIT:
Another interesting read
http://www.shell.com/home/content/aviation-en/aeroshell_site/technical_articles/techartpages/techart12_30071515.html

[stewart]

stick with vp

[Motorrad]

Not to question.. Because you are the final answer as far as Im concearned... Just curious as the differance... I havnt found anyone yet to tell me why (been searching the net for about 2 hours now). 

Only reason I thought of avgas is I ran it in my old husqvarnas (1970's) and bultacos. diluted.... run it in my triumph, and norton. (My cousin is a pilot)   But alot of local guys run it in their HOT VW's latly because Methonal (alcohol) has become hard to get localy....

I have 2 small airports within 10 miles that will sell it to me for roughly $4.35gal..... vs c12 which is about $58++ for 5gal can (if memory serves me right) more if anything as Im probly thinking back to 2 years ago.   or $7.99gal for 100oct vp no lead pump fuel.     Just trying to weigh out the options vs price.... if I lose a bit of HP and it cost me 1/2 as much to run..... how much HP could I lose? (1,2,5?)   Might be worth it.

[stewart]

i think you should always question...and this  question is a great one to ask..  fuel is the often forgotten piece of the puzzle in the use of a motor..yet a motors only function is to turn fuel and it energy to a form off power to use,or ride in our case...the endless possablety off chemcial soup make up diffrent fuels...when cost is a factor sometimes  power is less...but a great place to start is reading vp and others study of fuel make up  ,,may help on the detials you seek

[BDI]

I think that deciding what fuel you want to run and then build the engine around the fuel is a very good way to go.

[Danger4u2]

Avgas has chemicals to keep it from icing at high altitude.

[Motorrad]

Avgas has chemicals to keep it from icing at high altitude.

According to my local airports, (talked to the head guys)  this is false and just a rumor....

The Jet fuel has the ice agent in it...
"There are two specific anti-icing agents allowed for use with 100LL. But they are not added at the point of manufacture. The end-user would add an anti-icing agent as they see fit when refueling."  That was told to me specifically from my local airports.    My local airports also take readings on the fuel every 3 days, and when it reaches point of being close to spec (99.8octane mon rating)  they take it every single day till they either A have to toss it, or throw more ontop of it to bring it back to spec...   So just ask your local SMALL airport guy and see, they are more friendly than you think...

Im going to hunt down those VP research things like Stewart said.. but Im always sceptical of them since they need to sell fuel.... Kind of like asking Taco bell if they make the best burrito in town....

Does anyone know what F&L and VP use for a base fuel now?   As far as I know Sunoco and 76 were the only ones that created their own base fuel....  all the otheres were buying it from one place or another (some I hear were doctoring avgas, but that is just hear say, lots of that here in socal the off road capital of the world).


And back to the price thing..... I verifyed $4.35/gal...     

I did the math.... just the ammount of times I went out this month (9 days in the desert)  if I had the KX (blew up the first trip), I could average well over 5gal a day if I was lazy and ate chips and cookies for most of the day... but we will calculate lazy for sake of arguement...... if that was VP c12...   Thats over $500 in fuel.. OUCH...     Stuff adds up if you go out and do alot of prerunning, practiceing etc.   
If it was just a occasional weekend duner etc that would be one thing.   But for a young guy like myself married for 2 years looking to start a family (key word there) money is going to get tighter than it is now...  so Im trying to think ahead, dont want to be in a situation where I cant afford to feed my beloved KX because Im feeding a rug rat..   Like stated before, I want to build the motor around the fuel, not go the other way around and have it an afterthought like most do...

-Dave
   

[Motorrad]

Im no Fuel chemist... but looking at these numbers.... Things dont seem $6 a gal different.  Just posting things as I find them... Still looking for VP's research.

 
Chart half way down the page.
http://www.vpracingfuels.com/spec/Tech_BulletinMRSeries_Jun07.doc

100LL (blue) is the fuel in question..Rest dont pertain to us.
http://www.aviationfuel.org/avgas/avgas_specs.asp

And for fun. F&L SP-1 (what I used to run till local avail got hard)
http://www.fandl.com/offroad%20dammit/f&l%20sp1%20.pdf

F&L Sp-3
http://www.fandl.com/offroad%20dammit/f&l%20sp3%20.pdf


Found this regarding 100:LL.... Dont know what it is.. .But looking for a VP rating (found a rating but doesnt tell the Type of measurement (IE KPA)
SPECIFIC ENERGY MJ/kg         44
REID VAPOUR PRESSURE kPA   44 or 6.381PSI

VP reads as
7.3psi Reid Vapour Pressure...    which works out to be 50.33KPA

Not shure if this affects anything besides vapor lock
Some reading on "Vapor Pressure"
http://www.astm.org/Standards/D323.htm

[Hillclimb#42]

I've checked out some of this. Seems that MOST reputable racing fuels are good stuff. We can all probably spend more money on our fuel and get better results, than we can expect from premium pump gas. Cost is more, yes, but more fun is priceless.
  VP has a long list of fuels with many various applications. They have multiple claims on their fuels championing most motor sport's series, events, and races. They have scientific research showing what percents gains with what percent increase in jetting. Totally great stuff.
  I think its mostly important to make sure we get the right fuel for our application. Too high of an octane on under modified bike is just as bad as low octane in a high compression motor right? Maybe not as bad, but at least pointless.
  Please correct me anywhere and everywhere....

  Q16 is for high compression, modded bikes,(and dragsters) like the Stewart 500's
  U2 is no longer available
  U4.2 is oxygenated fuel for moderately modded 2 strokes
  C12 is like the all-around eveything likes kinda fuel, claims to cover 75% of applications
 What about that MR8 2stroke GP bikes use it?

I plan on getting on VP train. Just found good pricing. I have stock bikes thru modded bikes and want the best for all bikes, so probably will be running C12.
How does stock bike do on U4.2?
or What's the fastest fuel for stock or slightly higher compressions?
When it calls for increases in jetting,  what do you do to start. 2 sizes bigger than you're runnin'. Even if it says 5% increase in jetting, some fuels do, how does that calculate into jet sizes?
Hot Fuel+lean jetting= unhappy nicasil.

[Hillclimb#42]

Reply to my own question then. I emailed them at VP and got a very good response. Seems that U4.2 is replacing U2 and thats why I don't see that U2 anymore. U4.2 has better power THAN C12, but you have to chase the jetting a little bit with temp, and environment changes. C12 is a great fuel with a little less on the performance end, but better on consistent jetting.
  As far as jeting was concerned, they suggest going up a main jet, maybe two sizes, up one on the needle, and fatten the mixture screw a half turn. Leave the idle jet alone apparently.
This was all recommended basing on the fact that I am already running high octane fuel, I should mention.
  I even brought up that I hear bikes on VP, pop on the top end, but he responded with that is not a vp characteristic, and that it must have been bad jetting set-up, stuff in the jets or water in the fuel.
  Taken back a little that he said no to the q16 for me. Maybe after some Stewart mod's. Then I'll be ready for the BIG BOY FUEL.

[Johnniespeed]

I want BIG BOY FUEL too ! 

[Uzi9mm]

"Prist" is the most used anti-ice additive.  Prist is used in jet fuel and occasionally in 100LL.  Some jet fuel comes with Prist pre-mixed.  100LL does not.  If the jet you operate does not have a fuel heater, then you better ask for "Prist".  As fuel cools water comes out of suspension and can freeze on things it comes in contact with, like a tubing bend or a fuel filter.  The standard lapse rate is -2deg C / 1000ft.  Jets typically operate at 35-40000ft, so the temp could be 80deg colder at altitude than at sea level.   I run 100LL @ 40:1 with Belray H1R with no problems yet.