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Author Topic:   FUEL
CLIFF73
Dirt Roller

Total posts: 24
posted August 11, 2003 11:47 AM  
I run a toy mini with 22r with little work done to it.Been running 93 octane most of the yr.The last couple fo races ran the 112 octane from the track.I'm getting much better results with it.Should I be concerned in burning anything up?

speedyd1
Dirt Maniac

Total posts: 170
posted August 11, 2003 12:17 PM  
i think its all in your head - and not the one on the motor. compression dictates octane needed so unless you are running something in the neighborhood of 13 to 1 or greater then you are wasting your money. 93 will run just about optimum at 10 to 1 and below.

towmandan
Dirt Freak

Total posts: 370
posted August 11, 2003 12:52 PM  
the octane rate of fuel is like its stability the cheapest unleaded you can buy burns very hot and is very unstable a hot spot in a cylinder a hot piece of carbon on a piston or valve or to much compression can ignite the fuel without a spark 110 or 112 fuel is very stable and slow burning the whole idea of race gas is to take the compression without igniting untill the spark plug sets it off the old myth of race gas hurting parts or burning stuff up is not true but on the other hand 110 or 112 will not perform as well as 93 in a 10 to 1 motor in other words your better off with the less octane you can get by with for best performance the only advantage I have found is race gas will let one run a little cooler water temp......I hope this helps....Towman

CLIFF73
Dirt Roller

Total posts: 24
posted August 11, 2003 01:01 PM  
Ok..That does clear a few thing up for me..Now how do I find out my compression ratio.I bought this car race ready.I've checked with a compression gauge was 180+ all the way across.Was told by lc engineering that stock was around 165.thanks for your replys

b4racing
Dirt Forum Champ
Total posts: 626
posted August 11, 2003 03:38 PM  
stock is stock You can have a stock cammed engine and have more compression than a very exotic 20,000 engine. Isky cams has a deal that tells about this and why it is this way. The compression ratio is what you are wanting. They have a calculater in the tool box that will tell you. Later BObby

speedyd1
Dirt Maniac

Total posts: 170
posted August 12, 2003 12:33 PM  
you'll need to cc head(combustion chamber), measure the crushed thickness of the headgasket x diameter, measure the bore diameter x the depth down in the hole the pistons are, and add in any valve reliefs on top of the pistons.
total cc's 73.00 = +/- 9 to 1
64.89 = " 10 to 1
58.4 = " 11 to 1
53.09 = " 12 to 1
Etc......
Hope this helps. If you haven't milled more than "say 50 thousands" off your head you'll be fine with 93.If your pistons exceed the top of the block then make sure you subtract that amount also.

MINI2.3DIRTRACER
Dirt Maniac

Total posts: 115
posted August 16, 2003 11:52 AM  
WOW-THIS IS LIKE CALCULAS, I'VE HAD MY HEAD MILLED .060+ STOCK CAM (FOR NOW) AND NO PORTING DONE YET. (I KNOW I'M ON MY A- - , BUT I GOT A PLAN JUST TRYING TO FIND TIME AND $) ANYWAY I'VE BEEN RUNNING 93 OCT.?? I'M GOING TO LOOK AT THAT CALC YOU WAS TALKING ABOUT BOBBY. SPEEDY SEEMS TO HAVE A GOOD METHOD, LOOKS LIKE ALOT OF TIME AND MATH, BUT I'M GOING TO SEE IF I CAN WORK THE FORMULA.
THX

CLIFF73
Dirt Roller

Total posts: 24
posted August 18, 2003 09:39 AM  
Thanks for all the advice.Will try to put in use..

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