What kind of fuel should i run on my Big Bore summit?

[nick.shuffs]

Hey guys, i just bought a 2010 ptek 800, with a 860 engin tech big bore, i belive it has 13to5 compresstion domes in it. the previous owner told me he ran about 20 percent C10 race fuel in.

I ride very often and was wondering whats a cheaper option for me? wheres the cheapest place to buy race fuel around calgary? could I run av gas low lead half and half? or just ad an octance booster to shell Premium?

thanks

 

[ABMax24]

I don't recommend octane booster, it's not worth the money. If he actually ran C10 it has less octane than typical Avgas, so if you ran 20% you should be fine. Although I'd probably run closer to 35% Avgas in it to be safe.

Avgas should be your cheapest option, last winter i was paying $1.82/liter where i was paying $5.00/liter for VP C-111. If gasoline is $1.20/liter and Avgas was $2.00 to run 50/50 Premium/Avgas would cost $1.60/Liter.

I personally run 80%-100% Avgas in my turbo Pro.

 

[slededjr]

13.1 you should be fine with 92 octane. I'd mix a bit a race gas I AV Gas to be safe unless you know the 92 you're getting is good and fresh. AV Gas averaging around 1.35/L right now.

 

[Longhairfreak]

A 13 to 1 motor is a pump gas motor.

 

[nick.shuffs]

I don't recommend octane booster, it's not worth the money. If he actually ran C10 it has less octane than typical Avgas, so if you ran 20% you should be fine. Although I'd probably run closer to 35% Avgas in it to be safe.

Avgas should be your cheapest option, last winter i was paying $1.82/liter where i was paying $5.00/liter for VP C-111. If gasoline is $1.20/liter and Avgas was $2.00 to run 50/50 Premium/Avgas would cost $1.60/Liter.

I personally run 80%-100% Avgas in my turbo Pro.

ok thanks for the info, ive heard that av gas is hard on these engines? and the race fuel is leaded and these motors like that? motor is 13:5 compession

 

[Flyer]

Avgas, 100LL, actually contains a lot of lead. It may require that you clean your spark plugs from time to time. It will damage oxygen sensors, but I don't think any snowmobiles have them.

 

[slededjr]

AV Gas will be one in it. 13.5 to 1 is border for pump gas. You'll be fine up in the Alpine but down low you may get some detonation.

 

[pipes]

ok thanks for the info, ive heard that av gas is hard on these engines? and the race fuel is leaded and these motors like that? motor is 13:5 compession

you sure it's 13:5 and not 13.5:1. Iv'e never heard of a compression ratio of 13:5. That would equate to a compression ratio of 2.6:1.

 

[j335]

I have a 14-1 860 and run 1-2 gallons per tank of VP110 to target ~94 octane, however, I know I can get away with 91 at higher elevations. The problem is places like Revy where you start pretty low. Usually I don't lay too heavy on the throttle until about 5000 ft and keep an eye on my EGT.

Have you got EGT's to watch?

 

[bayman]

I ran 13.5:1 in my 860 and never had an issue with pump gas 91. But as mentioned above, get some EGT sensors and keep an eye on it.

 

[neilsleder]

At elevation 13.5:1 good pump gas is all you need. At home ( Edmonton ) I ran a splash of race gas. And I say good pump gas as in buy your gas from a busy gas station and not Fast gas or something like that.


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[ABMax24]

Avgas, 100LL, actually contains a lot of lead. It may require that you clean your spark plugs from time to time. It will damage oxygen sensors, but I don't think any snowmobiles have them.

Avgas contains about one third the lead of race fuel, it runs 1.12 g/liter were typical VP fuel is about 4 g/Liter.

 

[ABMax24]

ok thanks for the info, ive heard that av gas is hard on these engines? and the race fuel is leaded and these motors like that? motor is 13:5 compession

Avgas and race fuel are both harder on fuel lines due to the solvents used in them to add octane, as for motor parts you should be fine, particularly if you run an oil designed to be used with race fuels.

 

[RK Tek]

The compression ratio is only one part of the equation that determines the required octane.. the timing and head design are players in this as well..

As stated above..octane boost is not a good idea... It really does nothing to raise octane and some can cause issues with lubrication.. AV gas when used in small amounts (under 30%) is a good way to increase octane..

 

[sledrat403]

Can you find out if the timing has been changed on ignition? That will also affect deto with your comp ratio.

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[0neoldfart]

Your fuel requirement will depend on several factors. One that hasn't been mentioned is the squish relief area cut into the head. For example, a 670 HO head that has been decked .030" will require the squish area to be about .069", or it won't live unless running straight C-12. Your best bet is to determine who's engine package it is, measure the squish area, check if there is a timing key installed, and give them a call for their recommendations.

 

[nick.shuffs]

Your fuel requirement will depend on several factors. One that hasn't been mentioned is the squish relief area cut into the head. For example, a 670 HO head that has been decked .030" will require the squish area to be about .069", or it won't live unless running straight C-12. Your best bet is to determine who's engine package it is, measure the squish area, check if there is a timing key installed, and give them a call for their recommendations.

thanks a lot for all the great info! I'm gonna try running c12 about 20% and try mixing av gas maybe around half n half. The sled was build by absolute power in Edmonton, they said it just needs a splash of race fuel incase I get a bad patch of pump gas. So I should be sAfe. Thanks again everyone