CAN A COX SURE START RUN ON STRAIGHT FUEL?

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CAN A COX SURE START RUN ON STRAIGHT FUEL?

Postby SCROWOASH » Wed Feb 17, 2016 5:57 am

Hi Everyone

I live in a remote town of Zambia, Africa. i recently bought a cox hyper viper with a cox sure start engine while on holiday. The issue is that there is no way i can obtain nitromethane here, methanol is a little easier to obtain.

Can this engine run on straight methanol/castor fuel? Would i have to alter the methanol/castor ratio maybe to 82/18%? Will i need to adjust the compression possibly to 11:1?

Any advice on this issue will be greatly appreciated.

Regards

Scrowoash.
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Re: CAN A COX SURE START RUN ON STRAIGHT FUEL?

Postby SteveM » Wed Feb 17, 2016 6:38 am

Typically, Cox engines will run on a fuel mix that contains 15% to 30% nitro.

http://coxengines.ca/files/FG.pdf
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Re: CAN A COX SURE START RUN ON STRAIGHT FUEL?

Postby SCROWOASH » Wed Feb 17, 2016 11:23 pm

I was afraid you'd say that! i have enough nitro in stock for probably 1 litre of fuel mix @ 15%. I guess i will have to try source before this runs out.

Thanks very much for your reply.
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Re: CAN A COX SURE START RUN ON STRAIGHT FUEL?

Postby ffkiwi » Sat Feb 27, 2016 1:39 pm

As per the previous reply-you're pretty much out of luck on this one....YES it IS possible to run a Cox on straight fuel BUT they're most unhappy, become hard to needle and sag badly when you disconnect the starter battery. They were designed and built around nitro fuels in the 10-30% range (depending on the model and size) so don't really handle straight fuel at all well. You may be able to improve things a tad by fitting the 1702 high compression head, as engines running 0 nitro require higher compression than ones running nitro. Alternatively-check how many gaskets are fitted under the glowhead and remove all but one (you need the one to ensure the head seals properly!) If there is only one gasket fitted then you are really up against it. You could try and source RC car fuel which is usually 16% or better nitro-DO NOT USE IT AS PURCHASED though as the oil content will be too low for the Cox. You can then add castor to bring the oil content up to something around the 20-22% total mark. Doing this will of course dilute the nitro % slightly-but there is no alternative (other than mixing your own-which seems out of the question in this case)....of course if you find some high nitro car fuel (30%+) then there is no real problem, once you got the final oil content right. I would not recommend trying to run the Cox on less than 10% nitro. That's about all that can be done in your specific situation. Does anyone do full size drag racing in Zambia? Drag racers use nitro in large quantities-so if you can find some drag racers there and explain your situation they might give you a litre or so. still fairly long odds I imagine...

ffkiwi
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