Wednesday, 16 February 2011

Stress-Free Fuel Testing

Last month I was saved from taking the gas-axe to the CB special by the expertise and wisdom of Mark at BSD (see earlier post). Being a huge fan of experts, pretty much regardless of the field, it was an easy decision to ask Mark if he'd tackle the fueling work on Diplo Jnr's XT. Diplo Jnr has made a quantity of ethanol by distilling last autumn's cider production. The resultant juice is around 82% ABV and suitable for blending with aprox 15% by volume of gasoline to make his own, home-grown version of the commercial E85 available at some forecourts. (The 15% gasoline is required to aid cold starting as it has some of the more volatile fractions missing from straight alcohol). Re-jetting to get the simple, normally aspirated, sluggish 4 stroke to run on alcohol involves dispensing an estimated 30% more fuel. Much as I love trial and error (the largest department at Diplo Technologies Inc) it seemed wise to keep stress levels at bay and ask Mark at BSD to take on the challenge in the comfort of his dyno room.
Within 10 minutes our expert had the XT running sweet on some commercial E85 that we took along by upping the main jet, re-drilling the pilot jet and raising the needle a tad. We actually get a 5% power gain at this point. Next stage was to switch to Diplo Jnr's own fuel. We got the bike running but intermittent missing and spluttering was tracked down (by Mark's nose for these things) to excess water in the fuel. Conventional distillation should enable us to get a maximum of 96% pure Ethanol, beyond which unsavoury chemical processes can be applied (the use of benzine is the most common !!!!).I know we're way short of that and our target of 85% should be good enough. Back to the 'shop and we'll re-run the still to see if we can get rid of a bit more water. MORE DISTILLATION !


Toby Savage said...

Blimey! Respect for all.

Thud said...

Is there not a little for....erm ...lubrication?