Maybe you got a bit of flying and running in making the best of the weather, I am imagine days like this will be few and far between and then the ground will be covered with that fluffy white stuff.

Can't wait to hear of your results with your home brew biodiesel.

Your comments on the Canadian Tire Cetane boost working as well as the AMSOIL Cetane Boost got me thinking again.

I did some poking around to find the auto ignition or self ignition temperatur of the various ignition improvers we have been using.

methyl ethyl ketone peroxide aka 2-butanone peroxide, MEKP - 109 deg C chemical formula C4H16O4
Octyl Nitrate aka 2-ethylhexyl nitrate - 130 deg C chemical formula C8H17NO3
amyl nitrate aka 1Pentyl nitrate - 208 deg C chemical formula C5H11ONO2
iso-propyl nitrate aka 2-propyl nitrate, IPN - could not find one C3H7NO3
1,2,4-Trimethylbenzene - 210 to 240 deg c C9H12

Quite a range from around 100 deg C upwards to near the same auto ignition temperature of kerosene itself. So it makes sense that the addition of a compound with a lower autoignition temperature would mean you require lower compression but there must be something else going if Andy's observation of the trimethylbenzene mix and that with octyl nitrate seemed to work the same.

From here http://www3.telus.net/dieselcombat/diesel_fuel.htm this snippet regarding ignition improvers

quote

" has the effect of further lowering the self-ignition temperature of the fuel but more importantly reducing the lag time for ignition to commence once this temperature is reached."

some previous references I have noted mention the addition of tetra ethyl lead or ferrocene to the diesel fuel that the FAI team racers use, allows a higher compression setting by controlling "knock" (detonation ??). In other words modifying the way the fuel burns. These addititives are also used with gasoline as anti knock additives and so is trimethylbenzene.

I am not in a position to test as my test engine is down for a rebore, but in light of Andy's comments concerning the trimethylbenzene and the octyl nitrate seeming to work much the same, what effect would we get it we used a mix of both of these cetane boosters. Say 1% of each or 2% octyl nitrate 1% of the other. Would this let us run a slightly higher compression and have a positive impact on throttle ability?

And another thought, fuel formulas we see usually have around 2.5 to 3 % amyl nitrate. This has a fairly high auto ignition temperature. Perhaps when we substitute octyl nitrate we should be using less say 1.5 to 2% as it has a much lower auto ignition temperature. I have been using around 2.5% just because it seemed right but now I am wondering if this was too much.

I think the comment made early that kerosene is still king is a pretty good observation. It is relatively inexpensive, easily obtainable, and clean right out of the bottle - no fuss no muss. I ran my old PAW 2.49 on B85 biodiesel with no added lubrication for a total of around 1 hour running time. The wrist pin is wore out as is the connecting rod big end, compression is down but it was to start with. I don't think the B85 as is has the proper lubrication properties even though it feels oily and a there was a lot of oil coming out of the engines exhaust.

I wish I had more knowledge of organic chemistry, it might help more sense of some of this.

More testing to do. I have a PAW 1.49 that I think I might get out try some other mixes with before the cold cold weather sets in.

cheers, Graham in Embrun near Ottawa Canada.