Peking to Paris /fuel octane?

Keith Andrews · Post by **Keith Andrews** » Wed Oct 10, 2007 9:19 pm

Last nght i visited the local VVC club.
As a guest speakers they had Harold McNair / Anne Thomson and their 1930 - Delage whow competed in the 2007 Peking to Paris race last June /July.
http://www.pekingparis.com

Very interesting, espec as I had followed the 2005 race on the Descovery Channel a few months ago.
I did pick up on 1 piont made, whle in Russa, they had a choice of modern 90 something octane or the cheap russian 80 octane...
They tried the 80...mlage increased from 270 km to something like 360km per tank, the car ran better and smoother....Halold elaborated a little further...and strongly suggested we should be running our old vechiles on whte spirits...modern fuels they just dont run as well, as fast or as economical.

I have posted elseware about this...we have octane boosters....
How can we add a octane reducer?

Also the second part of the talk was the Le Mans 100yrs....that also was very interesting, especially because the Star of the celebrations, the 1906 Darracq 4B, was entered/owned by Harold McNair and Anne Thomson

Keith Andrews · Post by **Keith Andrews** » Thu Oct 18, 2007 7:39 pm

Bump
How can we add a octane reducer?

PAUL BEAUMONT · Post by **PAUL BEAUMONT** » Fri Oct 19, 2007 1:16 pm

Keith, its called paraffin isn't it?
Joking apart, these sort of meetings are great arn't they, but over here they seem to be fewer and fewer.
You got your Bradford back axle sorted yet?

Keith Andrews · Post by **Keith Andrews** » Fri Oct 19, 2007 8:12 pm

This is what I have found out
Parafin/kero/pegasol are all basically the same thing with an octane of somewhere between 0 and 15
these should have the engine started on petrol then switch to kero, gumming is a bgg issue unles the engines are worked hard...even if blended with petrol.
Another long term possible issue is washing of the bores...apparently a 60:1 mix of 2 stroke bike oil will fix this..IF it is actually an issue.

Deseil/petrol blend is very similar...a better option as far as burning/ gumming/washing walls..but has an even more major issue...will eat out the rubber in fuel lines, pump diaphams, carbs etc...so a no go

Jet A1 fuel...basically this is a more highly refined kero, with a few additives like anti guming stuff.....Seems so far to be the best opition

NOTE:
1/ none of the above are any good as a blend or straight on modern hi compression (over 8:1) short stroke, hi reving.
2/Early fuels did not have lead...
3/English pool fuel 1938 to 1954 varied between 67 to about 78 octane
being basicly mix of kero and petrol

On paper, using jet A1 / 91 blend a 20% jetA1 would give approx 70 octane and 30% 80 0ctane

Fortunatly most vintage engines have square or near to square cam profiles, which means the CR is very close to dynamic CR (bradford has a square cam)
What CR for what octane...here are ball park figures
5:1 approx 70
6:1 approx 80
8:1 approx 90
9:1 approx 95

As the octane of a fuel is increased in a given engine...so must the timing advance, and visa versa due to the race between the speed of explosion and decompostion of the compressed fuel mix (auto explode under pressure as in a deseil engine (knock)...This paremeter varies on the stroke, compression, rpm range and revs.

There is another jet fuel Jet AA very similar to jet A1 but have not been able to find out too much about it, other than it is similar, so it could very well be a good possiblity.

Oh well head out to the Airport sometime soon.

Keith Andrews · Post by **Keith Andrews** » Mon Oct 29, 2007 8:53 pm

I been doing a lot more research, asking questions ....so now have quite detailed 'libarary' on the subject, ranging from the chemical composition of alternatives, tests/ experiances other have had over the last 30 odd yrs in tractors, cars. servce vechiles etc to detailed history of feuls, their componistions and octanes/ whys and graphs etc
I have run 2 trials
a/The engine is very worn, a huge lot of blow by, compression very low and audable piston slap in 1 side... thu carb fully rebuilt. tappets, timing all set to factory.
b/Trial coarse is inconsistant, around town, up down hills, short runs..general daily driving.
c/ on last yrs Club Economy run..open road cruising around the 40 to 45 mph over approx 100 miles without any concern to economical driving recorded 38 mpg

each draining the tank and mixing up 10 liters then run till mt
1st: 2L jet A1 fuel 8L of NZ 91 octane...(Therical octane is 72 to 75)
Note since making this mix, have found the kitichen measuring jug was not measuring correct....so the mpg is incorrect ..slightly larger than 10L but still 20% mx.
The idle speed /mixture needed retuning. lowering rich and throtlle stop.
Car cold starts easier, engine runs smoother, and on the very steep hills changing down to a lower gear is later.
Taking off in top gear is easier (not recomended but good method to check for knock) mpg worked out to just over 40 mpg (note above re was more tan 10L)
Conclusion: ran far better, thu would hesitate to us this 20% mix on an engine with good compression, the chances of knocking are very likely

2nd 1.5 L jet A1 fuel 8.5L NZ 91 octane...(therical octane is 78 to 80) This is still under test
Comparissons are with 1st test above
Again the idle, speed mixture had to be readjusted ...and again lowering throttle stop and mixture.
Cold start seems slight improvement over, seems to change about the same place on steep hills..engine runs a little more smoother
Mpg...have to wait till run out of gas over next few days...