The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Amal, Carburation, Fuel => Topic started by: Viking on 03.02. 2016 21:02

Title: Air fuel ratio A10 engine
Post by: Viking on 03.02. 2016 21:02

What is the optimal Air fuel mixture ratio in the A10 SR engine ?
14,5 or ?

I am planning to fit at AFM meter in my A10 SR, to test if the mixture i correct in all driving conditions....

Would like to have a Rolling road test bench, But i am limited in space...

Title: Re: Air fuel ratio A10 engine
Post by: BSA_54A10 on 03.02. 2016 21:43

This is a how long is a piece of string type question.
The text biook number of 14.715 makes a bold assumption that you are burning OCTANE ( 8 carbon + 18 Hydrogen ).
However in reality what is in your tank is any else but Octane and with the advent of real time engine management, we now have "fuel" which is mosty waste organic solvents and by-products from the plastics/fertalizer industry.

Title: Re: Air fuel ratio A10 engine
Post by: muskrat on 04.02. 2016 18:37

G'day Viking.
Orabanda's dyno findings are around 12 to 12.5:1
http://www.a7a10.net/forum/index.php?topic=3122.msg21340#msg21340
Cheers

Title: Re: Air fuel ratio A10 engine
Post by: chaterlea25 on 04.02. 2016 19:49

Hi All,
A kind of parallel question, recently I picked up a CO2 meter, that tests the CO2 in the exhaust gasses
Of course no instructions came with it !!!
Does anyone know what % CO2 I should aim for in the exhaust gasses??

Cheers
John

Title: Re: Air fuel ratio A10 engine
Post by: muskrat on 04.02. 2016 21:59

Good  *????* John. I'd like to know as well.
The only figure I could find was 12-15%. So in ppm 120000-150000.  *dunno*
 Viking, the 14.5:1 would be for modern fuel injected lean burn type engines.
Cheers

Title: Re: Air fuel ratio A10 engine
Post by: chaterlea25 on 04.02. 2016 22:33

HI Muskie,
I must look for an instruction leaflet ? or test on some sample vehicles ???
It has two ranges, 2 and 10 %

http://www.ebay.co.uk/itm/BLUE-POINT-EXHAUST-GAS-ANALYZER-/231768755987?_trksid=p2047675.l2557&ssPageName=STRK%3AMEBIDX%3AIT&nma=true&si=zTRgZsCqYI1e7MtuSMqBlqzhkMs%253D&orig_cvip=true&rt=nc

John

Title: Re: Air fuel ratio A10 engine
Post by: oka on 15.02. 2016 10:42

I have aimed for between 12:1 and 13:1.

It is where you have the maximum horsepower and gives a nice margin to too rich 10:1 and too lean 15:1.

Modern cars which run 14.7:1 also have a lamda sensor which regulates the fuel injection. Not quite what we have with the Amal.  ;)