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Calculating fueling on alcohol EFI# ANOTHER QUESTION???
speedster356 - December 21st, 2010 at 10:04 PM

How would I calculate fuel flow for puimp sizing, ejector size, and throttle body dia on an aircooled single cylinder of 600cc running on alcohol? This is EFI.
Not sure of HP, maybe 45?
At the stage of selecting electric fuel pump etc.

http://i291.photobucket.com/albums/ll298/petemcleod/21122010443.jpg

http://i291.photobucket.com/albums/ll298/petemcleod/13072009111.jpg


http://i291.photobucket.com/albums/ll298/petemcleod/13082009144.jpg


http://i291.photobucket.com/albums/ll298/petemcleod/ajs_oldest_bike_ever_1926_3.jpg


vlad01 - December 21st, 2010 at 10:39 PM

I think 34% more than regular fuel.


mactaylor - December 22nd, 2010 at 04:57 AM

is that a lycoming cylinder head?


dangerous - December 22nd, 2010 at 05:21 AM

900ml per HP per hour is what the engine will want.

So a 45 hp engine will want 40.5 lt in and hour.

If you flow through into a bucket it will need about 675ml in a minute,
or 112.5 ml in 10 seconds.

As a margin for error or other things,
you may like to make sure your pump can supply 50% more than this,
but through the nozzles, the engine will want around 112.5ml in 10 seconds.

An interesting comparison,
my supercharged engine flowed 3lt into the engine in 10 seconds at 7000 rpm.

If you are boosted you have to factor in any parts that use HP.


speedster356 - December 22nd, 2010 at 07:14 AM

Perfect, thanks Dave. A little Bosche will be fine then. What about compatability with Methanol? any problems there you think?
Head is a 1929 AJS bigport, engine cases are 29 roller bearing AJS, bottom end is BSA B50 with JE forged piston, the rest is made by me.


fast68 - December 22nd, 2010 at 07:46 AM

looks pritty cool:cool:


SuperOwen - December 22nd, 2010 at 12:14 PM

Cool project!! Are you going to try hide the system and make it look semi original or is this more of a custom build?
I know its not VW but keep this thread updated!


speedster356 - December 22nd, 2010 at 03:11 PM

Stealth. ECU (check here microsquirt) is the size of a credit card. This is sitting between the tanks along with the pump etc. I'm machining a 32mm carb from billet and this will be the throttle body with original Amal float bowls hanging off it. I'll run the TPS (which is rotary) also under the tank cavity, so it will be pull cable from the throttle grip to a rotary quadrant with the TPS mounted (just off a nornal car carb) then it'll be a pull cable from the quadrant to the carb/throttle body so it should be all hidden. The frame is full 4130 CroMo.


speedster356 - December 31st, 2010 at 08:30 AM

I'm using a carb with a slide and not a throttle body with a butterfly.
How will this effect the perfromance (trying to maintain the original look with a carb). I've fabricated a 38mm carb. I guess the progression will be different with a slide carb? is that all do you think? Can anyone tell me what the cutout is on the front of a normal carb slide is and what is it's function?

http://i291.photobucket.com/albums/ll298/petemcleod/carb.jpg


speedster356 - December 31st, 2010 at 09:07 AM

Can anyone tell me what the cutout is on the front of a normal carb slide is and what is it's function?

From the crack of the throttle through 1/4 throttle openings, the slide cutaway determines how much fuel flows into the engine. It doesn't do this by allowing more air into the engine--that duty is handled by the straight, front edge of the slide. It does it by changing the velocity at which the air streaks under the slide; just like you do with your thumb over the hose.

So in a throttle body situation the slide cutout is not requred I guess as my carb/throttle body only regulates the airflow.