Fuel Injection Design

[Clive Apps Techno-Logicals 416 510 0020]

> 
> I do have a dyno result for the bike, and the results are at the rear
> wheel so it would account for losses.  The run I have is not the greatest

no these results include the losses
but the torque peak should be at the same approx RPM
because you are using rear wheel figures add about 10% to the low end and 25%
to the high end on the airflow calcs ( should be a curve with slighly
log type increasing slope at the high end (rotational losses are not linear
they increase logrithmically with RPM)

> run it was taking when I was working out the bugs in the bike, will redo
> here shortly.  Max torque occurred at 6800 RPM with 55.2 ft-lbs, bike
> redlines at 10500.  You say that VE(I assume this is volumetric
> efficiency) should be around 110% to 120%, book I have says around 75% for
> a stock motorcycle engine  in good condition.  I am using a stock engine
> and assuming good condition.  I am not completely sure if I understand how
> you say to get the air consumption curve.

the 75% is for a very stock type blah type engine
a stock 900 cc bike that redlines at 10.5 K is not a stock bike
you may find the real VE numbers by asking someone who has done a lot of tuning
on these for a stock racing class
on your bike I would use 110% for VE, it is a pretty wild ride stock
and if you guess to large you will be too rich (ok) instead of too lean (melt
parts)

> You say:
> "multiply the RPM x air comsumed at RPM x VE at RPM x frictional loss
> correction to get an air comsuption curve"
> Since I have the torque curve then I should multiply 
> (RPM)(Volume one cylinder)(VE)  Where VE would be the torque at that RPM
> 				but in percent form??
> 
> So at the 6800 RPM from my dyno run I would have this for 908cc engine:
> (6800)(227cc)(.552)=852067cc/min
6800x227x1.1 = 1697960 cc/min ~ 170l /min

then plt this result against the loss curve (say 15% at this RPM)
so you need an addtional 17.6% (1/.85) or about 200 l/min

> And then for each point along the torque curve do the same thing??  And
yes
> this will give me an air consumption curve.
exactly

> Am I on the right track?
pretty close

> Or do I use the torque curve and say that the max of the curve is what I
> say the Max VE is and then slice it into parts and compare it against the
> RPM.  This way the air consumtion at 6800 RPM would be(assuming VEmax=75):
> (6800)(227cc)(.75)=1157700cc/min
> Then at each RPM spot I would chose what the VE would be according to the
> VEmax being 75.  

yes but the VE max will be close to 110% see above

slice the curve up in 100 RPM increments
this will give you ~100 useful points

once you have the airflow curve
you can calculate the fuel curve to suit

> Appreciate the help.  Don't spam me too hard I am trying to learn this
> stuff but have yet to find the books that explain a lot of what I need.
> Thanks


Clive