Hello Gordon,
last year I spent quite some hours making a Excell to calculate CDE from VE.
It actually worked quite well, needs some adjustments after.
Seems that CDE can be used to equal rear and front VE tables.
Would be interesting to exchange findings
I could not figure a way to message you.
Regards BND

 

Hi Marc
You need to have a few more posts in the forum before you can send Personal Messages ...is how I think that works.

I obviously don't know how you are working out the numbers but I have seen another spreadsheet but it had two major flaws so I couldn't see how it could possibly be accurate.
it seemed to be based on some mythical ideal trend line which I have no idea where it came from or on what mathematics it was based upon
and, the biggest flaw, was that it took no account what so ever on front vs rear. What ever you started with (which could be horribly wrong) it would make a calculation against the mythical trend line and move BOTH front and rear CDE tables by a same amount ...which obviously can't be right at all.

I'm actually using MegaLogViewer to take a log file and generate an RPM vs MAP VE table, and looking at how smooth the trends are across the MAP and up and down the revs.

I'm going to start again and see if I end up at the same place as I did last year ...today was the first ride out of the year

 

Gordon... I moved this thread to a DR sticky.

 

I see im to much of a Greenhorn, to Private Message
didn't know that.

=)

Well its quite a calculation, no myths, just math, it seems to work quite well.
At least do the logs suggest that.
CDE basically adds fuel below 60Kpa (DJ).
As far as I understood the approximation formula: (60-50)*2%=20%
Lower Kpa: 60-30*2= ... and so on.
The effect is increasing at lower Kph, so is Charge Dilution.
We can see that quite well, @ higher RPM, New VE is much closer to actual VE and more stable.
I got the Old and New VE with in 2-3 % instantly with this Calculation.

The thing is, I read a lot about that stuff and tried a lot but there is not really a lot of info or people trying to figure out how.

How complex is that Program you re talking about ?
And it that really good ?


@ Mr. Wizard
What is a DR sticky ?

Yeah I know im still green

 

DR= Dyno Room... a special area for tuning conversations.

Sticky = a thread that is stuck to the top of the forum so it won't disappear.

 

Thanks, Sticky was clear, but DR not.

 

Thanks Mr Wizard ...one of those questions that keeps coming up again and again, a bit like cam timing

All of the bits of info are scattered across quite a few threads, how about I try to pull them all here, with what I found as an example ...in a day or two.

I'm going to re-tune my bike from the ground up so will hopefully get some useful real world pictures.

 

Bump =)

@ Gordon

Well its quite a calculation, no myths, just math, it seems to work quite well.
At least do the logs suggest that.
CDE basically adds fuel below 60Kpa (DJ).
As far as I understood the approximation formula: (60-50)*2%=20%
Lower Kpa: 60-30*2= ... and so on.
The effect is increasing at lower Kph, so is Charge Dilution.
We can see that quite well, @ higher RPM, New VE is much closer to actual VE and more stable.
I got the Old and New VE with in 2-3 % instantly with this Calculation.

The thing is, I read a lot about that stuff and tried a lot but there is not really a lot of info or people trying to figure out how.

How complex is that Program you re talking about ?
And it that really good ?

 

CDE don't add fuel. Its an offset the MAP reading below 60Kpa (affecting the MAP also impact VE)


@ Gordon. Using the spreadshet I supplied (I guess that's the one your talking about), tune both your front and rear CDE at the same time, then adjust onely the rear to make the rear cylinder VE close to the front cylinder VE.
We have found that only the front cylinder value affect the MAP reading.
The trend "line" is take from the Map Default table

 

Ok, it does not add fuel in the sense of actually adding.

If its a offset and it is changed, isnt the result the same as adding or subtracting Fuel or increasing VE, which is essentially also a way adding fuel ?

Comparing VE and New VE in the logs, it shows, with the same F&R-VE, the rear VE is a bit to large in 2 areas, idle and around 1700 RPM at a stable 30-35 Kpa, while the front is pretty much spot on, except for the negative load, (engine break) Of course you can't take the Front VE and copy it to the back, its more like a average between front and rear.

Very interesting is, what you state above.

"only the front cylinder value affect the MAP reading"

If I understand it right, that would mean, if the rear shows high VE in the 1700rev. 30 kPa area, that the (equal) VEs have to be reduced at 30 kPa 1700 and the Front CDE has to be increased to compensate.

What I tried with the spreadsheet seems to be similar.
It basically takes the original CDE, and converts it by comparing the equal and original VEs. Its quite complex, because the CDE Tables resolution is low and doesn't match VE Resolution.

@Frédéric

Would you be interested to share findings ?
Where are you @in France ?

Im in Switzerland

Send me a PM I can't, im toooo green