CAJ Innovations Forums - fuel usage display

raz

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fuel usage display
10/19/09 at 01:06:57

How is the liter/hour display calculated? Is it based on the injectors' nominal 270 cc/min? If I cruise at 100 km/h it should obviously match the mileage as in l/100 km but it seems to always read significantly lower. Maybe that indicates my deadtime (InjVOn) figures are set too high? I still haven't got around to verify those dreaded deadtimes though I would love to know.

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« Last Edit: 10/19/09 at 01:07:38 by raz »

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YaBB Administrator YaBB Administrator Offline I love YaBB! Posts: 679 The Land of YaBB	Re: fuel usage display Reply #1 - 10/19/09 at 16:57:17 That was a fudge from the start. I've been thinking about redoing it lately.
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raz

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Re: fuel usage display
Reply #2 - 10/21/09 at 09:25:27

I just tried applying 270cc/min to some known cruising data (rpm and effective pw) and that ended up way better than I expected. Could it be that simple? I didn't really expect the nominal figure to be that easily usable.

I have never had any success in finding a nominal flow figure for the V10 though. Anyway it should be configurable of course.

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_Cliff_ Full Member Offline I Love YaBB 2! Posts: 126	Re: fuel usage display Reply #3 - 10/21/09 at 09:27:58 Can you provide a bit more detail to your calculation.
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raz

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Re: fuel usage display
Reply #4 - 10/21/09 at 11:03:09

No magic whatsoever:

270 cc/min nominal flow rate of injectors

Average data from 3 minutes cruising:
94 km/h
3759 rpm
4554 us final pulsewidth excl. deadtime

the rpm should be divided by two but we also have two cylinders, so

3759 * 4554 / 1000000 = 17.12 seconds total injector open per minute

(17.12 / 60) * 270 = 77.03 cc/min

77.03 * 60 / 1000 = 4.62 l/h

At 94 km/h that is ~ 4.92 l/100 km which sounds just about right. I don't know what the Optimiser would have said at the time though.

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_Cliff_ Full Member Offline I Love YaBB 2! Posts: 126	Re: fuel usage display Reply #5 - 10/21/09 at 12:01:23 Thanks for that. I'll get that in for the next release.
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raz

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Guzzi 11OO Sport, My16MkV,
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Stockholm, Sweden
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Re: fuel usage display
Reply #6 - 10/21/09 at 19:48:50

I found a nominal flow figure for the IW724 (Centauro/Daytona/MGS01) injectors. But it's rated at another fuel pressure, 285 cc/min @2.25 bar. I think that could be translated to 330 cc/min @3 bar but I'm on thin ice here. As usual.

EDIT: Found another figure that says 308 cc/min, unknown pressure. And yet other claims that it has the same flow as the IW031 used in the 2V 1100's... seems I'm not the only one on thin ice.

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« Last Edit: 10/21/09 at 20:33:38 by raz »

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jocke

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Re: fuel usage display
Reply #7 - 10/21/09 at 22:36:35

raz wrote on 10/21/09 at 19:48:50:

I found a nominal flow figure for the IW724 (Centauro/Daytona/MGS01) injectors. But it's rated at another fuel pressure, 285 cc/min @2.25 bar. I think that could be translated to 330 cc/min @3 bar but I'm on thin ice here. As usual.

EDIT: Found another figure that says 308 cc/min, unknown pressure. And yet other claims that it has the same flow as the IW031 used in the 2V 1100's... seems I'm not the only one on thin ice.

The fuel flow will increase with the square root of the pressure increase.

3 bar is 33,3% higher then 2,25 bar. 33,3% pressure increase = 15,47% more fuel.

15,47% more fuel is 329,1 cc/min

As a good info for pressure increase vs flow increase.

+10% = +4,8%
+25% = +11,8%
+50% = +22,5%

Jocke.......

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« Last Edit: 10/21/09 at 22:41:52 by jocke »

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_Cliff_ Full Member Offline I Love YaBB 2! Posts: 126	Re: fuel usage display Reply #8 - 12/18/09 at 08:05:56 I've just added Raz's suggested method to the latest Optimiser firmware.
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raz

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Re: fuel usage display
Reply #9 - 06/07/10 at 06:23:32

It's a little hard to tell, but I think it's much better now. Cruising at about 100 km/h shows around 0.5 l/h. My actual average is closer to 0.6 so I think it's a fair reading.

Edit: Of course I mean around 5.0 l/h and my average is just below 6 l/100 km. We actually have something that could be called a "Swedish mile" though it's spelled "mil" and pronounced like meal. And it's exactly 10 kms, so in Swedish, we'd say 0.6 l/mil which equals 6 l/100 km. Hence my confusion

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« Last Edit: 06/08/10 at 04:23:03 by raz »

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