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Author Topic: Engine Displacement  (Read 8251 times)
Rabbid
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« on: November 24, 2012, 12:41:04 PM »

Hi All

I'm looking to try and work out what is used for the reference cylinder displacement when calculating load etc. Main reason is for asking is a 2.0 engine rebored or stroked out to a larger size worth writing home about.

I've searched so far but have been unsucessful.

Any pointers for dealing with changed displacement?

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Rick
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« Reply #1 on: November 24, 2012, 12:59:27 PM »

MLMAX - do a search Smiley
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Rabbid
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« Reply #2 on: November 24, 2012, 01:21:48 PM »

Thanks but that is maximum possible air flow for load calculation, which would be adjusted on boosted cars for example.

I'm on about the actual calculation of load

i.e

Load = Mass ingested over Mass Standard. From what I understand mass standard is displacement in cc multiplied by 0.00122521 g[cc]

http://s4wiki.com/wiki/Load

I am trying to workout where the ECU would get the displacement cc from

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Rabbid
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« Reply #3 on: November 24, 2012, 01:23:34 PM »

So far I've found posts relating to KUMSRL and KISRM but I'm not 100% sure on how these would relate to engine load.
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Bische
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« Reply #4 on: November 25, 2012, 11:31:42 PM »

KISRM converts rlroh_w to ps_w and KFURL converts ps_w into rl_w.

I believe you should scale KISRM to get ps_w in line with boost pressure(I dont remember the variable name off my head) and thus getting rl_w back in line. I could be wrong but that is how I would approach it.
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nyet
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« Reply #5 on: November 25, 2012, 11:52:51 PM »

KUMSRL converts kg/hr of air into load per rpm

It is inversely proportional to displacement.
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Rabbid
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« Reply #6 on: November 28, 2012, 02:16:28 AM »

Seems KRKTE uses displacement in its calculationt too.
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ABCD
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« Reply #7 on: November 28, 2012, 02:51:21 AM »

KUMSIRL=Vh/2578, where Vh is cylinder volume in Litre

KRKTE = Vh*50.2624/Qstat, where Qstat is Injector static flow in gm/min.
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ABCD
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« Reply #8 on: November 28, 2012, 02:52:25 AM »

Quote
It is inversely proportional to displacement.

Wrong

KUMSIRL in directly proportional to displacement.
« Last Edit: November 28, 2012, 11:23:41 AM by nyet » Logged
Rabbid
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« Reply #9 on: November 28, 2012, 07:09:04 AM »

Certainly seeming alot more difficult than a standalone ecu which just asks for engine displacement and number of cylinders  Cheesy
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nyet
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« Reply #10 on: November 28, 2012, 11:33:20 AM »

Wrong

KUMSIRL in directly proportional to displacement.


HMM. I rechecked this. As far as I can tell, KUMSRL (not KUMISRL) is, in fact, inversely proportional to displacement. I don't actually know what KUMISRL is.
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nyet
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« Reply #11 on: November 28, 2012, 11:40:56 AM »

Here you go. You were right, KUMSRL is proportional to displacement:

(((.001072 (kg / hr)) / (1.27500 (kg / (m^3)))) / (0.5 * (1 / min))) * 100 = 2.80261438 liters

Not sure why 2.8 though, and not 2.7

Am i using the wrong density for air?
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nyet
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« Reply #12 on: November 28, 2012, 12:05:47 PM »

Certainly seeming alot more difficult than a standalone ecu which just asks for engine displacement and number of cylinders  Cheesy

In any case, I think ABCD definitely has it right.

displacement/2578 will get you in the ballpark.
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ABCD
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« Reply #13 on: November 28, 2012, 11:55:26 PM »

Here you go. You were right, KUMSRL is proportional to displacement:

(((.001072 (kg / hr)) / (1.27500 (kg / (m^3)))) / (0.5 * (1 / min))) * 100 = 2.80261438 liters

Not sure why 2.8 though, and not 2.7

Am i using the wrong density for air?


Hi nyet,

I cud not get what have you calculated here. Pls elaborate.

density of air = 1.293 gm/L at 273K
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nyet
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« Reply #14 on: November 29, 2012, 12:07:45 AM »

(((.001072 (kg / hr)) / (1.29300 (kg / (m^3)))) / (0.5 * (1 / min))) * 100

Let google do the conversions for you Smiley

the .5rpm (1/min) is for 4 stroke (1 cyl filling = 2 cycles)

100 is for conversion to %
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ME7.1 tuning guide (READ FIRST)
ECUx Plot
ME7Sum checksum checker/corrrector for ME7.x

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
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