newbie question, engine load

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newbie question, engine load

Postby Dave Harries » Thu May 10, 2007 12:09 pm

Having read alot on this forum there is one thing I can't get my head round and that is the engine load in grams . I have been mapping my classic scoob with a MoTeC ecu in it for about 3 yrs now, through various engine stages and the load is the actual boost pressure in the manifold . How does the engine load in grams compare to boost ? Sorry if it has been answered before but I couldn't find anything with the search.
Cheers Dave
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Postby UKspec » Thu May 10, 2007 1:59 pm

If load units are supposed to be g/rev, then:
=(MAF*60)/RPM

If load units are supposed to be g/cyl, then:
=(MAF*60)/RPM/2
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Postby Dave Harries » Thu May 10, 2007 2:06 pm

I read that when I did a search but how does the grams relate to psi of boost? this is what I can't get my head round
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Postby Freon » Thu May 10, 2007 3:58 pm

There is a correlation, but you cannot just multiply boost by a number and come up with load, or vice versa.
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Postby Jon [in CT] » Thu May 10, 2007 4:34 pm

Dave Harries wrote:I read that when I did a search but how does the grams relate to psi of boost? this is what I can't get my head round
There is a numeric relationship, but you also need manifold air temperature, volumetric efficiency and cylinder displacement to perform the calculation. I suspect the MoTeC needs to perform that calculation in order to determine how much fuel to supply.
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Postby ravenhil » Thu May 10, 2007 11:24 pm

my first post in this forum...

I'm somewhat familiar with tuning using Unichip so I am trying to channel my experience into ECUflash. Functions like fuel accel is absent (proly under a different term) and ignition timing and AFR is changd with respect to rpm vs throttle position.

In ECUflash, fuel trims and ignition timing maps are represented by rpm and engine load in grams. I've tried to change the x-axis values to "Throttle" but it screws up the figures royally.

I don't mind working with load if I could get a better understanding. So I take it that 4.28 g is the maximum engine load that a WRX will ever encounter?
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