[Diy_efi] Basic Speed-Density equations?

[Grant Beaty]

What about switching from a car with a MAF to speed density, on the stock
ECU? Is some kind of circuit required to get the throttle response correct?

I've got a nifty little fuel/timing piggy back called the GReddy E Manage.
Although it does not officially support speed density, It can directly
manipulate duty cycle on a 16x16 map of MAP voltage vs. RPM. Ajustable in 1%
increments (is this enough for good drivability? The car has 6x 550ccs, and
I might upgrade to 850). Temp correction could be applied to the MAP input,
but the only thing I'm worried about is throttle response, since I know MAFs
don't response instantly due to their distance from the TB (its a turbo and
intercooled car).

Thanks for any help,
Grant Beaty

-----Original Message-----
From: Eric Fahlgren <eric.fahlgren at mscsoftware.com>
To: diy_efi at diy-efi.org <diy_efi at diy-efi.org>
Date: Friday, June 14, 2002 12:34 PM
Subject: Re: [Diy_efi] Basic Speed-Density equations?


>AnalogWz at aol.com wrote:
>>
>> Can someone please explain the theory of speed-density engine load
measurement?
>> Does any manufacturer publish a detailed theory of operation?
>
>Jim,
>
>Read the first couple of pages in Bruce & Al's paper on implementation
>of auto-learn functionality.  Basic theory is that engine VE is the
>same at a given RPM/MAP point across a wide variety of other conditions.
>This allows you to estimate flow based upon RPM (speed), MAP and air
>temperature (density) and thus calculate injector pulse width accordingly.
>
>http://www.bgsoflex.com/ve_tuner.pdf
>
>Eric
>
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