[Diy_efi] Festivus salutations & idle engine power query

[Mike]

Ah, good point, havent considered that as being significant, do you have an estimate on
how much I might consider 'derating'  the power figure for less efficiency at idle ?

Would 30% be in the ball park ?

Thanks

Mike

At 03:06 AM 12/28/2010, Bruce Beachman wrote:
>Hello,
>
>Wouldn't BSFC (brake-specific fuel consumption) factor-in here?  Combustion efficiency would be lower at idle than at torque peak, so I would think that scaling a power calculation based on injector duty cycle would get more inaccurate as you deviate from the BSFC found at power peak. I would guess that for the same duty cycle, less chemical energy would be liberated from the fuel at idle, and your idle power number would be lower (if you haven't already accommodated for that in your calculations).
>
>Best,
>-Bruce Beachman
>Beachman Racing
>On Dec 27, 2010, at 4:19 AM, Mike wrote:
>
>> Hullo all,
>> 
>> Hope you all had a great christmas and take care for festivities over the new year break :-)
>> 
>> Has anyone any representative data as to how much power is required to keep a conventional
>> ICE from say 4 cyl to 8 cyl at its warmed up idle speed with no aircon and fully charged battery
>> (ie minimal drain by engine alternator) and lights off, conventional engine driven water pump and
>> engine driven oil pump etc
>> 
>> My own calculations with an RB30ET (Nissan 3L straight 6 turbo % 0.8% injector duty cycle)
>> show a consumption of approximately:-   2 Kw with an error margin of about +10% -40%
>> Though I think this is on the high side, it wasnt possible to resolve the DC to less than 0.8%,
>> i think it is closer to 0.6 to 0.65 % or so.
>> 
>> This is based upon the max injector duty cycle of 85% for a 225Kw delivery, the engine is
>> rated at 150Kw at 7.5psi boost, the boost is easy to increase with a relief valve and the
>> limit - as tested with several vehicles in Australia for the same injectors for the turbo engine
>> (which are larger than the n/a engine is at 225Kw...
>> 
>> Expecting, that after allowance for a quiescent amount, the figures would be approximately
>> proportional for smaller and larger engines ?
>> 
>> Comments ?
>> 
>> Mike
>> 
>> 
>> 
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