Cool Mornings, denser air
Discussion
Have noticed the Griff playing a lot more sweetly and really gunning over the last week or so on the morning drive to work. I read somwehere that the cooler air means its denser and hence more air to the cylinders. Certainly has a greedier induction roar when it comes on, even the girlfriend has commented (the car not me 
)
Is there any real theory behind this or is it just tosh?
Dave
) Is there any real theory behind this or is it just tosh?
Dave
That's absolutely true - cooler air does mean denser air, therefore more oxygen entering the engine, and proving the ecu works this out and puts in more fuel, then you get greater power.
Never noticed any difference in power myself - thats probably marginal - but you can tell that engines run smoother in cooler weather.
Never noticed any difference in power myself - thats probably marginal - but you can tell that engines run smoother in cooler weather.
mrmaggit said:
Aha! another convert from Harleys to Griffs. Mine was an '89 FXRT, did over 50,000 miles on it. Mined ewe, it didn't like running when it was hot weather.
maggit
nice, i still miss not having one, first was a '77 FXE (my favourite), then a '75 XLCH and recently a twin cam FXDWG, the engine was a diamond but the bike was ridiculous. I intend building an early FLH replica (with bike engine and brakes) when I can afford it
It’s my understanding the Lucas Hot Wire system (fitted as standard) automatically takes account of changes to air temperature and density as these things affect the cooling of the said “hot wire” which is the fundamental measuring element in the airflow meter. As the temperature of the wire changes, due to volume and quality of air passing over it, so its electrical resistance changes, which is monitored and acted upon by the ECU.
Of course I may be talking complete b******s.
Cheers.
Simon.
Of course I may be talking complete b******s.
Cheers.
Simon.
jigs said:
Stupid Question - why can't the air be cooled first via the A/C unit?
The power loss through having the ac on would probably negate any gain through increased air density.
Most turbo'd cars have a intercooler which cools the inlet air temperature, but that's the because the compression effect of the turbo significantly heats the air up.
jigs said:
Stupid Question - why can't the air be cooled first via the A/C unit?
The AC would use way more power than it would create.
Turbo'd cars use water intercoolers (charge coolers) to ensure as much cool dense air can be sucked in as possible. I don't think this can be done on a normally aspirated car though.
A/C uses power from the engine to cool the air, to cool air being drawn through it for the engine would need more of that power offsetting the benefits of the cool air in the first place. No such thing as a free lunch.
m u s t t y p e q u i c k e r
>> Edited by Apache on Thursday 2nd October 15:30
m u s t t y p e q u i c k e r
>> Edited by Apache on Thursday 2nd October 15:30
Okay then - we've all got a reason to look forward to Winter.
PS I think you'll find that it's the higher humidity of cold air that improves the combustion and hence the performance.
PPS Mattrsv - you're not the p*ss artist formerly known as ponce?
>> Edited by jigs on Thursday 2nd October 20:00
>> Edited by jigs on Thursday 2nd October 20:03
PS I think you'll find that it's the higher humidity of cold air that improves the combustion and hence the performance.
PPS Mattrsv - you're not the p*ss artist formerly known as ponce?
>> Edited by jigs on Thursday 2nd October 20:00
>> Edited by jigs on Thursday 2nd October 20:03
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