Fuel Misers

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Drago

Drago

Legendary Member
Long stroke brings greater torque because of the potential for a longer and more complete combustion cycle. Not so good for peak power due to vibes and greater reciprocating masses.
 

lazyfatgit

Guest
Location
Lawrence, NSW
I lost the thread at about page 9. Apologies if aircon has already been mentioned.

Anything that interferes with aircon in summer here is not going to be practical. It’s amazing how fast a car heats up even with tinted windows.

What do the hypermilers do in 40C days in blazing sun?
 

Colin_P

Guru
What do the hypermilers do in 40C days in blazing sun?

I have the A/C blasting, it makes virtually no differnce on a large engined diesel. In fact I leave it on all the time with the climate control. The only times it has been off is to see if it did indeed make any perceptable difference to MPG, it didn't. On small petrol engines that don't have the torque to pull the skin off a rice pudding it might knock 1-2 mpg off. But sometimes you just have to live a little and sod the consequences.
 

raleighnut

Legendary Member
I have the A/C blasting, it makes virtually no differnce on a large engined diesel. In fact I leave it on all the time with the climate control. The only times it has been off is to see if it did indeed make any perceptable difference to MPG, it didn't. On small petrol engines that don't have the torque to pull the skin off a rice pudding it might knock 1-2 mpg off. But sometimes you just have to live a little and sod the consequences.
If you have A/C fitted then the engine is driving the compressor permanently whether A/C is being used or not, switching it off does not disconnect the belt it just doesn't use the 'cold' you're producing. If you took the compressor off would you get better mileage though ?
 
OP
OP
Drago

Drago

Legendary Member
Switching the aircon off allows a clutch in the drive pulley to disengage, so the pulley can turn but does not drive the pump. Switch the aircon on and the clutch engages and the pump is turned, thus using more fuel.
 

Colin_P

Guru
If you have A/C fitted then the engine is driving the compressor permanently whether A/C is being used or not, switching it off does not disconnect the belt it just doesn't use the 'cold' you're producing. If you took the compressor off would you get better mileage though ?

It does use more but it is an almost inperceptable difference on a larg'ish diesel. As I've mentioned above it does on a small petrol engined car though, they can take a 1-2mpg hit for having the A/C on.
 
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