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Old 13th June 2007, 11:43   #31
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I have rather skipped to the end of this thread, but I'm sure I used to get better mileage out of my Rover 620 (British-built Accord) in UK's occasional heatwaves
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Old 13th June 2007, 14:02   #32
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Originally Posted by paras211 View Post
but a cai will reduce throttle responce too right?? so i prefer sri
also mumbai floods up too
what would 'sri'be? and how would mumbai floods affect your CAI setup. and no CAI is not going to reduce your throttle response.
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Old 13th June 2007, 21:47   #33
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[QUOTEwhat would 'sri'be? and how would mumbai floods affect your CAI setup. and no CAI is not going to reduce your throttle response.][/quote]

sri-short ram intake a shorter pipe so better responce
a cai goes down to the bumper so if one has to drive in a some water logged area or if you go through a big puddle fast there is a possibility of hydrolock i.e water being pulled into the engine
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Old 14th June 2007, 01:52   #34
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Originally Posted by tsk1979 View Post
@zappo, if what you say is true its a problem.
Unlike Petrol and Diesel which change volume slightly on changing temperature, Gas changes volume at a much higher rate(Provided pressure is same)
PV = nRT(Ideal gas equation)
or P1V1/n1T1=P2V2/N2V2
If pressure is constant
V1/T1= V2/T2
So if at 200K a gas occupie 5L volume
At 250K it will occupy 6.25L. If we take a more realistic number 20 DEgrees vs 50 degrees 10L gas volume will expand to 11.5L(approx)

So filling gas by volume is pure wrong. If what you said is true, all CNG guys should head to the service station at 5am in the morning and get 10% increase in FE.
That is why I am a bit worried when he says that his average all of a sudden fell by more than 2.5kms.

Also, think about it this way. A flowing gas can not be weighed directly. In a LPG bottling plant those automatic nozzles come down and fill up the cylinder and then the weight is again checked by the onboard computer. If required it is filled up a little more the second time. The dispensing weight in each run is again calculated in the same round-about way.

For a autoLPG or CNG outlet the equivalent to this will be to first weigh the car and then after the fill weigh it again to know the weight dispensed. Since that is not done (can not be done?!) it is calculated based on the volume dispensed.

Of course the chip in those automated dispensing pumps are calibrated for different geographical areas as per the standards. Obviously a dispenser in Himachal and one somewhere in south will be calibrated differently based on the average yearly temperature, pressure etc. Problem arises if the variation becomes too big and goes far outside the standard range.

Now, calibration of those chips are done that I know. But weight calculation by working out the volume is my application of general idea as I can not see how otherwise a pump can find out the weight. At least I can not think of any other way at all.

P.S. : By the way pressure will not remain constant I think. As the temperature changes with season so does the atmospheric pressure. Eg: A low pressure development first cools down the temperatures and then may even bring in gale and thundershowers (which further cools down the atmosphere).

Last edited by Zappo : 14th June 2007 at 01:56.
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Old 20th August 2009, 00:57   #35
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There are two point which work in opposite directions

Reason stated below(without any technical jargons of thermodynamics)

The hot air pushes the piston(difference in air pressure inside and outside). The temperature of the burning fuel will always be same almost. If atmosphere is cold the pressure will be high(temp and pressure inversely proportional). this will result in lesser difference in pressure, hence less efficiency of the engine

In cold weather the air is dense. this means more oxygen packed in a particular amount of volume. Now this will result in better burning of the fuel, hence efficience will increase.

As far as AC is concerned, it will consume the same amount of energy as long as the AC settings are not changed. The main thing in AC is the compressor. As long as this motor is on it will draw the same amount of mechanical energy from the engine.

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