Does anyone know what the weight /unit volume of petrol is?. The reason I'm asking is that I need to enter an accurate mass co-efficient into my AP-22 meter.

 

Does anybody also know the~

1. Cda

2. rolling resistance

3. Tilt factor

4. Roll factor

 

Would mucho appreciato any of the above for my little box of tricks...

 

Thanks in advance

 

God knows if this is right but here goes.

 

http://www.ex.ac.uk/cimt/dictunit/ccspengm.htm

 

try this i think lol.

What is an AP-22 meter?

Thanks for that but its not quite what I'm after. Just need to know how much say, 1 litre petrol weighs & then its easy to know how much a full or half tank weighs. I can add this figure + my weight into the AP-22 box which can then work out exactly how much power is at the rear wheels.

 

The AP-22 is an accelerometer/data logger, that can measure your 0-60, 0-100, 1/4 mile time etc. (Is, I believe ~99% accurate).

 

If your interested then hopefully this link below will work~

http://www.race-technology.com/WebPage/Products/Accelerometer/ap22/Ap22Introduction.htm

 

I have the id meter.

I got it as it matches the DSBC blitzmakes as well.

 

Beauty of the AP22 thing is that you don't have to wire it in at all, and it logs data for download and manipulation etc.

Oh and it is only £160 and can be used in any car.

The weight or petrol will be similar to that of water (1 litre = 1Kg), not exact but probably close enough.

I think there is a utility for calculating the rolling resistance on the RaceLogic web page.

I recollect that the Cd is about 0.31.

Try using the defaults for the other two - there is also some advice given in the manual.

Yeah, I'm gonna weigh 1 litre of water tonight anyway and will probably go by that information.

 

I only asked the other info in case someone has found out already thus saving me some time!!.

 

I've had the AP-22 for about six months and havent really used it that much. One of the attempts measured 190bhp at the back wheels, thought this was a bit too low?. I know that an auto will lose ~25% in the transmission and was expecting 210-220bhp.

 

I'll post the weight of water and the other co-efficients later. May even get some runs done!.

Originally posted by rock_star:

Yeah, I'm gonna weigh 1 litre of water tonight anyway and will probably go by that information.

 

Assuming that 1 litre weighs 1kg is accurate enough as Andy said.

 

isn't petrol/oil much lighter, which is why it floats on water ?

 

go and get a petrol can and do the job properly

Here you go

 

The specific gravity (SG) of a liquid indicates whether it is lighter or heavier than water. The SG of water is one kilogram per litre. A fluid with a SG less than one will float on water, (e.g. petrol which has a SG of 0.65),

 

So 1 litre of petrol = 650 grams

Originally posted by Jezz_S13:

Here you go

 

The specific gravity (SG) of a liquid indicates whether it is lighter or heavier than water. The SG of water is one kilogram per litre. A fluid with a SG less than one will float on water, (e.g. petrol which has a SG of 0.65),

 

So 1 litre of petrol = 650 grams

 

I just did a quick search on google and found a site saying petrol has an SG of 0.74 (740 grams per litre)

 

Another site claims it is between 700 and 800

grams/litre

 

Of course, in summer it will be less and your car will also be more aerodynamic due to the air being less dense even though your car is now slightly bigger

 

 

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LOL.

Mine came from a web search too, I tried to blag it as being clever but the truth is, the web told me to do it!!!

Did you also know that the sg of fuel varies depending on it's temperature.

 

Yawn....boring.....sorry.

 

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This is very confusing but it boils down to the different type of fules/oils ect.

The sg for motor fuel/oil ect is .88 although the typical value is .86? (yes i have no clue about this)

 

Also Marine fuel aircarft fuel has a far greater density than Car fuel.

1 kg per litre is close enough. Are you also gonna take into account whether the driver had a big breakfast and whether you've got air or pure nitrogen in your tyres ....

Aviation fuel (jet-A1) has an average sg of 0.807 but since when fuelling an aircraft you are talking thousands of litres it is very important for the captain to know the sg (which is why it is recorded three times a day) in order to correctly calculate the required fuel load for the journey. The changes in fuel density can make a very large difference to the total fuel uplift.

 

Not really related to this thread but for once a subject I know something about.

 

 

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1kg/litre is close enough for 1 litre, but for a full tank it could be quite a way out....

 

 

And don't forget..... after a damp day the car wil be a few kilos heavier due to water....

 

Why get everything so accurate when the device itself isn't even that accurate - errors will add up and subtract to give you a close enough figure!!! Also your car may be down on power or it may be up - don't use what you *think* to be the correct figure for your car to adjust the factors you are using for the box...

 

CheerZ,

 

Andy

Is your washer bottle full? What the SG of screen wash?

The SG of screen wash needs to be the same as the water in order for it to mix, the detergent plays havoc with the surface tension of the water though.

 

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Originally posted by 300z:

This is very confusing but it boils down to ...

 

Have you done a lot of boiling petrol Waz ? It's never struck me as a great idea.

Originally posted by Steve.r:

The SG of screen wash needs to be the same as the water in order for it to mix, the detergent plays havoc with the surface tension of the water though.

 

 

Does that mean that the CD is lower when washing the screen. The Screenwash has alcohol in it so the SG isn't the same as water. Something to do with oil having hydrophibic stuff, alcohl must be hydroplillic. Detergents are both hydrophillic and hydrophobic to make an emulsion of oil and water. fooking hell where did tht come from?

Hmmmmm.....desperately trying to think back to my chemistry class for a reply to that one.......nah, you win

 

 

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Also, jet fuel is kerosene, Zed's don't like it toooo muuuch

This is true but it makes a great de-greaser.

 

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I managed to do a run this lunchtime, as I went to Tescos to get my lunch!.

 

Too much traffic around to do anything hairy but got it sideways a bit on a roundabout. Kept it in 2nd gear so the auto box wouldn't do anything strange and used about half throttle.

 

I tried to convert one of the excel charts into pdf format making it easier to post but it lost some info in the process?. So I just dumped the excel file into my rides section. If your interested in having a look then here is this lunchtimes run~

 

 

I used a value of 0.7 for the petrol by the way. My total car mass was (approx) 1637kg.