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A bit of chemistry.

on Sun Apr 01, 2018 11:04 am
This is a bit geeky so if you are easily bored stop reading now...
So I noticed that the BMW was putting a fair bit of water out of the exhaust. Especially when cold. Initial thoughts were head gasket but it was running very well and there were no other indications. Then the other day when I ran out of lpg I switched to petrol and I noticed a fair bit less water. Contaminated Lpg?
Then it dawned on me...
Water is a product of combuston. When you burn a hydrocarbon the carbons are converted to CO2 and the hydrogens to water, H2O. LPG is lighter than petrol so contains proportionally more hydrogen so when you burn it you get more water. On a cold morning and until the exhaust temp is nice and high that water will condense in the exhaust, but even when fully up to temp you will get water out. I'm not used to seering this because my focus was a diesel so has even less hydrogen compared to carbon so makes less water when you burn it. Simples.
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Re: A bit of chemistry.

on Sun Apr 01, 2018 11:17 am
Yeah that's interesting. I watched a you tube video once like that.

Anyhow you are a chemical engineer
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Re: A bit of chemistry.

on Sun Apr 01, 2018 11:48 am
Cool - loves a cold morning and a hot steamy exhaust ...

The BMW next used to be very steamy .... but the Audi is ..... Cool
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Re: A bit of chemistry.

on Sun Apr 01, 2018 1:48 pm
I’ve forgotten everything about chemistry lessons

Google seems to agree with you
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Re: A bit of chemistry.

on Sun Apr 01, 2018 3:47 pm
Ah yes, a nice steamy exhaust.

Best one I had was actually nearly a year ago no when I did that big 3 peaks walk (well, 2 of them!)

I took the Jeeaaaaaaaaaaaaaag and parked up near Ribblehead viaduct as I was a bit early. This was approx 6.45am on a crisp April morning...I got out to take a few shots as the sun rose and behind me was the gently chunter chunter of the V6 with two steady stacks rising from behind the car, with barely a flutter. Lovely morning, lovely view, lovely drive down, lovely car.
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Re: A bit of chemistry.

on Sun Apr 01, 2018 7:17 pm
Was the Jag a 3 litre?
Chatting with a lad today who has a 3 litre X Type. Gets 24mpg if driven sensibly on his normal route, drops to 16mpg in town and only manages 28 on a motorway.
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Re: A bit of chemistry.

on Sun Apr 01, 2018 7:23 pm
Yes, it was the 3.0. I was thinking I might get 20mpg average. Nope, more like 17. I thought I'd maybe crack 30 mpg on the longer journeys....erm mmmm. ..more like 28!
Very guzzly for the performance and stuff. But it was cheap and it could shift so I was happy enough.
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Re: A bit of chemistry.

on Sun Apr 01, 2018 7:45 pm
Yes
Drivem sensibly my last 330i would msnage 28 mpg on my commute, 36 mpg if I stuck to 70 mph on the motorway and about 22 mpg if driven with a heavy right foot. I'm hoping this one is similar.
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Re: A bit of chemistry.

on Sun Apr 01, 2018 9:14 pm
Yes, I gather the BMW 3.0 are decent on fuel.
My 9-5 was decent. Around 25-30 mpg average and 46mpg on a steady 60mph run.
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Re: A bit of chemistry.

on Sun Apr 01, 2018 9:17 pm
36 is decent for 70mph. The Picasso only does 46 at 70.
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Re: A bit of chemistry.

on Sun Apr 01, 2018 11:37 pm
Mrs Teeps Corrolla Verso only does 28 mpg around the doors.
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Re: A bit of chemistry.

on Mon Apr 02, 2018 8:43 am
MegaCrixel wrote:Yes,  it was the 3.0. I was thinking I might get 20mpg average. Nope, more like 17. I thought I'd maybe crack 30 mpg on the longer journeys....erm mmmm. ..more like 28!
Very guzzly for the performance and stuff. But it was cheap and it could shift so I was happy enough.


That's awful. I get 20mpg on mixed driving and my commute. On a motorway run it's 29mpg. Still awful, but 2L bigger and several horses.
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Re: A bit of chemistry.

on Mon Apr 02, 2018 9:51 am
Oh yes, it was bad! But I still luuurved the Jeeaaaaaaaaaaaaaag.
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Re: A bit of chemistry.

on Mon Apr 02, 2018 10:03 am
I'm struggling to not keep hoofing mine in 2nd all the way to the red line. Mpg is suffering...
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Re: A bit of chemistry.

on Mon Apr 02, 2018 11:54 am
Vraaaiiiiiiiiiiiiing!
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Re: A bit of chemistry.

on Mon Apr 02, 2018 8:44 pm
I cannot see the exhaust. The car thinks it's green.

Anyhoo giving it the beans up the mountain where I could see the way was clear. As there were a lot of bicycles and hikers around. I parked and switched off the engine, yeah some steam from the exhaust.. well the back. Might have been some mud on it. But definitely steam.. and no I didn't piss on it.





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Re: A bit of chemistry.

on Fri Apr 06, 2018 4:45 pm
George puts out a bit of steam on the cold days, more so when the LPG kicks in as the temp rises.

The steam condensing inside the exhaust system is how they rot, from the inside out. All those nasty chemicals eating away at the metal until one day you hear the exhaust note change and the pound notes start escaping too Crying or Very sad
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Re: A bit of chemistry.

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