25 replies to this topic

[Archived3]

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Edited by Mrplastic, 17 March 2019 - 10:27 AM.

[Ethel]

Fuel economy is chiefly down to how much work there is accelerating the car and pushing the air out of the way when cruising. Minis score well by being both light and small. The engine itself matters less (within reason), but taller gearing, a higher compression ratio and a cam that doesn't allow intake charge to pass straight  in to the exhaust with excess valve overlap and closes the inlet earlier to make best use of the compression stroke all help.

 

Mpi's may well do best having the longest diff at 2.7:1, no power sapping mechanical fan, and the most sophisticated fuelling. Another good call would be the A+ 998 E spec that was sat on a 2.95:1 final drive when in a Mini.

 

Pump yer tyres up and make sure your brakes aren't dragging.

[surfblue]

 

803cc? I thought the lowest was 850? Please tell me more

 

The 803cc engine was the start in 1951 of the A series as we know it.  It was fitted to the Austin A30 and replaced the side valve engine in the Morris Minor.

 

The stroke was the same as the 948 Minor/ A40 and the 998 cooper, but the bore was a tiny 58MM.  The engine got the nick-name  "The Mighty Atom", when supercharged and running on Aviation fuel.

 

The "General Post Office" quickly ordered the van version in considerable numbers, and because its engine was so well suited for their needs, continued to order the 803 engine when the 948 was introduced.

 

When the A30 van was discontinued, the GPO bought the Minor van, but still ordered the 803 engine,  and presumably were such good customers that BMC built them a special engine to sit on a Mini gear box.

 

The RAF also had some 803 saloons that were adapted for invalid hand control.

 

I knew the Minor had the 803, never heard of one fitted to a Mini. Wonder are there any survivors?

[absx2]

My mk3 fitted with a bog standard Metro city E 998 with the 2.9:1 diff did bang on 50 mpg from deep Cornwall to Castle Combe and back 450 miles. I kept it at around 75 mph which strangely was 75 mph on the sat nav with the occasional 80 or so for a run up to the hills. 

38 mpg commuting last time I checked. The diff ratio is hideous around town though.

 

My Rover cooper carb with just shy of 90 bhp manages 22 mpg but spends most of the time between 4000-6000 rpm which is about the same as quoted for a cooper S back in the day. My wife could get 42 mpg out of it on a 38 mile round trip to work and back when i used to let her drive it so a lot of it is down to how heavy your right foot is.

[rich_959]

Must be something along the lines of an injection engine with a long legged final drive, as per MPI mini's?

 

Ah, I see Ethel beat me to it. 

 

Back in the day when I had my MPI Sport LE, I used to get terrible mpg (honing around country lanes like an 18 year old does) but on motorway trips I used to get well over 30mpg, which I thought was ok. Could just do with twin tank to help the range. I haven't had enough miles in my current MPI to assess the MPG before taking it off the road. 

[Cooperman]

pg I can get my Mk.1 Cooper 'S' rally car down to around 12 mpg in the Welsh  lanes and as low as 10 mpg on twisty special stages!

[DeadSquare]

pg I can get my Mk.1 Cooper 'S' rally car down to around 12 mpg in the Welsh  lanes and as low as 10 mpg on twisty special stages!

 

I used to strap 2 jerry cans of petrol in the back of my pick-up when I mopped up stragglers, because fuel capacity used to be only about 5 gallons, and on HMC  OS 147/148 rallys, there were invariably a couple of dry tanks.

[Cooperman]

 

pg I can get my Mk.1 Cooper 'S' rally car down to around 12 mpg in the Welsh  lanes and as low as 10 mpg on twisty special stages!

 

I used to strap 2 jerry cans of petrol in the back of my pick-up when I mopped up stragglers, because fuel capacity used to be only about 5 gallons, and on HMC  OS 147/148 rallys, there were invariably a couple of dry tanks.

 

On my first Cooper, a 1964 998, with 5.5 gallon tank it was a bit difficult to do a 120 mile first or second half of a rally in Wales. I used to carry a gallon in the boot in a can. The early 'S' also only had a 5.5 gall tank, unless a second tank was bought and fitted. It was not until 1966 that twin tanks were standard on the 'S', but I'm sure you also remember that.

 

Living on the edge of Wales you will have a lot of experience of high petrol consumption on your more local rallies. 

 

I used to navigate an ex-works Datsun 240Z on MN rallies with one Mr.Videan and it did around 6 to 8 mpg when hurrying. I'm glad i was not paying for the petrol!

[DeadSquare]

@Cooperman   On rallys as I hoofed it out of a corner, I too often felt that I hadn't really taken it as fast as I could've, but with circuit racing practice it was more satisfying because I could be a bit more daring each lap until I lost it and found the limit.

[humph]

Since 2010 my spi Sidewalk has averaged 37.15mpg. It'll sit at 70-80 all day if you can stand the racket inside. Car has a stage 1 kit with k&n inside the original box & lcb. Oh and it's on 10s rather than the standard 12s.

Edited by humph, 27 November 2018 - 05:09 PM.

[Bobbins]

My '98 JDM Cooper (SPi/MPi mongrel) has averaged 45.4 mpg over the last 2,500 miles - mixed motorway / fast A-road / country lanes, I really can't complain considering most of my miles are using the air-con as well, it's good for keeping the glass from misting up as well as keeping cool in the summer.

 

I use an app called Fuelly which is very easy to keep tabs on the economy, although I don't drive it to be particularly economical