44 mpg

[cormorant]

I am trying to get really good fuel consumption out of Rosie - standard 1098 apart from 3.7 diff and K and N type air filter.

Used for 2 x 11 mile runs per day to work and back, and not exceeding 55mph I am now up to 44mpg on a regular basis.

Not bad, I still have a 12g940 head, large bore exhaust and separate manifolds (Marina exhaust/Oselli torquemaster inlet) to fit!

1248 tpm Mini speedo seems to be exceedingly accurate as checked with a handheld GPS. I wonder if anyone has ever got 50mpg out of one of these engines?

[MarkyB]

Don't think I have but I don't keep very good records.
What tyre pressures do you run?
Shed any excess weight, spare cylinder head, starter and dynamo etc.
If the engine uses no oil you could try slightly thinner oil.
Electric fan only comes on when needed and doesn't use engine power all the time.

[paulk]

I had a regular 46 mpg from our old 1.
Used sainsburies super unleaded fuel (only 2p a litre more) but would regularly get 6mpg better with this than normal unleaded.

I'm heading towards fitting an HIF carb myself as I'm lead to believe they had a leaner cruise cycle.

I know its tiny amounts but I wondered if changing all the bulbs to LED's might give a tiny bit of help.

Just think less electric used = less charging = less fuel used. In the winter I drive 45 mins each way to work (not always in Minor admittedly) and from October to March it's in the dark. That would equate to a far bit of electricity needed.

[Peetee]

I'm not convinced using the parts you intend to uprate with would better your consumption for the trip you do unless most of it is done at or near 55mph. With them you will loose out on low down torque and you need every bit of this in stop start traffic.

[cormorant]

Hi Peetee don't you think the mere fact of losing the "hotspot" on the dreadfully inefficient standard manifold would help the fuel consumption? And less back pressure in the exhaust system? And an little bit more compression from the head?

As for type pressures I have them all at 30psi. Might try the super unleaded and see if anything happens

[alanworland]

Twisting your wing mirrors at 90 degrees would reduce the wind resisatnce!

[cormorant]

Twisting your wing mirrors at 90 degrees would reduce the wind resisatnce!

Yes....thinking of re-routing the air intake so it blows onto the fan blade in the correct direction

[alanworland]

Apparently, when the exhausts from a Spitfire were angled to the rear it increased forward thrust by about 30lb!

[Peetee]

Hi Peetee don't you think the mere fact of losing the "hotspot" on the dreadfully inefficient standard manifold would help the fuel consumption? And less back pressure in the exhaust system? And an little bit more compression from the head?

I'm sure there would be a combination that would improve on the standard set up but just felt it necessary to suggest that bigger is not always better. As an example, on my 1275 car, I could notice the reduction in pick up at low revs after changing from a 1.5 to 1.75 carb.

[Roni]

Just for a comparison for you, I have a car with the same spec engine, but with the 4.22 diff, and am now getting regularly 40 mpg in mixed town + country (100 kph) driving. It was a bit of fun getting the correct needle. This made a difference in the power and the economy of quite a few mpg.

[mrmorrisminor]

On my totally standard 1098 I get around 40-42 mpg regularly on a mix of town and 40-40 mph roads, using standard unleaded. On a long run over the Christmas hols last year with a few folks from the board here I managed 47mpg! but that was all 40-50mph roads, no traffic and pootling behind the 948 in front.

[rayofleamington]

I wonder if anyone has ever got 50mpg out of one of these engines?

The best I managed out of the pick up with 3.7 diff was 47mpg at this level it was so lean it missfired. The 1098 is very worn but still going well.

The 12G940 and bigger exhaust + split manifolds should help economy, however the bigger carb may do the opposite. With a good breathing engine and a 1.25" carb you'll have good torque, and can make more benefit from lower revs, allowing better mpg.
A bigger carb will allow more accelleration and higher revs - both of these reduce mpg.

I've never done any testing to proove that set up on a Minor, but it follows proven logic.

[cormorant]

Yes I'm planning to keep the smaller carb at first with the other mods as I noticed from David Vizards book that a bigger carb isn't always necessary and as this car never really revs beyond 3500/4000 rpm and the cam is standard there may be no point using the HS4 I have.
47 is impressive though I guess it was running too lean Ray.
I will try super unleaded on the next fill and report back!

[tingo]

My manual gives best performace data for a standard 1098 as:
60 mph -> 35.7 mpg
50 mph -> 41.4 mpg
40 mph -> 48.5 mpg
30 mph -> 56.4 mpg

I admit I don't believe everything that salesmen tell me , but maybe you could up your mpg if you cruise below 55mph.

[bmcecosse]

If you want economy - best stick to what you have - you don't need larger valves etc. Look out for an 848 engine, but even a 948 would give some benefit. Best would be to increase the compression ratio of your engine - by skimming the head. As others have said - shed all excess weight (passenger seats/trim etc) - may be worth changing all the glass (except windscreen) for plastic ?

[MarkyB]

Driving style can make a major difference too.
Read the road ahead so you are not accelerating or cruising up to a red light or a traffic jam.
If you can keep the car rolling it helps too because you have momentum rather than inertia.

It amazes me how many people will accelerate hard, then brake hard, even in long queues of traffic.
Their not getting anywhere, but I guess they are going fast so must arrive quicker.

[cormorant]

How much can you safely take off a standard 12g202 head Roy?

Don't think I am quite ready to run around in a car with a totally stripped out interior just to save a bit of fuel..........but quite interested in trying a few different things as an experiment. Actually 44mpg seems pretty good compared to any other vehicle from the sixties and not bad now really. Wouldn't really want a smaller engine, so will do my best with the 1098

[bmcecosse]

Should be ok with 80 thou off - I had one at 120 thou off, but the surface could be seen to move with finger pressure!

[cormorant]

Should be ok with 80 thou off - I had one at 120 thou off, but the surface could be seen to move with finger pressure!

What comp ratio do you get with 80 thou?

p.s. don't like the sound of 120!!!

[bmcecosse]

Hopefully ~ 10 :1. You may need to use premium fuel - but many argue that gives better mpg enyway - enough to justify it's extra cost!