MPG

[John Larkin]

After years of MPG figures in the very low twenties in my S3SE FHC on Webers, probably due to mainly urban driving, I am pleased that I achieved 30.6 MPG on a 2300 mile jaunt recently. Is this a typical figure for a long fast drive?

John Larkin

[robcall]

Don't you run a 5-speed John?
thats cheating

[John Larkin]

Hi Nigel,

Good to hear from you. How's the Sprint?

Yes I do have a Sierra five speed in the Elan, but I had actually forgotten the significance of that. Not (morally) cheating then!?

My trip was to the Stelvio Pass and back. I'm glad I finally did it --- wanted to for years.

John Larkin.

[mac5777]

Hi John,
With a 5 speed on a FAST drive sounds right. I once tried for the best MPG in my SE3 coupe with 145x80x13, a 3:55 rear-end and a semi close trans and got 34.5 MPG. But that was the most borrowing 200 mile drive ever and was very hard not to play with the webers. Its the FAST part that is holding your MPG down.

Sarto

[Galwaylotus]

When I drove my (newly purchased) 145 bhp S3 SE Coup? home from the far side of merry olde ..., I got over 30 mpg on a reasonably fast run. I had to make the ferry so I wasn't hanging about but wasn't the fastest vehicle on the motorway either! Since then I've had cutting-out problems and haven't done any driving.

[kstrutt11]

I've seen as High as 36MPG (UK) on my +2 with a Sierra 5 speed on my drive to work which is a mixture of urbun roads and country roads. As you can hapily use 5th gear right down to 40mpg this seems to make a significant difference.

Kevin

[ElliottN]

My (4.5 year) lifetime average is 26.8 mpg - S4dhc, 1700cc, 4-speed, 3.9 diff. I regularly get 30 mpg on longer freeway/open road trips, but 31 is the best I've ever hit.

[Frank Howard]

John,

My Stromberg car with standard 4 speed and 3.77 differential recently averaged 38 mpg on the highway sections of a 600 mile moderately paced trip to Winnipeg and back. To tell you the truth, I was a bit disappointed. I thought it should have done better.

[billwill]

USA gallons are different size than UK gallons.

Is the mile the same length?

[John Larkin]

The USA and the UK are two nations separated not only by a common language, but also by a shared definition of the mile. Ireland and Scotland, being Celts, used to be diifferent...

Thanks to Wikpedia for this information:-

Various English-speaking countries maintained independent length standards for the yard, which differed by small but measurable amounts, and thus led to miles of slightly different lengths. This was resolved in 1959 with the definition of the current international mile by Australia, Canada, New Zealand, South Africa, the United Kingdom, and the United States. The international mile (and before 1959, the statute mile) is the distance typically meant when the word mile is used without other qualifying words (e.g. nautical mile). The international and statute miles are both equal to 5,280 feet, but the international mile is defined in terms of the international foot (0.3048 m), while the statute miles of the various English-speaking countries were based on the national foot of each country. The (mostly obsolete) U.S. statute mile is based on the U.S. survey foot and differs from the international mile by about 3 mm.

The name statute mile originates from a statute of the Parliament of England in 1592 during the reign of Elizabeth I. This defined the statute mile as 5,280 ft or 1,760 yards; or 63,360 inches. Before the statute of the English parliament the Irish mile was 6,721 feet and the Scottish mile was 5,951 feet.

John Larkin.

[Galwaylotus]

Thanks for the information, John. I think the answer to the question, as it relates to our beloved Elans is that there is no difference in the UK and US miles! MPG, however, is different by an approximate 5:6 ratio, the US gallon being 3.785 litres and the Imperial gallon 4.546 litres each rounded to three decimal places.

[bill308]

Great info guys. For those of you with Type-9 conversions, how did the change affect your results?

I've a Voights conversion sitting in my basement and I'm getting ready to order up a set of BGH gears to try to improve the ratios.

The gear set of choice, at least in my mind is:

1 2.66
2 1.75
3 1.26
4 1.00
5 0.82

This gearset is a little shorter than the close ratio gear box thru the first 3-gears, but has an 0.82 overdrive 5th. I'd pair this up with my 2.55 axle .

Bill

[RotoFlexible]

I just calculated the mileages for the first 2,200 miles on the rebuilt and upgraded engine. We increased displacement to 1700cc, compression to 10.5:1, ported, "fast road" type cams, and a header. It makes about 145 hp on the dyno.

The average over 2,230 miles is 29.64 mpg (US gallons). The best tank was 33.5 mpg, mostly on the highway at 4000+ rpm. (Think what it would do with a 5-speed!) The worst tank was 26.47 mpg, the first tank after the rebuild, and each tank after that was better than the last for the first four tanks - about 1,000 miles (plus dyno time) for break in.

I'll probably be making a change to a slightly richer slow-running jet to cure a slight low-power roughness. It will be interesting to see what that does to the average.

I didn't keep detailed records before the rebuild, but I recall getting about 26 mpg when I did check. More power and lower consumption - life is good!

[bill308]

Correction to my above post. The axle ratio to be used is a 3.55, not a 2.55.

Bill

[Galwaylotus]

"Correction to my above post. The axle ratio to be used is a 3.55, not a 2.55."

Hmmm. Just thing what your fuel economy might be with a 2.55:1!!!