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[cem_devecioglu]

Did a little test on last tank of LPG, set cruise bang on 65mph instead of the usual 80, over the course of 300 miles? Got almost exactly same mpg as i usually do, and pence per mile was 10.5 instead of 10.6.

Glad there is no saving as i was bored doing 65, and it was taking ages to get places 

Back to usual cruise speeds  8-)

Tunnie , honestly I dont think this calculation reflects correct values.. 

the force you must spend increases  proportional with your speed squared in a fluid , called drag..

check drag at high velocity..

http://en.wikipedia.org/wiki/Drag_(physics)


 I guess some extra factors that Kevin mentioned mislead you..

Drag is the major factor when cruising at motorway speed but I think the Omega is geared to hold the engine at the most efficient RPM when doing 80+ mph.

I do seem to get better MPG if I let the speed drift up in to that range....

there are also other factors that can effect mpg..that I didnt mention..

air lift which can drop the friction coefficient between the tires and road..

but increasing revs at a fixed gear wont help imo as
you need more fuel at a fix time slice and energy losses on the engine increase with increasing temperature proportional to revs increase which also at high speeds wont be negligible..


 

[Kevin Wood]

but increasing revs at a fixed gear wont help imo as
you need more fuel at a fix time slice and energy losses on the engine increase with increasing temperature proportional to revs increase which also at high speeds wont be negligible..

The 4 pots have all the torque high up in the rev range to squeeze the power out and a fixed induction system unlike the V6s multirams so it's possible that they are more efficient at higher revs where they're "on cam".

I find the Westfield the same. You might just as well go for it on a motorway run because MPG doesn't start to drop until plenty over the speed limit. Comes on cam at about 3500 RPM / 80 in 5th.

Kevin

[cem_devecioglu]

but increasing revs at a fixed gear wont help imo as
you need more fuel at a fix time slice and energy losses on the engine increase with increasing temperature proportional to revs increase which also at high speeds wont be negligible..

The 4 pots have all the torque high up in the rev range to squeeze the power out and a fixed induction system unlike the V6s multirams so it's possible that they are more efficient at higher revs where they're "on cam".

I find the Westfield the same. You might just as well go for it on a motorway run because MPG doesn't start to drop until plenty over the speed limit. Comes on cam at about 3500 RPM / 80 in 5th.

Kevin

imo for a real measurement road traffic, distance, geograpy  , wind and gear changes through the travel must all be fix which is really really hard to apply ..

And Westfield's profile is so different than a miggy as  the drag is really minimized :-/

[Kevin Wood]

And Westfield's profile is so different than a miggy as  the drag is really minimized :-/

On the Omega, it is. A Westfield has the aerodynamic properties of a small post office once you get close to 3 figure speeds.

The Omega's Cd is around 0.30 IIRC. Westfield? More like 0.70, so I'm told.

Kevin

[Mr Skrunts]

And Westfield's profile is so different than a miggy as  the drag is really minimized :-/

On the Omega, it is. A Westfield has the aerodynamic properties of a small post office once you get close to 3 figure speeds.

The Omega's Cd is around 0.30 IIRC. Westfield? More like 0.70, so I'm told.

Kevin

Pretty good on the Miggy


Body

Aerodynamic drag co-efficients:

Saloon - Cd 0.29

Estate - Cd 0.32

[cem_devecioglu]

And Westfield's profile is so different than a miggy as  the drag is really minimized :-/

On the Omega, it is. A Westfield has the aerodynamic properties of a small post office once you get close to 3 figure speeds.

The Omega's Cd is around 0.30 IIRC. Westfield? More like 0.70, so I'm told.

Kevin

  whaaat ..

I'm shocked.. :-?

[Kevin Wood]

whaaat ..

I'm shocked.. :-?

That's what happens when the wheels, suspension, exhaust, occupants are exposed rather than covered in bodywork.

Improves a lot if you remove the windscreen but not a very wife-friendly modification.

The frontal area is a lot smaller than an Omega's, so it's not as bad as it may seem, but they do hit a brick wall at 3 figure speeds. I reckon to match the top speed of a V6 Omega you'd need over 300 BHP.

Acceleration from rest is a different matter, of course.

Kevin