High economy 3.6???

[Hosier77]

Hello peoples,
I have recently acquired a 3.6 XJ-S 'spares or repairs' car so that i can put the 3.54 diff in my V12 racer instead of the 2.88 unit, thus giving me less excuses for being last at every race!
On closer inspection the 3.6 doesnt look as bad as first assumed, and is quite usable, its tatty, front of sills corroded through, dented boot, smell of petrol, blowing exhaust and no brake pads, but fundamentaly usable with a weekends work.
The thought occured to me to put the 2.88 diff into the 3.6, thus giving it the possability of truly bizare cruising ecconomy, and of course rubish performance. I am tempted to use the car in this way for the remainder of its 4 months MOT and then sell it for spares, as a sort of experiment thingy.
Maybe if it is really good i can use it as the suport vehicle (instead of the girlfreinds fiesta diesel), maybe turn it into a pick up (boot lid rotted anyway)...
Yes i know, i should get out more....
I heard of one chap getting over 30mpg on a run from a 3.6, maybe i can squeeze nearer 40?

Ralph

[SimonR]

Hi Ralph,

This sounds like good folly! I guess it'll take you a while to get from 0-60 (the standard 3.6 manual's gears are tall enough!) but it'd be very interesting to see what kind of fuel economy you can get on a long cruise.

I'd also be interested to know what speed you're doing when it comes onto the cam at about 4500 RPM in 5th...!

I take it the 3.6 has a trip computer so you can read your results as they come in?

Do keep us updated on your progress.

[Jon]

I think 34 mpg is possible from mine on a steady motorway run (circa 60 mph) with no hold-ups.

As the engine speed is only about 2000 rpm at this speed I doubt you'd be able to get more than me to the gallon, although it would probably cruise more economically than the stock XJS at say 90 mph.

Then again, I could be wrong!

[ng4xjs]

Go for performance every time. The odd extra mpg in the scale of things never really amounts to much. My standard setup 4.0 ltr. gives a good 28 on a run driven without too much care. My wife's Euro-box driven badly is not that much better. "Grace and Pace" but with the emphasis on pace, obviously.

Nick