Specifications

Ive just been idly browsing the mine of information at the top of the forum and have found some amazing figures:

5th gear = 41 x 31= 0.76 - 26.48 mph per 1000 rpm
(so 3000 rpm should = 79.5 mph)

Fuel consumption @75 mph constant= 34.9 mpg (8.1 Its)

My car in all in all its loveliness does a road angel indicated 69 mph @3000 rpm and even with the bigger 17" wheels at the rear the best I've worked out on my weekly trips to Cardif is 28.6 mpg (although obviously not constant i do fill up on the dual carriageway and fill up before London's traffic, ah the fear of no fuel gauge!)

Any thoughts?

The car runs a standard setup but with a devil exhaust and has been rebuilt/regularly serviced the last being 2000 miles ago where it had new plugs/oil/gearbox oil/filters/tune up.

My turbo comp reads 32 average on a good long motorway run but that may well be

Mine reads c25mpg but as i don't have a fuel sender that works and the fact that the speedo under reads due to the wheels being larger ive resorted to doing some maths. Is there any obvious reason why this is happening?

yeh, my computer reads about 33 for a gentle 70 cruise, no overtaking though. Sat nav also reports an accurate speed on 17inch rims too, again about 1mph off. As for measuring it accurately.... ..... .... hell no, just pour it in and fly away.

My Atmo does about 7mpg.................i think there for i am?

the best i have seen is 36mpg

CO pot might be out of adjustment. This controls idle fueling and part throttle/overrun

Or it could be simply a setup issue with the engine...

Maybe you have a different ratio gearbox for some reason??

I take your point having just done the maths if i had an atmo gearbox instead it would do 73mph@3000rpm

drove down from Scotland to Devon recently in the turbo on the motorway at about 75-80 the whole way did a comfortabe 35 mpg. Also does 80 at about 3100rpm

i'd agree with rupert here, even on the quick trip to the old man's, 30 minutes on mixed roads, i can get a good 35mpg...always guestimated 3000 in 5th as being about 70.....

one point though, i'm after a gsp based speedo cos mines ropey, but are they not that accurate as civilian gsp applications are always callibrated a bit out for some political reson that i wont bore you with


(yes i'm on the wine again!)

35mpg on mixed roads!

Are you sure that's not downhill all the way with the engine off?!

coasting on the over run...... I got 99.9mpg.

Get up to 70, take foot off right peddle, maybe engage clutch too, reset computer, coast 400m and there you have it.