23 replies to this topic

[andrewinlondon]

Hi,

Is it common for everyone with standard Mini Coopers ('97, P reg) with no engine mods (and only an RC40 exhaust and K&N air filter) to average 90mph on the motorways?

I'm generally sitting at 4,000 revs at 90mph, and about 4,300 at the ton.

Can the engine cope with this sort of constant revs and speed etc? Does this cause undue oil heating etc that might lead to longer term damage?

Can the rest of the car cope with this speed, namely, the breaks and suspension, if one has to break suddenly etc?

Cheers,

[Dan]

Is it common for everyone with standard Mini Coopers ('97, P reg) with no engine mods (and only an RC40 exhaust and K&N air filter) to average 90mph on the motorways

No, because that would be illegal!

Twinpoint Mini's were designed to do motorway miles mainly, that's why they have the ridiculous diff.
The published maximum speed for the twinpoint is 90mph and you should be seeing about 4300rpm at this speed, with 70mph being about 3700rpm. Your speedo is probably a little out (not uncommon) as you can't change the relationship between engine speed and road speed in any one gear without swapping the gearbox or FD (or wheels, so these figures will be slightly different for a sportspack). The new air filter wil have quite an effect on the car as the injection engine automatically re-fuels itself to cope with the extra airflow. Essentially it is kind of like fitting a stage 1 kit to a carb'd mini.
You could fit an oil cooler if you like as long as it is a thermostatic setup. The twin point injection computer monitors the oil temperature as one of its parameters so it would log any faults, ask the dealer at service time if there's anything recorded in the fault log. If you fit a cooler which is not thermostatic the engine sometimes won't run at maximum performance as the computer won't let it 'till the oil has warmed up properly.
A Series engines love revs (although the small bore is better than the big block), have you been to any Mini racing? That's a lot more tough on an engine!

[Madmax]

wish i could do 90 on motorway crusing, would that be a 2.9 diff ratio??

mines at 5/6k rpm at 90-100mph

[Prawn]

mine seems happy to sti at 90mph (5000rpm with a 3.44 diff and 12'' wheels) as long as i want, and its actually more comfortable than it is at 70, the engine pitch is higher, and somehow less noisey, and it generally seems more comfortable at 90ish, having said that, it does drink the fuel at that kinda speed, and keeping that speed up will leave u with cold brakes, so i dont know what would happen if u ever had to stop very suddenly, as i know my greenstuff pads on grooved discs dont work properly until tehy have warmed up....
in am mpi i dont see 90 being much of a problem at all

EDIT: im also fairly sure that MPI's had a rather stupid 2.75 diff, which is just silly!
2.9 is tall enough, but 2.75 just seems mad
anyway.... im pretty sure all mpi's were 2.75.... correct me if im wrong

[Dan]

Close but no cigar, it's 2.76.

[dklawson]

I've had my car in a very short burst up over 80 mph... and it was a white-knuckle experience. 90 mph??? You guys with new cars have different animals than mine. On 10" wheels with a 3.44 final drive I turn 4000 going 65 mph. I would be running a constant 6000 RPM to go 90 mph!

[Jordie]

had my 988 at 85 constant for over 10miles.

Its a 988, hs4 1.5",piperX cone filter,rc40 exhaust s/s single box with straight thru, lucas sports coil + ignition parts.

Was coming home from white rose centre down m62 with my g/f in fast lane. Car was shakking like mad.

[AlexF2003]

The engine will be fine but the gearbox can and does suffer as most MPi owners know!!!

Oil temp unless it goes over 120-130 is not a problem usually.

Alex

[Alex1380]

im on a metro turbo 4pin diff (no idea what ratio) but mine sits at 110mph all day long doing about 5500-6000rpm its loud but sits there, i want a 5 speed gear box and a supercharger errrrrrmmmm.
droool
Alex.

[TimS]

i manage around a ton at 6750rpm

[Madmax]

i might just be looking like a bit of an idiot here, but im assuming the gearbox (engine too) has to be removed to change the final drive

as its the crownwheel and pinion that must be changed?

havent looked at any tech manuals yet

[Dan]

There are mechanics who claim they can do it with the lump in the car, but I think they are strange mythological beasts with small hyper flexible hands and fingers and tools fashioned by the gods.
Once you have the lump out of the car you can change it fairly easily without splitting the engine and gearbox if you want to though.

[TimS]

yeh, you could un bolt the diff from the engine in the car but then theres the pinion too

[Madmax]

tempted, vvvvveeeery tempted

i would love to cruise at motorway speeds without needing new ears every 3 miles

[Dan]

If you're considering the 2.76 bear in mind it severely restricts acceleration. You notice it on the twinpoint even though the ECU has some pretty advanced load compensation routines, on a carb'd car with distributor based ignition you will really feel slow.
There's lots of options available for the FD though, check the parts books to find a good compromise and remember to change the speedo drive gears as well.