39 replies to this topic

[solihullian]

What tyre size are you running, a 286 would in most cases be fine with either, excpept that your motorway journeys would be a painful experience.

the tyres are 165/60/12, the car will be used on motorways but only on occasions to travel to shows and the car is not my daily driver so i'm sort of edging towards the 3.6 diff now.

[Vipernoir]

An MPi will pull a 2.7fd happily (though not hill-starting laden on the Stelvio Pass) but an MPi doesn't have an enormous first gear - it has a standard first gear.

[MRA]

Yes but it also only has about 50lbf ft of torque.

The OP has 90, so would easily pull a 3.1

Is the Stelvio Pass anywhere near Swindon ?

Edited by mra-minis.co.uk, 07 March 2013 - 11:27 PM.

[solihullian]

i think the best thing to do is to maybe try it with the 3.1 first then if its too tall in 1st gear then swap it over to the 3.6, there are mixed opinions from all parties but i might go with what MRA says to start with and see how it goes, i think that my engine should be able to cope with a tall 1st gear and the car is only used very occasionally so it should be ok.............i think

[Cooperman]

It's not how much torque it has, but where in the rev range the torque happens. If peak torque is at, say, 4200 rpm and 1st gear is mega-high, you could find that the clutch has to be slipped until you are doing 15+ mph.
With a 544 cam, a SCCR box and a 3.44 FDR the acceleration was very poor and the car would have been quicker through the gears and especially off the line with a standard engine and gearbox.
Over-gearing with a 'hot' cam is poor in terms of overall performance. If high gearing is wanted for M'way cruising, then a 266/MG Metro cam is what is needed with standard gear ratios and a 3.1 FDR.
Without the right overall gearing to suit the cam, then the performance will not be as good as it could be. A 286 cam is for acceleration and high (i.e. up to 6800 rpm) revs. Otherwise it's the wrong cam for the job intended.

[MRA]

I agree that a 296 would be a little cammy to get off the line but a correctly set up 286 would not have any issues getting off the line,

Kent states a 286 is good ffrom 2000 up to 7500

I have run loads of 1275 with 286 cams since the 80's and I mostly used 3.44:1 and 3.1:1, never had any problems getting off the line, the things would wheel spin through first if provoked, but gentle driving they are good off the start and less gear changes, and much much better off the line in the wet..

[Cooperman]

I can only tell you what mine have been like with 286 and 544 cams.
The 286 will only pull cleanly when hot from about 2800 to 3000 rpm unless the throttle is 'feathered', which rather ruins the object of having a 'hot' cam, i.e. to improve performance including acceleration.
It the throttle has to be 'slipped' to keep the engine at 3000 rpm or above when accelerating from rest, then a car with a softer cam will be faster. That's why a low diff is necessary to compensate for a high 1st gear.
Still, everyone to their own and if a 'hot' cam with unmatched gearing is wanted, then that's fine. Yes, of course it will drive, the question is only how well it uses the capability of the cam.
The 286 is a 'full-on' competition rally cam and needs to be revved to get best performance. My car pulls to 7000 rpm which is about 100 mph in 4th gear. That's what this cam is for. I don't want to be slipping the clutch up to 20 mph, so I run a 3.9:1 FDR and that works very well.

[MRA]

One of my customers against my advice fitted a 3.9:1 in his Moke, he said it felf fast to 60, but the wheel spin was terrible, very hard to control, it was all gear changes and on the motorway anything above 60mph and you needed ear protection., he has since sold the engine as its jsut not feasable any more.... this is not a one off either.

We already know that that a reasonable Mini can pull a 2.76:1 FD, yours has more power and torque, yes the torque is a little higher up the rev range but really it won't give you any issues other than occasionally requiring a down change to accelerate off.

998 Minis where fitted with 2.95:1 FD and they had a good turn of speed.... nothing close to what you will have though

Ive even got a 3.1:1 in my 6 speed....

Edited by mra-minis.co.uk, 08 March 2013 - 12:19 AM.

[mini*mad]

I had a 998 mini city e which came with a 2.9 diff
Had a stage one tune (pretty much airfilter and exhaust) and pulled off the line ok
Not massively quick but cruised nicely

Infact here is an incar video from a couple of years back


If that can do it shouldn't be a massive problem

Depends what you want from it, top speed or acceleration
The E stood for economical as its better on fuel

With your power I think 3.1 would be the best of both worlds!

Edited by mini*mad, 08 March 2013 - 12:38 AM.

[solihullian]

Thanks for the input guys, it is appreciated, I've had the engine for a while now and I did used to drive it quickly, I understand coopermans point about the 286, what if I were to downgrade slightly to a 276 with the 3.1? Do you think that it would be more driveable? Or a Newman/morspeed PH3 cam as I have used one of those before and the torque was brilliant, it wasn't at all cammy, maybe that's the way to go as I really don't drive the engine as quickly as I used to but I still want a decent-ish turn of speed.

[solihullian]

IMHO you should if you've not already got the box, use a cooper S/GT A series gearbox (just about perfect for the road) and a 3.6 final drive with the 286. This is a excellent combination for a road car........That would save you a **** load of cash.......

Have you seen the prices that people are asking for 1275gt gearboxes? If I could find one then I would get one, some people are asking over £200 for GT boxes and then there is no guarantee that it's not going to need a rebuild.

[Cooperman]

I can never understand why folk fit a 286 cam and are then reluctant to really rev the engine. To make a 286 worthwhile you will be revving to 6700 rpm in the gears so as to be just after peak power at change-up time. Peak power with a 286 is 6400 rpm.
It is not a motorway or general road driving cam, that is for a 266 or similar. A 286 needs REVS and lots of them to work well. Keep over 5000 rpm when wanting to go quickly, and over about 4000 all the time when driving. For that a low final drive is needed with a close ratio gearbox to ensure that when you change up at 6700 rpm you are still right 'on the cam' in the next gear.

[Old Bob]

Yes but it also only has about 50lbf ft of torque.

The OP has 90, so would easily pull a 3.1

Is the Stelvio Pass anywhere near Swindon ?

If only

Bob

[Cooperman]

In my 1310 cc 1964 Cooper 'S' which has a 286 I regularly rev to 7000 rpm and cruise at around 5000 rpm.
When hot it can 'fluff' at below 3000 rpm and won't pull well until it gets over about 4500 rpm.
That is what a 286 is for - top end power for rallying.
An engine with a 286 needs a centre main bearing strap, a fully balance bottom end, rods & pistons and very good induction and exhaust systems. Plus, of course, a low final drive no higher than 3.44:1.
Others may disagree, but take a look at the power and torque graphs for the 286 on Kent Cams web-site.

[solihullian]

I can never understand why folk fit a 286 cam and are then reluctant to really rev the engine. To make a 286 worthwhile you will be revving to 6700 rpm

Sorry cooperman I can't not comment on this anymore, even in the standard MG Metro engine a 286 will pull to 7500rpms very easily......

solihullian you do realise what running a SCSR gearbox and a 2.7 final drive means ? At the nation speed limit of 60mph (A roads), the 286 not even be in the power band. It will not pull anywhere near it's maximum rpms in top gear. In fact you'll be lucky to see
5000rpms in top........ It'll be effectively a 3 speed box with overdrive..........

who's using a 2.7 diff?