10 replies to this topic

[Luke.c123]

Hi there I'm building an engine for my mini, current spec that I'm planning to build to is:

Bored to 1310
Kent 276 cam or similar
Stage 2/3 head
I'm also running on 10" wheels on 165/70 tyres

I use the car everyday for work so I don't want to be revving it like a nutter. But then again I want decent acceleration with an alright crushing speed.
I've done a lot of reading up and have looked a lot into 3:1:1 , 3:2:1 , 3:44:1 and would just like to know of people's suggestions and experiences.

Thanks
Luke

[Cooperman]

If you have standard gear ratios a 3.44 would give excellent acceleration with a cruising speed of approx. 16.5 mph/1000 rpm in top gear. So 4000 rpm, which is 'on the cam' with a 276, would be 66 mph. Remember, a 276 will give maximum power at 6100 rpm, so you are going to be revving it if you intend to use the cam you ae fitting.

If you don't want to be using over 6000 rpm in order to make it go at its best, then a 266 cam might be better. I built a 1275 with a 266 cam and with only very slight other modifications, but a very careful and accurate build, it gave 84 bhp at 5700 rpm and used a 3.44;1 FDR.

It drove very well and was surprisingly quick for a Mini.

[carbon]

If you do much motorway or longer distance driving you will find the 3.1 more relaxed. I've got this with a 266 in 1293 motor on 10 inch wheels and its is a good match.

 

As Cooperman says the 3.44 may be a better bet for a 276 if you're looking to get the most out of it.

[Luke.c123]

Okay cheers guys, much appreciated

[Cooperman]

Yes, a 266 cam and a 3.1:1 FDR would be better for a daily driven car doing main road work and can be made to work very well.

A 276 really does need to rev to over 6000 for best performance and unless you are revving to over 6000 a lot of the time a 276 is 'over-camming' for the use of the car.

for good performance for everyday driving the torque curve is more important than peak power, and a 266 is one of the most ideal cams for everyday driving and good power with no need to rev much over 5800 rpm to get good top-end performance.

Edited by Cooperman, 30 June 2014 - 10:11 PM.

[Luke.c123]

Okay thanks Cooperman, much appreciated

[Mini Manannán]

I wouldn't bore it straight to 1310 either Luke, not a lot of gain for a loss of rebores.  Unless you're on a knackered 1293 already of course

[Luke.c123]

well i do have bore damage.

 

ive got the engine stripped completly at the moment, and the 2nd bore had a fair ammount of runst in. i was told it was a low milage engine... around 30K and everything as far as the other bores and crank shells does show this.

 

the bore is also pitted so i want to ensure that it is all cleared up when i am done.

[Luke.c123]

ohh and it is a completly standard 1275 metro engine 

[Cooperman]

ohh and it is a completly standard 1275 metro engine 

 

I would advise a Kent 266 cam, a nicely gas-flowed head, a compression ratio of around 10.2:1, an HIF44 carb and a slightly lightened flywheel.

 

Then run a 3.2:1 FDR for good cruising. The peak power will be at 5700 rpm with best torque at around 4000 rpm and a fairly flat torque curve.

 

IMHO too many owners are concerned with high-revving cams which give a lot of power at over 6000 rpm, when in fact they want to drive them at between 3000 and 5000 rpm for the majority of the time and don't want to be having to re-build the engine on a regular basis due to the continual use of high revs.

 

The SW5 is another cam you might want to consider, although I've never worked with one they have a reputation for good mid-range torque characteristics.

[Luke.c123]

Okay thanks guys, this really helps :)