42 replies to this topic

[Spider]

 

 

What FDR would you get on a 1275 with a 286 cam? 3.4? 3.7?

 
3.4 if you do some motorway cruising or a 3.6 if you don't.
 
From my own experience, Helical Gears are consistantly reliable to about 125 Flywheel HPs, though Matt Read recons about 170 HPs. I'm not as optimistic as Matt!  Just make sure the gear case is not cracked and one that's in spec!

The gearbox will take a lot of power but the killer is sudden loading such as flying starts or quick changes under power, that will be when the box gives up. I may be wrong but what point is there in going for these HP figures unless they can be reliably used in anger? If you are considering this route for goodness sake get the box crack tested first and join the AA.

 

 

Yes, that is spot on and good info.

 

Having 125+ Ponies on tap is one thing.

 

How they are used is quite another.

[timmy850]

Hi, I´m considering to upgrade my 1275 Cooper to 1380 but I have a low budget. Can I just change Pistons, bearings and pump ?

You should really only go up one bore size when rebuilding your engine. The next one up is 1293cc. 

 

If you go straight to 1380 you've got no more rebore sizes unless you get the block sleeved. There is no significant increase in power in overboring your engine anyway, you're better off doing a well planned build with the right head, cam etc.

[Colbster]

 

Hi, I´m considering to upgrade my 1275 Cooper to 1380 but I have a low budget. Can I just change Pistons, bearings and pump ?

You should really only go up one bore size when rebuilding your engine. The next one up is 1293cc. 

 

If you go straight to 1380 you've got no more rebore sizes unless you get the block sleeved. There is no significant increase in power in overboring your engine anyway, you're better off doing a well planned build with the right head, cam etc.

 

 

This ^^^^^^  +1

[MJWarren]

Hi, I´m considering to upgrade my 1275 Cooper to 1380 but I have a low budget. Can I just change Pistons, bearings and pump ?

You should really only go up one bore size when rebuilding your engine. The next one up is 1293cc. 
 
If you go straight to 1380 you've got no more rebore sizes unless you get the block sleeved. There is no significant increase in power in overboring your engine anyway, you're better off doing a well planned build with the right head, cam etc.

That's just opinion, there are no 'rules' as to how or when you can rebore your engine or to what cc

And there will be a increase in power by going to 1380.

[CPC]

I have a 1380 that's 80bhp at the wheels (around 96/98bhp at the fly) with a swiftune sw10 cam ( similar to a 286 cam im told)  and its also fitted with a 3.1 final drive, i bought it like this but if i had the choice id go for a 3.4 final drive.

 

With my car it's like a 3 speed with 4th as a overdrive/crusing gear, if i rev to to 7000rpm in 3rd thats just over a indicated 90mph with if you change into 4th it does not really go any faster as it drops of cam.. I dont drive like this on the road so not a major issue and the change from 1st to 2nd is okay with a bit of a drop between 2nd (60ish at 7000rpm) and 3rd.

 

I'm looking into changing my final drive rather than tuning the engine further

Edited by CPC, 17 April 2015 - 10:30 AM.

[Dusky]

Hi, I´m considering to upgrade my 1275 Cooper to 1380 but I have a low budget. Can I just change Pistons, bearings and pump ?

You should really only go up one bore size when rebuilding your engine. The next one up is 1293cc. 
 
If you go straight to 1380 you've got no more rebore sizes unless you get the block sleeved. There is no significant increase in power in overboring your engine anyway, you're better off doing a well planned build with the right head, cam etc.

That's just opinion, there are no 'rules' as to how or when you can rebore your engine or to what cc

And there will be a increase in power by going to 1380.

Actually thats not really true. As the piston friction and weight incrase too for a very small cc gain. It will also intruduce more flexing etc etc. Good Engines are more than cc's.

[Mini Manannán]

Hi, I´m considering to upgrade my 1275 Cooper to 1380 but I have a low budget. Can I just change Pistons, bearings and pump ?

 

In a word, no.  If you start you're own thread asking this you'll find out the ins and outs,.

[feybrand]

I just tried to wipe that bug of my screen

[Spider]

I just tried to wipe that bug of my screen

 

I've had the same one for months!

 

Spray doesn't work either!!

[Cooperman]

It is hard to think of a more mis-matched transmission than an engine with a 286 cam being mated to standard wide ratio gears and a 3.1:1 FDR.

I once tried a 544 cam (not that different from a 286) with straight-cut close ratio gears and a 3.44:1 and even that was a bit too high for decent acceleration when pulling away from rest. I now run a SC CR gearbox with a 3.9:1 FDR with a 286 cam and that is about ideal, although the cruising speed is low. It has to be revved very high to get it to really go well an d stay on the cam.

The 286 does need the close ratio gear set and, consequently, a low FDR.

[MJWarren]

Hi, I´m considering to upgrade my 1275 Cooper to 1380 but I have a low budget. Can I just change Pistons, bearings and pump ?

You should really only go up one bore size when rebuilding your engine. The next one up is 1293cc. 
 
If you go straight to 1380 you've got no more rebore sizes unless you get the block sleeved. There is no significant increase in power in overboring your engine anyway, you're better off doing a well planned build with the right head, cam etc.

That's just opinion, there are no 'rules' as to how or when you can rebore your engine or to what cc

And there will be a increase in power by going to 1380.

Actually thats not really true. As the piston friction and weight incrase too for a very small cc gain. It will also intruduce more flexing etc etc. Good Engines are more than cc's.

Sorry, I'm not following whats not true? And what's going to start flexing???

[Dusky]

That there is a notabele gain between 1330 and 1380. I suggest reading vizards about overbores etc.

[MJWarren]

1330 to 1380 you might not notice the gain as much but there will be a gain

The question I was referring to was going from 1275 to 1380.