Mini cooper s destroke

[Stubby13]

Just wondering if the 1400 crank will go into the 1600 turbo block.
Looking at destroking to under 1500cc

Thinking of sett grinding the 1400 crank and maybe +1mm pistons trying for around 1450cc
Tia.

[Megaflow]

Anything is possible, but if the block is common between 1.4 & 1.6, which a common bore size suggests it is. Then you will need a set of custom rods to get the piston to the correct height in the bore.

[HJG]

Or custom pistons. Rods probably easier though.

[Stubby13]

I was thinking of 1600 rods and on the offset ground crank and a block skim to suit

[gazza285]

What big end shells are you proposing to use after offset grinding the crank?

[Stubby13]

Not sure on journal sizes, standard to be honest, so the 1600 rods maybe useless anyway 🤔
Otherwise max oversized if there's enough meat in a standard crank?

[Megaflow]

Highly unlikely to be enough meat on the standard crank for an offset grind to correct piston height, a set of custom shells is then going to be required.

What ever way you go about it, there will be something custom and one off involved, which means £££££.

[gazza285]

Megaflow said:

Highly unlikely to be enough meat on the standard crank for an offset grind to correct piston height, a set of custom shells is then going to be required.

What ever way you go about it, there will be something custom and one off involved, which means £££££.

That’s why I asked, oversize shells are measured in fractions of millimetres, the difference in stroke will be a much larger than that.

[Megaflow]

The bearing shells are the least of his concerns with an offset grind. The stroke difference between the two engines is 10.8mm.

If my early morning maths are right, he’d need to grind 2.7mm off one side of the pin diameter, that is going to destroy the main/pin overlap, and produce a seriously weak crank.

[Stubby13]

Cheers everyone for your thoughts.
Yes your all right regarding modern production techniques and tolerances.
The ofsett grind is doubtful.

Anybody got any good info/links for dimensions of these engines, the goal is a scrap yard solution <1500 turbo. The machine work isn't a problem.

Was hoping someone would reply with 1600 clio rods is what you need ,been done before.

[Megaflow]

Sorry, it is highly doubtful you’ll find a scrap yard solution.

That’s not to say there isn’t one, but you are going to go blind on conrod dimensions to find the correct one, even if it is available.

[paintman]

I'm just curious why you want to do it in the first place.

[Stubby13]

Msuk rules upto 1500 turbo for road/ targa rallies.
The mini cooper s can be got for cheap enough if there is a scrapyard answer then they would be a popular choice.

[paintman]

Ah. Thank you.

[Megaflow]

If you are looking for a cheap scrap yard solution, I wonder if you need to go the other way.

This assumes the bore centres are the same between the 1.4 & 1.6, which as they were developed together and are built on the same line, is a pretty safe assumption, I would take a 1.4 core and put the 1.6 externals on it, a custom map and away you go.

Yes, it will be 1400, not 1500, but it will be a lot cheaper than any custom made parts. Ironically you might find the 1.4 crank is stronger as well, because the shorter stroke will mean more main/pin overlap. The big question make will be rod strength.

Oh, and make sure you use decent fuel to protect the pistons from detention.

[Stubby13]

Yes ,thought of this route.
Leaves about 5mm ish to machine off the block and pistons may not be up to it?

[Megaflow]

Why would you need to machine 5mm off the block?

[gazza285]

Do they use the same block? So the 1400 has a shorter stroke but longer rods? Or are the blocks different heights?

[Stubby13]

There's 10mm more crank stroke on the 1600 .
5 up and 5 down.