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Discussion Starter · #1 ·
Hi everyone, the N-14 engine in my 2010 R56 JCW exploded the other day, hole in the engine block, pistons falling out etc.
Does anyone know if I need to get another JCW engine (quite rare) or just any old N-14 engine and use the block and all the parts from the old engine to rebuild, maybe with a set of forged pistons?
All advice appreciated.
Thanks
 

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Hi everyone, the N-14 engine in my 2010 R56 JCW exploded the other day, hole in the engine block, pistons falling out etc.
Does anyone know if I need to get another JCW engine (quite rare) or just any old N-14 engine and use the block and all the parts from the old engine to rebuild, maybe with a set of forged pistons?
All advice appreciated.
Thanks
same engines on gen 2 cars ie n14 is just that, can also use a Peugeot gti 175 as in 207 and 308 307 same engines , more chance finding a psa engine than a mini one, let me guess it was the cylinder closest to the gearbox ie 1 or number 2 cylinders is very common for failure
 

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Discussion Starter · #3 ·
So I can buy any N-14 engine and swap the block? (sorry, just want to be 100%). I'll have a word with the mechanic about which cylinder it was and let you know. I've been reading the lohen "common N-14 problems" and it blames "coking of inlet valves", does that sound right to you?
 

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2008 Mini Cooper S hatchback,Automatic,Mello Yellow
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You can do forged pistons. The crank shaft will allow it. But you will need new main bearings and though not that important, but for insurance reasons have the crankshaft brought in and cleaned up on a sanding machine.
I was gonna go with forged pistons(even though I knew!), I forget that they are heavier even though they are aluminum. There will be no gain in a stock programmed Mini Cooper computer. The power level will be slightly worse. In the end It would be better if you looking to just get back on the road. With stock pistons. That is what I have done. The biggest thing in my experience rebuilding my engine. Was the cylinder number 4 pistons rings. they were out .050 thousandth. And needed to be replaced. And now having all 4 cylinders operational. It is like when it had 25 thousand miles. It's better! I could drive from here to anywhere I want. Back to having full power up the side of mountain type new. A fitting reward for time invested. The JCW heads are not that rare!
They have them out there. Salvage yards have them. Further more the N18 engine differences between the JCW and Stock S cylinder heads, are only the camshafts lift/duration; I think! Something to check into. The N18 was a real vanilla type engine. Not much aftermarket support toward the cylinder head design.
If your thinking about running forged pistons anyway. You will be porting out the exhaust and putting stronger valve springs in anyway to support the higher RPM it's gonna be running.
But off hand the only thing you would have to do is have your new cylinder head refit with your present or JCW camshafts to make that work, by taking it to a machinist where they line bore the journals for the camshafts on the cylinder head.
 

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Apparently it was cylinder 4 (timing chain end)
thats rare on them normally its the other end because the block is hotter on the gear box end this causes a lean out when any petrol gets a lean stage from heat it increases the temps in the cylinder and this tends to crack or melt things down.. when i find them with the other cylinders its deffo due to another failure causing it,, ie injector failure or water pump or thermo housing even a blocked radiator can also do same trick,, telling you this because some people have cured the outcome and not why ot happened in first place,,
also be careful with some people inputs on forums ie many people who worked on one mini made loads of mistakes and now think they are specialists and know what they are talking about etc,, these people can cause others more pain and expense from wrong directions etc,,, i and a few other work on these cars all week long in garages and only direct people in correct way and also know how all the systems work and also what something ends up broke,,, ie also need to fix why ot went wrong and not just the outcome
 

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Discussion Starter · #7 ·
Thanks for the help.
I just had the timing chain changed and a service, do you think that had something to do with the failure? I was assuming from what I've read it was probably due to coking.
 

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Thanks for the help.
I just had the timing chain changed and a service, do you think that had something to do with the failure? I was assuming from what I've read it was probably due to coking.
coke build up on these engines cause rich running not lean outs ie there is is more fuel in the combustion chamber ,, and the way a petrol engine works is the only thing that cools the combustion process is more fuel so rich running would have the reversed effect,, when a petrol engine leans out the temps are out of control and the 14.1 fuel air mixture point is not met and thats when the melt things down,, as these engines are direct injection and not port injection they always fuel to the cylinder,, when when the inlets coke up its restricts air flow hence why get rich running,, i would deffo suspect injector on that cylinder as its a running issue perhaps, also water pump and jockey wheel etc ,, but like said before they tend to do number 1 or 2 cylinders seen many take out the piston skirts
 

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it won't be just down to carbon build up but will be oil ingress which leads to the carbon build up over time,

combustion of it lowers octane levels and promotes pre ignition at low or high speeds and at varying levels of boost etc, so even those driving at modest engine speeds if with a moderate throttle (as with the one I have here that had a holed piston) can generate tremendous cylinder pressures and temperatures as a result and it can end like this, add remaps to the condition and it can get worse,

pretty certain the engines/internals differ between a 174hp N14 (which is the same as a dealer fit N14 JCW internally) compared to a factory 211hp N14, the blocks might be the same perhaps, take a look at RealOEM and look at the component numbers perhaps,

if wanting to forge it then it might not matter so much for the bottom end,

beware used blocks, many are worn/damaged and in need of a re-bore, even with sellers saying they ran well or whatever,

I have a couple of blocks/bottom ends, one with a repair sleeve bored and honed to suit standard size, another in the machine shop which will probably go +0.050mm, cranks ok in std sizes etc, polished to go with re-lined block, untouched to go with re-bored block,

oil entering the inlet manifold in particular from the PCV outlet seems to get sent toward cylinders 3 & 4 more, these are usually the worst for carbon build up on the valves as well as subsequent ingress into the combustion chamber,

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