Good.
I'm going to start a project in which I'm going to modify my cooper s R53 to a JCW but first I would like to know what the differences are between the two engines.
The first modification i am going to do is to buy an old cylinder head and i am going to clean it and change everything. i am going to enlarge the holes in the exhaust manifold of the head and i am going to enlarge the intake valves.
Has anyone done this modification before? Enlarging the cylinder head valves by machining?
I would like to know opinions before starting the project.

 

Early JCWs (the one I have) were differentiated from the standard engines by:
-ported head (larger intake and exhaust "holes" as you describe). The valves were the same.
-spark plugs were one heat range colder
-smaller SC pulley (and shorter belt to match).
-ceramic coating on the SC impellers (this became standard on non-JCW engines later)
-cat-back exhaust
-remapped ECU
-JCW badges front, rear, and on the valve cover
-JCW intercooler trim

Later JCWs (in addition to everything above) had a revised air filter box and larger injectors - this gave a few extra ponies beyond the early JCWs.

I think you're going to quickly realize that larger valves aren't really feasible. There's only so much realestate in the combustion chamber and you end up thinning the walls between the valve seats (or between valve seats and spark plug threads) which can lead cracks/failures of the head.
But, by all means, you could replicate a JCW build easily enough with a custom ported head and aftermarket SC pulley, exhaust, and tune.
I'm curious to see where this project takes you. Please keep us posted.

 

This old John Cooper Garages JCW Tuning Kit conversion video is always a fun watch...

 

Thank you very much for your reply. From what you tell me, the cylinder head of the JCW R53 does not have bigger valves but only bigger intake and exhaust ports, right?
Can you tell me the dimensions of the intake and exhaust ports? I will keep you posted if so.

 

This is a good reference resource, which notes (in part):
"Upgraded Cylinder head - The difference from a cooper S cylinder head being slightly enlargened (sic) on the exhaust ports."

The JCW Register: Guide to the John Cooper works tuning kits for the R52 and R53 generation of Mini Cooper S

 

If you go with a standard JCW tune... It will pass smog... a few on this forum do the re-flash for reasonable cost...Dealer wont do it.

The head is not a concern.. The factory porting wont make much of a diff...especially if you go with a 13-15% SC pulley.
Try to find a plain black pulley instead of a 'Bling' billet anodized one... helps to fly under the radar of the smog inspection and preserves future value.
See if you can find a factory JCW airbox... AM CAI's, just not worth it to me.... but it's your ride and do it how you want.

Boost cures a lot... especially if you do it from a "systems approach" and have a well sorted tune.

The more you push the HP... The less "flexible" and temperamental the engine becomes... If you will be satisfied with JCW+ power levels rather than a tune you'll be happier on a day-2-day basis with the car.

Koni Specal-Actives with a better rear swaybar will outperform the factory JCW suspension and preserve valuable ride height.

Of course... Do all of the age related maint (regardless of mileage).... all the engine seals, tensioner, belt, gaskets, intake system maint, SC maint, coolant flush, coolant tank replacement, cooler/new spark plugs (for the JCW configuration) T-stat housing replacement, all 3 motor mounts, strut mounts, leaking PS hoses, etc etc. ... Before you do your mods.


Keep us in the loop and good luck with the project.

 

Correct, valves are the same. And if I'm not mistaken, the size of the port entryways are the same so they still match up to the manifolds. It's the size and shape of floor, ceiling, walls, throat, and turn radii that are modified for less restrictive flow.

 

okey. thank you very much.
I'm looking for a cooper s or JCW cylinder head for R53. Can anyone help me?
I'm also looking for the JCW exhaust pipe, if you know of anyone tell me.