My head needs a little bit more of a rebuild than I had anticipated, as it may have dropped a valve seat (haven't figured it out yet, could also be carbon buildup). Since it has to go to the machine shop anyway, I'm going to have it ported. Has anyone else done this? I'm hoping it will improve fuel economy. I've been getting 50.5mpg average since I bought the car in 2015, so I do have a number set as baseline. I'll let you know what happens when it's back together.

I'm aware that this isn't necessary. My car is well out of warranty, so I can afford to experiment.

 

I doubt porting will help increase gas mileage enough to support the cost. 50.5mpg? I've never heard of a Mini getting that kind of mileage.

 

50 MPG is exceptional and I have not ever ported a head. I wanted to inquire what you found when you took head off since you mentioned a possible dropped valve seat. I had head trouble and when I tore it down found a #4 cylinder seat drop on the exhaust side. I understand this is common when the car is overheated. Wondering if you found the same and if so what was the fix from your shop. I understand the best method is to remove seat, cut a new bore, install a new insert and cut your new 3 angle for valve to mate to. My head shop instead, pushed the seat back in position and "impacted around the seat to deform the metal a bit to keep it from falling out again. Much cheaperand easier of course but I have not seen or heard of that method. Time will tell on my 2012 mini base r56

 

What I found was indeed the valve seat. It had JUST failed. Barely bent the valve. Another one was on its way out, so I had them all done with thicker seats. Everything went back together as easily as it came off, and it's still running strong with about 11k on the original head, post-rebuild. I never ended up porting it, but I was on a tighter schedule than I wanted to be, so I just needed to get the thing put back together. I did, however, put a lightened crankshaft pulley on it, and it does feel a little peppier than it used to.