Upgrading the TSW R53 MINI Cooper S

Hmm, I'll have to investigate...

Yes, I've ported a few heads before, though I'm certainly not a trained pro.

 

The old Alfa heads I used to work on had enormous oil return holes at both ends of the head (and also the engine had an eight quart capacity when dry). The engines had plenty of other issues, but oil return was not one.

Looking at the MINI head, I see two roughly 1/2" holes for the oil to return through, not counting the front of the head. One of the 1/2" holes is a break-through hole with funky geometry. I might be able to port that a bit, but the head is already fully dressed. Hmm.

 

Putting the car back together

To continue the story:


Thumper mentioned that I should pay some attention to the oil return galleries in the head. Also, there has been some discussion of strategies to reduce oil starvation. Since the head was already assembled, I couldn't drill out the oil galleries, and besides, the galleries match pretty closely the return galleries in the block, so the best time to make changes here would be when the head and block were bare. I decided for now to cut funnels in the return gallery ports in the cylinder head - particularly the one that breaks through the head casting incompletely, leaving a strange and very poorly-flowing hole. With a 6" long carbide burr, I was able to get to the return gallery ports and make some cuts to open them up.


The block deck was very easy to clean up. I love these modern multi-layer steel gaskets!


Here is the head, all cleaned up and dressed for success.


I installed the cylinder head and established the cam timing before putting on the oil pan. I must have turned the engine over about twenty times by hand just to be absolutely certain that the timing was correct.


The stock exhaust manifold got a third sensor bung welded in to fit the wideband O2 sensor for the Autometer gauge. I pondered the location of this sensor for quite a while. Of course it couldn't interfere with anything else on the car, and also it needed to stay pretty far away from things to keep from heating up things like, oh, the fuel lines, for instance. Also, I wanted it upstream of the catalytic converters so that the readings would make sense.

While I had the exhaust out, I checked it for leaks. Sure enough, the pre-cat was cracked nearly all of the way around, just inside of the integral heat shield. I did a lot of welding to put it back together. Even with the crack, the car passed its smog check (emissions test) a month ago, so the exhaust is still workable, if totally ugly.


I realized after I installed the head that I had not yet transferred the intake manifold studs over to the new head. This is easy to do on the car, though. I like to use a set of stud removal and installation tools, like the one shown here (this is a MAC set but they are all very similar).


While the subframe was out, I replaced the rubber steering rack mount with a polyurethane version. I don't know if this will make any difference, but hey, it's worth a try.


Huh? One of the 6mm threaded holes for the steering rack heat shield stripped out. Oh yeah, I've torqued that bolt, uh, zero times over the years. Anyway, I repaired the hole with a Timesert kit.


This is a 6mm X 1.00 Timesert kit. Shown are the tap drill, the counterbore, the oversized tap, and the insert installation tool, along with a variety of steel inserts.


Success! The new O2 sensor fits perfectly.


If you have an R53, and you remove the supercharger, be certain to replace these two o-rings. They are on the connection between the water pump and the engine block. The o-rings on my car were so smashed that they no longer sealed at all.


Here in the center of the picture, you can see where I've cut back the fan shroud to clear the upper radiator hose. I believe it was K-huevo who identified this plastic part as the thing that wore a hole nearly through the old hose.


After putting the cooling system together, I ran a pressure test to make certain that the system did not leak. In fact, at 20 PSIG the system sprang a leak at the water pump inlet due to an incorrectly placed hose clamp. I reseated the hose clamp (the OEM spring clamp), and the hose sealed right up.


The next test was a first hot-fire. I did this with the car still not completely put together. I did reset the ECU before starting the engine. I was surprised at the nice, even idle, even with the new cam and the port work.


Here is the main gauge cluster, now with the wideband O2 gauge lit up. Looks good!


Ah, back together at last. Coming soon, a test drive!

 

You know it!!!!!!!!!!!!!!!!!

{edit} Mynes is in California now, not Arizona. Good thing I asked before driving out there!

 

Oh, I can talk about the cam all day - I just can't say who made it! The embargo is scheduled to lift early next year, though.

 

First test drive

First test drive

I drove the car on a 30 mile loop this morning. Here are my impressions at each point.

1. Start-up.

The car sat for about 14 hours in the garage after several idling hot fires yesterday. The temperature in the garage was about 50 F, and the outside temperature this morning was about 40 F.

On start-up this morning, there was a loud ratcheting sound from the engine. I heard the same sound yesterday on the first hot-fire. After about ten seconds, the sound faded away quickly. I did not touch the throttle during this time. My eyes were glued to the oil pressure gauge (a mechanical unit tapped into the filter housing) and the oil pressure there remained steady at about 25 PSIG.

I believe the sound is there because the chain tensioner is not pumped up with oil. After the sound went away. I shut off the engine and waited a couple of minutes. On restart, the sound was still gone. This is a new noise; the car did not do this before I did all of this work.

I'll let the car sit for several hours today and see if the noise returns. If this problem persists, I'll have to buy a new chain tensioner. Thanks to the engine designers for making this accessible from the outside of the engine!

2. Warm-up and drive out to the highway

The drive out of my neighborhood (a mountain valley community) and out to the highway is about 12 miles. This gave the car a chance to warm up, and it gave me a chance to evaluate the new clutch and the "daily driving" character of the car.

The clutch, a Valeo unit that comes with a new single-mass flywheel, is divine. It is roughly equal in feel to a stock clutch, with a really nice, crisp action and a fairly sharp "knee" in the pedal effort curve where the clutch disengages. Engagement is silky-smooth and trivial to modulate. NICE. A big, big bonus is that the gearbox is now silent. I hear nothing from the gearbox inside the car, unlike with the aluminum flywheel I had before. Oh, and despite the greater mass (and rotational inertia) of the new steel flywheel, blipping for downshifts is still easy, and the engine RPM drops promptly on upshifts.

The engine at this point felt docile and quite easy to use. The car drives easily on level ground at 1100 RPM without bucking or thumping. Cruising felt the same as before the mods, except smoother.

3. Highway on-ramp and 5 mile run

The on-ramp is a downhill, on-camber, 270 degree ramp. My car eats these alive. This time, I nailed it through the last quarter of the ramp and on to the highway. The engine sounds more... sonorous. It has a deeper timbre, like it means business. Through 4000 RPM, the engine feels about the same as before, as though the benefit of the ported head and the higher-RPM bias of the camshaft balanced out to a smooth medium. Power builds from here, though. By 6000 RPM, the power is well beyond what the car had before. By 7000 RPM, the power is still building, and the engine rams into the redline (in my car, redline is around 7200 or a bit less at the moment). I think this cam will work better with at least a 7500 RPM redline, and probably more like 7800 RPM.

I can see, though, that the car will benefit greatly from a good tuning session. The new wideband O2 gauge indicates that the Air/fuel ratio is dropping below 10 during hard acceleration (my car has always had jet black tailpipes because of this). With a better tune, this thing should really fly.

4. Winding mountain road

After about eight or ten miles, I reached the exit for my favorite "test track" - a tight mountain road that hugs the side of the hill. This road is packed with sharp turns (but no true switchbacks), and the pavement is actually quite good. Traffic is more than I'd like due to the proximity to town, but the convenience is hard to beat. I generally take it easy on outside turns to be safe and to be courteous to others, as the outside turns are completely blind. The inside turns, though, are taken near the limit. Besides, the penalty for screwing up an outside turn is a long drop, followed by death.

Here, the engine shined. Extremely versatile! For outside turns, the car would just purr along as if nothing was going on. On inside turns, the car would pull through with serious power. Rev-matching was effortless. I was impressed with the contrast, and with how fast the car could pull off the "Jekyll and Hyde" impersonation.

5. Headed home

After the mountain road, the return trip seemed so... boring. No drama at all, which is fine by me. The car is doing well.

Conclusions

1. Need to keep an ear listening for that start-up rattle.

2. Valeo clutch+flywheel kit = awesome.

3. Engine work, uh, worked. Worked extremely well, actually.

4. Engine now needs a tune as expected, but it is running smoothly and will easily drive around until I can get to Mynes January 9th.

 

Update to the update

I let the car sit for about nine hours, and then started the engine. The ratcheting noise from the engine returned immediately, despite the oil pressure of 65 PSIG. This time, it didn't go away after 60 seconds, so I shut the engine down. A brief restart confirmed the noise didn't magically disappear.

I've got a new hydraulic chain tensioner coming from Pelican Parts. On Thursday, I'll see if I can put it in the car without taking the subframe out. It looks like there's enough room to get to it from the top, though it may be a bit of a struggle.

I wonder why the old tensioner was fine until removed once? Strange.

 

Thanks - and no, it's not a Hubie camshaft.