Extreme Engine Tech: Building a BMW S52 – Part 1: The Short Block


Topping off our bottom end will be a JE ProSeal cut-ring head gasket. We opted to run the stock thickness (.070) due to the increase in compression ratio from the Mahle pistons.
Here you can see the cut-rings laid out next to the gasket. The benefit of cut-rings is their impressive sealing ability. You lay the gasket down as normal and then place the triple groove cut rings on the block. When you tighten down the head the cut-rings will cut into the head creating a much tighter seal. This is especially beneficial to engines that will see forced induction. No, I’m not foreshadowing anything- this engine will stay naturally-aspirated.  
We decided to get new timing chains to replace the factory chains we have that have reached almost 200K miles. It’s a great security blanket for just a few extra bucks spent at Pelican Parts. 
Along with the timing chains we also picked up a new EMP-Stewart High-Performance Water pump from Pelican Parts. We’ll go more into the benefits of this water pump over the OE pump in a future “Cooling Upgrade” article. 
Now that we have our shopping list done it’s time to take everything over to Pure Performance in Laguna Hills, CA to start the assembly process.

If you’ve been a reader of MotoIQ for some time then you know we’ve gone to Pure Performance for a few of our BMW upgrades, including Project E39 M5’s brake upgrade. Along with helping out with some of our BMW projects Pure Performance also builds and runs race cars in a few NASA classes and the 25 Hours of Thunderhill. With a resume like that we knew they could handle the simple task of putting our S52 together.


Once our new block was back from the machine shop sporting it’s new 86.6mm bore it was time to start the assembly. First things first as with any engine build, make it pretty!


  1. Not sure when this was posted but thanks! I’ve had a lot of BMWs in the past but nothing later than an e30 and am now looking into a ’96 e36 328is. I’ve been searching for REAL information about a sensible but effective build to reach the M series performance levels and this is the first REAL build I’ve found that speaks my language (brought up on hot rods and muscle cars) My main question is how can you increase the stroke without shortening either the rods or piston pin height?? Or do the M3 pistons have a different pin placement than the m50/52? (I was trying to avoid using all the m50 etc, frankly you need a damn score card to keep track of it all.

    One of the first questions I had after reviewing engine specs was if the M car crank will fit the IS block and cool – yes it will! Another was how much the cast iron blocks can be overbored another point! So now I can toss out all that fan boy (never actually built a motor but know it all) “info” and get back to a proper build, bore, stroke, pistons, cams and go. One question if you are still reading… actually I am going to add this up top. RE pistons 323 328 vs M3 seems to me you can’t increase the stroke without shortening something either the rod length or piston pin height.?

  2. Thank y’all for this write up. Restoring my M3 (minus stuff that weighs too much) and my dad rebuilt my motor for Christmas from this post. Big time.

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