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Project: E36 M3 – First Upgrades: Under The Hood

It has been a while since we last saw my E36 M3 project car. With every project, there are surprises that come along. It’s inevitable. But sometimes these issues can be a lot more serious than originally expected. But after the basic maintenance items, we turned our attention to getting the car fit for use on the road, as well as the track.

M3 on the lifter

The M3 gets worked on at ARC Automotive

Since we are planning on racing the car, I want to make sure the engine is as reliable as possible. In fact, I specifically chose the S50B30 US-spec M3 because it is essentially a tuned M50 – something that comes out of a standard 325i. That way, parts are relatively inexpensive and plentiful, but the engine is virtually bulletproof. Alvin of ARC Automotive is pretty much an expert on these cars, being a BMW USA trained and certified master technician (and having built his own US-Spec M3, which we’ll get to in a later episode). With him at the helm of the project, I’m confident of a smoking track car.


The S50B30US is a 3.0L straight-six, based on a standard M50 but worked over by the BMW M Division.

The main criticism of the M50B30US is the relative lack of power. The European spec engines (when new) put out 286 bhp at 7,000 rpm and 236 lb/ft of torque at 3,600 rpm. The US-spec engines had a relatively paltry 240 bhp at 6,000 rpm and 225 lb/ft of torque at 4,250 rpm. It’s more than enough to get some thrills on a racetrack (in fact, it’s still more than a current-model Toyota 86, which is a lot of fun in stock form), but we will definitely have to do something to make the loud pedal go louder eventually.

M3 in the air

Exhaust removed to access the transmission tunnel

Barely 2 weeks after I took delivery of the car, the clutch was starting to slip. And as with most project cars, when the original part fails, an upgrade gets slotted in. In this case, I went with a UUC Stage 2 flywheel and M5 clutch. This kit uses the clutch disk, pressure plate, and throw-out bearing from the 3.6 liter E34 M5, and is rated up to 450 hp at the wheels – more than what we expect to put into car. The rotating mass of these increases, however, but the Stage 2 flywheel, which is just 8.5lbs, is designed to offset the weight increase.

UUC Flywheel and Clutch

UUC Stage 2 flywheel and M5 clutch is installed to handle more power… which will come eventually

Cooling is a major issue in the Philippines, simply because of our high ambient temperatures. It becomes doubly important in a track or race environment. If this isn’t addressed immediately, I can risk eventual overheating and damaging the engine. To upgrade the engine cooling system, I went with a UUC/Zionsville Alloy Radiator. This racing rad has a cooling capacity that’s over 50% greater than what is required by our motor. Its aluminum tanks are also much more resistant to heat and cracking, so it wil’ be more durable over the long haul.

In addition, a lower-setting temp switch was installed. This switches the aux fan on earlier and helps keep the engine within proper operating temperature. The switch triggers a new Spal electric fan. There are those who claim power gains over the stock viscous unit, but if it does, it’s almost negligible. The reason I opted to do the swap is for cooling efficiency. Simply put, an engine-mounted fan (like a clutch-type) will be further away from the radiator, and thus less of the airflow reaches the radiator. Now if there are power gains, then that’s just gravy.

Finally, a Stewart racing water pump gives me the durability and a 20% increase in water capacity to really get the engine temp nice and even. If all this sounds like overkill, maybe it is, but we want to be absolutely sure that this motor can handle all the hard driving it’s going be subjected to!

Radiator Comparison

OEM Radiator on the left, and UUC/ZI racing radiator on the right.

The S50B30 US has a known weakness in that the top end tends to starve of oil during high speed cornering. In fact, all it took was 3 laps around the Clark International Speedway for the valves to start doing their diesel impression. The E46 M3 oil pan and oil pump are great bolt-on upgrades. Fuel starvation is another common issue for these engines, and a secondary fuel pump is a common and proven way of addressing this, so that went on the car, as well.

After taking the car to the Clark International Speedway for some hard laps, the work put in by Alvin and the boys at ARC Automotive have paid off. The car runs well, engine temps are very stable after over a dozen laps. The M3 also shows no signs of any starvation issues – oil (a ticking noise coming from the valves) or fuel (engine cutting out in the middle or towards the exit of a corner). The clutch engagements are crisp and immediate – in fact, ex-Asian Formula 3 pro George Apacible noticed the clutch before I told him of the upgrade.

There is one thing that’s been bugging me though – the car has a noticeable flat spot after 6000rpm, well short of the 6750 redline. While it has decent pull at corner exits, the car doesn’t feel all there. I guess that’s something to look into before the next track day or race…

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