I’m a planner. I like to have a full list of what I need to do in order to complete something successfully. It’s just the engineer in me. Swapping an S52 engine into my E36, in place of the M50, is fairly straightforward but there are still quite a few parts that are needed to make sure everything is bulletproof once completed. In this post I’ll go through my planned parts list as well as some added detail on a few key items.
- New Parts to be Purchased
- Dual valve springs/seats/retainers (Supertech SPR-H1005D/BM, 98lb seat pressure)
- Camshafts (Schrick 264/256, Intake – 264 degree, 11.2mm lift; Exhaust – 256 degree, 10.6mm lift)
- Vanos rebuild (Dr Vanos Stage II)
- Head bolts (ARP 2000 stock size)
- Stock head gasket set
- Rod bolts (OEM)
- Connecting rod bearings (King Racing CR6640XP)
- Oil pan baffle (Achilles Motorsport)
- Upgraded oil pump (Achilles Motorsport)
- Oil cooler cap for external oil cooler (Rally Road)
- Oil cooler with lines (Grassroots Peformance)
- Oil pressure sensor and gauge
- Oil filter housing gasket
- Oil pan gasket
- Dipstick o-ring
- Header hardware install kit
- Coolant pump (Stewart Warner)
- Aluminum coolant expansion tank (Mishimoto)
- Upper timing chain tensioner
- Big bore throttle body (Riot Racing 68mm)
- Clutch/pressure plate/flywheel kit (FX Stage II)
- Clutch accessory parts
- Clutch pivot fork
- Clutch pivot fork bronze pivot pin
- Clutch pilot bearing
- Clutch throw-out bearing
- Clutch release arm spring clip
- Clutch release bearing guide tube
- Transmission input seal
- Transmission output seal
- Transmission shift shaft/selector rod seal
- Transmission magnetic drain plug
- Flywheel lock tool
- Crankshaft rear main seal
- Driveshaft center carrier
- Flexible fuel lines in engine bay
- Thermostat, OEM temperature
- Auxillary fan temperature switch, 80*/88*
- Spark plugs (NGK 4776 BKR7E-E)
- Front subframe reinforcements
- Might Need to be Purchased
- Idle control valve
- 3.5” MAF
- Starter motor
- Camshaft lifters
- Camshaft sensor
- Revise TRM ECU chip
- Timing chain guides
- Cooling fan
- Shorty equal tube headers
As you can see, there’s quite a few large components that I plan on purchasing but there’s also a ton of little “while I’m in there” sort of parts to procure as well. Let’s dig into a few of the more important parts and why I specifically chose them.
Supertech SPR-H1005D/BM dual valve springs, seats and retainers:
Upgrading the valvetrain is always a good idea in well worn engines (like my 157k mile S52) when the planned use will include sustained high rpm with significantly higher than stock horsepower. For the M50/S52 family of engines there are really only two choices for high performance motorsport grade valvetrain components, Supertech and Ferrea. After a good bit of research, it seems like most motorsport teams who race BMWs go with Supertech valvetrains. Other benefits for Supertech are that they’re readily available, lower cost than Ferrea and offer higher performance in certain regards.
The are actually three different Supertech valvetrain kits to choose from. The website in the following link does a great job comparing the specifications for each (look under the section for “BMW S42 / M42 / M50 / S50 / S52 / M52 / M54”):
There are two primary specifications that I’m reviewing when making a comparison between the three different dual valve spring setups:
- Seat Pressure – This is how much pressure, in lbs, that the valve spring exerts on the valve to keep it closed when the valve is resting on the base circle of the camshaft:
- Too light a pressure and the valve might “float” at high rpm. This is when the valve stem/lifter arrangement loses contact with the camshaft. This leads to horsepower loss and potentially failure of valvetrain components.
- Too heavy a pressure and you’ll have excess wear on the valvetrain components. However, a high pressure may be necessary with higher boosted applications where intake manifold pressure is extremely high and will try to push open the valves.
- Open Pressure at 12mm Lift – This is how much pressure that the valve spring exerts on the valve when the valve is 12mm open of off its seat (i.e. maximum lift). The maximum lift on the Schrick camshaft that I’ve selected will be 11.2mm so this is a very good representation of what my valvetrain will see. The same general breakdown of too light versus too heavy also applies in this case.
After discussing this with my “head guy” who has a lot of experience with BMW cylinder heads and forced induction engines, I’ve selected the SPR-H1005D valvesprings with 98 lbs of seat pressure and 236 lbs of pressure at 12mm lift. The highest spring rate was chosen as it’s not actually that high compared to engines from other manufacturers and a higher spring rate will be good if I ever take this engine above 10 psi of boost. These Supertech valvesprings (with corresponding seats and retainers) should give my S52 a bulletproof top end.
Schrick 264/256 Camshaft Set:
The final component to my valvetrain upgrades are the intake and exhaust camshafts. The only role of camshafts are opening the valves to let the air/fuel mixture into the cylinder and the exhaust gasses out. Camshafts can thus open valves a certain amount (lift) and for a certain amount of time (duration). However, to get maximum usuable horsepower it’s NOT as simple as maximizing lift and duration. Camshaft profiles must be selected for the planned use of the engine and car. For instance, for my use, I need to develop good torque down low through the mid-range while I wait for the centrifugal supercharger to spool up and add boost. I need a good bit more lift and duration but not nearly as much as a high horsepower turbocharged engine would need.
Here are the specifications for the stock S52 camshafts:
- Intake Camshaft – 10.2mm lift, 252* duration
- Exhaust Camshaft – 9.7mm lift, 240* duration
I’ve chosen the general consensus Schrick “264/256” camshaft that most centrifugally supercharged E36 owners go with when running stock pistons:
- Intake Camshaft – 11.2mm lift, 264* duration (9.8% increase in lift, 4.8% increase in duration)
- Exhaust Camshaft – 10.6mm lift, 256* duration (9.3% increase in lift, 6.7% increase in duration)
VAC Motorsports summarizes this specific Schrick 264/256 camshaft set with the following text on their product page:
“This cam set for BMWs inline 6 is one of the best overall performance upgrades you can install. Not a peaky, or hard to live with pair, this matched camshaft set increases performance throughout the available rev range and has always been a best seller- especially for the street performance or dual street/track uses cars as its a smooth power gain with very little compromise in idle quality. Manufactured in Europe from premium blanks.
On the street your BMW will be faster and more powerful in all areas. Idle is streetable and power band is linear. Improved torque along with horsepower will improve 0-60 as well as highway performance. Gas mileage will not suffer terribly. You will feel “BMW should have made it this way from the factory”. If you are still running the stock M3 or 328 pistons, this is an excellent match for your engine. On the track, these cams are excellent for the beginner or the seasoned racer. Flat power band means a fast, easy to control car around the track with less stress and strain on the engine. These camshafts can truly be run without internal engine work, although uprated valve springs are absolutely a recommended safety measure for tracked cars as the OE springs will NOT tolerate any over-revs.”
Good thing I’m upgrading my valvetrain! Overall, I think my head will be what I need and should last a really long time.
I’ll be focusing on the oiling system upgrades in my next post. Stay tuned!