E-30 S52B32 Transplant
(Click images to increase size)A good customer/friend decided he was in need of more power and torque from his E-30 M3. The S-14 was great at high RPM’s but didn’t have anything at the low end. So we waited patiently for an E-36 M3 donor car. After a year wait we bought a totaled 97 E-36 M3. This had the S52B32 or 3.2 liter engine. It also had EWS and OBD2 fuel management system. This made the wiring to his 88 M3 a little tricky.
We started by pulling both drive trains, along with the fuel management systems, from each vehicle. We checked the E-36 clutch for wear and decided to install a new clutch assy. We needed to order E-24 635 engine mounts in order to mount the S52 to the E-30 sub-frame. Special shims were also made to raise the engine ¼ “. The shims were made out of ¼ “ aluminum. Also the inner part of the engine mount needed to be trimmed in order for the mounts to mount flat against the sub-frame.
The oil pan had to be swapped out, because the sump for the E-30 is in front of the sub-frame.
The S -52 oil sump is to the rear of the sub-frame. So we bought a new oil pan and sump for a 94 525i. We installed these with the engine on the engine stand. While the engine was on the stand we drilled and tapped a place in the head for the coolant temp sensor from the S-14 engine. This sensor is compatible with the E-30 temp gauge where the e-36 temp sensor is not. We also used the e-30 oil temp sensor. We used the sensor in place of the oil drain plug and ran the wiring own to the sensor. The oil pan was hanging at or slightly lower than the sub-frame. To protect the oil pan from damage we fabricated a metal splash pan and bolted it up from the sub-frame to the core support. We also placed a metal sheet to divert the air from the area where the oil cooler was to go through the radiator to help in cooling.
After setting the engine in, the transmission was installed. We used the driveshaft from the E-36 with the E-30 center support bearing. The stock 410 rear from the E-30 M3 would be to low a gear for this engine so we installed a higher gear ratio, limited slip differential from a 1987 325IS.
The shifter was transferred over from the e-36 in order for the shift lever to line up properly. We installed a shift kit from UUC to shorten the throw. This made the shifting more precise.
We had down pipes fabricated, in order to bolt up to the S-52 exhaust manifold to the E-30 M3 exhaust.
This was something Gerry wanted. He had a straight pipe to take the place of his catalytic converter for track events. The fabricated pipes let him keep this set up intact. It also helped with the clearance problem at the sub-frame. The original E-36 down pipes would have ran right into the sub-frame. The E-36 downpipes were designed with the sub-frame in front of the oil pan. With the oil pan in the rear of the oil pan it didn’t give the exhaust enough room to clear. We were very happy with the results with the fab work. We used only 2 oxygen sensors before the cat. We tied and sealed the unused wiring.
The trickiest part was the wiring, due to the fact we were wiring in an OBD2 system. We split the harness and used the ETM (Electric Troubleshooting Manual) to match up the wiring needed.
This engine came from an EWS car so the drive away protection had to be bypassed in order for the DME (Engine Control Unit) to supply spark, injector pulse and power to the starter for crank mode.
EWS uses a transmitter from the key that sends a signal via an antenna ring that surrounds the ignition lock to the EWS control unit. The EWS control unit then tells the DME it is ok to start. So in order for this to work I had to wire the appropriate inputs to the EWS control unit from the E-30 chassis wiring. The key and antenna ring then had to be taped together and mounted under the dash. That way the original ignition lock could be used. Another problem was the S-14 is a 4 cylinder and the S-52 is a 6 cylinder. So the signal input to the tachometer will be wrong. After finding the signal wire from the DME via the crank sensor, we wired it up to the appropriate input wire to the E-30’s cluster. To change the cluster to a six cylinder signal we had to change the coding plug.
We took a coding plug from a 325is cluster and the tach was much more accurate.
It was still off by 800 rpm’s at redline. This ended up being ok because the redline difference between the engines is 800 rpm. So we can use the redline on the tach.
After we got it wired and running, we focused on getting the wiring routed and wrapped to look factory.
The relay bracket was relocated to where the coolant reservoir was mounted.
The main harness loom was mounted to the firewall with mounting brackets from an M coupe. We welded the diagnostic bracket on the rear of the right shock tower.
The cooling system was also modified. We used an E-36 radiator mounted at the top with a radiator mount.
The fan clutch and fan blade had to be used from an E-30 325. The coolant reservoir had to be relocated to the left side of the engine. The coolant hose from the reservoir to the engine had to be modified. We used the original E-36 hose and cut it to fit. The hose ran nicely and laid in the old holder for the air box. The heater hoses were also cut to fit the heater core inlet and outlet pipes. The reservoir mounts had to be welded to the body in order to secure it. We then modified the plastic tube to run from the radiator to the reservoir along the body. This was done by slowly heating and bending the plastic tube. The cooling system was then filled with BMW coolant and pressure tested for any leaks. After no leaks were found, it was fired up and let run at temp to make sure the thermostat opened properly.
There wasn’t room for an air-box so we used a K&N cone air filter set up. To help insulate the incoming air from the hot air in the engine compartment, we fabricated a cold air set up. We did this by using the flexible heat shielding from the e-36. Molding it around the air filter and securing it to the frame rail at the bottom.
This way the air that goes into the air filter will come from the grill area and not the engine compartment.
We took p/s hoses from the E-34 M-50 engine and with some fine-tuning got the hoses fitting very nicely in the space available.
We also wanted AC in the vehicle. It was going to be used as a daily driver. So we had AC lines made and used the E-36 compressor.
The throttle cable had to be replaced also with the one from an E-34. The pedal travel had to be adjusted in order to get the throttle travel correct.
Now we are ready for a test drive. Boy it is quick, so much more low-end torque than the S-14. Gerry will be pleased. It just happened to be cold and wet that day! SKID PAD TIME!!!! I’m glad I had the chance to take it out in this weather. It is really tail happy. So to make the car more neutral we adjusted sway-bars and tire pressures. After a couple laps out on the track we can really get the car dialed in. Ok, this project done it’s off to the next one. I wonder what we should do next? :)