E9 3.0CSi Engine and Transmission Swap

[E9 3.0CSi]

Hello everyone! Me and my father are planning to completely restore his E9 before summers end, and therefore we've seen it fit to begin searching for parts. We're planning on keeping it totally stock, save for the engine and transmission. We've been looking on the S38B38 and S52B32 with gearboxes as viable replacements, but will it be pain free? We don't want to heavily modify any engine or transmission mounts, and we would like to keep the stock differential. Will it be possible without severely reducing its life span? Also, are there any reinforcements needed to be made to the chassis, mainly the diff mount?

Thanks in advance and best regards.

Bjarne Cox

 

[x_atlas0]

The S52 will be significantly more work, as the engine mounts, driveshaft, transmission cross member, electronics, speedo, and possibly shift linkages will all have to be custom. The S38 (in comparison) is a much easier swap, as the stock motor mounts can be used and the transmission is a known quantity. (you want to use the Getrag 265 instead of the 280) It does require a bit of firewall modification to make fit, however, due to the cam carrier width.

 

[E9 3.0CSi]

Okey, thanks for your time. I think we'll go with the S38, seems to be a far more attractive option. Modifying the firewall ain't much of a problem, and getting our hands on a 265 won't be too hard. Should we also change the brakes to something bigger? Will E34 M5 bolt right on?

Best regards and thanks.

Bjarne Cox

 

[M5dCS]

e34 m5

Yes this engine will bolt right in with an exception, the thermostat housing for the b36 and b38 requires the you move the radiator about 2inches further forward or change the water manifolding and water pump and thermostat housing to the earlier b35 style. A couple of us here have done this conversion and I'm sure we'd all be glad to give advice. Good luck,Leroy

 

[E9 3.0CSi]

Thank you, M5. I don't know what we'll do about that yet, but thanks for the info. Will the cooling-performance suffer if we switch to the earlier version?

 

[x_atlas0]

Okey, thanks for your time. I think we'll go with the S38, seems to be a far more attractive option. Modifying the firewall ain't much of a problem, and getting our hands on a 265 won't be too hard. Should we also change the brakes to something bigger? Will E34 M5 bolt right on?

Best regards and thanks.

Bjarne Cox

The stock stoppers will already easily overrun any tires you can put on without rolling and tubbing. Bigger brakes won't help much. Heck, the stock brakes are similar in setup to the E34 M5 brakes; 4 piston up front, 2 piston in the back. Stainless lines and DOT 4 fluid are a good change, though.

Cooling performance with the E9 is, in general, pretty poor. At the same time, the gauge isn't heavily damped, so the needle readout actually shows what the temperature is like, unlike in more modern cars. Switching to an AC radiator or a 3-core rebuilt unit is a good idea. As I recall, the AC radiator is ~30% thicker than the non-AC one, based on what I remember when I switched mine over. It does make for a tight fit if you stick with the mechanical engine fan.

 

[rb1971]

Just finishing up a resto where we did this mod.

We didn't have a firewall issue, and changed to an electric fan and new radiator so didn't have a clearance issue there. But we did have to get a custom oil filter hookup, and change the brake booster (we went with a hydraulic booster from an M1 but there are other solutions). I used a custom engine mount from Koala (Brett is a great guy) - I've heard other folks say these will bolt right up but that was not my experience.

Another issue is the intake. A lot of folks just run a K&N or similar sitting in the engine bay, but I had a good welder make a metal box similar to that used on modern M cars running to an intake just behind the left hand lights, and then down behind the airdam just like Dinan did up until recently. The pressurized intake looks great.

 

[rb1971]

Re the brakes, I went with the Wilwood front brake kit but agree that the car already has good stopping power in stock form.

 

[E9 3.0CSi]

Thanks for the info all. I think we go with the stock brakes but we'll maybe have to change some cooling components.

Kind Regards.

Bjarne Cox.