1972 3.6csi (now 3.6CS)

[julianCS]

Hello everyone,

here is my project. Nearly 2 years ago I bought a very good 72 CS bare shell that sitting in a barn for like 20+ years with a bunch of parts. I had no idea what I want to build.

My first idea was a complete restomod with M62b44 engine, zf s5d gearbox from e36m3, ITB setup, standalone ecu, MK60 abs, R&P steering, custom rear suspension with strut towers, e24/e28 rear end, LSD, rear bracing, some underside bracing, stitch welded chassis and some other goodies.

Engine and gearbox was already adapted to the Car, engine mounts fabricated, transmission tunnel enlarged and custom brake linkage for E32 Brake booster.

Then after driving a v8 swapped e30 I found this engine not so suitable for e9 chassis. So I removed it and sold it.
Also get away from custom rear strut towers (don’t want to cut out all of the perfect parts, if I had rust i would consider this more). So I went back to oem rear end but with rear coilovers and some bracing inside trunk to support towers and add stiffness also to differential area.

Now I will continue with some straight 6 engine. S54 and S38 was in the selection. At the end, I found the s38 a little more interesting, because I already had previous 2 e46 m3s with the s54 (a piece of finest engineering btw!, but had never a car with m88 or s38.
So I bought a S38 3.6 with getrag 5 speed from E34m5 last week.

Engine is already in. Straight drop in without any issues. Only small cut at the framerail for the thermostat housing. Made the M62 installation look like a real nightmare.
The transmission bracket I had fabricated for the M62+zf s5d does also fit by surprise this gearbox.
Radiator is a Mishimoto e36 m3 (famous in e30 scene for engine swaps), I cut out a part of the left box, welded 2 brackets to hold in place and it fits very nice with maximum cooling area.

not sure about the plenum, i think i will add some nice looking (and sounding) CNC’d velocity stacks.

will do a full engine rebuild when the car is at the paintshop in a later step of the project. Some parts for this engine are a pain to buy for a reasonable price.

also made a brake setup.

I will complete everything engine related, until August when the KW custom suspension(1 year waiting time) should arrive and I can continue with rear end installation and R&P geometry,

Very very much to do and the progress is so slow. Motivation is also a problem from time to time, when you see no “results”. This is my first project that is nut to bolt.

 

[daicos35]

Looks fantastic. Could you provide us with more information on the rear coilovers please?

 

[julianCS]

Yes, sure I can put some photos online as soon as I have the coilovers.

just for completion: Front are e9 spindles where i tig welded speed sensor brackets and used E24 wheel hubs to accept wide range of brake discs. I shrinked reluctor rings on those. Fronts will have kw topmounts and a different spring setup than V3‘s to accept bbs rc035.

On rear i measured what will fit in there and made a drawing that I handed to KW to build a custom Competition 2A coilover for the rear. I stealed some parts of the kw clubsport for the G-Modell RSR(?) Porsches. look it up on Google if you want to get a idea of how it will look.

Some serious bracing and reinforcing is required in the trunk area to take all the load from the coilovers. Especially when driveline is stiffer with harder damper characteristics and stiffer sway bars.

No perfect welding skills, but it will do the job.

 

[daicos35]

that is so interesting... i will be intrigued to see how it turns out.. the custom rear kw coilover set up sounds great.. i know they have been flirting with doing this for the E9, yours may be the blueprint!!

cheers< mike

 

[julianCS]

This was my first rough idea for rear tower/diff support support. The red plates will be welded onto the towers, rest is screw on. But I will change the upper connecting point from the main tube to a different point or make it stiff and not with a bolt. Because in this configuration it will not take the load correctly. Maybe also change the diagonal tubes from welding to the main tube, to a bolt connection like the main tube. Then I would be able to add in the middle of the tube a thread to give it some preload.

Any input or ideas are always welcome

 

[x_atlas0]

Julian-

What didn't you like with the E30 M6X? I drove E34/E39 540s for ~10 years, and I really like the drivetrain. I was considering it for my E9 too, since my M30 is somewhat tired.

 

[julianCS]

Mostly the instant huge amount of torque in the whole rpm band. I don’t think the chassis will like this. As this makes fun to push around a stiff e30 and going from cruising to sideways without downshift is really incredible, but coming from high revving S54‘s I like the 6 cylinder characteristics a bit more on lighter cars.

And the required work for M6x swap is huge, key points are gearbox tunnel, oilpan, steering rack and brake booster..
The solution I made for brake booster, worked well but was in the end not good/perfect enough for me.

 

[julianCS]

So…the project going slightly in a different way. Removing the „i“, it will be more a 3.6CS than a CSI. So I ordered something an these beauties arrived yesterday.

In fact this is a technically downgrade for the S38, but I think it will suit the E9 just perfect and I never had carburetors in my cars. In worst case, going back to ITB/EFI is a very easy task, so I will try it.

Still waiting for the coilovers to continue with the bodyshell, KW confirmed production and delivery in August.

 

[nosmonkey]

Some really interesting ideas being implemented into this project. Very much looking forward to the progress of this build, keep the content coming!

 

[daicos35]

I like it!! I have an M30B35 bored and stroked to a 3630cc off top of my head, with triple sidedraft webers, mechanical advance electronic distributor.

You mostly lose a bit of refinement and fuel economy, but you def dont lose any power.

Question is how you will adapt a manifold (I use a kormann 1 piece), and use of an old school distributor, or programmed individual coil, pick up off harmanic balancer? etc etc (they would smooth it out a bit, bring back some more modern refinement).

What compression did they run that engine at?

Fyi, had mine tuned and jetted, have neot had a single tune problem in 10 years.

Other tip would be to remove the chokes all together. they tend to cause the tune issues.. are they electric, are they fed off coolant, all those added complications,,, A bit stumbly as the engine warns up, but no issues at all.

 

[julianCS]

The carburetors are 50‘s Race carbs.
So no choke - no problems. At least „this“ specific problem… it will be only driven in good weather.

Compression is 10:1, 100% stock at the moment. Maybe schricks later.

Ignition distributor is currently sent to 123 ignition to see if they can build their stuff in it. Could be interesting because late m30 use the same ignition.
If they can’t build one, I will use the oem distributor. And plan C, if the car doesn’t run good enough: VW VR6 coilpack with programmable ecu and crank/cam pickup.


There is no adapter on the market available for s38. I made some drawing on CAD. I will print the manifolds with cheap PLA and the look how they fit. If all good, I search for a company/quote that can 3d print them in metal. Otherwise it will be a 5 axis cnc job, also not cheap. We will see….

For throttle actuation, I would drive the 2 outer carbs directly from shaft of the middle one with adjustment screws (to synch them). Most setup I see are driven from a shaft above the carbs.

 

[Ohmess]

Stevehose and I both run out triple Weber setups with "intercouple" throttle linkages like the one you are describing. Here is mine:

As to intake manifolds, have you looked at DBlias? I think that is what is pictured here:

https://e9coupe.com/forum/threads/bmw-m90-questions.40073/post-358706

 

[julianCS]

Stevehose and I both run out triple Weber setups with "intercouple" throttle linkages like the one you are describing. Here is mine:

View attachment 145710


As to intake manifolds, have you looked at DBlias? I think that is what is pictured here:

https://e9coupe.com/forum/threads/bmw-m90-questions.40073/post-358706

The s38 is 24V head, the available adapters I have found are all for M30 12V head.

One question, is this fuel distribution line selfmade? I hate rubber fuel like on carbs, so I want to make or buy some nice hardlines. I saw on 2002faq pretty one for M10 dual webers.
Link

Welding is no problem, but problem is to find these nice stainless fittings and t-connection pieces to produce one for the triple webers.

 

[Ohmess]

Yes, the hardline was custom made. I bought it with a set of carbs as part of a "kit" the prior owner had put together. Those 2002 hardlines look fantastic.

 

[3moons]

The s38 is 24V head, the available adapters I have found are all for M30 12V head.

One question, is this fuel distribution line selfmade? I hate rubber fuel like on carbs, so I want to make or buy some nice hardlines. I saw on 2002faq pretty one for M10 dual webers.
Link

Welding is no problem, but problem is to find these nice stainless fittings and t-connection pieces to produce one for the triple webers.

Could these be reverse purposed and/or modified to suit your application? Would they allow the use of off-the-shelf Weber to M30 manifolds?

BMW M30 Engine ITB Adapter Plates

Adapter plates to mount the BMW M5 M6 single throttle on an M30 engine. The single throttle can be used by the M88 or S38 engine and then fits on the M30 with these adapters! Plates are absolutely accurate and made of high-strength aluminium alloy! The installation pictures of our customer show...

euroworksperformance.com

- S

 

[nosmonkey]

I would see if you could get the flanges water/laser cut out of some thick ally then have a manifold welded up to suit. A company like DanST engineering could probably do this all for you as they make a lot of itb/bike carb manifolds

 

[julianCS]

I also came across this idea, but I don’t think this will come cheaper than print/milling my own design. And don‘t forget the problem that I have 50 carbs and not 40/45 like usual webers on m30. So the available manifolds are this diameter.

 

[Ohmess]

I also came across this idea, but I don’t think this will come cheaper than print/milling my own design. And don‘t forget the problem that I have 50 carbs and not 40/45 like usual webers on m30. So the available manifolds are this diameter.

Woah. 50s are huge.

 

[julianCS]

Yeah I know, maybe it will be a bit harder for initial jetting of the carbs. The perfect size per calculation for stock s38b36 is 48 webers. OEM intake diameter is 48mm for B36 head and 50mm for b38 head.
But as I didn‘t find some reasonable priced ones, i choose the 50s. I could benefit from them with some cams.

 

[JFENG]

2 outer carbs directly from shaft of the middle one with adjustment screws

That is a good idea for easy synchronization,

but it puts more stress on the center carb throttle shaft. I don’t know the torque threshold, but the shafts can get twisted. This is arguably why the “3rd” carb is actuated directly via its own dedicated throttle linkage arm.

John