Heart of My E9

WISE9UY

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Hi All,

My journey has begun and it is now time to choose the engine for my 2800CS. The previous owner already put in a 3.0 with twin Weber conversion and 4 speed manual so there is no loss of originality.

Having recently acquired some E24s, I have the following options:
M30B32 with about 175psi average compression (less than 5% variance per cyl)
M30B34 with about 165psi average compression (less than 5% variance per cyl)
M30B32 with Callaway C1 turbo conversion with about 135psi average but slightly higher variance. I expect this car has lower compression pistons / head.

With many having gone down the road of engine conversion, what is your insight opinion? I like the idea of the Callaway for something different, but equally, do I need that added power that ultimately comes with more to go wrong?

The second item is, of those that have made this choice, what is the preference? Jetronic or Motronic? Both the 3.3's are Jetronic.

The final question, with regards to fuel delivery, for those that converted from carb to injection, what changes were necessary in terms of fuel lines?

Cheers!
 

WISE9UY

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any changes in your list to suspension or brakes ?
is the four speed a zf or a getrag ?

I guess the focus of this thread was on the engine, but here are some anwers :)

Brakes will hopefully be E34 all round pending confirmation that the calipers will fit. I have E24 series II calipers to play with to check fitment because I have seen that series II E24's can be upgraded to E34 as a straight swap. At minimum I have vented disc all round from my series I E24

Suspension will all be renewed and I will likely be running H&Rs with a 40mm drop combine with Bilstein sport shocks.

I have three four speed boxes lol but will be going with either a 5 speed dogleg Getrag 245 or an overdrive G245 together with a 3.05 LSD.
 
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WISE9UY

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So I was looking for threads on engine selection and found my own thread from just over a year ago wow...

A few things have fallen into place such as choice of driveline, suspension and brakes. The suspension will be ground control coilovers; brakes will likely be 3.0CS vented disc all round (but I will investigate the larger E34 caliper option for the front) and the drive line will comprise a Getrag 265/5 (OD) mated to a 3.64LSD. But the motor selection is still up for consideration. Here are my options:
- M30B32US with about 175psi average compression (less than 5% variance per cyl)
- M90
- M30B32US with Callaway C1 turbo
- M30B35

I have seen positive comments on the B35 owing to the Motronic 1.3 engine management, which is apparently the one too have. The donor vehicle for this would be a 1990 535i.

The Calaway Turbo was a nice proposition BUT I just don't crave that type of power in my E9 as 200hp (plus minus) is more than enough. It already gets along very well with the carburetted motor but I would like the refinement and efficiency of fuel injection.

So yes, open to any feedback!
 

Wladek

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I guess the focus of this thread was on the engine, but here are some anwers :)

Brakes will hopefully be E34 all round pending confirmation that the calipers will fit. I have E24 series II calipers to play with to check fitment because I have seen that series II E24's can be upgraded to E34 as a straight swap. At minimum I have vented disc all round from my series I E24

Suspension will all be renewed and I will likely be running H&Rs with a 40mm drop combine with Bilstein sport shocks.

I have three four speed boxes lol but will be going with either a 5 speed dogleg Getrag 242 or an overdrive G242 together with a 3.05 LSD.
You probably meant 5-speed Getrag 262 CR (dogleg) or 265 OD, and 3.07 LSD?
If you want to put 3.07 diff with 5-speed you should go wit 3.5 engine, if 3.2 then change diff ratios to 3.25 or better 3.45.
 

WISE9UY

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You probably meant 5-speed Getrag 262 CR (dogleg) or 265 OD, and 3.07 LSD?
If you want to put 3.07 diff with 5-speed you should go wit 3.5 engine, if 3.2 then change diff ratios to 3.25 or better 3.45.

I have updated my original post that you refer to. I was not as familiar with the designations at that time. It is my most recent post from 2:30am today that is relevant as I have decided on the 265 OD with the 3.64 diff. My motor choices are now:
- M30B32US with about 175psi average compression (less than 5% variance per cyl)
- M90
- M30B32US with Callaway C1 turbo
- M30B35
 

twistinglane

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Maybe depends on the condition of the M90 and B35? Have them available or will need to find? For people who are not motor nuts, the more available and known B35 may have appeal. M90 may lead to more electronics work for Motronic conversion too. But if you have access to good M90 and want something a bit out of ordinary why not!
 

WISE9UY

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The M90 is very tired so will need a full rebuild, but I can readily buy an M30B35 engined car with reasonable miles for up to 5k. The cost of rebuilding the m90 would be as much as that and then will present engine management issues versus what will likely be the most refined (being the latest) version of the m30 - the B35. Hrmm... am I subliminally deciding on the B35? With 208HP and 305NM torque that should be enough for a non-racing E9.
 

Layne

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L-jet is truly awful and should not be considered. Motronic 1.1 is a quantum leap ahead, but Motronic 1.3 is far better still. (That's the injection from a B35 engine). You should retrofit it even if you go with any of the engines above, but if you can get the whole B35 easily, just do that. Ideally, you'd put 10:1 pistons into the B35 and that would pretty much be the ultimate M30.

As for the fuel pipes, you need to add a second one all the way from the back. I used steel pipe like original and ran it alongside the original. Some more details in my thread "72 Restomod". Probably impossible to do that without removing the rear subframe.
 

Kizilsakal

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I would say since you are changing the engine, maybe making the move to an aftermarket modern standalone engine management (megasquirt, haltech, vi-pec, aem....) is logical.
They would give you a lot of freedom, very good performance, efficiency and reliability. also if you change things later on just need to re program that's all.
 

autowerks

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you may want to consider side drafts, adds HP, your car will be quicker, the sound when you push the throttle is just amazing and gas is cheap.
 

WISE9UY

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Some great feedback thank-you!
@Layne thanks for the link to your build. That will be helpful. Equally interesting to hear the view on L-Jet... what makes it so horrible just wondering?

@Kizilsakal I have seen discussions on going for Megaquirt etc and somehow would rather keep everything stock. Bolt out and bolt in is a nice path given that I am not chasing performance mods, but I take your point that we never know what the future holds so at least then the car is ready for that.

@autowerks Funny you mention the carbs. Right now the car has twin down draft Webers and the car is no slouch. I agree that the throttle sound is nice and also more responsive than electronically managed M3o's. Gas really isn't the focus as the car is not driven daily but I do crave the nice refinement of full engine management. Conversely, with the mechanical pump, distributor with points and all else being simple tech, there is great confidence in never breaking down!

When considering the B35, my plan would be to just purchase an entire decent car and transplant the lot. Finding those candidates is not yet too bad because those are still cheap.... I will just be hated by some when I will have to gut a nice example of whatever it would be.
 
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