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Who's running a 1.8L head, 2.0L block, & L-Jetronic??


Mucci
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I just picked up a 1.8L motor with harness and ECU from an '85 318. I'm thinking of doing a mild NA motor build: 1.8L head, 2.0L block and the L-Jet conversion.

 

For those who have done this I'm wondering what kind of issues you encountered. 

- Does the 1.8L head bolt right to the 2.0 block without issue?

 

Also curious what kind of power/torque can be expected from this setup with all stock internals?

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On 12/21/2020 at 12:17 PM, Mucci said:

- Does the 1.8L head bolt right to the 2.0 block without issue?

It will if flat top pistons are used, other configurations may have issues. 
The  1:8L  distributor runs in opposite direction as well due to 1:8L cam gear  being cut opposite.

 

Have an 85 318i donor car but like you,  have not actually started yet but have researched it. preparing a fresh 2L short block for it at the moment

Edited by tech71
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10 minutes ago, tech71 said:

It will if flat top pistons are used, other configurations may have issues. 
The  1:8L  distributor runs in opposite direction as well due to 1:8L cam gear  being cut opposite.

 

Have an 85 318i donor car but like you,  have not actually started yet but have researched it. Building up a fresh 2L short block for it at the moment


Are the OEM 2.0L pistons flat top?

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I once put E30 1.8 fuel injection system to 2.0L engine (121 head). Worked just fine without any messing with f/injection fueling (air meter).

 

You’ll want some CR to make most of it. Assuming that there is some domed pistons in your current 2.0 engine that is. Flat pistons with 1.8i head won’t give much cr = no smile. 

 

 

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1 hour ago, Mucci said:


Are the OEM 2.0L pistons flat top?

Not all by a long shot, there are a few different 2002 M10 engine heads out there.

121, E12 and E21 2.0 are the most common, all will physically bolt to an M10 block but each has a different shaped combustion chamber and piston to fit. Mixing and matching pistons and heads aimlessly can result in engine damage.

 

Welcome to the journey, here's a good starting point:

 

And another:

 

https://www.bmw2002faq.com/articles/technical-articles/engine-and-drivetrain/converting-to-318i-electronic-fuel-injection-r37/

 

 

Edited by tech71
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Don't some (most/all?) of the 1.8L heads have the fuel injector ports directly in the head, rather than in the manifold? Something to at least double check/keep in mind.  Also - not going to pull punches here - if you're going to bother going through the effort of fuel injecting a car, just skip right over the all the Jetronic systems.  They're really a pretty crappy implementation of EFI.  Learn a little bit and go with Megasquirt or Haltech or something else similarly modern/effective/tune-able/simple/meant for this type of classic upgrade.

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8 hours ago, AustrianVespaGuy said:

  They're really a pretty crappy implementation of EFI.  Learn a little bit and go with Megasquirt or Haltech or something else similarly modern/effective/tune-able/simple/meant for this type of classic upgrade.

 I wouldn't say crappy, it was what it was for the period and available tech and it works. My donor car starts quick, idles smooth and runs good. It's too bad the car itself is so thrashed.

 Yes, it is a rudimentary system by todays standards but.... Baby steps dude!  And it's all in the barn and paid for😉

And ouch, my learning is up for either thanks.

 

 

Edited by tech71
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You mentioned 1.8L head with 2.0L block. What exactly do you mean by that ?

The 1.8L you are referring to has the same block and bore diameter (89mm) as the 2.0L.

The difference is in the crankshaft. The 1.8L you are referring to has the short stroke (71mm) crankshaft while the 2.0L has the long stroke (80mm) crankshaft. You can use the same block to build either a 1.8L or 2.0L, just depends on what crankshaft you choose. While the pistons are the same bore the pin to deck height is different for the  71mm short stroke motors vs. the 80mm long stroke motors. The pistons are matched to either of the crankshafts. You can't mix 1.8L and 2.0L pistons because they have different pin to deck heights. Furthermore, each style head had a different combustion chamber design. You can only use the pistons designed for that specific combustion chamber. As far as the rods, they are all the same for all M10 motors.

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7 hours ago, AustrianVespaGuy said:

Don't some (most/all?) of the 1.8L heads have the fuel injector ports directly in the head, rather than in the manifold? Something to at least double check/keep in mind.  Also - not going to pull punches here - if you're going to bother going through the effort of fuel injecting a car, just skip right over the all the Jetronic systems.  They're really a pretty crappy implementation of EFI.  Learn a little bit and go with Megasquirt or Haltech or something else similarly modern/effective/tune-able/simple/meant for this type of classic upgrade.

If you’re willing to foot the bill I’d be happy to buy a megasquirt system and have it installed and dyno tuned. 

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7 hours ago, tech71 said:

Not all by a long shot, there are a few different 2002 M10 engine heads out there.

121, E12 and E21 2.0 are the most common, all will physically bolt to an M10 block but each has a different shaped combustion chamber and piston to fit. Mixing and matching pistons and heads aimlessly can result in engine damage.

 

Welcome to the journey, here's a good starting point:

 

And another:

 

https://www.bmw2002faq.com/articles/technical-articles/engine-and-drivetrain/converting-to-318i-electronic-fuel-injection-r37/

 

 


Great info, thanks for passing it along!

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13 minutes ago, Slavs said:

You mentioned 1.8L head with 2.0L block. What exactly do you mean by that ?

The 1.8L you are referring to has the same block and bore diameter (89mm) as the 2.0L.

The difference is in the crankshaft. The 1.8L you are referring to has the short stroke (71mm) crankshaft while the 2.0L has the long stroke (80mm) crankshaft. You can use the same block to build either a 1.8L or 2.0L, just depends on what crankshaft you choose. While the pistons are the same bore the pin to deck height is different for the  71mm short stroke motors vs. the 80mm long stroke motors. The pistons are matched to either of the crankshafts. You can't mix 1.8L and 2.0L pistons because they have different pin to deck heights. Furthermore, each style head had a different combustion chamber design. You can only use the pistons designed for that specific combustion chamber. As far as the rods, they are all the same for all M10 motors.


ah, I wasn’t aware the .2L was made up simply in stroke. 
 

What I’ve got in the garage is a ‘75 M10 from my 2002 and now a ‘85 M10 with L-Jet from an E30 318i. 
 

I’m simply trying to assemble the best combination of parts from the two for a NA setup. 
 

From my research so far it’s sounding like the 2.0L bottom end mated to the E30 318 head is the best setup. Larger displacement and a better flowing head with larger valves and better ports. 
 

I’m also leaning towards bumping CR to 9.5:1, doing a bit of porting and getting something like a 292 cam. Maybe an overbore if it’s not too costly. 
 

My goal is around 140-150 NA hp

Edited by Mucci
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34 minutes ago, Mucci said:

My goal is around 140-150 NA hp

Thats a big increase (40 to 50%) and may be difficult(if not impossible) to achieve using LJet.  It does have limitations on fuel delivery and is not programmable.

I myself am hoping for a more modest 10 to 15% increase from my project engine.

 

Edited by tech71
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12 hours ago, tech71 said:

And it's all in the barn and paid for😉

Well that's certainly a valid point.  If you already have it and it works, then no need to sink extra cost unnecessarily!  But I still defend my opinion that Jetronic is not great.  Ok CIS was worse, but the Jet still uses the big dumb AFM 'flapper' in the airstream to try to measure intake oxygen, which suffers from being rather inaccurate, slow to respond to actual engine load, and non-adjustable.  This would be my biggest concern with trying to match the system with a larger stroke 2.0L build especially in combination with better pistons/cams; the electrical response from the AFM is very non-linear so if you increase the airflow much beyond the level for which it was designed, the ECU may or may not be able to interpret/fuel things appropriately anymore.  Though I suppose it's easy enough to try and see!  And if you make a really hot motor, then it might also be possible to use the larger AFM from the 325i.

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