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

[MitchaPaLoOza88]

15 hours ago, AustrianVespaGuy said:

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.

 

Being an Ex-Saab guy. The K-Jetronic would be Krappy, the L-Jetronic is Less crappy. 

[Mucci]

2 hours ago, AustrianVespaGuy said:

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.

There’s lots of documentation on converting to a MAF sensor instead of the barn door. I remember that from my E30 days. Back then there was a company called WAR I think that made conversions with programmable software for a few hundred. 
 

I believe I remember you can “chip” the L-Jet ECU with a custom map too... is that not correct? 

[AustrianVespaGuy]

2 hours ago, Mucci said:

There’s lots of documentation on converting to a MAF sensor instead of the barn door

I didn't actually know about that, but that would indeed be a really excellent upgrade to the system!  MAF > MAP > AlphaN > AFM, so that'd basically leapfrog from the bottom of the pack straight up to the top!  As for chips, there's a lot out there but I think the majority of them mostly just adjust the ignition advance table but the fueling is a bit limited by the factory narrowband, meaning your either stuck with its feedback or you ignore it and *hope* the fuel table is correct for your engine setup -> Generally fine for a stock engine but again once you've changed stroke and cams around, a bit less sure-fire. Another point where the engine management systems with wideband feedback have an advantage.  Full disclosure, I've Megasquirted both my 2002 and E30, meaning I both know my way around EFI conversions and am unashamedly biased!

[PatAllen]

fwiw combustion chamber of the late 1.8i head wont match hi cr pistons of a 2.0 motor. if you run flat tops its ok then but you get low cr in the range of 8:1. maybe good for low psi turbo set up

 

hth

[Mucci]

1 hour ago, PatAllen said:

fwiw combustion chamber of the late 1.8i head wont match hi cr pistons of a 2.0 motor. if you run flat tops its ok then but you get low cr in the range of 8:1. maybe good for low psi turbo set up

 

hth

Yea I came across that in my research recently. I also thought the 318 head had larger valves but apparently they’re the same size as the late E12 head (according to RealOEM). 
 

If the only 318 head benefit is better flow I’m thinking it might be better to stick with the E12 head, port it and stick a cam in. Then I don’t have to deal with matching pistons or reducing the CR. 

 

What’s the cheapest way to get 9.5:1 with the E12 head? Looks like the $600 IE cast pistons are only for the 121 head. If the only way is spending close to $1k I’ll probably skip that and put it towards future boost. 
 

 

[Mucci]

On 12/22/2020 at 10:07 AM, AustrianVespaGuy said:

I didn't actually know about that, but that would indeed be a really excellent upgrade to the system!  MAF > MAP > AlphaN > AFM, so that'd basically leapfrog from the bottom of the pack straight up to the top!  As for chips, there's a lot out there but I think the majority of them mostly just adjust the ignition advance table but the fueling is a bit limited by the factory narrowband, meaning your either stuck with its feedback or you ignore it and *hope* the fuel table is correct for your engine setup -> Generally fine for a stock engine but again once you've changed stroke and cams around, a bit less sure-fire. Another point where the engine management systems with wideband feedback have an advantage.  Full disclosure, I've Megasquirted both my 2002 and E30, meaning I both know my way around EFI conversions and am unashamedly biased!

Well after more research I was a bit off. 
 

The “tunable” / removable chip ECU I was used to is Motronic, not Jetronic. However there are still MAF conversion options - one from Split Second for about $350 not including the MAF. Looks like this doesn’t touch ignition, just AFR. 
 

There’s also the conversion to Volvo LH 2.2 EFI which is more tunable and uses a MAF sensor. Some good threads on that via search. 
 

However the route I’m now leaning towards is MICROsquirt. For about the same cost ($388 w/ harness) it offers much more flexible tuning rather than trying to trick the Jetronic. Also supports MAP, MAF, and Alpha-N. I’ll use all the 318 parts since I’ve already got them, wire in the Microsquirt and maybe add some 24# injectors and be off on my quest for 150hp!

 

In regards to “MAF > MAP” I’d be curious to hear why MAF is preferred. 
 

According to Haltech (and maybe this is specific to their Elite 550 software) MAP w/ IAT > MAF:

 

”The benefit is you are not limited to the air flow the MAF can read when using speed density, or trying to get the calibration correct for the MAF you want to use and having to recalibrate it anytime you change anything with the intake side of the car.”

[tech71]

1 hour ago, Mucci said:

What’s the cheapest way to get 9.5:1 with the E12 head? Looks like the $600 IE cast pistons are only for the 121 head. If the only way is spending close to $1k I’ll probably skip that and put it towards future boost. 
 

I dont think there is a "cheap" way anymore.  New Mahle high piano tops are still available but will easily run $1000. Appear to be in 2nd oversize and then there's boring the block.

Finding a decent 121 head  to use with the IE pistons may be cheaper.

 

https://www.wallothnesch.com/en/piston-2002tii-89-47mm-0-5-with-e12-cylinderhead-you-need-4-for-1-car-11-18-01.html

 

Another option would be the (still available for around $600) Mahle 10:1 bathtubs in 3d oversize ( a full mm)  You want power? Bore that sucker to max and run these with 121 or 121ti head and appropriate  camshaft-fuel delivery system.

Lots of sources for these including Maximilian.

While your at it, lighten your flywheel and switch to single row, new timing chain and sprockets.

3d option is to go low and blow

Edited December 30, 2020 by tech71

[jimk]

1 hour ago, Mucci said:

According to Haltech (and maybe this is specific to their Elite 550 software) MAP w/ IAT > MAF:

 

”The benefit is you are not limited to the air flow the MAF can read when using speed density, or trying to get the calibration correct for the MAF you want to use and having to recalibrate it anytime you change anything with the intake side of the car.”

Where is this stated on the Haltech site, I've never seen it before.

Select a MAF of the appropriate capacity and this statement is bogus.  Get the calibration curve for the MAF and there is on "trying to get the calibration correct".  It's a matter of doing your homework before hand.  And re-map is necessary when using a MAP sensor whenever anything is changed on the intake side of the car because the MAP reading no longer represents the same air flow as before any intake side modifications.  

[AustrianVespaGuy]

3 hours ago, Mucci said:

What’s the cheapest way to get 9.5:1 with the E12 head? Looks like the $600 IE cast pistons are only for the 121 head.

Well IE *used* to sell 9.5:1 cast pistons for E12s, so might be worth calling and asking them, however poking around on their website also suggests you can get custom forged pistons from them for only $650 so. . . yeah that's probably what most people looking for new pistons should just do, right?

https://www.iemotorsport.com/product/forged-pistons-m10/

3 hours ago, Mucci said:

In regards to “MAF > MAP” I’d be curious to hear why MAF is preferred.

As far as this goes, I'll try to break in down in a fairly simple way to make the trade-offs clear.  With EFI, the whole idea is to make sure to inject the *right* amount of fuel to properly burn with the amount of oxygen in the combustion chamber.  But figuring out exactly how much oxygen is in there is a bit tricky, because even though the VOLUME of the cylinder is constant, the amount of oxygen in that volume changes all over the place with throttle, temperature, elevation, etc.  So the various options for how to calculate this are:

 - AFM - measures how much air volume is flowing past it.  But still needs temperature to better calculate the density, doesn't really cover ambient pressure changes due to elevation, and it's pretty far up-stream from the combustion chamber.  Oh and it's really just a flapper door in the airstream connected to a potentiometer so correlation between that resistance reading and actual oxygen content is. . . pretty piss poor.

 - Alpha-N - this just uses the throttle position (from a TPS sensor) to estimate how much air is entering the engine at a given throttle position.  So super simple but obviously not very exact either.  External temperature and pressure sensors can 'help' refine the calculation, but it's still really just an educated guess.

 - Speed Density - this uses the air pressure in the intake manifold (MAP = Manifold Absolute Pressure) for the calculation.  It's also pretty easy since it just takes one vacuum line going to a pressure sensor, captures pressure changes due to altitude, and is the SAME environment that the cylinders see. But it also still needs temperature data to really finalize the oxygen calculation.

 - Mass Air Flow - aka MAF, and as the name indicates DIRECTLY measures the MASS of the incoming air.  And this is exactly what you want, not 'adjusting' for temperature, pressure, whatever; its just the pure kilograms of oxygen going into the engine, divided by the number of cylinders, and DONE.  There is a small drawback though, and that is that the electrical response of a MAF sensor has both a limited range and is very non-linear.  This means it does need to be sized properly for the engine (so that the airflow is neither too fast nor too slow to get a good reading), and the engine management system needs to be able to accurately 'understand' the non-linear input response.  But get these things right and you understand why all the OEMs do it that way: it directly measures what you need to know for proper fueling!

Edited December 31, 2020 by AustrianVespaGuy
link

[Mucci]

2 hours ago, jimk said:

Where is this stated on the Haltech site, I've never seen it before.

Select a MAF of the appropriate capacity and this statement is bogus.  Get the calibration curve for the MAF and there is on "trying to get the calibration correct".  It's a matter of doing your homework before hand.  And re-map is necessary when using a MAP sensor whenever anything is changed on the intake side of the car because the MAP reading no longer represents the same air flow as before any intake side modifications.  

 

It was an email response I got from their tech support when inquiring about ditching the AFM.

@AustrianVespaGuy AH! That makes it all very clear. Thanks for laying it out.

 

Also, oops, I must have misremembered but I thought the IE forged pistons were $1k+. $40 more for forged pistons over cast sounds quite worth it. 

 

$650 is still quite a chunk so I'll have to decide whether I go that route or stay with the flat tops and save for boost down the road if the planned NA setup isn't quite punchy enough. 

 

I'm currently thinking:

 

• E12 head - ported w/ 292° cam
• IE long tube headers and Ansa Sport exhaust (already on the car)
• MICROsquirt with MAF
• 24# Injectors
• Pertronix ignition (on the car)
• Full gasket & seal refresh incl. rings & bearings along with whatever else is worn that I come across. 

 

I'd be stoked if I can get near 150hp with that setup and don't have to do pistons or boost but not sure that's possible. There are some very variable results in the dyno thread. 

 

...speaking of ignition, since I have the 318i sitting here, is there any benefit to running that distributor with the matching 292 cam instead of the Pertronix that's already in the 2002 motor?

 

 

 

Edited December 31, 2020 by Mucci

[Son of Marty]

IMHO  at your level of tuning you will make more hp for your dollar by skipping the porting on the head, BMW really did a good job there, and putting that money into higher compression  pistons, at this point your old pistons and bores passing as good is somewhat marginal anyway.

[tech71]

1 hour ago, Mucci said:

 

...speaking of ignition, since I have the 318i sitting here, is there any benefit to running that distributor with the matching 292 cam instead of the Pertronix that's already in the 2002 motor?

Wont work, the 318i camshaft distributor gear is cut opposite. The 318i distributor turns opposite.

To get a 318i dizzy to work in an E12 head you would have to swap cams.

[AustrianVespaGuy]

Your plan sounds pretty good but since I've already thrown in my 2 cents on this thread here's another nickel's worth:

2 hours ago, Mucci said:

MICROsquirt with MAF

I wouldn't start with MAF; do either speed-density or Alpha-N first because it's easier/less parts to get up and going, and then do a MAF upgrade once you know your way around the whole EFI thing a bit and can plan it out properly.

 

2 hours ago, Mucci said:

Pertronix ignition (on the car)

Ok to start with, but once you've got Microsquirt in and working it's quite trivial to have it control the coil directly. I'd do this (and possibly wasted spark or COP) even before changing to a MAF. Plus if you go this route distributor/petronix/etc. choice will no longer matter as MS will be handling everything. (Chanting: "Wasted Spark! Wasted Spark!")

 

2 hours ago, Mucci said:

I'd be stoked if I can get near 150hp with that setup and don't have to do pistons or boost but not sure that's possible.

The old flat-top pistons won't get you there but the above coupled with new 9.5 or 10:1 pistons WILL!

Edited December 31, 2020 by AustrianVespaGuy
pistons

[Son of Marty]

I'm with AVG on the distributor pertronix of bosch will get you going but you'll still lack adjustability with out pulling the distributor and having it recurved, I'd go with a reprogrammable system as soon as I could.

Edited December 31, 2020 by Son of Marty

[Mucci]

4 hours ago, AustrianVespaGuy said:

Your plan sounds pretty good but since I've already thrown in my 2 cents on this thread here's another nickel's worth:

I wouldn't start with MAF; do either speed-density or Alpha-N first because it's easier/less parts to get up and going, and then do a MAF upgrade once you know your way around the whole EFI thing a bit and can plan it out properly.

 

Ok to start with, but once you've got Microsquirt in and working it's quite trivial to have it control the coil directly. I'd do this (and possibly wasted spark or COP) even before changing to a MAF. Plus if you go this route distributor/petronix/etc. choice will no longer matter as MS will be handling everything. (Chanting: "Wasted Spark! Wasted Spark!")

 

The old flat-top pistons won't get you there but the above coupled with new 9.5 or 10:1 pistons WILL!

Ahh, maybe I missed that in the microsquirt description, I didn’t realize it could control ignition as well. Sounds like that’s the best route. 
 

So dizzy hole gets plugged somehow and I’d need a CPS?

 

Thanks for all the details!