How to modify a 318 engine

BMW E30 318i M10 rev limiter

Hello oldi fans,

I have a question about the E30 318i M10 engine:

How does the speed limit work here and how do you override it? Or how do you modify it?

My 318i M10 Kat from February 1985 is completely rebuilt, with absolutely all options of forged pistons, H-connecting rods, 2L crankshaft, nitrided, fine balanced, Hemi combustion chamber, compression 11.5: 1, camshaft 292, titanium plates, Schrick springs, spray oil cooling, S14 Oil cooling ... whatever was possible was done. And it was done very, very neatly. He runs away from a 325 in the sprint without any problems, performance and smoothness are there ... I could be more than satisfied. :)

The only problem: it closes at 6200 tours and goes into the limiter. Exactly where he really wants to go ... and it should. According to the engine builder Bamotec in Nuremberg, 7500 tours would be mechanically zero problem, I have this approval. Now he has 2000km on it and should turn ...

Originally I thought: it has a TSZ ignition and the limit with the short-circuit slide in the distributor finger. And with that one could simply dethrott him. Puff cake!

With that I have brought it from around 5800 tours to 6200. But after that there was no point in tensioning the spring any further, masking it or completely removing the slide in the finger. Even a new distributor finger without this slide does not change anything ... 6200 tours and no more.

So there has to be more than just the mechanical limiter in the distributor. There has to be a second electronic limiter.

There are actually only 2 options:

- is this limiter in the TSZ control module? Because that is shed and cannot be changed from the outside. So there would have to be variants of these modules ... does anyone have numbers? Does something fit from the 6-cylinder? ... then I would have game material there.

- or from the injection control unit. It's a Bosch L-Jetronik, not a Motronic. I once had it open, no CPU, no EPROM, nothing ... purely analog control. Somewhat later variants could be reprogrammed, only there is nothing to change with the program ...

It is also not the injection itself, all exhaust gas values ​​are perfect, nozzles and injection quantity are matched, there is also no pump or flow rate interrupted, it cuts out the ignition as in series production, at least exactly the same behavior as series production or as you are used to from other engines .

But it has to work somehow, at that time DBilas also had the flat slide single throttle on offer ... only you won't find any information about how dethrottling was done in the year 85.

Would be great if someone had information ...

greeting

Martin

Similar issues
18 answers

Made chic, so that you can enjoy it all, there are now four individual throttle connections on the engine (were offered by Alpina). With the standard intake system, the achieved 6200 rpm is the end.

The intake system has also been modified, as has the throttle valve. Fully upgraded, whatever went ... it was done. The throughput is there, all channels are large enough.

Even the now still installed cast elbow is processed ... so properly processed, ned just a bit wishy-washy. There is throughput, but not the last word either.

In a few weeks there will be a complete stainless steel exhaust system in the right size on board ... and it will only be of use to me if it can turn.

I just have to decide whether 6200 tours are the last word ... because I also have a DBilas system there and the A4 from Alpina as a replica. It wouldn't make sense to go to single throttle and then still have such a limit.

I can skip it by (already ...) programming everything myself again with my favorite toy Trijekt ... but that's exactly what I didn't want with this motor project ...

The centrifugal limiter in the distributor finger is only available in non-catalytic converters, otherwise the (further injected, but) unburned fuel would "plague" the catalytic converter.

Kat engines are limited by the control unit (end of fuel injection, ignition does not have to be switched off).

Nice engine that would look good on my 318i too.

As OO - II - OO has already written, the speed is limited by the control unit. There you can't reprogram anything with the L-Jetronic, but you can set the rev limiter up by soldering in an additional resistor.

There is a resistor that is responsible for limiting the speed. You have to find this and solder in another resistor in parallel so that the combined resistance value is reduced. The lower this resistance value, the later the speed limiter comes.

I haven't tested this myself so I'm not sure if it works. I have the information from here and from here. There you can also see that the resistance you are looking for is not in the same place in every E30 L-Jetronic control unit. However, it describes how to find it.

Do you plan to have the 318i tested on the dynamometer? I would be very interested in the result :)

The links are helpful, but unfortunately show the standard non-cat variant in the single-board version. As Kat I unfortunately have the double-decker in there. But then I know in which direction to look. I also have another Kat control unit there ... just to be on the safe side and it's checked / running.

I haven't done the performance test yet. First of all, I wanted to take it easy on him during the break-in period. But it is much better than before and almost cracks the 200 mark, but only almost ... :)

But I can still retrofit something, there are still toys ... fans, exhaust ...

Quote:

@ Red1600i wrote on April 21, 2021 at 7:38:29 PM:

Hello oldi fans,

I have a question about the E30 318i M10 engine:

How does the speed limit work here and how do you override it? Or how do you modify them?

My 318i M10 Kat from February 1985 is completely rebuilt, with absolutely all options of forged pistons, H-connecting rods, 2L crankshaft, nitrided, finely balanced, Hemi combustion chamber, compression 11.5: 1, camshaft 292, titanium plates, Schrick springs, spray oil cooling, S14 Oil cooling ... whatever was possible was done. And it was done very, very neatly. He runs away from a 325 in the sprint without any problems, performance and smoothness are there ... I could be more than satisfied. :)

The only problem: it closes at 6200 tours and goes into the limiter. Exactly where he really wants to go ... and it should. According to the engine manufacturer Bamotec in Nuremberg, 7500 tours would be mechanically zero problem, I have this approval. Now he has 2000km on it and should turn ...

Originally I thought: it has a TSZ ignition and the limit with the short-circuit slide in the distributor finger. And with that one could simply dethrott him. Puff cake!

With that I have brought it from around 5800 tours to 6200. But after that there was no point in tensioning the spring any further, masking it or completely removing the slide in the finger. Even a new distributor finger without this slide does not change anything ... 6200 tours and no more.

So there has to be more than just the mechanical limiter in the distributor. There has to be a second electronic limiter.

There are actually only 2 options:

- is this limiter in the TSZ control module? Because that is shed and cannot be changed from the outside. So there would have to be variants of these modules ... does anyone have numbers? Does something fit from the 6-cylinder? ... then I would have game material there.

- or from the injection control unit. It's a Bosch L-Jetronik, not a Motronic. I once had it open, no CPU, no EPROM, nothing ... purely analog control. Somewhat later variants could be reprogrammed, only there is nothing to change with the program ...

It is also not the injection itself, all exhaust gas values ​​are perfect, nozzles and injection quantity are matched, there is also no pump or flow rate interrupted, it cuts out the ignition as in series production, at least exactly the same behavior as series production or as you are used to from other engines .

But it has to work somehow, at the time DBilas also had the flat slide single throttle on offer ... only you won't find any information about how dethrottling was done in the year 85.

Would be great if someone had information ...

greeting

Martin

OK, to then "disassemble" the engine again!

Can happen...

But then it was fun.

Then I assemble the next one ... the 2.4L M10B24 is already on the pallet, ready for installation. :)

Just out of pure interest, have you ever driven the fuel pump directly via 12V without detours?

Yes, the pump is new, original BMW. Also checked during installation ... and via a manual switch on the fuel pump relay. I can test it manually ... also the flow rate. She managed over 180L at 3.0 bar, that's enough ...

The pump pumps, nothing is missing. And the limitation at 6200 also seems to be a completely normal series, it runs flawlessly. The main wiring harness is also brand new ... 36 years old, but NOS like the rest of the vehicle ...

But this engine only has its maximum power beyond the 6000 ... and that's what I want.

If it were installed by Alpina single throttle and with the usual 300 cam in Race 02, these 2L M10 engines would have around 230-240PS at 7200 tours and go up to 7800 speed end.

With the 318i suction system this is of course a complete illusion, I only have 292 degrees because of the Kat in it. It never has the throughput for it ... but with this processing it should still reach 6800.

And with that, the first 160 hp should definitely be there.

He will. You just have to leave it now. :)

And I can do that. :)

Quote "The standard intake manifold system with curved oscillating pipes and a central throttle valve can only be used for limited increases in performance. The reason: the length of the oscillating pipe is designed for a certain nominal speed, so that it is not possible to exceed this speed (5800 / min) by large amounts and thus not to increase performance. "

Source: Making cars faster, page 357, Gert Hack, Motorbuch Verlag Stuttgart, 16th edition 1987, ISBN 3-87943-374-7

Ooooch, I've been told so much that this or that doesn't work ...

Even if a device says hack ...

This can also be extended by 1-2mm to the kink.

Just like the one from the E21 323i, that is already noticeable.

Small cattle also make crap.

So, operation succeeded.

My 318i anno 2/85 has installed the Bosch 0 280 000 328 control unit, so 1.8i Kat from 9/84 with L-Jetronik ...

The series control unit normally closes and regulates at 6200 tours. But that is not what I want.

The speed-determining resistor has the number "704". It sits on a solder carrier and is individually measured by Bosch.

Today I got a second replacement control unit and made this modification. If you solder another resistor with 470KiloOhm piggyback on the R704, the speed limit changes to 6800 tours. And if you remove it again, it can be dismantled without any problems.

That even fits quite well with the series tachometer of that time, there the really red area starts at around 6800 ... for series engines, not for mine, it can do it without any problems.

So, rebuilt, tried it out, it now regulates squeaky clean at 6800 tours.

I am happy. The driving performance shows a clear improvement. He continues on the track and goes into the 4th gear in the limiter, the 4th is turned out further and is now approaching the 195 km / h mark with 6400 tours. If you go to the 5th, it stops at 5200 tours, so the 5th is still a gentle gear.

Which currently brings him to the performance data of the 320i with about 129PS or makes it comparable. It ran with 6000 tours and 129PS around 197km / h.

However, the six-pack in the draft was clearly weaker than this small four-cylinder, I also had it (i.e. the 320i ...) as a year-old car. Supple and beautiful, but unfortunately very gentle.

Or with the 2002Tii, its origins are also 130PS.

OK, which somewhat cemented the desire for the new exhaust system. A fulfilled wish opens up new wishes. Then I'll be tackling the fan system at GTG soon. And open it for 7200 ... the next 10hp.

So, here are a few pictures from the action :)

It was clear that the engine with the 292 ° sports cam manages the 6800 rpm.

Which power band is specified for this cam anyway?

Is it even worth going to 7200 with the setup?

Remember, high speeds also increase wear.