Dirty m30b34 vs m30b35

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Beemernut
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Dirty m30b34 vs m30b35

Post by Beemernut »

Hi all.

I just did some VIN research on my euro 535i parts car up north, and found that it has the higher-comp "dirty" m30 under the hood (assuming it's original, no reason to believe otherwise). So now I'm quite excited about the potential of that extra 33 horsepower. I bought the car in non-running condition due to a broken ignition tumbler, fwiw.

I searched all over the place and found no real comparison between the 215hp dirty m30 and the 218hp m30b35. Seems the compression ratios are 10:1 vs 9:1 respectively. Is there any particular advantage of one over the other? What components are different? I assume pistons at least? Is one of them easier to extra a little more power from?

Thanks in advance.
Mike W.
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Re: Dirty m30b34 vs m30b35

Post by Mike W. »

The B35 is a slightly more modern engine. Designed, or I should say a light redesign, in part for emissions. The block is functionally the same, the head while it will bolt up to an earlier block, is somewhat different. Slightly larger, 1MM intake valves. Larger intake ports with a different shape, which means the intake manifold is different. Different exhaust manifolds, again, they'll bolt up, but much larger at the opening to the downpipe. The piston shape is different, kind of sculpted with peaks and valleys instead of flat with a small flat dome, all done I'm sure for emissions. In other words it's a better flowing engine which is why they could approach 10:1 HP with only a 9:1 CR. To further complicate things, some places list the euro 10:1 engine as 218 DIN, but only 215 SAE HP, or not far from the B35 output.

To add another level of complexity, BMW has been known to underrate power. E12s went from 176 to 169 when displacement dropped from 3.0 to 2.8, but there was universal agreement that the 2.8 was faster. 3.3s of the same era were listed at 173 HP or 3 less than the 3.0. E28s, 533s were quicker than 535s,but listed with one HP less. M50B25 going to M52B28 and only gaining 1 HP? Really?
Ju@n
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Re: Dirty m30b34 vs m30b35

Post by Ju@n »

Beemernut wrote: Oct 28, 2021 12:16 PM
Just 2 cents
If memory serves, talking DIN, it's 218 vs 211
As a base for more development, B35 should be better, having a better head, intake and exhaust.
Mike W.
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Re: Dirty m30b34 vs m30b35

Post by Mike W. »

Ju@n wrote: Oct 28, 2021 4:18 PM
Beemernut wrote: Oct 28, 2021 12:16 PM
Just 2 cents
If memory serves, talking DIN, it's 218 vs 211
As a base for more development, B35 should be better, having a better head, intake and exhaust.
You might be right, seems like I recall several different HP ratings and part of it might be DIN vs SAE. But there was also a slightly higher compression on a few. 9.2:1 instead of 9.0:1 and I believe it had 2 HP more.

Edit
Thinking more, seems like I've seen 213, 211 and 208 HP ratings. I think the 213 is the slightly higher compression, DIN, the 211 is DIN and the 208 SAE.
vinceg101
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Re: Dirty m30b34 vs m30b35

Post by vinceg101 »

My .01cents:
I think a large factor and difference is that B35's were designed to run off Motronic 1.3 vs. 1.0 that the B34's run off of. It has widely been reported that 1.3 is a much better management system and able to maximize the performance from that era of the M30.
Now it has also been reported that upgrading a high compression B34 to 1.3 is about the best configuration for this motor. No personal experience, but plenty of anecdotal evidence.

Oh, and the high compression B34 was non-catalyzed running off different ECU's which further muddies the waters on this discussion.
Nothintoseeere
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Re: Dirty m30b34 vs m30b35

Post by Nothintoseeere »

The b35 head is derived from the alpina m30 engines. It use alpina combustion chamber shape/volume and the larger inlet valve but not the larger exhaust valve which help power at high rpm only with a alpina camshaft. Not required with the b35 camshaft.

Alpina modified the inlet ports to look more like they do on the b35 head. So think of the b35 head as a mass produced alpina head. The changes really needed a new casting.

Bmw used it because HC emissions where lower and so was nox and CO production because of the lower CR (alpina used a higher CR and still meet NOX emissions criteria with a catalyst) but mostly because combustion is more complete with improved fuel air mixing in the combustion chamber and less fuel falling out of of the air stream in.

That cylinder only gives lower power output when compared to the b34 head due to the lower CR. With higher compression pistons and a camshaft it can become more than the sum of it's parts. Essentially get more air and fuel into the m30b35 engine and it will out perform a modded m30b34 with stock casting.

The engine management system is definitely more sophisticated on the b35. The ecu has ignition timing programmed into it and that is distributed by the rotor (I.e it fully mapable) rather than than the camshaft dictating ignition timing. That by itself does not liberate more power but it makes it harder to modify a b34 engine.

However since you have a m30b34 engine just getting it running with all its horses.

The reason why a 528i maybe quicker than a 530i with a lower powerput is simply due to the torque put pit vs rpm. Peak power does not tell one how quick a car is but how power/,torque with rpm.
Ju@n
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Re: Dirty m30b34 vs m30b35

Post by Ju@n »

Mike W. wrote: Oct 28, 2021 8:17 PMYou might be right, seems like I recall several different HP ratings and part of it might be DIN vs SAE. But there was also a slightly higher compression on a few. 9.2:1 instead of 9.0:1 and I believe it had 2 HP more.

Edit
Thinking more, seems like I've seen 213, 211 and 208 HP ratings. I think the 213 is the slightly higher compression, DIN, the 211 is DIN and the 208 SAE.
That does sound about right, the B35 with different pistons sold somewhere/time in Europe with 9.2 compression is a strange occurrence and lacks documentation :(
Nothintoseeere wrote: Oct 30, 2021 11:15 AMThe engine management system is definitely more sophisticated on the b35. The ecu has ignition timing programmed into it and that is distributed by the rotor (I.e it fully mapable) rather than than the camshaft dictating ignition timing. That by itself does not liberate more power but it makes it harder to modify a b34 engine
Just clarifying here, the Motronic 1.0 on the B34 does dictate when the spark occurs, just like in the Motronic 1.3, there are 2 big differences (probably several more under the covers) between these 2. The first uses simultaneous injection pulses, whereas the second has batch fire. And the first one is mostly fixed (meaning it injects fuel looking up the value in a table, and optionally checking for the narrowband input to add/subtract fuel), while the second one does have "adaptations". Meaning it actually kind of learns where the table is "incorrect" for the engine.
Mike W.
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Re: Dirty m30b34 vs m30b35

Post by Mike W. »

Ju@n wrote: Nov 01, 2021 9:44 AM
Mike W. wrote: Oct 28, 2021 8:17 PMYou might be right, seems like I recall several different HP ratings and part of it might be DIN vs SAE. But there was also a slightly higher compression on a few. 9.2:1 instead of 9.0:1 and I believe it had 2 HP more.

Edit
Thinking more, seems like I've seen 213, 211 and 208 HP ratings. I think the 213 is the slightly higher compression, DIN, the 211 is DIN and the 208 SAE.
That does sound about right, the B35 with different pistons sold somewhere/time in Europe with 9.2 compression is a strange occurrence and lacks documentation :(
One guy isn't absolute but I have heard it too.
RobertRO wrote: Oct 20, 2005 3:14 AM
Another solution would be to use the original BMW M30B35 pistons that were available on early (1986-1988) E32 735i Euro models. The compression ratio for those pistons is 9.2:1, and the engine was capable of 220HP and 315Nm torque, compared to 211HP and 305Nm torque of the well known 9.0:1 M30B35.
But I think that the M30B35 9.2:1 pistons are a very rare animal; it would be much easier to find the M30B34 10:1 pistons (which, again, would provide about 9.5:1 when installed in a M30B35 block + head).

I would also love to hear more on this subject.


[Edit by RobertRO on [TIME]1129794685[/TIME]]
In addition, if you dig into Realoem, it shows the early euro B35 pistons as early and euro only, along with notating the world pistons as low compression.
No. Description Supp. Qty From Up To Part Number Price Notes
01 Nueral/alcan piston 91,970MM("0") 6 11251714374 $234.36
01 Nueral/alcan piston 92,050MM("00") 6 11251714375 $234.36 ENDED
01 Nueral/alcan piston 92,220MM(+0,25) 6 11251714376 $234.36
01 Nueral/alcan piston 92,470MM(+0,50) 6 11251714377 $323.18
01 Nueral/alcan piston 91,985MM("0") 6 11251735939 $316.61
01 Nueral/alcan piston 92,065("00") 6 11251735940 $316.61
01 Nueral/alcan piston 92,235MM(+0,25) 6 11251735941 $316.61
01 Nueral/alcan piston 92,485MM(+0,50) 6 11251735942 $316.61
For vehicles with
Low compression engine
S858A=Yes
01 Nueral/alcan piston 91,985MM("0") 6 11251735939 $316.61
01 Nueral/alcan piston 92,065("00") 6 11251735940 $316.61
01 Nueral/alcan piston 92,235MM(+0,25) 6 11251735941 $316.61
01 Nueral/alcan piston 92,485MM(+0,50) 6 11251735942 $316.61
03 Snap ring C22X1,5 X 07119934460 $0.35
04 Repair kit piston rings 91,970MM("0") 6 11251714383 $98.12
04 Repair kit piston rings 92,050MM("00") 6 11251714384 $146.20
04 Repair kit piston rings 92,220MM(+0,25) 6 11251714385 $98.12
04 Repair kit piston rings 92,470MM(+0,50) 6 11251714386 $98.12
Tiit
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Re: Dirty m30b34 vs m30b35

Post by Tiit »

Wikipedia page says, there was a 220 hp b35 without catalytic converters available in some markets. Anyone heard about this?
I have an Australian late 85 e23 735i without catalytic converters. Rated less than dirty motor, but more than 8.1 b34. Which b34 version was installed to late e23 in other markets?
I have m90, low comp b34, e23 b34 mystery motor and b35 in my possessions right now. Once I have some spare time, I’ll do full comparison between them all.
Mike W.
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Re: Dirty m30b34 vs m30b35

Post by Mike W. »

Tiit wrote: Nov 01, 2021 9:26 PM Wikipedia page says, there was a 220 hp b35 without catalytic converters available in some markets. Anyone heard about this?
I have an Australian late 85 e23 735i without catalytic converters. Rated less than dirty motor, but more than 8.1 b34. Which b34 version was installed to late e23 in other markets?
I have m90, low comp b34, e23 b34 mystery motor and b35 in my possessions right now. Once I have some spare time, I’ll do full comparison between them all.
Interesting, I'd not heard that. But looking at Realoem it appears 635s and 735s in some markets, including Australia, were really 3.3s, see the quote below. And 3.3s, 9:1, or 9.3:1, I've seen both listed, compression, without cat, were rated at 197, which is much more than a green/cat B34, but less than the 10:1 B34. With yours in particular, I'd be looking at the left side of the block, under the intake manifold. 3.5s had 3.5 cast into the block, as that was the only block intended for a 92MM bore. I'm guessing yours says 3.3/3.0, meaning it was for an 89MM bore. Curious the games they played. Speaking of the Au market, were those cars made in Europe or South Africa? I can see SA production making a lot of sense, closer and RHD already, but I have no idea.
For vehicles with
National version Switzerland
or
National version Australia
or
National version sweden

L804A=Yes

L810A=Yes

V010A=Yes
01 Mahle piston 88,97MM("0") 6 09/1982 11251262838 $196.42
01 Mahle piston 88,97MM("0") 6 09/1982 11251262838 $196.42
01 Mahle piston 89,05MM("00") 6 09/1982 11251262839 $170.75 ENDED
01 Mahle piston 89,05MM("00") 6 09/1982 11251262839 $170.75 ENDED
01 Mahle piston 89,22MM(+0,25) 6 09/1982 11251262840 $170.75 ENDED
01 Mahle piston 89,22MM(+0,25) 6 09/1982 11251262840 $170.75 ENDED
01 Mahle piston 89,47MM(+0,50) 6 09/1982 11251262841 $170.75 ENDED
01 Mahle piston 89,47MM(+0,50) 6 09/1982 11251262841 $170.75 ENDED
Last edited by Mike W. on Nov 02, 2021 3:35 PM, edited 1 time in total.
Nothintoseeere
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Re: Dirty m30b34 vs m30b35

Post by Nothintoseeere »

Thanks for correcting on the differences between motronic 1.0 and 1.3..

Of course the other difference is the how the ecu knows crank position. Motronic 1.3 does it on a modern way.
Tiit
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Re: Dirty m30b34 vs m30b35

Post by Tiit »

Mike W. wrote: Nov 02, 2021 2:14 AM
Tiit wrote: Nov 01, 2021 9:26 PM Wikipedia page says, there was a 220 hp b35 without catalytic converters available in some markets. Anyone heard about this?
I have an Australian late 85 e23 735i without catalytic converters. Rated less than dirty motor, but more than 8.1 b34. Which b34 version was installed to late e23 in other markets?
I have m90, low comp b34, e23 b34 mystery motor and b35 in my possessions right now. Once I have some spare time, I’ll do full comparison between them all.
Interesting, I'd not heard that. But looking at Realoem it appears 635s and 735s in some markets, including Australia, were really 3.3s, see the quote below. And 3.3s, 9:1, or 9.3:1, I've seen both listed, compression, without cat, were rated at 197, which is much more than a green/cat B34, but less than the 10:1 B34. With yours in particular, I'd be looking at the left side of the block, under the intake manifold. 3.5s had 3.5 cast into the block, as that was the only block intended for a 92MM bore. I'm guessing yours says 3.3/3.0, meaning it was for an 89MM bore. Curious the games they played. Speaking of the Au market, were those cars made in Europe or South Africa? I can see SA production making a lot of sense, closer and RHD already, but I have no idea.
For vehicles with
National version Switzerland
or
National version Australia
or
National version sweden

L804A=Yes

L810A=Yes

V010A=Yes
01 Mahle piston 88,97MM("0") 6 09/1982 11251262838 $196.42
01 Mahle piston 88,97MM("0") 6 09/1982 11251262838 $196.42
01 Mahle piston 89,05MM("00") 6 09/1982 11251262839 $170.75 ENDED
01 Mahle piston 89,05MM("00") 6 09/1982 11251262839 $170.75 ENDED
01 Mahle piston 89,22MM(+0,25) 6 09/1982 11251262840 $170.75 ENDED
01 Mahle piston 89,22MM(+0,25) 6 09/1982 11251262840 $170.75 ENDED
01 Mahle piston 89,47MM(+0,50) 6 09/1982 11251262841 $170.75 ENDED
01 Mahle piston 89,47MM(+0,50) 6 09/1982 11251262841 $170.75 ENDED


I checked it. My e23 735i production date 1/86 has 3.5 cast on the block. That’s great! That means it’s something unique. It doesn’t have cats and o2 sensor, but does have egr. My late 85 e28 has the common 8:1 b34 with cat and o2 sensor.
Also, despite e23 being heavier than e28, it has 3.25 diff (e28 has 3.46).
In Australia late 70s and early 80s 735i had m90 in it. For a few years in 80s 735i was offered with b32 and 85 onwards seems to have this mystery b34 in it. I’m so exited to measure compression and cam profile to find out more.
test5
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Re: Dirty m30b34 vs m30b35

Post by test5 »

Tiit wrote: Nov 01, 2021 9:26 PM Wikipedia page says, there was a 220 hp b35 without catalytic converters available in some markets. Anyone heard about this?
I have an Australian late 85 e23 735i without catalytic converters. Rated less than dirty motor, but more than 8.1 b34. Which b34 version was installed to late e23 in other markets?
I have m90, low comp b34, e23 b34 mystery motor and b35 in my possessions right now. Once I have some spare time, I’ll do full comparison between them all.
Where do I subscribe? :laugh: Looking forward to it!
RobertRO
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Re: Dirty m30b34 vs m30b35

Post by RobertRO »

Here's a picture of the rare and elusive BMW M30B35 9.2:1 compression piston.
As you can see, the 9.0:1 compression engine is actually a machined version of the 9.2:1 one.
Image
(right-click and select "Open image in a new tab", if the picture is not displayed)
Blue Shadow
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Re: Dirty m30b34 vs m30b35

Post by Blue Shadow »

Tiit wrote: Nov 01, 2021 9:26 PM Wikipedia page says, there was a 220 hp b35 without catalytic converters available in some markets. Anyone heard about this?
I wanted to look into the different hp numbers being thrown around here by reviewing the BMW sales brochures for different late 80s models in different languages that were available years ago on car-cm-jp. One of those vehicles was the 87 E24 with 9.2:1 compression, output 220HP at 5700 and DME III (according to the brochure, must be the 1.3 Motronic). This was a non-US model because the brochure includes the M635Csi.

There are a lot of HP numbers being thrown around here. We might want to try to use with the US numbers or the € numbers as I see both in some posts. But that would take a lot of research in period documents to get to the bottom of these numbers. But usually the DIN number is a couple digits higher. For example, a German brochure for the 1984 E24 shows 9.3 compression, 184 HP for the cat equipped vehicle.

We know the Kat version of the B34 is the 182 US/185 DIN HP motor.

87 E32 shows the US B35 having 208 HP with 9.0 and regular gas, another difference seen in these brochures providing a digit or two different output levels at times.
Mike W.
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Re: Dirty m30b34 vs m30b35

Post by Mike W. »

RobertRO wrote: Nov 19, 2021 5:11 AM Here's a picture of the rare and elusive BMW M30B35 9.2:1 compression piston.
As you can see, the 9.0:1 compression engine is actually a machined version of the 9.2:1 one.
Image
(right-click and select "Open image in a new tab", if the picture is not displayed)
Interesting. Seems odd BMW would machine a piston top instead of casting it to spec. Well, really Mahle or KS, but that costs money, unless it was a very, very early "world" piston and almost experimental.

Also looking at it, I see a lot of material removed. Eyeballing it, which is not particularly accurate, but eyeballing it I see ~75% of the piston has been machined. Now it could be more in places and less in others, but if 75% has been machined, it would only take .4MM to achieve a 2 CC difference in volume which would change compression to 9.2:1. Uneven of course, but from here I'd guess it's more like 5MM on the left side, with less as it goes to the right. Not that I can really tell from a picture. Also I thought the valve cutout at the bottom of the 9:1 picture was needed to clear the valve, and if so it would be well into the interference area on the domed piston. Unless the piston height is different to the pin, which could be. And all, please note I'm stating opinion here based on a picture, not claiming facts.
mottati
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Re: Dirty m30b34 vs m30b35

Post by mottati »

i've got a US B35 that i put together and is now in one of my e23s. The pistons are not machined like in that photo. They look like the piston in the left photo.
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