M70B54S or how to bring an ordinary 850i engine to CSi level

[B10 BITURBO]

I have always wandered,,, and i ask just out of curiosity,,

why to do such a conversion,,, taking 2 engines apart,, just to use the M70 head,,, and put in the Schrick camsafts,, if someone could save a LOT of money.. just buying new camshafts that will fit in the M73 cylinder head,, regrinded from DBilas ...or what ever.. i am positive that there are so many manufacturer out there that can do such a job,, out of the oem M73 cams

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Does it also have to do something with the wiring ??

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I have always wandered,,, and i ask just out of curiosity,,

why to do such a conversion,,, taking 2 engines apart,, just to use the M70 head,,, and put in the Schrick camsafts,, if someone could save a LOT of money.. just buying new camshafts that will fit in the M73 cylinder head,, regrinded from DBilas ...or what ever.. i am positive that there are so many manufacturer out there that can do such a job,, out of the oem M73 cams

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Does it also have to do something with the wiring ??

It's all about the electronics to control the engine. The M73 electronics are a PITA to program (OBD II). You can throw hotter cams into the M73, but you won't actually squeeze as much as you can out of them without proper tuning. Wolf (Wokke) has chips that run on the M70 DMEs that maximize the performance out of the M70 heads with the hotter cams and the larger displacement of the M73 block.

This option gives you the best bang for your buck in terms of upping the performance unless you go all the way to FI.

[whiteghost1]

It's all about the electronics to control the engine. The M73 electronics are a PITA to program (OBD II). You can throw hotter cams into the M73, but you won't actually squeeze as much as you can out of them without proper tuning. Wolf (Wokke) has chips that run on the M70 DMEs that maximize the performance out of the M70 heads with the hotter cams and the larger displacement of the M73 block.

This option gives you the best bang for your buck in terms of upping the performance unless you go all the way to FI.

Or you could bolt on your m70 ancilliaries onto your cammed m73 so you could just run your stock OBD I system.
After you get it tuned you are probably going to be close to M70B54S specs as in essence, that's essentially what you are doing = a cammed/tuned m73b54.

Actually now that I think of it, DUDMD (Look him up on this forum/Facebook) does a tune for the m73, I bet that it wouldn't be hard for him to tune for a cammed m73 - for those who are looking for options.

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Or you could bolt on your m70 ancilliaries onto your cammed m73 so you could just run your stock OBD I system.
After you get it tuned you are probably going to be close to M70B54S specs as in essence, that's essentially what you are doing = a cammed/tuned m73b54.

Actually now that I think of it, DUDMD (Look him up on this forum/Facebook) does a tune for the m73, I bet that it wouldn't be hard for him to tune for a cammed m73 - for those who are looking for options.

I actually just pinged Dima last night for a code on my e38 M73. However, it appears that his coding is more for the "butt dyno". Meaning you will feel a difference in throttle response and it help smooth out the power band. But when it comes to actual power gains, you are talking 10-15 HP at the wheels. The hotter cams and coding on the OBD I available from Wolf can get your M7054s hybrid (to your point) close to CSi performance (~370hp+).

[B10 BITURBO]

I mean,, if you have both engines,, and instead of rebuilding everything and the M73B54 is in great shape,, just take the loom from M70 and change camshaft ((if that is the most simple way !))

[whiteghost1]

I saw DUDMD yesterday for an entirely different reason and asked him about options for M73's. The M73 tune he has only maxes out at +15HP, this is at the peak on a completely stock motor. He told me that the majority of the gains on a stock m73 is under the curve = daily driving.

He already has a dyno at his new shop and has the capabilities, just has to set it up. It is much easier to tune for an OBD II car if you have the equipment and know what you are doing, no need to swap chips, use emulators, etc.....It would be interesting to see if one brought a cammed m73 into his shop on his dyno to play with. If you could mirror the Schrick profile (or do an even better profile) there is absolutely no reason why a cammed m73 can't mimic the power of an M70b54S.

The thing is no one has documented a cammed M73 physically (to my knowledge) and the matching tune is not yet available so the comfort level is low. The M70b54S is just picking up steam as a swap to be done. Once someone breaks the mold and does a cammed M73 w/tune, I'd predict that this would be a viable option for those rare M73 cars out there, kit cars, as well of a heck of a lot less work for those M70 owners as Bi-Turbo eluded to. Not to take away from Wolf, he been great & carried the torch much further disseminating information and answering questions + ended up making a tune, whereas Kapitan just gave birth to the swap. But everyone likes options and that is a totally realistic one.

[B10 BITURBO]

i saw dudmd yesterday for an entirely different reason and asked him about options for m73's. The m73 tune he has only maxes out at +15hp, this is at the peak on a completely stock motor. He told me that the majority of the gains on a stock m73 is under the curve = daily driving.

He already has a dyno at his new shop and has the capabilities, just has to set it up. It is much easier to tune for an obd ii car if you have the equipment and know what you are doing, no need to swap chips, use emulators, etc.....it would be interesting to see if one brought a cammed m73 into his shop on his dyno to play with. If you could mirror the schrick profile (or do an even better profile) there is absolutely no reason why a cammed m73 can't mimic the power of an m70b54s.

The thing is no one has documented a cammed m73 physically (to my knowledge) and the matching tune is not yet available so the comfort level is low. The m70b54s is just picking up steam as a swap to be done. Once someone breaks the mold and does a cammed m73 w/tune, i'd predict that this would be a viable option for those rare m73 cars out there, kit cars, as well of a heck of a lot less work for those m70 owners as bi-turbo eluded to. Not to take away from wolf, he been great & carried the torch much further disseminating information and answering questions + ended up making a tune, whereas kapitan just gave birth to the swap. But everyone likes options and that is a totally realistic one.

bingo............

[4drian]

I have Wolfs first and prototype engine. We were originally going for M73 heads with DBILAS cams, with the M73 block into the M70 electronics, but DBILAS couldn't deliver the cams in time.

[affa]

Besides the electronics, the M73 heads have roller rockers. It'll change the cam geometries.

Just thinking out loud, if you just drop in a set of cams meant for a M70 I think it'll make the effective profile narrower, with less area under the curve. Can't really tell the max lift height without measurement... Probably higher from just eyeballing it...

Funny enough the effective overlapped area will also be smaller so ironically M70 block with M73 heads and hot cams MIGHT actually work out to be a great FI set up.

[B10 BITURBO]

Besides the electronics, the M73 heads have roller rockers. It'll change the cam geometries.

Just thinking out loud, if you just drop in a set of cams meant for a M70 I think it'll make the effective profile narrower, with less area under the curve. Can't really tell the max lift height without measurement... Probably higher from just eyeballing it...

Funny enough the effective overlapped area will also be smaller so ironically M70 block with M73 heads and hot cams MIGHT actually work out to be a great FI set up.

Never heard that idea using M73 heads on M70.. and going F/I,,,,,,, the M70 as oem is pretty good for F/I 8.8 cr is super,,, and

Per Kristian Harildstad is blowing 1.2 bar on OEM stock invols,, and the power is ,,, 700 WHP... the gaskets is the main reason,, for not blowing more

[affa]

The low compression comes from the m70 short block, yes.

I was just tossing it out there that the roller rockers in the m73 head together with a hot m70 NA cam MIGHT actually give a desirable cam profile for FI application.

For FI we want more lift but not more overlap. A hotter cam (e.g. Schrick) has higher lift but also wider duration and therefore overlap. For FI we don't want much of the latter.

The way the roller interact with the cam lobes (as opposed to a solid rocker a la M70 with a longer and flatter wiped contact surface) might:

1 give us even higher lift, but can't be certain without measurement. (Depends if the rollers sit higher than the solid rockers would have).

2 give us less overlapped area under the curve, although degrees will be the same. Because the lobes are wiping against a circular roller tangentially rather than on a flattish traditional rocker, the valves will open and shut more aggressively, reducing the overlapped area.

[affa]

Anyway it's all moot as you can't really drop M70 cams in a M73 head. Bearing size etc....

Though I might try M73 rockers into a M70 head and trace some numbers (if they even go in). I have both stock and Schrick cams and the heads are coming off soonish... Will start a new thread if there's something worth mentioning...

We now return you to the regularly scheduled programming. Sorry for the hijack.

[clubE31]

....lovely and sad.... why does no tuner starts to tune a CSI.....(only thing I can find are chips) !?

wokke..... I got a spare csi if you want to start

[affa]

I don't think BMW left much on the table with the S70. Wokke has done very very well with the M70B54.

Following from MWrench in roadfly many moons ago:

"The V-12 was not and engine designed for serious tuning, just a torque monster to move luxury vehicles. It is a decendant of the M20 6 cylinder engine. Source of this information is the book written by Dr. Karlheinz Lange, who was director of engine development for BMW."

Anything substantial beyond what wokke is offering will have to go down the FI route.

[B10 BITURBO]

I don't think BMW left much on the table with the S70. Wokke has done very very well with the M70B54.

Following from MWrench in roadfly many moons ago:

"The V-12 was not and engine designed for serious tuning, just a torque monster to move luxury vehicles. It is a decendant of the M20 6 cylinder engine. Source of this information is the book written by Dr. Karlheinz Lange, who was director of engine development for BMW."

Anything substantial beyond what wokke is offering will have to go down the FI route.

Absolutely NOT,,,,,,,,,,,,, the only thing the M20B25 and M70 share is the bore and stroke,,, otherwise the M70 share the M40,,, same rocker arm construction,,and the cylinder head construction is similar,
otherwise it is an engine of its own

[affa]

If the M70's design was identical to the M20 then it wouldn't be a descendant now would it?

I'm not saying they are the same (I'm just a recently shot messenger ). But the fact remains the top end of the M70 leaves a lot to be desired and is the bottle neck for any additional performance beyond what BMW M and wokke have done in NA mode.

That's why they made the N series.

[B10 BITURBO]

M20,, M30 and M70 share an awful cylinder head design,, compared to the 24v S38,, M/S5x

[Omega man 1969]

....lovely and sad.... why does no tuner starts to tune a CSI.....(only thing I can find are chips) !?

wokke..... I got a spare csi if you want to start

:-) Have you not read my thread ?

[wokke]

remapping the OEM M73 DMEs is anywhere between very tricky and impossible. It depends on the DME version.
With all the engine experiments I'm running so far one objective is to make it as simple as possible with using easily available parts.
I'm convinced that even the crappy head design still leaves quite some room for improvement:
- porting and polishing the heads
- individual throttles per cylinder with modified intake headers
- dump the BOSCH engine management and use individually programmable DME units
- enable knock sensoring via the above incl. automatic ignition timing adjustment to take advantage of the used fuel quality
- using different rods with a lower weight

And this for sure isn't all. But at least my budget doesn't allow to realize all the above
And quite honestly, the M70B54S performs very well IMO, especially if the M70 is taken as a benchmark.

[4drian]

- using different rods with a lower weight

Hmmm! Can we make this work with a 5.7 block?
Edit: I mean, did Alpina utilise lighter internals?

And quite honestly, the M70B54S performs very well IMO, especially if the M70 is taken as a benchmark.

Can confirm. Surprised many M3s and a couple M5s

[Fatandre]

Wokke, Is all of this worth it?
I mean lighter rods, crankshaft and pistons is big $$ Not to mention Individual Throttle bodies.
Why not just supercharge or turbo the Fux&er?

[affa]

I'm sure wokke will chime in himself but it seems wokke has picked all the low hanging fruits there are with the available OE and junkyard parts bin. Sure one can always do more, but the $/hp curve will start to look exponential. Servicing and parts availability will also become a nightmare when you start using bespoke and one off parts.

Engine is an air pump, it's all about volumetric efficiency. FI is of course the way to go for big hp but you can't beat the longevity, reliability and drivability of a well engineered NA rig. For which BMW has already done most of the homework...

I myself is still torn between which way to go.....

[Fatandre]

I have always been a fan of N/A engines and would want to go that way
I am running a S70 for now, but still want more!!!

[affa]

Mine is a lowly early M70 so I'm not avert to doing major surgery...

Question is whether 370ish is enough or do I really want 450+

It's not a question of need....

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Mine is a lowly early M70 so I'm not avert to doing major surgery...

Question is whether 370ish is enough or do I really want 450+

It's not a question of need....

+1 same conflict right now.