Somebody edumacate me on cranks and trigger wheels please

[richard.pykett 36]

OK, so I have an M50B25 nv engine for the E21 Group 5 project - usual stuff, crank position sensor on the front cover.

We want to go to a 2.8 crank, so that we can rev the thing higher for longer than we could with a 2.5 cast crank (600hp or so 7500 - 8000 rpm turbo).

Through trying to get the turbo mass as low as possible, I've ended up with lots of hot turbo pipes which sit quite close the the giant toothy crank pulley thing.

If the engine were converted to an OBD2 crank, the trigger wheel would then be internal on the back end of the crank. This would mean we would have a smaller pulley/harmonic balancer up front - further away from Murchies nasty hot turbo.

This means munching a very accurate hole at the back of the block and probably adding a lump of metal by some fair or foul means, to the back of the block so that it could be suitably bored and tapped for the CPS. I think I have the process nutted out for this.

So what I need to know for all you Oracles/Obewan Kenobis out there is:

• Which M5x 2.8 crank has the integral crank position trigger wheel? and
• Is there an M5x iron block with the internal CPS option. (I think only M3??)

Many thanks chaps and chapesses.

Cheers

Richard

Edited May 11, 2015 by Skintkarter

[No name user 379]

Ah if you go after market ecu you change triggering position so wouldnt worry about it too much

[richard.pykett 36]

Thanks Steve. Wasn't so much the control I was concerned about (so ignore the OBD2 reference) more just what do I need to do to fit a smaller harmonic damper to the M50 and dodge some of the heat soak from the turbo.

I see pictures from overseas, supposedly of M52 2.8 cranks, which have the internal trigger wheel found on later OBD2 engines.

I know that the M54 has this arrangement, but wasn't sure that we saw an M54 2.8 version here, only the 3.0 (realise we had 2.0 and 2.5). Don't think we want to increase the stoke to 3.0, so 2.8 is still the preferred option with a 140mm rod and suitable low comp piston.

So need to find a 2.8 crank with the internal trigger wheel, unless you have some other weasel cunning plot?

[No name user 379]

My turbo M42, the turbo sits right infront of the harmonic balancer has done for 30k no problem, your not running the car long enough to be a issue also change to GT101 hall senors the stock bmw units are a pain

[richard.pykett 36]

Thanks Steve - the Oracle as always.

[No name user 379]

Thanks Steve - the Oracle as always.

SSSHHHHHHHH Oracle is a dirty word in NZ lol

[westy 614]

The e46 2.8 m52tu has internal crank trigger. Sounds like the one you're looking for.

Looks as though you're sorted but.

[CamB 48]

also change to GT101 hall senors the stock bmw units are a pain

Where's a good place to buy these locally?

[No name user 379]

Where's a good place to buy these locally?

Motorsport Electroincs out howick way

[CamB 48]

Excellent - thanks. Am going to avert my eyes from all the other nice stuff he has.

Do you think I'll get a stable cam sync if I use that sensor through the front cover of an M10 and pick up off a single raised cam sprocket retaining bolt. I am imagining a 5mm+ long bolt, with a spacer underneath so the sensor picks up that but not the other 3 bolt heads.

Pic for reference:

Mounting the sensor will be easier said than done, but that's another issue. Just looking for what it can trigger off.

[No name user 379]

I use a button head cap screw works fine, i would however machine the end of the bolt head so its flat with surface area doesnt take much for the 101 to work but making double sure never hurt

[richard.pykett 36]

The e46 2.8 m52tu has internal crank trigger. Sounds like the one you're looking for.

Looks as though you're sorted but.

Thanks for this Tony. So sounds like we need an E36 2.8 crank if we stay with the current M50 crank pulley/damper/CPS, or we need to pick up a an E46 2.8 block, crank, pulley and CPS if we are to reverse engineer this into the M50 block.

Anybody have a buggered E46 2.8 block etc...please?

[westy 614]

Could be a bit tricky but I'm thinking you're used to that ha.

These from realoem.com appear to show the e36 on the front cover here http://www.realoem.com/bmw/enUS/showparts?id=CD12-EUR-02-1997-E36-BMW-328i&diagId=11_6074

The e46 appears to have a separate piece for the trigger wheel. Part 8 here http://www.realoem.com/bmw/enUS/showparts?id=AM52-EUR-01-1999-E46-BMW-328i&diagId=11_1547

With sensor mounted here http://www.realoem.com/bmw/enUS/showparts?id=AM52-EUR-01-1999-E46-BMW-328i&diagId=11_2167

Not sure if the earlier block will have a suitable area to mount it.

[westy 614]

Oh and all tu blocks are ally.

[richard.pykett 36]

Could be a bit tricky but I'm thinking you're used to that ha.

These from realoem.com appear to show the e36 on the front cover here http://www.realoem.com/bmw/enUS/showparts?id=CD12-EUR-02-1997-E36-BMW-328i&diagId=11_6074

The e46 appears to have a separate piece for the trigger wheel. Part 8 here http://www.realoem.com/bmw/enUS/showparts?id=AM52-EUR-01-1999-E46-BMW-328i&diagId=11_1547

With sensor mounted here http://www.realoem.com/bmw/enUS/showparts?id=AM52-EUR-01-1999-E46-BMW-328i&diagId=11_2167

Not sure if the earlier block will have a suitable area to mount it.

Thanks Tony - E46 it is. I'll need to add a lump of something to the block. Idea is that if this can be done, I'd set the alloy block up in the mill and tram the CPS hole etc... then remove it and substitute the cast iron block without disturbing the setup, then bore and face the hole for the TPS. How hard can it be...???

Just need a toasted e46 2.8 bottom end now.

Cheers

Richard

[westy 614]

Any reason not to jump to the 3ltr m54 crank?

[richard.pykett 36]

Any reason not to jump to the 3ltr m54 crank?

Hmm... We originally wanted to do the build with an N/A S54 to have revs similar to the original M12 2.0 (well close anyway) but costs looked like they would spiral by the time we brought a possibly dodgy one in and rebuilt it. We would be restricted to probably 400hp tops, likely less with our small budget.

Our boys convinced me that after driving the 1M, a turbo would be OK provided it was loud enough and revved.

We know that the m50 nv 2.5 will go to 7500 or possibly 8000 with solid lifters, so close enough and it can make up to 1200 hp if you are Scandinavian. But we have the issue of it being a cast crank. Kayne Barrie has been in my ear about rod/stoke ratio and a longer rod is better for a number of reasons. With special turbo pistons we can get a 140mm rod in there and with the 84 throw 2.8 crank, the rod ratio is 1.66 (ideal is apparently 1.7 or greater according to the gospel of KB).

If we go to the even longer stroke 3.0, the rod may need to be shorter than 140 to leave enough meat above the piston pin in order to get a reliable piston. Rod/stroke ratio then goes down to 1.56 with the 140 rod and 1.5 with a 135 rod.

Logic might be flawed somewhere, but we think that the 2.8 will be more of a rev box

[No name user 379]

The m50 will go to 8500 on hydraulic lifters without a issue i can prove that , any higher you'll need solid, cast cranks are know to absorb harmonics better than billet even Nascar still use a cast cranks at times.

There's very little point i pulling big numbers out of any motor if your not making power there all you do is break stuff for bragging rights or a cool dyno sheet, my M50 with stock everything on a 250,000km motor apart from cams was still making torque and power at 7500 and no sign of lifter issue so why flog it.

Want more low down stroke it to whatever as for gospel? Remember its all very well people giving great advise but your the guy that's driving it and that your yet to do, so really you have no dam idea how its going to go, your longer rod gives better compression loading on the crank blah blah blah.

Here's a better deal finish it then drive it you should be around 1000-1100kg if not lighter, add to that 5-600hp 400ft/lb torque so around 2:1 power to weight , now im more than likely got this totally wrong but at a guess you'll be a ton faster than a 1200kg making 350-400hp to which i believe can lap Hampton in 1:10.

Bottom line theories are a awesome thing they can also screw with your head, plan things yes but your still got to know how to drive it and set the thing up to prove they were worth the time and money to start, many have done more with less.

[westy 614]

Hmm... We originally wanted to do the build with an N/A S54 to have revs similar to the original M12 2.0 (well close anyway) but costs looked like they would spiral by the time we brought a possibly dodgy one in and rebuilt it. We would be restricted to probably 400hp tops, likely less with our small budget.

Our boys convinced me that after driving the 1M, a turbo would be OK provided it was loud enough and revved.

We know that the m50 nv 2.5 will go to 7500 or possibly 8000 with solid lifters, so close enough and it can make up to 1200 hp if you are Scandinavian. But we have the issue of it being a cast crank. Kayne Barrie has been in my ear about rod/stoke ratio and a longer rod is better for a number of reasons. With special turbo pistons we can get a 140mm rod in there and with the 84 throw 2.8 crank, the rod ratio is 1.66 (ideal is apparently 1.7 or greater according to the gospel of KB).

If we go to the even longer stroke 3.0, the rod may need to be shorter than 140 to leave enough meat above the piston pin in order to get a reliable piston. Rod/stroke ratio then goes down to 1.56 with the 140 rod and 1.5 with a 135 rod.

Logic might be flawed somewhere, but we think that the 2.8 will be more of a rev box

Well that answers that question ha.

[CamB 48]

1200 hp if you are Scandinavian.

Haha - so true.

There's a 500hp M10 in Sweden with an unmodified (and unrebuilt) M10B18 bottom end - not bad for a 60s tech 8 valve. Biggish turbo, cam and headwork of course, but if I can trust google translate I think it even still has the standard size valves.

[richard.pykett 36]

There's a 500hp M10 in Sweden

That would be Mike Delmont on low boost on a bad day

[CamB 48]

I'd say Mike has a bit of a capacity advantage

[No name user 379]

500 hp M10 ?

Its on holiday at that level

[No name user 379]

I'd say Mike has a bit of a capacity advantage

His motors alot smaller than 2.5

[CamB 48]

I've never asked him - just assumed what I'd do in his position (which is an M3 block / crank, considering the Evo version to push it out towards 2.5l).

To be fair, I have a 2002, an M3 crank, and pistons/block for 2.1 litres. I just can't figure out how to fit the big turbo in the engine bay and also not explode the rest of the drivetrain (or the engine). I probably don't have enough cam (Schrick 292) for the big revs / big power package either. Then there's is a small problem of not being a good driver....

I need to talk to you some time about the right turbo for my goals, but I want to get it running first with what I have (buttplug Silvia turbo on a spare M10B18).

And back on topic, based on a suggestion elsewhere I will give a cam trigger (bought one from MSEL) a go on the M10 based on 3x stainless steel cam sprocket bolts (which the hall sensor should ignore) and 1x raised steel one. Hopefully A4-70 stainless is close enough to grade 8.8 to not cause a problem.

Just need to find time between job and small kids now.