m50b30 hp/tq specs? 2018 update.

[Brokebuilds]

After extensive search, there is only a few outdated threads on the internet that shows what one has put down on a dyno with a n/a m50b30 3.0l build. I understand its supposed to replicate a s50 so most answers i see are estimates of 250 so on so on.... But! fast forward to 2018 what are these engines putting down for power stock on a dyno? Is it worth the process?

[BigC986]

I have a friend that is currently in the process of doing this build using an m54 rotating assembly. I think the simple answer is that all engines as they age will lose power. As far as it being worth it goes? I think it is. It's a cheaper way of replicating an s50 vs buying/rebuilding and original s50 engine. The m54 pistons are also better and provide less drag which increases power.

[digger]

from what i have seen you end up with less power than S50 because all that happens is they only up the displacement (not understanding how engines work)

[Liquidity]

Engines are rated in bhp, has nothing to do with what it will put down on a chassis dyno at a shop.

[Brokebuilds]

Thats a interesting statement liquidity.
Would be nice to have some updated numbers on this n/a build instead of turbo numbers.

[pbonsalb]

Probably next to no one has dynoed with everything else stock but the engine internals and also run a stock S50 tune, so it’s hard to isolate the gains from just the displacement increase. And it is probably not common to find two identically modded motors, one with M54 3.0 internals and one an S50. I’d go with the obvious — it should put down about what an S50 makes if using S50 or S52 cams). The S50 has a different bore and stroke to get the same 3.0L, but that should not make any significant differences for a street motor.

[Liquidity]

Except for pretty much everything you said is completely wrong. But way to make yourself sound smart.

The longer the stroke, the more low-end torque it will have, the shorter the stroke the more top-end horsepower it will have. These completely change how a car drives and the required gearing to make them useable on the street or the track. Then you also have the “who cares” factor because no one really cares how much power a bone stock car has unless it’s actually fast - which an e36 m3 most certainly is not.

[pbonsalb]

I understand that, and noted that the rod and stroke difference. These differences are really pretty minor and mostly theoretical in this application. If doing extensive modding, you could take advantage of the shorter stroke, but with the stock cams I doubt it’s worth quibbling over.

You are obviously considering only very highly modded motors since you mention that gearing must be different for each motor. BMW obviously was not doing so since it specified a 3.15 for the low torque high revving S50 and a 3.23 for the high torque low revving S52. Go too short and you will want a 6 speed for the overdrive (I have run 3.15, 3.23, 3.38 and 3.64 diffs with a 5 speed on an S52 with many mods including Schricks and 7000-7200 rpm redline and wanted an overdrive with the 3.64 though I liked it the most everywhere but highway trips).

The hybrid engine you are considering is exactly that - a hybrid of a big slow revving S52 crank and small light high revving M50/52/54 bore pistons. Again, the slightly lighter M54 pistons won’t be making much difference. Certainly not enough to be a deciding factor on a street motor. And if you are going all out and want a very high revving motor, the M54/S52 crank is not the best choice.

It’s a budget displacement increase. Maybe not the best route to an all out highly modded motor.

[Brokebuilds]

Great debate guys.Anyone with the actual finished product have any input?

[wrswrsnz]

Almost 2 years late but the answer is yes.

I converted a M50B25nv into what is effectively a US spec M3.
Parts:
M50B25nv Engine
M54B30 crank, rod, pistons
M52 Vanos
M50B25nv head (stronger valves + double valve springs)
6.5kg Flywheel
US Spec S50 Shrick cams
M50 Inlet manifold
S50 3.2L Euro headers
Custom Exhaust using locally hand-made resonators
Original 3.2L M3 Euro rear muffler and exhaust with decat and above resonators
Link G4+ Plugin ECU
S6S420G 6 Speed

Initially I stupidly used the green-top injectors, original M50 throttle body and inlet system.
When dyno tuned it made 264hp at the crank and 313Nm torque.

Almost 5 years later I changed to pink top injectors, bored the TB out 4mm (22% bigger cross-section) and replaced the inlet tubing with 89mm (vs 76mm).
When re-tuned it made 298hp at the crank and 343Nm, redline @7000prm, still producing 300Nm
Apart from not being able to achieve the same max rpm as a genuine S50 Euro it is making S50 Euro hp and torque.

[imolashaun]

I have a similar setup to you, except I have s52 cams, a vanos head, ebay headers and a factory catless exhaust.
I made 221whp so very much in the 260 crank hp range that you made. For some reason I can't get vanos working with the link so I'm lacking a lot of midrange torque.
Looks like next I'll be fitting a bigger throttle body and fabricating a 3.5 inch intake and try and pick up another 25-30hp

[imolashaun]

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