S50B32 Clone

[esoes06]

Block m50b25 nv. I measured the block height 210.7mm.
I will use rods 140mm. Crank 89.6
Pistons 24.8mm compressor height special production 86.50mm . Camshaft 47.7mm and NV Intake Camshaft
Ms41 ecu tuned. Cylinder head port polish and dual spring.
Throttle 80mm.
My goal is +300hp
What's your opinion.

[purpleparm]

Tell us more!!!!!!

[ForcedFirebird]

I think you will need to have the block sonic tested for cylinder wall thickness when boring from 84 to 86.5mm, 2.5mm (almost .99"). Most block are going to be "iffy" at .040 (1mm).

I did try it, personally, so this isn't blowing smoke. I used an m50 block and put stock diameter s50 forged pistons in it - ran like stink, but ultimately met it's demise.

Anyways, you can still get close by using the same m54b30 crank, +.5mm (or 1mm) custom m50/m54 pistons to change the pin height (m54 block height is different), and 140mm rods. This will get you 3014cc or 3050cc respectively, while maintaining the wall thickness. I just put one together for a member here:

https://www.r3vlimited.com/board/forum/general-forums/members-rides/the-project-forum/10023469-94-e34-touring-slicktop-daily-driven-slow-mover-3l-turbo-m50-in-progress?p=10061014#post10061014

[ForcedFirebird]

Carnage pic for posterity. As you can see, it cracked vertical along the spot where the thin wall near the water passage meets the thicker cast, between the cylinders where the head bolt resides.

[moatilliatta]

No need for 140MM rods unless you're going to spin the motor above 7400 IMO.

If you keep it to 7200 use the S52 Crank. Its really an extra 10HP with TQ. Few are using Honda 138mm rods on those, no reason unless you're spinning it higher in theory.

If you're shooting for 300 whp just go standalone with an Alpha-N / Speed density tune, S54 ITBs..

I'm at 285 on US S50 B30 on dynojet running AFR in high 11's on MS41. A Good tune on standalone and I maybe closer to it.

The Cams are going to make the power - depends on how much you want to sacrifice driveabity.

S50b32 is the euro motor, there is no clone.

[moatilliatta]

I think you will need to have the block sonic tested for cylinder wall thickness when boring from 84 to 86.5mm, 2.5mm (almost .99"). Most block are going to be "iffy" at .040 (1mm).

I did try it, personally, so this isn't blowing smoke. I used an m50 block and put stock diameter s50 forged pistons in it - ran like stink, but ultimately met it's demise.

So S50/2 blocks are different?

[ForcedFirebird]

So S50/2 blocks are different?

Yes. Generally a mfgr will keep a wall thickness for cooling purposes, the larger bored blocks will need larger rough openings prior to boring. When you try to open a smaller block, you will thin the walls. I knew it was close, and went with it anyways. Stock s50 cams, 3.2 s52 bottom end, +1 intake valves and I did a little bowl work on the valve machine. Put down 274 with a 413 DME we adjusted mapped at the dyno. Lasted about 5 weekend track events, put a used (resealed gaskets) 3.0l s50us and that made it about 100hrs or w2w racing before a driver money shifted it. That motor put down 247 when we installed it, and faded to 238 just before the valves got roasted.

EDIT: I know the s52 for sure, haven't measured an s50 block, although I do have one on the stand already for assembly (+.003" hone only for forged slugs). I would gather it's the same, though, 86mm is still a huge overbore on an 84mm block.

[ForcedFirebird]

Just went to the engine room and took some quick measurements. Measured several through the water jacket with a caliper, this is not a sonic test.

s50us 86mm bore 6.6mm avg wall thickness.
m50nv 84mm bore 6.7mm avg wall thickness
m52 84mm bore 7.4mm avg

Don't have an s52, and didn't check an m50tu

Cylinder that cracked is 5.8mm on that wall.

[esoes06]

Thanks for the comments and opinions. I think I need to elaborate a little more.
M50 nv block 210.7mm
M54b30 crankshaft 89.6mm stroke
140mm rods
87mm piston and compressor height 24.7mm (bore maybe 86.50mm or 86.75mm)
I calculated
44.8 + 140 + 24.7 = 209.5mm
210.7-209.5 = 1.2mm
The 1.2mm gap is ideal.
Nv cylinder head valves are large and double spring.
And port polish
Exhaust system custom
80mm throttle and cold air intake kit
275cc injectors
M54b30 47.7 intake camshaft and m50nv intake camshaft Exhaust
Ms41 tuned
Fan clutch delete
Lightweight flywheel
Difference from S50b32 itb and camshafts and crankshaft
But rods 1mm longer
Pistons are slightly larger
OK crankshaft stroke 1.4mm short
Handicaps are balanced
I have already built an M52b28
M54b25 pistons and 140mm rods
Crankshaft M52b28 i.e. 84mm stroke
47.7 camshaft and m50nv camshaft
M50b25 intake manifold 80mm throttle
Ms41 tuned and vanos tuned
The Dyno test results are amazing. 245hp
Now it's the 89.6mm crankshaft and the 87mm pistons. I think the dyno test results will be +300hp.

[esoes06]

Just went to the engine room and took some quick measurements. Measured several through the water jacket with a caliper, this is not a sonic test.

s50us 86mm bore 6.6mm avg wall thickness.
m50nv 84mm bore 6.7mm avg wall thickness
m52 84mm bore 7.4mm avg

Don't have an s52, and didn't check an m50tu

Cylinder that cracked is 5.8mm on that wall.

M52b28 block sleeves change and 85.50mm pistons now good work. No problem. M52b28 7.4 mm its good news

[ForcedFirebird]

Apologies. I read back my comments. I used s52 rotating assembly in m50 block. Previous post says "s50" but was intending to be s52 bore. If you want big power, I suggest keeping the bore as minimal as possible. You get more tq from the stroke, the bore adds minimal end result, compression is far more important.

1.2mm is a little tall for head to piston clearance. 1mm is adequate, and the squish will push gasses to the spark plug. The 400 head casting flows very well, there are early ones with less water jackets. If the m50/2 heads crack, it will be between an exhaust valve and water jacket. Some heads have 3 holes around every head bolt, some have 2.

m50nv heads have 7mm valve stems. They are good for turbo, not as much for port flow. Early m50tu valve retainers like the break,use s52 stuff.

[ForcedFirebird]

I've been building baby six engines for almost 20 years, and domestic engines since 1994.

The bottom end is the "dumb" part of the engine as a whole. As long as your piston dome shape compliments the design of the combustion chamber, the only significant variable is compression.

That being said, m54 crank, and rods, even, custom pistons to match total compression height, and static compression to match the cam profile, you can make a lot of power by simple valve job tricks.

All the power comes from the head.

[esoes06]

Apologies. I read back my comments. I used s52 rotating assembly in m50 block. Previous post says "s50" but was intending to be s52 bore. If you want big power, I suggest keeping the bore as minimal as possible. You get more tq from the stroke, the bore adds minimal end result, compression is far more important.

1.2mm is a little tall for head to piston clearance. 1mm is adequate, and the squish will push gasses to the spark plug. The 400 head casting flows very well, there are early ones with less water jackets. If the m50/2 heads crack, it will be between an exhaust valve and water jacket. Some heads have 3 holes around every head bolt, some have 2.

m50nv heads have 7mm valve stems. They are good for turbo, not as much for port flow. Early m50tu valve retainers like the break,use s52 stuff.

I calculated and the result is 1.2mm. Because the use of 95 octane fuel

[esoes06]

I've been building baby six engines for almost 20 years, and domestic engines since 1994.

The bottom end is the "dumb" part of the engine as a whole. As long as your piston dome shape compliments the design of the combustion chamber, the only significant variable is compression.

That being said, m54 crank, and rods, even, custom pistons to match total compression height, and static compression to match the cam profile, you can make a lot of power by simple valve job tricks.

All the power comes from the head.

I did the compression calculation. With 95 octane fuel, a clearance of 1.2mm is ideal.

[ForcedFirebird]

Has nothing to do with fuel. The piston to head clearance is to compensate for rod stretch at high RPM, and to accelerate the fuel mixture towards the spark plug.

http://www.theoldone.com/archive/quench-area.htm

https://www.enginelabs.com/engine-tech/quench-unlocking-performance-squished-between-the-piston-and-head/