S50B32 Clone

[digger]

Sure, but if the m52 block is thicker, might as well start there. After that block cracked on me, I am now leery about boring the m50 .100". I'd rather play it safe and not worry about the <200cc (84.5mm-87mm is 181cc difference). Use the effort for head work instead IMO.

Not sure what's available in Turkey but M52 may be alloy like here and he wont have S50/52 US unless they are same as m52 iron

[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 I'm going to try the 86mm piston. Sleeves

[esoes06]

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/

I don't agree with you. It is directly related to the fuel. High compression engine = high octane fuel.

[ForcedFirebird]

RB26 guys make >1000hp with around 4-5mm wall thickness so it’s plenty unless you get a rare dud or something goes wrong with the “tune” . MM do 87mm on the m20 turd

the engine needs more camshaft

Sure, but if the m52 block is thicker, might as well start there. After that block cracked on me, I am now leery about boring the m50 .100". I'd rather play it safe and not worry about the <200cc (84.5mm-87mm is 181cc difference). Use the effort for head work instead IMO.

[digger]

RB26 guys make >1000hp with around 4-5mm wall thickness so it’s plenty unless you get a rare dud or something goes wrong with the “tune” . MM do 87mm on the m20 turd

the engine needs more camshaft

[ForcedFirebird]

unless the bottom end lets it all leak out before it gets to the crank!

heh.

t
if one part doesn't do its ting, de whole ting doesn't do its ting.

It would have to be pretty bad...like maybe a hole in the piston, or lacking rings??? lol.

I had a car here at work a few years ago (EDIT: EIGHT + YEARS ALREADY WOW!!!). Compression was at 145psi, 200k mile 2.5 bottom end, dyno'd at 145whp. Refreshed the head, +1mm valves, 272 cam, a little bowl/seat work on the machine, added ITB's with headers, dual 2" exhaust with x-pipe at 3m and that same crank case put down 170whp. Then I added a 2.8 bottom end and it went to 217whp. Long version here: https://www.r3vlimited.com/board/for...-rotating-assy

[TobyB]

All the power comes from the head.

unless the bottom end lets it all leak out before it gets to the crank!

heh.

t
if one part doesn't do its ting, de whole ting doesn't do its ting.

[ForcedFirebird]

To add, if your pistons are 1.2mm below the block deck, then you apply the 1.7mm head gasket, your pistons will theoretically be 2.9mm from the head surface.

When building engines, I aim for .95mm.

To test, put used head gasket, torque with used head bolts, attach cam drive, rotate engine, remove head, measure clay/solder.

For example, when building "budget" m20 2.7l, I use 81mm crank, 135mm rods, stock m20b25 pistons, then shave the block 2mm to get the compression height back.

I suggest your pistons be higher (or block deck lower).

[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/

[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.

[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

[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.

[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.

[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

[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.