S50B32 Clone

[esoes06]

running the piston to head tighter increases the CR which is worse for knock, except that the additional squish velocity offsets this as to squeezes the end gas towards the plug reducing knock sensitivity. I would run the squish correct and if you need to lower the CR use other means. Its only about 1cc

Low or high compressor!!! The important thing is to use 95 octane fuel efficiently. High compression requires high-octane fuel. Compression was calculated according to 95 octane fuel. With 99 octane fuel, a 0.8mm gap is ideal. With 102 octane fuel, a 0.6mm gap is ideal.

[esoes06]

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

In my country there are various engine blocks. Aluminum or iron m52 available. My block aluminum and the pistons now are 85.50mm

[esoes06]

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.

Sometimes +5 hp makes a big difference.

[ForcedFirebird]

Maybe 5hp on 5.7 liters. Spec e30 racing is required to max bore at +.5mm, they don't make any more power than stock size, everything else is equal. Everyone is making 165whp.

If you have iron m52, then problem solved, anyways. You are essentially making a US s52b32. The link above is using Sunbelt cams, supertech valves and dual springs. You are not going to want to use the stock and NV exhaust cam with higher compression. The us s50b30 is already 210psi cranking compression at 10.8:1, if you were to use m50 cams, I would gather you will be over 225psi, and have detonation issues.

[ForcedFirebird]

Low or high compressor!!! The important thing is to use 95 octane fuel efficiently. High compression requires high-octane fuel. Compression was calculated according to 95 octane fuel. With 99 octane fuel, a 0.8mm gap is ideal. With 102 octane fuel, a 0.6mm gap is ideal.

Again, compression isn't why squish gap is important. The rods stretch at high RPM, making that gap smaller. Ideally you want the piston to almost touch the head at max RPM. This forces the fuel mixture to accelerate to the spark plug, also helps keep gasses in the chamber, and less on the gasket fire ring. The edges of the bore and gasket can become hot spots and ignite the mixture prematurely.

Check this article. It's common engine building knowledge: https://www.motortrend.com/how-to/ideal-quench-height/

Where did you find those calculations? I've never heard of adjusting squish for fuel types.

[ForcedFirebird]

I have been working at BMW Mechanics for 25 years. The Camshaft is precise at +350hp with 272 or 284.

Started rebuilding engines in 1996, took a hiatus from 2000-2004. Now I have the equipment to do this in house.

Not sure the stock heads flow enough to support 350hp. I would have to open my old desktop to see the flow numbers from my bench, but they are around 240cfm. Think I got them up to 280 or so with a +1 intake, but have only done a few high end port jobs on 24v stuff. My m20 heads flow 210cfm with stock seat +1mm valve.

[digger]

I have been working at BMW Mechanics for 25 years. The Camshaft is precise at +350hp with 272 or 284.

arent you proposing to use stock cams (m54 and m50nv)?

[esoes06]

S50b32
Bore 86.4
Crankshaft 91
Rods 139
Camshafts 256/240
Head valve int 35mm

My project Clone S50b32
Bore 87mm
Crankshaft 89.6
Rods 140
Camshafts 272/252
My cylinder head nv B25 and modified 35mm int valve Double spring. Why can't this setup produce +300hp?