S50B32 Clone

[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?

[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)?

[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.

[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]

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.

[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.

[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]

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]

After all these years being in BMW community , I have never seen anybody make +300hp on naturally aspirated S52 with any sort of bolt on modification even less with M50 block. But I am sure you just joined the forum two years ago and you will figure it out.

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

[ForcedFirebird]

I knew I saw someone break 300. He was making 279whp before the ITB and megasquirt.

https://www.bimmerforums.com/forum/s...5#post29785685

[digger]

We are also taking about 300 flywheel hp,

[ForcedFirebird]

After all these years being in BMW community , I have never seen anybody make +300hp on naturally aspirated S52 with any sort of bolt on modification even less with M50 block. But I am sure you just joined the forum two years ago and you will figure it out.

Not as far fetched as you think. Every stock long block s52 at the race track in the GT NASA series is making 250+ whp. m50 manifold, headers and nice exhaust. I just pulled one couple months agop since it started dyno-ing 243.

One of my clients running in SCCA EP series is making 208whp with an m20b25 12.5:1 and my head work, stock intake manifold, 288 camshaft. He's been competing with it for over 4yr, spinning it to 8500rpm. (VIDEO LINK)

Guys at Rabid Race are making 270whp with stock s52's and s54 throttles.

If you want to see what guys are doing to make reliable power, go out to the racing circuit. I've seen some crazy stuff guys do to fit in rule limits. Saw a de-stroked s50b32 to fit in the 2.8 category.

[DesertBMW]

My goal is +300hp
What's your opinion.

After all these years being in BMW community , I have never seen anybody make +300hp on naturally aspirated S52 with any sort of bolt on modification even less with M50 block. But I am sure you just joined the forum two years ago and you will figure it out.

[ForcedFirebird]

M52b28 block I'm going to try the 86mm piston. Sleeves

If you are happy with 86mm, use the m50 block.

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

I always forget that. Here in US, the m52tu is aluminum (m54 construction), the regular m52, that uses the single VANOS, is iron.

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

High compression is fine.

If distance from head to piston is ideal, you will have LESS knock. I have used 11.5:1 pistons and 93 octane, 3.2l 24v, 1mm squish.

[digger]

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

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