Build a 1400cc M10?

[ChrisBarns]

Hi, I'd like to build a 1428cc or less M10 for a hillclimb car. It will be fitted with forced induction which will then allow it to compete in the up to 2000cc class.

I know there was a 1500cc variant (for the 1502), and of course I could sleve down a 1600 or have a custom crank made but I was wondering if there is another way. Does anybody know of a combination of BMW crank and piston which would give less than 1428cc?

Thanks

[jimmyspeed]

you need this

http://en.wikipedia.org/wiki/BMW_M12

[ChrisBarns]

Well, yes. I did nearly mention the M12 but I need 1428cc or less. M12 is 1500. Otherwise I'd go and buy one this afternoon!

[jimmyspeed]

you should not give up on the m12 dream "Schnitzer introduced a turbocharged version that was driven by Harald Ertl, getting 380 BHP out of 1427 cc’s"

http://www.bmwe21.net/?page_id=496

you just need to find the recipe !


i found it for you - http://touringcarracing.net/Pages/1981%20Cars.html

80mm bore and 71 mm stroke, so a e30 m10b18 sleeved looks like it would work

[ChrisBarns]

Thanks, I ought to start with a 2002 block so that would be a bore of 89mm. I know nothing about sleeveing down an engine but reducing from 89mm to 80mm doesn't sound to hard.

[Jarno]

I don't know of any combination of existing parts that would give <1428cc.
If you are not budget restricted, my choice would be a custom short stroke crank. Valves are pretty close to the cylinder walls on a 89mm bore engine.

E30 combustion chamber looks something like this. Hole in the gasket pictured, is 90,5 or 91 I forget.
The engine would practically without squish area, and part of the combustion chamber would be against deck surface like on a Ford Y-block. combustion chamber design has moved on since then.

I'd probably choose some other engine for this if regulations allow then turbo it. Originally small capacity engine would save some R&D work=lot of time and money..

[ChrisBarns]

Thanks for the reply. You are almost certainly right - it would be easier to start elsewhere. Though there aren't many (any?) cars that are tough enough to take quite a lot of boost, are RWD and are light. A 2002 is about 900kg so not as light as some but is RWD and has a pretty tough engine / drive train. Older and lighter RWD stuff tends to have 3 bearing cranks and newer stuff tends to be a lot heavier. I was partially attracted to the M10 becuase there are at least off the shelf kits for turbo installation.

I don't think there is a massive performance gain from RWD, by the way, I just prefer it!

I could start with a 1502 block, which would only need a very small sleeve but then I wouldn't be able to class it as a 2002 turbo and run the wheel arch flares. Even then I'd need to find pistons, work out compression ratios and other complex / expensive when you get it wrong stuff.

Anyway - I think all M10s have the same stroke so sleeving down the only option.

[Andyboy]

You may be better off with an 1600 M40 and sleeve it down. They're lighter, just as strong and you have a cheap as chips 16v head to use from an M42/44.

[ChrisBarns]

Thanks Andy but if I put the M40 in I would move up into a very serious (read expensive)class!