EN40

There won`t be any cheap suppliers of this.Macreadys don`t list it in anything but rounds.You can try this lot.A good site for info if nothing else.

How about the supermarket? :-)

Does it have to be EN40? P20 is much more easiy available and will do pretty much anything that EN40B will, and both are nitriding steels.

Peter

Its for a crankshaft (EN40 is 'the' crank steel), but P20 might do.

Dave

OK, perhaps it might not have been such a good suggestion then. Never heard of a crankshaft made from P20 yet but lots of 'em from EN40, so it'a a proven material choice. That's quite a large home brew engine though Dave, sounds interesting so any more clues?

Having made the things myself in the past for race engines it's a lot of work and hassle to use EN40 given you need two sets of grinding ops plus the nitriding. Then of course if you ever need a regrind it means nitriding again. EN19 would be much easier. If you do go with EN40 you might be best advised to see if an existing crank manufacturer will add your billet to one of their steel orders for you. They'll have very good prices negotiated as they buy in bulk. Phoenix Cranks in Slough got the last billets we used for us much cheaper than if we'd gone direct to a steel supplier for a one off order. A billet weighing 80kg was about £100 I think but this was 15 years ago maybe so I have no idea what prices are like now.

Your billet also sounds very small for a 1 litre engine. About 6" diameter round stock would be more normal if you want proper counterweights in there. If all you're trying to do is make something that looks like a bit of bent coathanger I don't fancy its chances of lasting whatever steel you make it from.

Good Idea, Ill try and find a local crankshop.

Its a *very* oversquare engine, with a tiny stroke, hence small billet. not a coathanger crank, but it des have big journal overhangs (mains to BE) so should only need minimal counterweighting (fingers crossed, not finished detailed design yet)

Dave

Its for a sprint/hillclimber. the capacity rules are 1.4x multiplication for turbo engines, hence to run in the 1400 class 999cc is the biggest that can be used. I think it will actually end up at about 991cc having done the preliminary sums. Then slap on a big turbo (its a little more complex than that of course) and turn up the boost :) Im doing the sums for the turbo etc on the basis of around 200hp. car should only weigh about 5-600kg.... its been on the back burner for about 8 or so months, finally time to get moving on it. Its not a complete homebrew, only the crank really, though I think there will be a cylinder head to make sometime, to move the inlet/exhaust ports about to give a better package. Can you weld mold steels, and are they available in 1/4" sheets? Think bread and butter boat hulls but in metal, and for the top of an engine...

Dave

Sounds like a Cooper S crank to me :-)...

Regards,

Chris

Close..... ;)

Dave

I had the same thought. There aren't many cranks you can hack out of a billet of 3" x 4" and nearly every modern engine is properly counterweighted.

Why not find an existing steel crank from another engine and build your engine around that ?.

Alfa twin cams (60's >) had steel cranks, but don't know about the grade. Then there's stuff like the old bda engines - you remember, the one's with all the allen socket bolts in the head ?.

Regards,

Chris

The S engines came in various stroke sizes as well, right down to the

For the time, they were really tough little engines...

Regards,

Chris

that would be good idea, if it wasnt for the block being the only part I have to retain.... pesky rules eh? And no one currently makes a crank for doing what I want to do, so what with me having a garage full of machine tools away I go on another adventure in metal :)

Dave