M10 top end

[gjm 3258]

It's Friday evening, dark outside, too many flying bitey things in the garage when the lights are on, and for a variety of reasons I have time on my hands and no alcohol to help pass it.

So, I've started doing a teensy tiny little bit of planning for what I would like to do with an E30 coupe shell.

I made the decision a while ago to stick with a 4-pot engine. Lighter than many 6-pots, and more room to work. And fewer cylinders means fewer expensive parts required.

And that's as far as it got. In the interests of moving things along, I've since decided to go with an M10. It's original. It's a nice, simple, strong and reliable engine. (Yeah, I know, I'm missing a trick with the opportunity of some of the later engines but I'll live with it.)

Admittedly, this decision was influenced by exchanging some emails with a friend in Denmark, who has a friend in Sweden, who has done some silly things with M10s. (And that's without getting into the whole M12 and other variants discussion.)

Most recently, he's been developing some top end parts. Roller rockers maintaining better geometry than stock, but weighing more than 5g less. Each. That's over 40g saved from just the twiddly bits in the top.

This guy has been testing the rockers, too. He's set up a kit to test cams, rockers valves and springs. Pre-warm oil (of course) and see how long it takes for them to break. It's no fun doing these things at normal engine speeds especially when that's not where they're likely to be used, so how about winding the whole thing up to 10000rpm, walking away and and leaving it for several hours? Subsequent measurements show no measurable wear. An accidental spin to over 15000rpm didn't break anything, but that wasn't sustained.

So, this seems like a good idea. Just need a crank, block rods and similar that can do that, too.

And a gearbox.

And...

[aja540i 1906]

From my experience with engines in general the m10 was, typically of BMWs of the time, slightly over engineered and quite simple. It has famously made huge power figures in various forms and found its way into legend, but it is not magical and like all mechanical things it has limits.

I am certain you could build one to rev to 10,000 without self destructing, but there will be a downside, and i suspect the cost will be the first one!

On the positive side, because of its age and legend status there are plenty of people out there, including BMW, who have gotten results from the m10 and you have access to a wealth of info about them!

I have kept an m10b20 to put into my keeper e21 at some stage, but at the moment an m42 is a better prospect in bang for buck terms.

I hope you go fully mental with it because i want to see it done, but from my research it is a labour of love, not common sense!!!

[gjm 3258]

I don't think anyone has ever considered mentioning common sense when talking about me!

You're right. It is pointless. There are other ways of achieving the same thing, several of them being from Honda, but that's not the point. I know you know what I mean!

Cost is an issue. I reckon the top end - cam, rockers, valves, springs, etc would cost around $3500. Forged titanium H-beam conrods: another $3500. I can get a 2.7 stroker crank, but that's almost a mortgage away!

All these parts are rated solid and reliable beyond 10000rpm.

Let's have a chat about your M10 some time.

[Olaf 3320]

the M10 was based on a formula 1 engine of the time, yeah? or was it the other way around.

Anyway, don't let anyone tell you that selecting and building an engine based on the viability of trick rockers is a *bad idea*. #8 )

It sounds super, Graham! Are you building it as a fast road weapon, or a track day missile, or a racer?

[gjm 3258]

T'other way about. The M12 and M13 engines were based on the M10. There were a lot of differences, and the older they get the more powerful they were. In reality, I doubt anyone really knows exactly what power they made, but it was a lot. It's safe to say the F1 qualifying engines were making well over 1200hp at their height, although reports of 1500 may be enthusiastic. The race engines were typically 6-900hp depending on when and the circuit.

I don't yet know if it will happen. There are a couple of ideas I have that need verifying for actual viability rather than satisfying any 'be realistic' type issues.

If it happens, it will be ludicrous. Maybe not Koenigsegg One:1 ludicrous, but you get the idea.

[Olaf 3320]

nothing wrong with ludicrous, mate.

but what's the intended use (of your e30 project); road fun? track weapon? crossover?

Edited March 5, 2016 by Olaf

[gjm 3258]

nothing wrong with ludicrous, mate.

but what's the intended use (of your e30 project); road fun? track weapon? crossover?

Use? No idea. Fun, definitely. It's as much a case of doing it because it's there and I believe I can as anything else. I want it to be road legal and have long since cast off any thoughts of avoiding certs and the like - that's going to be needed.

Just one thing though... It'll not be like skintkarter's Gp5 E21! I don't have the skills to produce a build like that.

[Ahmedsinc 414]

Turbo M10B20.

Good, tractable power from low-ish rpm, reasonably low build cost, high fun level.

'nuff said!

[gjm 3258]

Turbo M10B20.

Good, tractable power from low-ish rpm, reasonably low build cost, high fun level.

'nuff said!

Yup.

It's an excellent starting point, and no mistake.

[Neal 545]

Not quite an m10 but love this m12 resto / rebuild video

[E30 325i Rag-Top 2959]

Nothing wrong with an M10 unit Graham, over-engineered as standard and capable of being tweaked a hell of a lot.

Kayne Barrie got some very impressive power / torque out of an M10 with side-draft carbs in Howard Woods 2002 race car, which won the 2-ltr Championship and mixes it up with the muscle cars as well.