Performance Cam - M10

[Eddie.]

Over the winter months, I'm going to give the M10 1.6 in my E21 a little TLC.

Mainly it's going to be:

- Sort the overheating issues
- Change all the gaskets
- General cleanup (including engine bay)

While I've got the engine out though, I'd like to add a few upgrades. I know most of you will say "swap it for an M52/M50/Mxyz..." and while I'd love something like that, the costs will spiral, and I'm now back in education and can't afford to pour thousands into a swap.

Anyway, my plans are reasonably simple:

- New, performance cam
- Bike carbs
- Better exhuast

Is there anything else worth doing to the engine, other than cam and carbs, that won't cost the earth? I know NA tuning is expensive and doesn't provide the same level of performance as boosted cars, but I'm not after silly figures, just to make the current engine a little more lively with a bit more theatre.

Where is best to get the new cam? I've seen the one on Dbilas and it looks decent enough, and is in Europe. I've heard Cat Cams can do something, but their website doesn't have any prices.

[nas80]

I would not fit the 1.6 back in, I would get my hands on a 1.8i from an e30, swap your original m10 sump pan over and put the bike carbs on that. the bigger valves in the e30 block and carbs should net you about 140hp with a decent tune. these engines are very cheap you can get them for about £100 and you will have a good 20-30hp boost for little outlay.

Im not saying do the m50 swap, in fact from what you say id advise against it, you also have to upgrade brakes, the bushes wont last etc etc etc. its a bit of a money pit conversion.

[Eddie.]

So you'd take an E30 M10, and take the injectors out, and convert it to bike carbs?

Where would be best to get a performance cam for the M10B18?

Certainly never thought of that, makes sense what you're saying too.

Yeah, I could probably get an M50 in, it's like you say, the brakes, bushes, etc etc that will end up costing me a fortune and I don't want to start down that road.

[Jeroen]

The fact that the M10 engine also weighs less and the weight distribution is better makes it fun enough even though you are down on torque and horses.

[nas80]

So you'd take an E30 M10, and take the injectors out, and convert it to bike carbs?

yep then later id turbo it lol

Where would be best to get a performance cam for the M10B18?

the USA - Turner motorsports / Ireland engineering / Vac all supply that kind of thing.

[Eddie.]

Is there nowhere in the UK that can supply them?

I don't want to get stung on import tax, etc.

Lol! I won't be turboing it. I'm guessing the likes of Bogg Brothers would be able to assist me with regards to converting to carbs from fuel injection.

[nas80]

your best off emailing cat cams. tbh though - you won get stung that much its 1.6 dollars to every pound.

[Duracel79]

You could try Newman Cams:

http://www.newman-cams.com/pdf/bmw.pdf

Or CA Automotive(for schrick):

http://www.ca-int.co.uk/home.php

Ben

[drjim]

I have a 284 catcam in the slug which gives 150-160bhp with a 2L capacity, ported e30 316 head (the original was cracked) aftermarket EFI and S14 throttle bodies. It won't idle when cold and even when warm it's "lumpy"

If you go bigger than the 284 you get even more horrible lumpy idle and need all sorts of expensive rockers springs and valve cutouts in the pistons.

If you use the car on the road be happy with the power you have or rather could have. Refreshing the existing engine to get it nearer to how it was when new makes a big difference. If you can find an e30 engine as NAS says you could just put the e30 efi on - OK it's K-jet but it should just work, and you have all the bits for Nas's turbo idea ready!

[Eddie.]

I want something a little more special though, seeing as it's not a car I use daily. It's for occasions, so each time I drive it should be an occasion.

A standard M10 won't be that.

I agree, I don't want a really aggressive cam, which is why I'm not looking at aggressive cams, I'm looking into mild ones.

I don't expect huge numbers, I'm not interested in that. If It runs at 120bhp, I'd be happy enough. I don't drive fast on the road, I don't do trackdays, so a very mildly tuned M10 will be fine for now.

If I had the budget, yes I would convert to an M52 etc, but I don't.

[J.K.jr.bad.]

From my experience: if you don't have money don't even start to do any upgrades.

Like drjim said I would stick to:
change to EFI with standalone ECU
for cam shaft I would use either 284 or even 292
Ported head
Custom exhaust manifold and correctly built exhaust
change engine to b18 or if you can get b20
Dogleg gear box.
LSD diff.

But all this cost quite a bit of money. If you don't have it. Enjoy carburetor. As far I remember it was quite good if everything worked properly.

Don't use bikes ITB. It is quite difficult to get them running also to hook up them was also a chalange. If you still want ITB, then go with special kits from Weber. Cost more, but it is direct fit and no hassle. At the end you will see that they wouldn't cost you more then trying to put bikes ones.

[polov8]

Save up and get these!



http://www.ebay.co.uk/itm/131042323732? ... 1423.l2649

Pretty kick ass set up!

[Eddie.]

I never said I don't have any budget for this, I said I couldn't warrant the cost of an M50/M52 swap.

I know a lot of you enjoy power figures and that's fine, but it doesn't interest me if I have 120bhp or 130bhp.

As long as it's fun, and it sounds half decent and it puts a smile on my face, that's all that counts.

I want to use bike carbs because I have friends that have used them, they're a simple setup and they provide decent enough results for the outlay. Cam is only there to add a bit of life to the engine, 284 is fine, I don't mind some lumpyness.

I'll be on the hunt for an E30 M10, as the advice Nas has given me is decent, I didn't know about the valves, so thankyou for that

[e21-Mark]

Spoken to a couple of well known m10 builders lately and both said there's no point just fitting a cam. In fact, both got good gains sticking with the OE cam and suggest making sure the cam chain/tensioner is replaced, to ensure correct timing throughout the rev range. A stretched chain will hurt power.

The guy who wrote the following knows his m10's and got 240bhp from his 316!

So you want m10 then ok you got it.! These are my own findings after lots of years and many many many dyno sessions tuning one for race use.

Everything here is stuff i've learnt the hardway, without any doubt the best worlds best builder of these engines is Lester Owen, but i couldn't afford lester money for a race engine. so i just bought the stuff i couldn't do without from him.

the only real weak point in these engines is the rocker arms, BMW origonals are better than pattern ones but even then will break is regulary asked to exede 7,000 rpm.
using revs upto 7500 i found using a lightened 316 flywheel and std 215mm clutches were just fine even with 190bhp, this gives a much lighter assembly than the seriously heavy 230mm type flywheel as fitted to Tii's.
once i'd tuned to the point when i was shifting at 7700 i found clutch covers started exploding with a worrying regularity, even using uprated sachs competition std type covers. at that point a bought a steel flywheel and 7.25 race clutch.

Once you get to 8,000 rpm the oil ways in the block are getting a bit marginal, particulary the drillings to and from the oil filter housing, the oilways meet up but there is a 50% miss match between them where they do with is bad news as they also make 90 degree turns at the same time, the cure is to drill the oilways out by quite a few mm, this massively will improve oil flow, finally drill a couple of extra supply holes in the centre main bearing shell, this will improve oil flow to no's 2+4 big end, it sound a little odd but thats infact what bmw did when they stretched the E30m3 to 2.5litres

crankshafts are indestructable, conrods will stand 8800 all day long, infact they will go to 9200 but only once, the second time at those revs they break! std rod bolts are fine, infact i've never even used a new set!

topend now, as long as you have got the later tii 46mm inlet and 38m exhaust valves std valves are plenty big enough, you can buy bigger inlets but its a waste of time and money, i have usfully increased the exhaust valve size but the gains aren't huge and only worth looking at for over 200bhp.
all the heads are quite good, ports only requiring a bit of blending to remove any sharp edges, valve guides can be ground flush with the ports without overly shortening there life.

to get real power these engines need real compression lots of cam and a nice tight squish to make them burn properly.
squish is easy, run the pistons 0.023 inch out of the top of the block, this gives 0.030 squish, any less and it wont burn properly and your loosing out on compression, this is a tighter clearance than most engines will stand but its fine on an M10 because the rods are so strong and dont stretch much.

now comes the tricky bit, almost any sort of real cam in these engines will give valve to piston clearance problems, made worse by the need for high compression.
if you use the 121 type head and skim it down to the point you have almost hit the inlet valve seats and your using 121 tii pistons you can get 12.1 CR, but you will need some massive cutouts machined in the pistons to clear the valves. it can be done i got 12.1 despite the 6-8mm deep valve pockets we put in the pistons.
you can only do this with the 121 head, due to its smaller chamber, inital higher cr and the fact that the pistons have very thick crowns. try this with an e12 head and you have no compression as the pistons will end up with holes in them!
having skimmed all this metal off the head, the timing chain tensioner needs modifying to keep the chain tight and the cam sprocket will need redrilling to get the cam timing right, its also a good idea to drill and tap the cap for the tensioner to make it manually adjustable as the tensioner can back off when you lift from high revs.

lester gets high cr by using a domed forged piston and machining the combustion chamber to accept it, its arguably better, but costs ££ to get the head machined and about £1000 in pistons, i used std off the shelf Mahle £200 pistons which coped with 8200rpm just fine.

cams for all round competition schrick 316 is best, and is just about within the scope of std rockers, if you get the rest of the engine right its good for around 195bhp.
336 is next, but much more peaky and you really do need those steel rocker arms to make use of it, not to mention a close ratio gearbox

carbs, twin 45's with 38 chokes will get you 180+bhp, 48's with 42 chokes 215bhp
engine management and throttle bodies is better though, i once cut up a weber inlet manifold and welded it back together without the bend and gained 10bhp! speaking to lester he confirmed he found the same by using a chevron inlet manifold which has only a slight bend not 30 degrees like std, unfortunatly this only works with throttle bodies as it would tip the carbs up too much. whilst on engine management double injecting was found to be worth 12bhp in the midrange!

there you go, i could write much more, including stuff about 2.2, 2.3, 2.4,2.5 engines but everyones already asleep i guess?

His suggestion to me, was to use an e30 318i engine (bigger valves) and add 40's, once I had done the timing chain etc. I paid £70 for a sweet engine and £200 for Weber 40's. If I rebuilt the head I could have done the cam, but then I'd need new steel followers and oversize adjusters. Domino effect.....

M52 swaps can chew their way through big wads of cash, so don't blame you for not taking that route. A bit of induction roar on a nice, tight m10 will certainly be fun enough for a weekend blast anyway.

Best of luck with it anyway.

[nas80]

yea e30 engine with bike carbs and a good tune you will be meeting your requirements and its very cheap to do also. id leave the cam and see how you like it to begin with.

when I had my 1.8 with a weber carb it ran pretty damn well and it was easily able to keep up with traffic.