I nearly have the e21 stripped to a bare shell looking at rust repairs soon, and so engine choices are starting to be thought about.
i have the m10 1.8 that was taken out, an could still be nice with a few tweeks, but, and there is always a but, i like things to be a bit different sometimes,
i also have a lotus 907 2.0 16v engine and box lying in the garage, without a home, its not BMW but what do you guys think? 160bhp 6500rpm all alloy and its a slant 4 but in the opposite direction.
there is also the 2.2 180bhp version for sale for £495 only 30 miles away.
if i was to spend 1K on the m10 what could i achieve?????
Spend 1k on the M10 might give you a 2L bored out block with high comp pistons (about £5-600 as I recall for forged) and a better cam (I have a 284 catcam that I got cheap), as long as you don't do too much else and do the actual work yourself/have free labour. But you need to do more than that. You may want to get a lumpy cam with big lifts, new followers etc. Better manifold is essential (I had one already, came with the cam), then we get onto intake, your 2L cammed M10 won't like a pierburg, or even an upgraded weber. I did it on the cheap with S14 throttle bodies for £100 from Jason, adaptor plate made by the engine man, needed new injectors cos the ones i had were shot, then of course ECU - I have a DTA which cost £800 with loom/mapped. Fortunately that will run the ignition which is done by a coilpack and triggered by the ECU from the crank. All those bits add to the bill. Sadly the original crank sensor setup we made wasn't solid enough, so had to spend another hundred or so on a kit from USA. While the engine is in bits you feel obliged to balance the whole lot and do lots of porting etc. It costs a bomb.
1k will get you a manifold and a better carb setup, you could upgrade the ignition I suppose, but the later dizzy is OK anyway. If you don't run an engine building place you will spend many times that in the quest to rebuild it. I know I did and I have about 160bhp. For spending 1k youd be lucky to get 110-120 realistically.
Put an M52 in is my advice. It's what I'd do if I had my time again (and didn't have an obsession with building it to the regs for a specific race series so it'd be in class E and I could ask for number 21, then never do more than trackdays). When Nas and I were going to take the engine out of the slug it was looking around 2k, problemchild is just doing his you could PM and ask how much it's costing him. If you REALLY want a built M10 I may be willing to sell mine, but not for 1k, needs to be 2.5. For that money you can fit an M52 and have some change.
my mate has an M10 in his race car and to get M52 power he has over 25k in the engine alone I think it was Leister Owen that built it. Dont get me wrong its frecking awesome but unless your going racing and need to stay within regs put a M52 in. Its not mega cheap to do it right but its a lot cheaper than tuning the M10, more reliable, better on fuel and if the lump lets go you can get a replacement in next day for under £500. Nas80 is the authority on the swap. he can provide converion kits through to an in and out turn key coversion. Helpfull bunch on here I wouldnt have stood a chance without the help I have received from a number of members on here so im sure you wont go far wrong whatever you decide. I do like the idea of a 4pot 16v screamer though I would love to have done a Vtec conversion but the M52 is so cost effective.
Thanks for the info folks, i didnt really want to go down the 52 route but i can see why a lot of you have, especially when the s14 are prices they are.
im glad you gave me real world figures for the m10 and i think the lotus idea is not a good one. i think i will see what the options are closer to the time, i may end up having a 5 speed for sale.
The trouble with M10 E21s is that to convert it to anything else BMW related it makes sense to get a lot of the 6 cylinder specific parts, which are getting rare and expensive. For around 170bhp I would stick in an M20 2.5. For someone who has done a 24v conversion I wouldn't do it again.
I'm having this debate with myself at the moment. I have a great 316 M10 shell and I'm most likely fitting the M42 1.8 16v, though I am tempted to stick in an M30 for the hell of it since it works with the M10 gearbox (speedo output). If you want to go down the different route, I'd be looking at a rebuilt CA18DET or SR20DET. There's even a rotary powered one in the states!
the 2.2 lotus engine n box for 500 sounds a bargain. your current drive train wont need changing and its such an easier engine to fit and im pretty sure it runs carbs too?
making engine mounts isnt difficult and the gearbox tunnel is huge on these cars.
dont waste your time on the m10 or m20. esp when there is a screaming twin cam you can fit!
thats what i thought, i want a screamer, shhh dont tell the wife haha,
yes the lotus does run on carbs, i have the 2.0 sitting but 2.2 is better!
i want a change fom torque monster 4 pot turbo's, well at least ones that cant reach 9000rpm any way.
looks like the m10 is out for now then, dont want the weight of the 6 pot up front, i have another idea but that will be when funds allow, and no its not an s14.
the lotus is the best "cheap option at the moment i think.
I had read that the M52B28 was basically as heavy as an M30B35.
If you were interested in a six (which it sounds like you're not), then the M30 is worth considering - they're cheap as chips, and will bolt up to your M10 gearbox.
I'm running an 318i gearbox in mine, and it hasn't fallen apart yet. Needs an uprated clutch though as 225 ft/lbs is a bit more than the old 1.8L.
An M42 or M44 would also be worth thinking about, but the none of the later 4 cylinders will bolt up to your M10 gearbox.
honda engines where my first thought, but when engines are starting at 1k for bare engine, plus accys, plus gearbox, they mount up.
but saying that pay the 2.5-3k and you ready to go 240hp.
im not against 6 pots just if i could get the same power from a 4 pot around 200hp, less weight would improve everything.
i have even considered a 325tds engine but would need a diff around 2.9 and dont think an e21 exists that ratio.
this is the problem with a blank canvas, way to many options.
