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M10 Head selection


318Turbo
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Hi guys.

I am busy building a BMW E30 track car. The engine that I will be using is the 2l M10.

The engine will be turbocharged and will be running 14-17psi of boost.

I need input from you guys as to what would be the best head to use? I have read about so many different opinions regarding the different heads. Some say the 1.8l L-Jet heads flow the best while some prefer the older E12 and E21 heads?

As far as I know the later E21 2.0 heads have the same larger valves as the newer 1.8 head.

If anyone has good information or experience with the variety of M10 heads and knows which one will flow the best and yield the best power, please share your experience.

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I think the consensus is to use a 1.8, not necessarily because of flow but the cylinder head volume is greatest at 63cc's vs 58/60-61 for the others. That way you can run a slightly thinner headgasket and get a "tighter squish", how close the valves come to the pistons. Theory is the closer they come the greater the pressure wave inside the combustion chamber leading to more complete combustion of the available fuel.

The head type is also piston dependent. Are you going to run custom pistons or stock? Which head is came on your block? If you're running custom pistons (forged will not only be stronger but also lighter) then it doesn't matter too much since you're building to order.

I've never seen a bench flow test of the different M10 heads in stock form but from what I've gotten out of reading every head related post I could find no one can really agree to one being significantly better. Besides, if you're pressurizing it any difference could be made up by an extra 0.5psi of boost.

http://www.bmw2002faq.com/component/option,com_forum/Itemid,50/page,viewtopic/t,313512/

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,329706/highlight,e21+head/

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,311197/highlight,e21+head/

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,284528/highlight,e21+head/

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Every generation of casting seems to be re- engineered a bit,

so I'd agree with the 1.8. If you compare it to a 121, it's

got bigger, smoother runners, better casting, and seems to

be a better controlled mold. Which makes sense, as it's a 25- year- newer

design. And probably had at least one run through a computer.

Likewise, the E30 block is a thing of beauty compared to one from the '60's.

And for a mid- compression turbo, the 8.not much c:r is probably pretty good,

if maybe just a touch low. Which you could fix nicely with a .5mm cut.

yup, 1.8, with no holes drilled into the intake side.

But do get the earlier 2l crank, as we've pretty well figured out that the

1.8 is cast- and not fully counterweighted.

hth

t

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Thanks for the replies and the links. They contain some very usefull information.

My car came standard with the 1.8 L-Jet fuel injection engine. My first turbo conversion are still running with the 1.8 block, standard pistons, rods, crank with aftermarket fuel and timing management system etc... On 10 psi the car is making 170 wheel horse power. This was my daily drive for quite a while but now I want to convert it into a race car.

So far I have bought a second hand 2L bottom end as the crank is what is needed to stroke it to 2L and because of the crank being forged. I would like to use 90mm forged pistons from JE... After reading through the links it seems that if I can get a E21 head and a set of flat top pistons it should give me a static compression of around 8.3:1. This sounds good to me.

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