Stroker using 200 or 731 head?

[Henriquesbruno]

Hi Guys! I have a fresh e21 320/6 m20b20 engine that im hoping to build into a 2.7 stroker using a b25 block eta crank and pistons.
Problem is that im struggling to find good condition eta pistons and dont want to spend 900 dolars on custom pistons. Is there a cheaper way of building a stroker using a 200 or 731head?
Ive heard of people saying to shave m20b25 pistons and (even m54) into flat top pistons but never heard of someone thats done it.
And please dont tell me to use a 885 head instead because my plan is to keep the 200head along with the its carb setup.
Fyi im not looking for aloot of power since this engine is to go into my bmw 2002.
Any feedback would be greatly appreciated because i cant find much info on this online

[shogun]

Moved from Forum software questions to E21 forum

[OLD MAN]

carb intake fits the 885 head also.

If you do not want a lot of hp why do a 2.7? 2.0 - 2.3 or 2.5 will be pretty great in a 2002.

We have a 2.5 with 885 head 2.0 intake and holley carb - works pretty greay for us. It is a built engine though with 288 cam and 10.5 to 1 pistons in it. 180hp or so at the wheels.

Use what you have and make it durable it will be fun!

rebuilt 2.5 2.jpg dynoready6.jpg

[Henriquesbruno]

Hii Old man!!! You where actualy the only person i was hoping would reply!!
I didnt know i could use the 885 head with the b20 carb setup!! Do you think the solex would handle that to?
I just wanted a 2.7 just incase i wanna do doughnuts or shame someone at a robot lol.
The 885 head seems like a good idea now tho. And might be cheaper than finding eta pistons.
But lets say i wanted to use the 200head with a 2.7 crank or even a c38(328i) crank is there any oem pistons i can shave into eta specs?

Thanks for the reply broo

[OLD MAN]

Not sure a 200 head would give you enough air flow for a 2.7, the valves in it are pretty small.

BMW engines are a lot like small block Chevy engines in that a lot of the parts are interchangeable.

If I were you I would just get a good used 2.7 out of an e30 and rebuild it. Easy straight forward and it will do all the doughnuts you can afford to buy tires for! LOL

[mxl556]

A 200 flows much worse than 731. Long time ago I needed a replacement head for my E30 323i and end up converting 200 ETA head as it is all I could find at the time. I swapped a 2.3/731 cam and drilled extra holes for bearing lubrication). Different in flow was obvious and I would not use 200 head if I had known...

[Henriquesbruno]

Ok ok u guys give me lots to think about now. But think ill try out a 2.7 bottom with a 200 head first then maybe port it and if that dont work, out ill just go 885. Ive read about 200 heads working well with a 2.7 bottom. So ill try that first coz like i sayd i dont need the highest power output. But im still wondering if there are any oem pistons i can shave into eta pistons, to build a stroker maybe with a diferent combination of crank and rods to a 2.7 one?
Coz my problem right now is finding good eta pistons.
But ill let u guys know what happens with this build

[cgifool]

A 200 flows much worse than 731. Long time ago I needed a replacement head for my E30 323i and end up converting 200 ETA head as it is all I could find at the time. I swapped a 2.3/731 cam and drilled extra holes for bearing lubrication). Different in flow was obvious and I would not use 200 head if I had known...

Ironically this is my situation as well.. PO overheated and cracked the head, replaced with a 200 ETA head, drilled extra holes etc. It does run well but I never got to drive it prior to that, so I have no idea the difference. Its one of those things I don't plan to do anything about until the head has to come off for some other reason.

[mxl556]

Ok, if I remember correctly, a 731 head flows better than a 200 head as it has bigger valves and slightly different EFI intake manifold to match.Only e30 320i/323i came with a 731 head. E21 323i came with the same 200 head casting as 2.7 ETA but had as many cam journals as 731 or 885 head and higher lift cam (~260 degrees).

E30 cars (2.0/2.3) that came with better flowing 731 head had L jetronic instead of mechanical K jetronic and different intake manifold (and exhaust too I think).


David, even though your e21 has a 200 ETA head, it should be identical (assuming journals were drilled correctly and cam was swapped) to the head your 323i originally came with.
Using a 731 head on the e21 with K jetronic may be beneficial because of better flow but you'd probably need a different intake manifold from an e30, or port the existing manifold.

[hdx]

Before the 885 head was available guys would put a e21 323i 200 head and camshaft on a eta 2.7 block . For a budget stroker .
It worked well . I had a good friend who built one in the 80s .

[Henriquesbruno]

Before the 885 head was available guys would put a e21 323i 200 head and camshaft on a eta 2.7 block . For a budget stroker .
It worked well . I had a good friend who built one in the 80s .

Hi brother thanks for the reply man.
Ive been reading about it (not much info on it) but think it will work as you sayd. I already bought the eta crank and pistons and will defo try to make it work and keep the carb setup too.
Thanks for lifting my spirits on this tho. Ill defenetly let u know of how it turns out. Wont be too soon, coz im a teacher and im broke right now, due to schools being closed where im from, but ill holla! Should make for a interesting 2002