how do i make my 325e a stroker and cheap

[timmytwotimes]

so i just got my first e30, and want to know the cheapest way i can stroke the motor. i dont have a lot of money, so if i could get some help, that would be great

[jlevie]

The cheapest way is use an M20B25 AFM, intake & throttle body, injectors, head, engine harness, CPS, ignition wires, and DME. The step up from that is different pistons to get the compression ratio back up.

[camip]

As stated above. I'm currently collecting parts to do this swap too.

[Pdxseth]

Sorry to thread jack but I remember seeing some where that the head is not a direct swap. Isn't their a little machine work you have to do


Sent from my iPhone using Tapatalk

[timmytwotimes]

how much do you think its going to cost me?


and would it be best to just buy a whole m20? or what

[Gary Horneck]

Good info here http://bmwnut.blogspot.com/2006/02/m...cars-325e.html I went with the EU 323i 731 head.

[e30trooper]

no head work needed. basicly you the topend of a 325i ( head, intake, AFM, TB, fuel rail, injectors,harness,dme,o2 and thermostat housing ) might as well get the head rebuilt/ or refreshed.
its basicly pnp. I spent around 600, that was all new gaskets and replacement parts , all swap parts and head sent out to a machine shop for rebuild/decking.

im to a point now where my car is only 5%eta now lol. Only thing eta left on my car is the exhaust.
Very fun powerband!

this is a pull with the headswap and the etas open 2.93 diff.

1st and 2nd gear olny


at the end of the day im happy, but i wish i could have put in a cam and had some port and polish work done. With the 373 the car is stupid quick

[tinkwithanr]

Depends, if your engine is a 'Super ETA' (has 'i' piston crown and c.r.=8.8:1, built in '88 i think), you just need the 'i' head, harness, intake, injectors, throttle body, dme etc as mentioned above. That would give you a very potent 2.7L engine with ~180hp assuming nothing is terribly worn out. However, if your engine is a normal eta, then you would only get a compression ratio of ~8.0:1 due to the flat top of the eta pistons. This is a great setup if your planning to boost, but not nearly as good naturally aspirated. It's arguable that you would be better suited to just swap in the entire 'i' engine if you aren't starting with a super eta bottom end.

hth

[e30trooper]

tink, thats why you have the head sent out and decked to make up for the compression lost.

[timmytwotimes]

Thanks guys, I think ill just swap the head and everything,like tink was saying. But would it be cheaper to buy a complete motor and just swap it all over or peace it together?

[camip]

Just depends I could have bought a whole I motor but didn't want $600 taken out of my account at once. So I'm just buying parts when I see good deals.

[tinkwithanr]

tink, thats why you have the head sent out and decked to make up for the compression lost.

You can deck the head, but then your going to need an adjustable cam gear to get your timing back in order. Plus I'm really not a fan of taking the material from the head as your also messing up the combustion chamber shape (not by a lot, but it does add up). Personally if you wanted to raise your compression back up, the best option would be to deck the block. Of course that's only an option if your rebuilding the bottom end to begin with.


As for price, it really depends on your time table and how lucky you are. If you can be patient and wait for a good deal to come around you can get one pretty cheap. I was able to find a slightly wrecked 325i for $400, and sold enough other parts off the car to break even so I basically got the engine and lsd for free (minus time tearing it apart). If your in more of a hurry I would say expect to spend at least $300-500 for a known good head, plus another $200-400 on the rest of the parts. It could also be worth looking in local junk yards for the smaller misc parts people might leave behind when they pull the motors (harness, afm, ecu etc).

[mbonanni]

I bought a 325 with snapped timing belt, this left me with the choice to either swap an i head and other needed parts onto the bottom end or buy a motor.

I ended up buying a full 325i motor with 150k on it. I regasket damn near the whole thing, new ignition parts, labor etc. cost me about $700 including purchase of motor. I think it would have cost me the same price, if not more, to make a 'stroker'. I bet the stroker would be more fun, but the i was just easier for me.

I still have the 'e' motor and plan to rebuild it, slap an 885 head with a cam and what not. buying the 'i' motor still gave me all the parts I need to do the stroker, so now I just have to build the other motor and drop in.

Either way, you will be more happy than the 'e' I am sure.

[StealthiE30]

I can hear my timing belt going, and I too will be doing this swap in the near future! Good luck with everything, and lets us no how it goes (ie build thread). :up:

[jlevie]

You can deck the head, but then your going to need an adjustable cam gear to get your timing back in order. Plus I'm really not a fan of taking the material from the head as your also messing up the combustion chamber shape (not by a lot, but it does add up). Personally if you wanted to raise your compression back up, the best option would be to deck the block. Of course that's only an option if your rebuilding the bottom end to begin with.

If you deck the head the maximum amount you can can gain a couple of tenths of CR. You'd have to remove a lot from the block to gain the other six tenths of CR (going from ~.8.0 to 8.8). And then you'd run into the problem of the valve clearance cuts in the piston faces and the requirement for a change in the cam sprocket timing (as stated).

The only realistic solution is SperETA or equivalent pistons.