Stroker

[bekker 7]

Ok so this has probably been covered many times, but perhaps someone could help me out.

I have an E28 525ee and I'd like a bit more get up and go.

I started a post about an m30 conversion but didn't have any responses and have since looked into it a bit more and its probably more work than I want to do (unless I'm wrong?).

But the 2.7 stroker is interesting.

If I do the b20, b23 or b25 head replacement, what else should I do?

Im open to suggestion about intake manifold etc, but do I have to replace the motronic or can I just swap the head and leave the electronics alone?

I know some people on the net are qouting around 200 bhp for this (full) conversion, and that would be nice, but realistically I'm mostly town driving and I just want to have a bit of fun doing it.

Cheers for any help.

[Gus 5]

read my stroker article i posted up from Total BMW

basically the easiest way to do it is to put the 731 head from e30 320 or 323 and whack that straight on ya block...any other decent way involves a full rebuild

325i intake manifold/TB and injectors etc is recommended too. not sure about ecu/chip requirements

[bekker 7]

Thanks Gus,

I did read the article but, and perhaps I didnt read it right, it seemed to be more about taking b27 bits and putting them onto other m20's. I dont think it said about the ecu and I think it also mentioned swapping pistons and perhaps more.

Thanks very much for your reply.

Out of interest, on a scale of 1 to 10 (1 being easiest) how hard do you think an m30 conversion would be?

Cheers.

[Gus 5]

probably easier, aside from the fact you need to change gear boxes...not really worth it as a 535 has a whopping 208 hp or whatever it is. m20 would be around 190 i would hope for?

as for 1 to 10, depends on the person!

[bekker 7]

Thanks Gus appreciate your help, but just so I'm clear, are you saying the m20 upgrade is easier and would I need to upgrade the trans for the m30? I know the m30 is a bit heavier too, so I need to consider that also. I thought they both used the 4hp22 auto trans?

I'd be pretty happy with 190 bhp, thats about the same as a 3.2 m30. What would I have to do for 190 bhp?

Cheers

[Gus 5]

what im saying is you would have to change your gearbox to do the m30, so it would probably be easier and cheaper to stroke your m20. as above with the 731 head, maybe a lumpy cam. the bottom end will prob be fine, so just a nice head rebuild and your away.

is it auto or manual? would def manual if it was auto first..much better change!

[bekker 7]

Thanks, its an auto.

I'm reasonably keen to keep the auto, its my work car and I'm on the road and on the phone a lot.

I'm planning a substantial rebuild later this year so will look at the head job (!) then.

Thanks for your help Gus, really appreciate it.

Cheers.

[BM WORLD 1264]

just fit the 2L/2.3L head/cam to it ,( a friend of mine has good one if you need) . 2l or 2.5L manifold , replace 525e ecu with e30 325i ecu of about same year and chip it if you want .

or save yourself the work and just sell the car and buy a e28 535i 218HP with 310Nm ,weight about 1380kg alot more torque and power than 525e i have owned both , i like the 525ee i had , torque pulled in early , lazy motor . but i have had a few 535i incl M535i i have now and they are much quicker and power just keeps going all the way to 6k rpm .

m20 and m30 have different gearboxes , driveshafts , and a few brackets etc are different in the engine bay . radiator etc etc . i could supply some parts if needed to do conversion ....

a freind of mine did the 2L head,cam, manifold conversion went well , still ran on 525e ecu ok'ish.

if you dont mind the little bit extra gas comsumpsion go for the 535i ... there is a couple on trade me now , quite cheap .

just watch for rust in all the usual places .

good luck with your project

[bekker 7]

Thanks, I thought about just getting another car but I love this one. Its got good history and great spec being the EE.

Regarding fuel consumption, it is a factor, this is my work car, but lets face it, if I was really that worried I'd be doing an M10 conversion!

Its good to know that someone else has done the conversion but left the motronic in place, thats my first preference. I think the 525e ecu was set up for economy so a chip might be a good idea, but what about the 535i motronic? The 525e and 535i were the only e28's running motronic (did the M5?). Did the 535i have a better chip?

The only other question I guess I have is which head to go for? Are there any real differences? As you point out, there are a few on trade me so the options are there.

Cheers for the help guys.

Edited April 11, 2007 by bekker