320i into 323i

[Coyote_ar]

Hi guys, i recently got a 1984 320i. The car is in great shape, and the engine too ... but its a 320i.

i mean, the car will cruise at 185km/h all day long, but acceleration sucks.

im planning on building a nice stroker in the future, turbo, the whole shabang.

but that will be another engine, meanwhile i would like to get some extra hp from my existing engine, so i was able to get a nice 323i crank.

so here comes the question, besides changing crank and pistons, do i need to change anything else on the engine to be able to mod it to B23?

any tips or personal experiences related to this mod, will be really appreciate d. Thank guys.

PS: this forum is great, loads of information

[HairyScreech]

iirc the bore of a 323 is the same as 320 but has the extra stroke to make up the increased displacement.

i would asssume that 323 rods or pistons are slightly shorter to allow for this increase in stroke as normal 320 ones would surely hit the top of the combustion chambers with just an increase in stroke.

you would also need to sort the fueling to suit, im sure there is a 323 motronic chip available as fitting motronic to the older cars is a common was to improve the engine management on the early cars.

andyboy would be the one to ask though, i expect he would know as would any of the guys that have had more dealings with pre-facelift cars.

[Coyote_ar]

rods are the same on B20 as in B23. the B23 pistons are shorter than the ones on B20 so they dont hit the head.

i forgot to mention this car has L-Jet, and not motronic. is one of the earlier models.

[HairyScreech]

if its an l jet then the fueling isnt exactaly the most acurate thing in the world anyway one step up from a carboreter, i was thinking it was, is it that all 323s and 320s or the same age are L-jet?

tbh i expect the Ljet could be tweeked to suit the fueling needed but it might also be worth considering an engine management upgrade while you are doing the job. For a short term fix you should be able to increase the fuel presure to make it dump a little extra fuel in for now, if my understanding of ljet is correct (which i hope it is or im failing this years uni) then it should also be possible to adjust the differential pressure valves to get the corect fuel flow, although i have no first hand experiance of the exact sysetm on the early cars.

as far as other mods is the 323 throttle body bigger? if not it may pay to use a 325 one, also i remember from somwhere that the 323 has the hottest cam of any standard m20 engine.

[HairyScreech]

ignition timing would also be just a case of using a 323 distrobutor as well.

[Coyote_ar]

thanks for your help man. anyway, my idea in this case is just to get some extra hp for cheap.

since the actual project is to get another engine, and do all the work on that one. bore it to 84mm, get a nice crank and stroke it to 2.7 or more, get a nice MS-2 in there and a turbo.

but since such a project will take some time, and this car is my daily driver, i would like to be able to have some extra punch from it.

M20B20 really sucks.

[HairyScreech]

i kind of liked my b20, i could cain it without breaking the law too much, with a brand new b25 i cant as im way over posted limits before 4000revs.

[Coyote_ar]

anyone knows if the ECU on the LJet for the B20 is different to the one on the B23?

according to realoem.com, the valves are the same for both.
throttle body is the same. fuel pump is the same. cylinder head seems to be the same too.

i did found out that the camshaft is different. the M20B23 has the 11319058577 while the M20B20 has the 11319058572

any other parts that may be different?

[Andyboy]

Same ECU, same injectors, same AFM, same everything. Later 150 bhp cars have a different ECU. All 323i's have a different distributor. I wouldn't bother, just drop a 325i engine for the time beaing and them build a 2.7.

[Coyote_ar]

B25 are expensive and hard to get here, B27 even worst. and importing used engines is forbidden.

so i guess ill have to stick to this block for the moment.

can i use the distributor from the E21 323i ? or the one from the E30 323i is different?