Need some help with the knowledgable

[SA E30]

Hey, I'm wondering if u guys could help me. I've got a mate who was thinking of using M50 328i parts in an M20 block.

He wants to use the Crank, Rods and pistons. He was wondering if this is possible ?

As was I, I'm sure u could use the crank and the rods, with changing the crank to accept a timing belt.

What pistons could hge use if the 328i ones don't work?

What displacement would this leave the motor at ?

Thanks
Steve

[SilentRavens]

You gave me the idea for using the 328i crank. I talked to Jeff Ireland about. Now since the IE kits get you 89.6mm (I think) stroke cranks a 84mm stroke crank shouldn't be a problem. Jeff said that the crank would need a special collar on the end for the oil seal. Which leaves me the question of how to make it work with a timing belt as opposed to timing chain :? .

If I can make the crank work, I think I am going to go with M20 E rods, and a set of custom pistons. Giving me a 2.8 (well ~2.79) liter engine with no boring :twisted: .

[nando]

I believe the M20's lower belt pulley bolts right onto the M50/S50 crank, so converting it to a belt is no problem (otherwise IE probably wouldn't use them).

[SilentRavens]

Thanks for the info...

[AdamF 88iS]

I believe the M20's lower belt pulley bolts right onto the M50/S50 crank, so converting it to a belt is no problem (otherwise IE probably wouldn't use them).

He's talking about timing belt vs timing chain with the sprocket pressed on the end of the crank.

[SA E30]

You gave me the idea for using the 328i crank. I talked to Jeff Ireland about. Now since the IE kits get you 89.6mm (I think) stroke cranks a 84mm stroke crank shouldn't be a problem. Jeff said that the crank would need a special collar on the end for the oil seal. Which leaves me the question of how to make it work with a timing belt as opposed to timing chain :? .

If I can make the crank work, I think I am going to go with M20 E rods, and a set of custom pistons. Giving me a 2.8 (well ~2.79) liter engine with no boring :twisted: .

Ok, well here is a picture of my engine parts notice the M52B28 (328i) crank, that has been modified already to accept the timing belt, from my M20 crank.

Oh, and I did find out if u can use the 328i complete setup, and yes u can. I was speaking to a guy who did run this in his 325iS Evo2, b4 he did the S50B30 conversion.





Here is a picture of an S50B30 piston modified to work with the M40 318i rods,and M52B28 crank. Also been modified to work with SR20 rings, instead of the normal rings.

The only thing that has been done is the top hasn't been cut at a 45deg angle, to fit inside the 84mm bore head gasket (which is the cheap way for doing it, cause a custom gasket costs quite a bit...I think works better)

[screamingbmwe30]

so you are going to use the complete m52 328i bottom end in your m20?

[SilentRavens]

SA E30, those parts should make a good bottom end for a M20! I have a couple questions though.

Why the M42 rods, did it have to do with the fitment of the S50 pistons? Also what had to be done to the crank in respect to the timing belt vs. chain? Did you just have to bolt on a different sprocket?

[SA E30]

so you are going to use the complete m52 328i bottom end in your m20?

Nope just the crank, although u can use the enitre bottom end in the M20

SA E30, those parts should make a good bottom end for a M20! I have a couple questions though.

Why the M42 rods, did it have to do with the fitment of the S50 pistons? Also what had to be done to the crank in respect to the timing belt vs. chain? Did you just have to bolt on a different sprocket?

I'm not using the M42 rods, I'm using M40b18 rods, I decieded on them against the M50b28 (328i) rods, due to it giving u a better rod ratio... although the 328i rods do work.

The crank, well all that is done is there is a part machined onto the nose for the oil seal, cause that part on the M52 is smaller, but the timing belt pulley just bolts onto the same place as where the old timing chain pulley was.

[SA E30]

Ok, so here it is, lets hope 3rd time lucky with this project. As most know I had an iS crank and it snapped (cause I knife-edged it, and made it unbalanced), I didn't think it caused any damage, but it seems like the piston no.5 got a bit bashed on the sides. as well as no.5 conrod, got a tiny kink in it, that I didn't notice.


This was all discovered by Boetie, at Budler.

These r my new plans.

328i crank, M40 318i rods (brings the rod ratio back into acceptable limits, otherwise u get a stonking car 1st-3rd, then the torque drops off in 4th and 5th), 3.0lt M3 Pistons.

The head i've got a 288deg cam, the head is ported and gasflowed. I'm running E36 325i injectors (sold my M3 ones, cause they were overkill).

Ported Throttle Body, Ported intake Manifold, 535i Air Flow Meter and Adjustable Fuel Pressure Regulator.

Then of course it's got the Branch and Freeflow, done by Powerflow.

CR is gonna be sitting at around 10.5:1, depending on if I need to skim my head at all (I doubt it, was done the first time I built the car up)

These r a couple of pictures, this is b4 I installed the 535i AFM, and Adjustable FPR. Here is a picture of my exhaust Dual 57mm





I'll post more pictures, as soon as I start working on the motor again, next week.

Also then the car should be going in for a nice respray, when I will post pictures of the rest of the car, fitted with Alpina's (ifI get tires soon enough), and Alpina Front Spoiler.

BTW I'll be so happy when that damn foam is removed from under the bonnet, cause it looks shoddy

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Next update

So far, I've recieved all my engine parts





As u can see the nose on the crank has already been modified, to accept a timing belt and not a chain.



This here is a comparison, of 2 M3 pistons, the one has been cut to accept SR20 Rings, which work out too like a 3rd of the price of M3 rings (I'm still decieding on which route to go) The bottom ring, is almost double the size of the M3 ring.

Next, I bought a fibreglass M5 (333i) M-Tech1 wing, for until I can source myself a real one, this will do for now.





And now onto my pride and joy, my wheels... Borbet Type A 16" 7.5" , I'm really considering getting the rears widenend to 9", and stretching some 215 onto them, German style.





Also I got a new back box put on, cause the old one wasn't loud enough, I'm still trying to decied if I want the tips to be touching each other, or having that gap.



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Next update.

New springs arrived on friday....
went and picked them up on saturday, not sure what the fronts are? Some imported ones, but I do know the rears r E30 M3 ones creating 40mm drop in front, and around 30mm in the rear. (E30 M3 springs r like gold here...seeing as we never got them)

Front



Rear




I'll take some pictures of the car when I start all my work... all I need to get is my 288 cam, Aluminium Flywheel, and rings and bearings.

Then out comes the motor, and the car goes 4 a respray.

[screamingbmwe30]

if you use the m52 2.8 bottom end in the car what c:r will it be? thanks

[SilentRavens]

Wow, I'm getting more and more impressed with your project there. :shock:

Another question, does anyone know the rod lengths for the M50B28 engine? What about the M40B18 rods you're using SA E30?

I was looking at just using the stock I rods, gets a rod ratio of ~1.6 with a 328i crank, which is okay...

[SA E30]

I'm actually not sure about what the CR would be in the M20, due to me not really having any experience with it. I'm guessing it wouldn't be lower than 10.5:1... cause then I wouldn't have seen the point in my mate running that setup. cause a 325iS Evo2 comes from factory with that CR.

The 328i rod length is 135mm.

Stroke= 84
Bore=84

It's a nice and square motor

[screamingbmwe30]

so your mate is running the complete m52 bottom end? have any dynos? estimated hp?

[SA E30]

so your mate is running the complete m52 bottom end? have any dynos? estimated hp?

Not anymore, he's now running a S50B30 (Euro M3). He said somewhere in the reigon of 130kw OTW... not sure about any other info such as correction factor or what not