aguk928

Time to start planning this sping/summer projects for my shark, and I think its going to be the engine and TT.

I have what is reffered to as an S2 here in the UK (85 Auto LH Injection), but picked up a smashed 83 S (CIS) for peanuts, great source for spares .

My S2 has 150K Miles on it while the S engine only had 34K miles so after dismantelling the S and then its engine I found that it was in fantastic condition internally. So I got to thinking as I need to rebuild my engine anyway is it possible for me to rebuild using the best parts from the S in to my S2.

Thus I need help from the 928 guru's. Is it possible to rebuild my M28 22 engine using the M28 12 block if I use the pistons from the M28 22 in the M28 12 block I believe the crank is the same I am not sure about the cam's but can anyone point me or advise is this is sensible or possible. What are the differences bewteen the 2 blocks, ignoring the fuel injection system.

MTIA.

John Veninger

Why did you take a part an engine with 34K miles? Hopefully just to put in some new gaskets.
You can install the intake system from the S2 onto the S motor without much of a problem.
The cams in the S2 are slightly different than the S, but not much.

Ian928

Pistons will only fit if they are the same tolerance group. Tolerance group for each bore is stamped on block above individual bores.

The crank is not the same but it is said that the block can be modified (easy) to accept the other type of bearings. If the "S" crank is OK, just use it as the stroke is the same.

m21sniper

No offense- and not meaning to jump you personally- but why would anyone do that?

I am pretty sure that the spiders(especially Euro spiders) will flow as well as the S2 setup as long as it's extrude honed/port matched, and that shouldn't cost any more than getting a used S2 intake on ebay.

Considering that the Spider intake is true automotive art i'd go out of my way to keep that in place. The 5.0 intakes are really very bland and ordinary, and also really hard to work around.

John Veninger

Because it's a EURO and the intake is still spiders in 85!

Jim bailey - 928 International

The 28/12 block does not have the rear flywheel boss for the timing sensor fully machined.

FlyingDog

As john said, the S2 top end will drop right onto an S bottom. The pistons for an S will not give you as high compression as the S2 pistons. (6 or 8cc for S and 2cc for S2 according to Mark K's measurements)

If I was you, I'd just rering and reseal the S2 engine and be done with it. Reseal and clean the S engine and sell it, or sell it as individual parts.

M21, the difference between the (Euro) S and S2 intake is: longer more curved runners (S2), larger diameter throttle body opening on the plenum (S2), and injector bosses (S2 for L/LH-jet injectors, S for K-jet injectors).

aguk928

I took the engine apart as the donor car had been standing for almost 10 years outside before I got it and I needed to know what its overall condition was especially as the car had had a front end smash. I had the cam towers and crank case magnafluxed to check for damage.

I wonder what the differences in the S2 and S cams are, anyone know of an info source on that?

The pistons luckily are of the same tolerance group so I can transplant them, and as I understand in the main it’s the piston profile in the S2 that gives the M28 22 engine its slightly higher compression ratio.

Is the only difference in the cranks the main bearing journals? But if the stroke is the same can I use the S2 con rods in the S or do I use the S con rods with the S2 pistons?

The S2 is a 4.7l and it still has the spider. The S is CIS and the S2 is LH with electronic injection. This appears to be no problem to transplant.

Thanks Jim I imagine its should not be to difficult to machine the boss, would it?

Thanks for the replies so far it looks like this may be a goer.

BC

Just make sure ALL the pistons are of the same tolerance groupe. Sometimes they mix them up in the same engine.

Also measure the bore to pistons tolerances before you assemble. YOu may want to coat the pistons skirts if you can if the tolerances are bigish.

Put the new rings in the bores as well to check the end gap.

Ian928

I guess you mean checked with penetrant method? You need a metal that can be magnethized to use Magnaflux.

aguk928

Good point.

So lets be totally accurate, the alloy parts where all pressure tested while the crank and cams where magnafluxed.

drnick

whats wrong with your S2 engine aside from its mileage? 150k isnt a high mileage at all, by itself.

aguk928

Why rebuild at 150K.

Long list of reasons, but here are some, a compression test and a leak down shows that the rings need doing. Based on some of the noises I get from the engine the main bearings need replacing and I can guarantee that the big end bearing will also need doing.

So the line of thinking is this if I have to go in and do the main, big and small end bearings as well as the rings and all the gaskets, then I may as well do the job properly and balance the con rods, pistons, crank etc and if I am doing that, then why not take advantage of the S engine I have and use its bottom end where the bores are in amazing condition.

When I got the S2, I had to replace the head gaskets and that allowed me to see the state of the bores which showed a fair amount of wear with at least .4mm taper at the top. OK I can re ring the pistons and do the bearings but if there is only a smallish amount of additional work to use the S block and build up an engine that I will have years/miles of great performance then why not?

So here are some questions.

1. Crank what are the differences and do I just use the S's crank instead of machining the block to take the S2's if the stroke is the same.

2. Is it possible to mount the S2's throttle body on the S engine without many modifications?

3. I am planning on using the S2's pistons which are the same tolerance group and the S2's heads any problems there or is there some advantage to keeping the S's pistons and heads? As I can determine the S's pistons give a slightly lower compression ratio so that would give me headaches with the ECU's mappings and the heads?

4. As to the front end what differences are there between the water pump, oil pump, tensioner and the timing belt pulleys? Can I use all S2 parts there?

5. OK as Jim mentioned, is it a major problem to machine the boss for the timing sensor?

6. Are all the mounts the same?

7. Most important am I nuts?

I think this is an exercise worth doing, any comments?

Thanks for the input so far.

Ian928

Here is my input, hopefully someone will chime in if something is incorrect:

Measure the "S" crank, I bet it is OK - then just use it.
As far as I know you can just keep your complete intake system, no modifications.If the "S" heads are in better shape, use them with the "S2" camshafts and housings. I don't think the valves differ, but you could measure to be absolutely sure. Use the high compression pistons if you can but check if they are worn. If the bores are that much worn the pistons might be useless too.As far as I know, yes you can.You could cut it off the "S2" block and weld it onto the "S" block?
As far as I knowNoI would have done the same thing...

aguk928

Great input folks,

am getting a much better idea for this project and I think is on. Need to plan this as I know I could go overboard with while I am at it I better do this and this.

But to have an engine with 34K on it in the end will be worth it.


Thanks to all so far and any other comments or suggesions from people will be appreciated.