GerritD

Hi Hilton,

that's fantastic, I'll send him an email straight away.

thanks!
Gerrit

Richard S

For M28/21 engines:
The left over 83 pistons were used up to engine number M28/21 82E 0596.
The newer 84 pistons started with engine number M28/21 82E 0597.

For M28/22 engines:
The left over 83 pistons were used up to engine number M28/22 82E 6113.
The newer 84 pistons started with engine number M28/22 82E 6114.

This info is found in the Porsche Parts Catalog. The difference is in the shape of the top of the pistons.

Hope this helps.

Rich

GerritD

Thanks alot Richard, this certainly helps!

danglerb

Might be worth taking a look with a bore scope, the block is pretty tough so it could be just rings, and the 84 engine might need those as well. No need to Nikasil the block unless you go to a piston other than factory.

GerritD

Good idea of the bore scope, I might do that before swapping the engine.

thanks again!
Gerrit

Ian928

I am not sure the cams on the 84 are better than the 80 ones. There was a thread here about it and I seem to recall that the early cams had longer duration. Maybe try a search?

mark kibort

no, the later cams have something like 8 degrees more duration. lift the same. Ive done this modification in most all forms over the past 20 years.
just put a 5 liter under the current heads cams and intake.

otherwise, no issues with going with the later cams and the newer block. the changes are so minor, they are not even worth mentioning.

Mark

mark kibort

your missing the point. you can have what is exactly the same as the euro 4.7 84, BUT with 5 liter. by going with the US 85 short block (not S4) it was only rated at 288hp, but thats another story as of why (cams, heads, etc)

if you are aming to achieve 300hp, isnt that what you already have. what am i missing? either way, the best choise is to use the 4.7 euro shortblock either the old 80 to 83 or the newer , late 83 to 84. the differnce is the valve cuts in the pistons. the cams are near the same, but he 83 84s are longer duration. heads are the same. you already said you are going to keep it CIS from the earlier models, right. (pointing to single distrib, CIS, etc)

by the way, the cylinders are alusil not nicasil. (from your earlier post) the process would cost a little to freshen up your current block. having been down that road before, its much better to just re-ring an old block and put on some new rod bearings. dont even split the case if the engine is known to be fairly good.
the block wont give you any power, if you are not certain the pistons are the latest of the euro S 4.7s. the shallow piston cuts are the give away to the newer types. they are only a few mm on the later euro pistons. the main reason there is more power is the slightly better cams, slightly higher compression (10 to 10.4:1) and ignition timing. However, you can do the 5 liter short block and kick up the HP in a BIG way. all you need to do is notch the pistons only .177" cut out for the valves.
there is also a 10hp advantage of doing this by getting the piston offset right ..... another story all together.

GerritD

Mark,

I need to rectify perhaps the information I gave : the original engine of my car, before I bought it, was a 4.7l CIS 300hp (M28/12) delivered from factory. However when I bought the car, this engine had been replaced by a 4.5l CIS 240hp (M28/01) Apparently, the ignition, ecu, distributor, Bosch injection unit, injectors... are the same, as nothing of components around the engine had been changed.
So I want to have the original power of the 4.7l engine without having to change alot of my other parts.

kr
Gerrit

danglerb

The non S Euro motor, the 4.5L has different intake tubes, throttle body, WUR (warm up regulator), heads, etc.

Hilton

Mark, he's in Europe. Early 5L blocks are rarer than GTS motors over there.

mark kibort

but for the cost of shipping from 928intl, he would have a monster motor compared to what he has now, AND be cheaper than a rebuild if he was going that route (all the talk about fixing the block, rebuild, etc)

yep, but I seem to take from his post that he just has a 4.5L bottomend that was put under all the same stuff that was on the car. clarify?

so, in reading your post, it sounds like you have ALL of the 4.5 euro stuff on the engine as well. NONE of the euro 4.7 M28-12. so that would mean, cams are junk, intake is junk, throttle body. heads, and plenum are all junk. (compared to the euro 4.7 S models)

you need a euro 4.7 Long block, or you need to piece the thing together by getting: euro heads, cams, intake , throttle body, and a short block. the early 4.5 cis system should work.

GerritD

Mark,
you are absolutely right. Let me rephrase my question differently :

I have a spare engine of 1984 (I don't know yet if early or late 84),
what should I replace on the engine to fit it in my 928S, without changing my original wiring / ecu ?
I know that for an early 4.7l 300hp CIS, nothing has to be changed regarding cabling, since that's what the PO did when swapping the 4.7l 300hp CIS with the 4.5l 240hp CIS.

kr
Gerrit

Snowglobe

Slight side step, but on topic. I was interested in getting a 5.0 block to put under my 84 Euro 4.7. I was thinking of getting an 85/86 block while the getting was good, and then I could do the work later or resell the untouched block if I changed my mind. The 928 intl sale to maximize a hoarder's savings has already come and gone, but I was wondering how much more it would cost to convert an 84 Euro 4.7 to a 5.0 hybrid, versus rebuilding/refreshing the 4.7. Seemed like a lot of extra $$ for little gain, compared to doing that to a 4.5. I know there would be a lot of "it depends/wyait" in the calculation. If I was willing to get new pistons, it seems that increasing the displacement on the 5.0 at the same time would also be opportune, but those two choices would astronomically increase the cost differential to a refresh. I haven't even taken the heads off the 4.7 so I don't know the condition other than it seems to run well.

danglerb

CI$ and LH injection have different injectors with different mounting in the intakes. You need a Euro S CI$ intake and throttle body. The WUR, warm up regulator is different, but I don't know in what way, just a different part number.

Something to consider with a 4.5 or 4.7L refresh vs 5.0L is that rings and headgaskets are I believe cheaper in the more common 100mm size.

Plenty of different things to consider, but I see the gains of the Euro hybrid well worth the costs.

Note the 32v 85/86 Euro motor is a lower compression than USA motor, so may not work as a hybrid motor bottom end.