Humboldtgrin

Also it's easier to use the coolant mod setup with these S3 heads, just drill out 1/8" hole in the coolant block off plate on the head and use a remote t-stat housing. It posted earlier on this thread. And the matting surface of the S3 head is the same as the 9448v heads in regards to the coolant holes. Valves are shorter and smaller diameter. List of parts:
S3 head and valve cover
944S timing components(most expensive)
Custom intake manifold I will probably use SFR
Modded crossover if using a turbo or SFR 16v stage 2 with 8v head flanges
DME reprogrammed for timing
Custom exhaust valves for the extra heat (ferrea Charges $62 ea)
Coolant pipes for 944S head
Bonuses:
Can mod coolant system easier if wanted for racing
SFR will have an jig for a turbo intake manifold after I have one made
Ferrea will have specs for the Exhaut valves.
LR will have chips made.

George D

Have any "work in progress" pictures?

Humboldtgrin

Not yet. It will be a pretty fast swap once I get all the parts needed. The next step is cutting valve reliefs in the Pistons. Just waiting on getting the tool. Still need exhaust valves and t-stat in-line coolant housing, custom intake, address the exhaust, get chips made, buy ignition parts and change the fluids. But that's all. If I was rich it would be done already.

V2Rocket

some more comparison shots
928S3 top, 944S middle, 944 8v bottom.

S3 has same coolant holes as 944 8v (different shape though).
944S has no coolant flow between chambers.
S3 has largest oil drain holes of the 3 heads.
my guess is the S3 head was Porsche playing it safe with their first DOHC production head, for emissions and octane reasons - keeping chamber cool and compression down.

Humboldtgrin

I would like to add to the differences. On my 944S head the oil feed tube for the chain tensioner is on the oposite side for the S3 head. The tensioners are the same but the oil feed lines are the exact opposite of each other. If purchasing a 928 S3 head make sure you get the right chain tensioner oil feed line and the right S3 valve cover.

V2Rocket

Was less productive this weekend than I had hoped to be, but still made a "gasket adapter" to use a 944 4v intake manifold on the 928 head.
The big step in runner size is far from ideal but it will work for NA use.

When I put the SC on top of this head I will just build a new intake manifold. Will be very short runners and small plenum, just enough to hold the air going into the engine, since the SC renders any real manifold tuning ineffective. It will also be very inexpensive.

fortysixandtwo

You'll still want to have a gradual transition between port shapes. As pictured, the head ports will flow like a much smaller cross section than they are.

V2Rocket

Gradual transmission is ideal yes, but there is simply no room to do so...944 16v manifolds are pretty tall as-is, so the "plate" can only be very thin to make sure everything clears the hood.

For my purposes the plate is for driving around with a stock 944 16v manifold (944S2 probably) to get a feel for the 16v motor and to do smog testing down the road.

When under boost, I am going to make a 928S3-head specific intake manifold with runners sized correctly to the ports.

Humboldtgrin

Unsing an adapter plate idea in your case couldn't you shape the port design on the adapeter to mimic a miniature velocity stack idea. Just by rounding off the edges on the inside runners on like a 1/2" to 3/4" aluminum adapeter plate? But could only work as long as the adapeter has the same port size as the head. Then you can chose to use any of the 944S/S2 and 968 intake manifolds.

V2Rocket

Yes you could do that, but...
I asked some 16v car owners to measure hood clearance, and it seems there is only 1/4-3/8" clearance from their manifolds to their hoods.

So a 3/4" spacer wouldn't work, without shortening the engine mounts.
And the 0.090" metal I used was free

If I were really inclined I could make a sort of insert thing to go inside the runner of the 944 manifold, to taper the shape to the 928 port...but I am not so inclined.

Humboldtgrin

you can get some LR solid engine mounts to lower the engine enough to use a thicker spacer.

V2Rocket

I made my own solid-rubber mounts which are a little shorter than new factory mounts. Should yield me 5 or so mm extra room.

I haven't installed them yet but will put information up when I do, to share my initial impressions.
As with everything else I do...they were very inexpensive.

But again...the plate is only for temporary use.
I am making a one-off manifold for boosting this head that will have properly-sized runners.

V2Rocket

just so this thread doesn't get lost...
944S2 manifold bolted to 928S3 head.

ramius665

Just a thought, would it be easier to just fill in the bolt holes for the 928 intake and drill/tap new holes for the 944 intake? That whole area should be pretty solid and I don't know what you could possibly hit by drilling new holes.

V2Rocket

There are 5 bolt holes on the 944 manifold.
4 of them line up exactly with the holes in the 928 head.
The only one that is in a different place is the very center bolt hole...where the center hole is on the 944 manifold, there isn't any metal on the 928 head to drill/tap into.

You can see the hole alignment in my "adapter plate" picture in post #171.