16v Engine rebuild options (pickle)

[Endat]

Ok, so I got a "rebuilt" shortblock from someone here, the block looked pretty good in the pics, and it has new stuff on it like he said, but there are scratches so deep down the cylinder walls I can dig my fingernails into them, the pistons also have marks from valves.. The workshop says its gonna smoke. I have been spending the past year sourcing parts and trying to rebuild this car, but that 1 piece is what stands between me and victory..

So far I'm about $5k into this rebuild (not including car), and this setback has caused me to take my car back from the workshop and rethink my situation. I loosely screwed together my engine and blocked it off so nothng could make a nest inside. I dont want a refund because of shipping costs, but I have compiled some other options

- put it together anyway and let it smoke
- take it back apart, have the cylinders machined and try again
- put my nice, ported/polished head w/ competition valve job on the OLD engine
- sell the 16v stuff and get a Turbo engine
- bore it to ~2.7L, upgrade the rods and pistons, and make some turbo manifolds for a highly boosted 16v monster


^ Everything here is for my S

[guru944]

endat,
I feel your pain;

So far i'm almost 5k deep also into my 944s Rebuild project. I would suggest doing it right, even if it takes more time... My car has been down since nov 11, 09. Times are tough.....however i'm looking forward to more NA power before the end of july. I will eventually go turbo K26/27 low boost 5-7psi, looking for ~400hp when i'm done with my 2.5liter Dohc.
There is a method to the madness after all...
Don't give up brother.
What ever spare parts you have suggest selling them to fund the rebuild.

Later...

[Aslet]

After doing a lot of this same stuff over the past winter, I feel your pain. I would suggest to take it apart, clean the cylinders and keep it stock. They sell slightly oversized piston rings just for this situation. I know it is tempting, but getting the car rebuilt and running should be done first. I know with my race car 944 project, I have a much longer list of small tweeks now that the car is running. I plan on getting the car running perfectly and set how I want it before I do any other work...

[Endat]

do oversized rings last as long and work as well? I was worried that if I had the cylinders machined, I would have to move to larger pistons as well.

Should I have the pistons checked under UV light to see if there are any cracks? they are obviously a little beaten up at the valve notches

Sorry for dumb questions, I have never encountered something like this before... Usually just the drill attached hone and some oil is enough for the engines Ive worked on

[cjpacitto]

Lindsey Racing sells the oversized rings LINDSEY PISTON RINGS 100mm 944/951 "Set" (#1) at LINDSEY RACING - Your Porsche Performance Parts Center They say the developed them for when you ceramic coat your skirts (see Swain Tech Coatings for engine piston coatings, race engine coatings, ceramic header coating, carbide metal coatings, thermal spray plasma coating, metalizing closures, spray welding for info) and then have to enlarge your cylinders so the coated cylinders will fit. This is exactly what I did with mine and the ring gap with standard rings was more than twice the max allowable. Lindsey oversized rings should be here Friday.

If you are considering this, please refer to the following threads for more info:
piston/cylinder clearance and piston coating
Project 924 S engine replacement

In my opinion, boring to a 2.7 would be really cool and used S2 pistons would probably be much cheaper than oversized (100.5 or 101.0 mm) pistons for a 2.5 motor. The S2 intake manifold will also bolt up to the S head and supposedly flows more air.

You could always look for another block in better condition.

[cvriv.charles]

Were the cylinders already honed? I would try honing the cylinders some or some more. Make an attempt at lessening the depth of the deepest grooves. Then use oversized piston rings to compensatefor the extra honing. Boring to 2.7L will cost you ton more. going the 951 engine way could cost you even more. Because wat if ou open tht engine and you end up right where you are now? You already sunk 5G's into this. Finish this engine.

[pontifex4]

Don't give up on the S drivetrain. As a package, it was really well designed. I sold mine this spring after getting a Turbo and I miss pretty well everything about it, particularly the sound, feel and the fuel mileage.

That said, I do think your new head (especially a higher flow one) deserves a fresh short block. You obviously did, too. Like you, I've also heard that the S2 intake manifold will bolt on, and I wouldn't be at all surprised if that provided a noticeable power gain, particularly with a custom head.

[rickharrison]

What's been done to the head?

How much could you sell it for?

You probably would lose $$...try a hone job and see what happens.

[Endat]

is there some sort of magic material i can use to fill the scratches? if not, what kind of machine shop do i look for to get the cylinders taken care of?

Originally Posted by rickharrison

What's been done to the head?

short of shaving the bottom part, everything.. new tensioner/pads, new valves & valve guides, 5 angle valve job, ported/polished airways.. it also has a fully rebuilt and ported/polished throttle body.. i also used an abrasive bit and a drill to polish the ports in the intake manifold

[cvriv.charles]

I swear I read somewhere... i thoink of some machine shops site that they actually weld the deep scratches in and then bore and hone the weld bead away leaving a repair cylinder at stock bore diameter. Can't remember what shop though.

[cjpacitto]

Originally Posted by Endat

what kind of machine shop do i look for to get the cylinders taken care of?

Any shop familiar with 944 engines. Where are you located???

[Endat]

north of Charlotte, NC

[cjpacitto]

Try these guys: Eurowerks | Zuffenhaus [ Charlotte, NC Porsche & BMW Service and Repair ] I'm not sure if they do machine work in house or not, but if they don't I'm sure they can tell you who to use locally.