engine Swap

[heung]

Dearest 928 Members,

I owned a Euro 928s 4.7 1982 with a manual 5 speed. Car being running well until recently where I found water in Cylinder 4. Upon stripping the head, I found pitting on the cylinder liner. The head was still good. Upon checking cylinder 1 to 4 the other 3 cylinder liners on the top sealing area has also traces of pitting corosion.

Needed advice from the experts and well learned what should I do. I have 2 options

(1) Order new liners with New Rings, used back the old pistons I probably needed all 8 as I sure the other bank will be about the same condition and proceed with the repairs.

(2) I have a doner car, an 86 S4. The S4 is an automatic. Swap everything into my 82 but kept the Manual box. Is this swapping possible? Has anybody done this and would I have problem with the flywheel and the dual clutch?

Cheers

[Danglerb]

Porsche 928 engines don't have liners, option is to have the block decked if the corrosion isn't deep, otherwise new block is needed. Depending on your location a 4.7 block might be a good inexpensive option, another is to use the short block from a US 85/86 5.0L motor.

Using the S4 will require some serious electrical work. Your 82 is Kjet CIS injection, S4 is LHjet electronic with dual ignition. The S4 short block is not compatible with Euro 16v heads.

[heung]

Thanks Deng for your input. Went out to check the block again. Cylinder 4 will need a weld fill up before regrinding to flatten out. The other 3 cylinders don't look so bad. With a bit of skimping it will probably square out. My concern now the pistons as piston 1 is now at TDC. Being a Euro model and being high compression, the piston is already seem slightly higher than the block. With more skimping, i will not be able to use the standard cylinder head gasket. Will probably need tailor made cylinder head gasket in order for the piston not to hit the cylinder head. Is there such a tailor made gasket? On the welf fill, what type of welding should be used??

What are the thoughts?

[kelanel]

i cant account for the quality of gasket but i know 928motorsports does make thicker than stock gaskets at request. they are usually custom materials with racing in mind though, not a stock victor reinz gasket.

[Danglerb]

If you can get a US 85/86 short block I would use that, 100mm bore parts are cheaper, and you end up with 5.0 instead of 4.7L. It does require fly cutting new 2v valve reliefs, but that usually isn't too costly.

Block and head stuff need precise measurements, and I have no idea on how practical it is to weld on a cylinder, thats machine shop stuff I try to avoid. Measurement details are in the workshop manuals though.

I believe Porsche offers a thicker head gasket, usually to compensate for milling the head flat. I would avoid anything non factory, especially the cometic types, they are very fussy to make work.

Corrosion in the heads may mean you have corrosion other places like around the water pump, so best to check it all before deciding the future of the block.

[heung]

Went to look at the Half cut of the S4 again. Engine bay and engine look like pretty good shape. The shop is willing to start the engine on the ground before I decided to purchase. I though it will be a good idea instead of trying to do more work with my old 4.7 engine. Everything from the dashboard to the front bumper is intact so I should be able to use all the wire harness and the ECU. (Where is the ECU located on the S4?)

My worries are

(1) Wireness might not to enough to get to the right place as the half cut is left hand drive and my car is a Right hand drive.

(2) As my 4.7 is a manual, will the housing and the flywheel bolt on to the S4 engine?

Any other concerns that I might not be aware of??

Cheers

[MPDano]

Originally Posted by heung

Any other concerns that I might not be aware of??

Cheers

Yup, follow the advice already mentioned. Or just get an S4 with an S4 engine in it and drive that and I'll take your High HP Euro off your hands.

[maybach_man]

i would think the biggest issue is to splice into the ce panel with the s4 loom

[Danglerb]

After a couple weeks of splicing wires to make it work, its going to be very hard to troubleshoot and make any future repairs.

[heung]

Thanks all, With all advices, I think the the most sensible way is to rebuilt the present motor. My next task is to seek for a top overhaul gasket kit for a 4.7 engine. Where are my choices?

Cheers