MC's M96.01 strip down and rebuild

[deMort]

Always happy to help

 

[apollokre1d]

Good luck

 

[paul987]

you have my attention
:worship:
Although I thought you may have had a better skateboard than the one in the second picture :dont know: :lol:

 

[infrasilver]

You know where I live. :thumb:

 

[ELA]

Great project MC, 3.7l sounds a great idea. I've spoke to Hartech at length on this subject; as they are currently developing this exact config and it looks a promising avenue to go down. I really wish you the best of luck with it and if you need a test mule to throw it in for running in, you know where I am :grin:

 

[ragpicker]

Likewise, following with interest. If/when the leggy boxster starts knocking, I'll be looking at something similar.

On the remote off-chance that there's anything I can contribute, just ping me a PM.

:thumb:

 

[PeterS]

You know where I live. :thumb:

It's OK, he has a tiled floor where he can drain the oil.

😄

Good luck MC, I know this won't end up like you intended it to when you started.

:thumb:

 

[MisterCorn]

You know where I live. :thumb:

It's OK, he has a tiled floor where he can drain the oil.

😄

Good luck MC, I know this won't end up like you intended it to when you started.

:thumb:

I expect it will take a long time and cost a lot. Do it once, do it properly. I am more interested in the state of the original engine at 118k WRT bearings and ovality than the end result. There just isn't much info out there, so I appreciate a sample of 1 isn't great, but better than nothing. You just don't see many of these engines available for stripdown and rebuild.

Nothing happening for the next 10 days. I am in the land of sunshine and cricket. I will be reading up on IMS bearing options though and would welcome opinions. It appears the original double row bearing is NLA but perhaps I could fit the later large bearing.

MC

 

[infrasilver]

I think someone on here found a double row with the same spec available, I would go for this if possible. The larger bearing will require machine work and when I was last offered this it was around £600.

If after all the expense of a bigger capacity engine with all the correct upgrades you don't fit it in your car you won't get anywhere near your money back just for the engine which I suppose is also the case if you do sell the car eventually with this engine in. I think you need to make the early decision of what you want to do but the strip down will reveal all.

The bores will most probably be slightly oval, I had mine re-rounded and top collars fitted to close the deck at a more reasonable cost than all new bores.

 

[wasz]

I expect it will take a long time and cost a lot. Do it once, do it properly. I am more interested in the state of the original engine at 118k WRT bearings and ovality than the end result. There just isn't much info out there, so I appreciate a sample of 1 isn't great, but better than nothing. You just don't see many of these engines available for stripdown and rebuild

This is great, you are doing it for the community

Really good, the more people post about doing these things the more the myth of the Porsche engine will be broken, and the more we share the more we reduce the fear of the unknown.

Lots of people (even experienced DIY mechanics) said to me "ooh a Porsche clutch that will be complicated and expensive", nah, its the same as any other car really!

 

[taffybloke]

good luck MC. I am looking forward to seeing the results opcorn:


Mike

 

[maldren]

The bores will most probably be slightly oval, I had mine re-rounded and top collars fitted to close the deck at a more reasonable cost than all new bores.

I'm intrigued by this, did they re-bore the cylinders (and lose the surface treatment) or 'bend' the liners back to shape?

 

[Harv]

I believe the process to re-round a cylinder involves the fitting of machined top rings which pull the cylinder back into shape. There maybe some heat and pressure involved in the process (both i think) and perhaps they are decked on a mill once fitted to get a perfectly flat cylinder top sealing surface (maybe not required if they sit below deck).

You soon get bogged down into the m96's issues and how to improve things if you can while it's apart.

The issue longer term as far as I can tell is the bore material (locasil loosing particles from its finish surface) so go to either to new nikasil liners (lasts forever) or steel. From what I can tell the early 996 3.4 with ferrous coated pistons seem to last very well and perhaps the bore material on these isn't too much of an issue with those early pistons although ovality will be.

The trouble I had rebuilding mine at 3.9l was whichever way I turned the life on the bottom end seems to be restricted by the bearings at 130k ish, they are too narrow. Is there much point making the cylinders go forever but you'll need strip the bottom end anyway. I guess it depends how long you want to keep the car, intended use etc

I've not seen a new dual row ims bearing but that would be my choice if it's now avail (no dust seals fitted) or move to a single row ims using the 3.6 ims cover plate, spacer (to take up the width difference), new centre stud and new bearing.

MC's if the crank is damaged then do research having it ground and re-hardened, I've read that oversize bearings are avail so don't see why this can't be an option (hopefully not needed though).

Something else to consider is balancing, the factory tolerance can be significantly improved and this would also give the opportunity for moving to a lightweight flywheel (which costs the same as a dual mass one from the right source).

Remember also the dual mass flywheel is not inherently well balanced and puts a lot of weight, pressure etc way beyond the last set of main crank bearings (again something you can improve)


:thumb:

 

[bazhart]

The first IMS had a double row bearing but also a roller chain sprocket to match up with the one on the crankshaft.

The best alternative we believe to be the much larger later bearing but although you can buy this with the shaft - it has a Hivo chain sprocket and will not run with your crankshaft.

To get round this we re-manufacture IMS shafts with both roller and Hivo end sprockets and the larger later bearing - so you might consider this. Several of these have been tested on road and track and the first large batch is nearing completion and will be available by the time you need to decide.

For information the problem with the early engines was the IMS bearing and the cylinders eventually cracking (usually when they reach an ovality of ten thou (or 0.25mm).

The Lokasil was similar but the pistons were hard iron plated whereas later ones were not.

But if you are going for Nikasil cylinders - that coating is so superior - they can run with any piston coating or no coating at all.

Our 3.7 conversions are running well and now going into production. We are happy to just fit the cylinders and supply the special pistons we have developed etc or any step in between that and a full rebuild (although we are getting so busy the former may end up quicker).

On a recent test our own Tiptronic 3.7 had identical performance to a std manual 3.6 (which is significantly faster than a 3.4).

A good way to do the job on a spare engine but I recommend you also get a cheap boroscope to make sure you get the piston circlips in right on final assembly.

Baz

 

[bakerboy4s]

Love reading all this stuff but it does bring a little Porsche paranoia back!