944M3

Finally purchased a complete S2 engine including headers, intake manifold, throttle, flywheel and bell housing. My original thought was to take the S2 crank and put it in a sleeved '87 block along with everything else needed for a stroker engine. I would then sell the 16v head and S2 block and parts. I don't have the expertise or the time to fabricate the needed parts to build a 3.0 16v engine.

But now with the engine in hand, I can't stop thinking of just going for it. Would I regret it later. I've read all the 3.0 build threads. I understand its not cheap nor easy and I know all the parts I would need to buy ie. pistons and rods among other things. But will be saving some money as I would be doing all the work myself. Not an expert but I've put together an NA engine and 951 engine before, for my current cars.

As I'm not a fabricator, I don't even own a cheap welding machine, I'm wondering if anyone has any parts from their stalled or failed 3.0 build project I can purchase. Cost/budget is a consideration, so if I can get some deals on pistons/rods or an intake manifold, modified headers and crossover, or even a turbo, it would help me decide to go for it.

With all that being said, I do still wonder if a 2.8 hybrid would be all I need. I'm not looking for a high horsepower engine. I would maybe track the car once a year for fun, I wouldn't drag race it. I'm just looking for a super fun torque daily (and yes I know it still wouldn't feel like an LS but I'm not going there). Would be fun to have something I can blow off some steam in when I'm having a bad day. So would an 8v with 88mm stroke crank and sleeved block be all I need for a fun low end torque car. I know others have made crazy power with a hybrid 8v. But I want a reliable engine running on pump gas with occasional e85 (yes I know I need supporting mods for that).

I've also thought about keeping the S2 short block and modifying an 8v head to fit. That way I have the stroke and the 104mm bore (keeping it Alusil). I would then buy pistons and rods to lower the compression. Though I would then have the added expense of beefing up the clutch.

Decisions, decisions.

JustinL

I did a very similar project to what you have planned. It obviously cost me more time and money than intended, but the end product is pretty awesome. There is another option to think about for pistons and rods, Pauter makes a shorter rod that can decrease the compression ratio. https://www.lindseyracing.com/LR/Par...ONNRODPAU.html That way you don't need to worry about finding custom alusil compatible pistons. It's cheaper and you are reusing stock pistons... but at least you know it will work.

You also need to think about a standalone engine management, injectors, spark etc. to go along with a 16v turbo setup. I went with MS3X and it works, but you need time and energy to set it up as it's not plug and play.

The obvious intake and exhaust manifold stuff is going to be custom and expensive, but there are people building these things every once and a while. It also depends on what stuff you already have and how you can use those parts, the S2 clutch is a bit smaller than the 951, but does have the advantage of the 60-2 trigger wheel.

944M3

Thanks for the tip, I was not aware of the Pauter rods. I think I've read the S2 pistons should be fine for mild turbo. I could then modify the 8v head to go on the 3.0 block and call it a day. Would also port for increased flow.

And yup, I'm aware of all the other accoutrements needed, and also tune. Trying not to think about it lol

Did you use stock S2 clutch disk? What engine compression did you go with?

ealoken

The biggest challenge for you will be the fabrication.
the 8v setup has a huge bolt-on parts advantage vs 16V.

I have just finnished my 2.5 8v turbo build, and i have started on the 3.1 16v.

projects have a tendency to go a bit over the top...

And yes, set a timeline for when you want to drive.

JustinL

I did custom pistons at 9:1 and a 951 flywheel, clutch with a 6 puck bronze disc. That necessitated a crank sensor on the front. My project ballooned into very expensive exhaust, turbo, intake, etc

944M3

Yup, the fabrication is what scares me. Though, I have thought about buying a MIG welder on Craigslist or Harbor Freight and giving it a shot. Plenty of YouTube tutorials. How hard can it be lol

fortysixandtwo

The two materials you'll be primarily dealing with are stainless and aluminum. They can be MIG welded, but TIG is usually a better choice for their applications.
For the exhaust, you can use most of the stock 16V headers; only the bottom flange needs to be changed. Mock everything up (downmpipe to headers) with the engine on a stand. Cut flanges off a set of junk turbo headers to fill in the gap. Try to keep the gaps as tight as possible, then tack weld the flanges into position. Have a professional welder finish the welds.
Same goes for the intake, you can graft a 16V and turbo intake manifold. It takes a lot of amps to weld aluminum so the HF welder may not be powerful enough. Oil soaked cast aluminum is also a pain to weld. For these reasons it's better to make alignment marks for the welder to follow instead of tack welding.

This is taking the cheap path, but if put together well, the parts will work just fine. Sure, some hp/tq improvements can be found with custom parts, but these are bolt on and can be changed if need be.

944M3

Thanks for the advice. Makes sense.

Still haven't decided which way to go, but I'm planning to disassemble the S2 engine this weekend. Hopefully the cylinder walls are in great shape.

blade7

Cylinder walls will most likely be worn oval, and tapered. Machine the S2 piston crowns to lower the comp ratio, and fit new rings if the bores aren't scored. Or spend several $thousands on liners and new pistons.

sm

Curious if oval and tapered cylinders need to be made round again when rebuilding a motor? I’m preparing to rebuild a motor with 149k miles on it.

944M3

Was actually thinking the same thing. Would the oval cylinder wear be seen with the naked eye or do you need to have the block measured at a machine shop?

I haven’t gotten the head off yet but I removed the valve cover and head looks pristine inside. Under the oil cooler and water pump the block looks brand new. Hoping the cylinder walls look as good.

I’m starting to lean towards building it into a 3.0 turbo. The curiosity of what it would feel like is getting to me lol

Voith

This engine has extremely small tolerances so naked eye - nope.

blade7

Check what the Porsche spec is.

944M3

Makes sense.

Is that an 3.0 104mm bore specific thing or do 2.5 blocks also tend to wear oval? First time I hear this so just educating myself.

Voith

Never heard of these becoming significantly oval or tapered but anything is possible.

Cylinders are made of silica which is mohs 7 hardness, diamond being mohs 10, steel mohs 4.