Jengah

Hi All -

I've found a replacement engine to go into my '08 CS. It's an '07 CS with 49K on it. Here's a list of things I think I should and might replace. I compiled this list based on my experience with engine swaps on my 996. Any advice is welcome:

MUST DO:

• RMS
• Plugs
• Spark plug tubes
• Serpentine belt rollers & tensioners
• Air filters
• Fuel filter
• Water pump
• Low temperature thermostat
• Coolant tank & Cap
• Motor mounts
• Transmission mounts
• Oil filler neck
• All fluids

SHOULD DO

• Clutch
• AOS (with UAOS or motorsports version)
• Coil packs
• Injectors
• Oil cooler seals

OPTIONAL

• Spin-on oil filter housing from LNE
• Timing Chain Tensioners
• Power steering rubber and plastic part
• Vacuum hoses/connectors/hardlines

Thoughts??? Different order? Anything else to do "while your in there"?

harveyf

First of all, I guess this assumes you are not going to disassemble the engine? Unfortuantely, on the M97 engine, you cannot replace the IMS bearing without splitting the case. That would be my biggest observation.
Other comments. If you do the clutch, you will want to do the flywheel. The flywheel has a rubber component that makes it a crankshaft torsional dampener device. The rubber fails.
The fuel pump filter is integral to the fuel pump.
I would replace all the coolant hoses on the engine side of things.
For what its worth, the stock oil filter on the M97 is a full flow filter.
Also the stock AOS is probably fine. A new stock one will probably outlast your ownership of the car. As long as you are familiar with the symptoms of failure and associated vacuum checks, you can replace it in place if it comes to it.

I'm currently rebuilding a M97 engine, 2007 version. My list is quite a bit longer but mine is a total rebuild.
Article 1 of several:
https://newhillgarage.com/2023/03/02...ngine-rebuild/

Jengah

Hi Harvey - (we connected already about our projects on email back in July)

Thanks for the reply. Just answer questions: correct, I'm not disassembling the donor engine. I'll run it until it blows and then either rebuild it (or the original engine) into a 3.8 or 4L, or look into an Audi swap.

As to the flywheel, the car came with a lightweight flywheel and it almost new. That being said, I've read from a very reputable source that a LW flywheel (instead of stock dual mass) can cause considerable damage, I believe due to less harmonic dampening and thus causing stress on the internals. Now my local Indy who races Caymans emphatically dismisses this idea. He argues "tell me how less reciprocating mass can cause more damage to a rotating assembly".. I'm sure there's an argument against it, but I get his point. Not sure what I'm going to do yet as this is going to be principally a track car.

cavediver32043

The OP mentioned RMS not IMS replacement; ...

harveyf

My bad. RMS is replaceable.
Regarding your mechanic and the flywheel: In a general sense, a harmonic balancer is a tuned device that can and should be designed to a specific engine. In very slow motion, it absorbs the burst of torsion on the crankshaft during the firing phase, and releases it back into the crankshaft in between that firing phase and the next phase from another cylinder. It is a finely orchestrated event.
Without one, you apparantly get high cycle fatigue failures. One burst of torque doesn't snap the crankshaft. But after many thousands of such events you can get a fatigue failure. Google "fatigue indurance limit".
Racers can play off the fact that they don't actually put that many hours of operation on the engine, so they can go with the somewhat riskier lightened flywheel and even dispense with the flexible element. They can also crack check their crankshafts during their winter rebuild cycle. In the short run they get some very small increment of performance increase and in the long run... well, there is no long run.
Me, unless you are racing in a professional series with real money on the line, I'd stick with the stock flywheel.

Back to your original question, I am in general replacing all the electro-mechanical sensors (crank position, cam position, knock, O2, etc) and, admitadly overkill, the entire engine wiring harness. And anything rubber or plastic in the engine compartment that costs less than $300. This is going to be my last track car so I am being generous in my rebuild.

Good luck on your effort. I'm glad you found a replacement engine. As I keep saying, we seem to be blowing up the engines more than we are wrecking the cars, thus there is a shortage of good used engines!

Dave in Chicago

+1 on what Harvey says. I ran LW flywheels on my Club Race car. Makes a bunch of stuff rattle that didn't rattle before, for sure. Leave them to dedicated race cars in need of ever lowering rotating mass targets. Likely, you can sell the LW flywheel to recoup cost.

Good luck!

Jengah

Yeah - I think I'm going to ditch the LWFW. I just re-read an old thread in the Pelican forums where Jake Raby chimed in about all the failures he's seen. In short, unless you are going to balance the LWFW with the rest of the engine together, it's too big a risk. Sure wish we could run one though. I'll never forget the day I first got to drive my e30 M3 with one. It made for so much more fun on every shift.

hueyhoolihan

start with parts that are known to have problems, are easy to install, and are inexpensive, then work towards the other extreme until you find yourself replacing perfectly good parts, are exhausted and running out of money.