[Torbjorn968]

The 944 race car with 968 engine only drove once this year, the radiator flushed most likely due to a clamp not tightened enough... the car has slowly gotten a new cylinder head during the summer but it has become clear that both me and my co owner lack the time to do things properly. Since there are some more issues (oil leakage and balance shafts that does not turn freely) with the engine it will be lifted and fixed by a relative to my partner in the project.

So what should one do when an engine from a 92 968 is out of the car to ensure a long and reliable life?

//TL

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[PorscheDude]

Things to consider:
rod bearings
oil pick up
front end reseal
rear main seal.

The parts themselfs are not very expensive.

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[bob blackwell]

Replace all of the seals on the rear of the engine (camshaft, balance shaft, etc.) it is not possible to replace them with the engine installed. This will be a convenient time to examine the condition of the clutch, throw-out bearing and flywheel as well and replace the pilot shaft bushing in the flywheel while it is easy to get to. Motor mounts will also be easy to replace at this time. Good luck, Bob blackwell.

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[Torbjorn968]

<!--quoteo(post=79644:date=Sep 7 2009, 10:09 PM:name=bob blackwell)-->QUOTE (bob blackwell @ Sep 7 2009, 10:09 PM) <{POST_SNAPBACK}><!--quotec-->Replace all of the seals on the rear of the engine (camshaft, balance shaft, etc.) it is not possible to replace them with the engine installed. This will be a convenient time to examine the condition of the clutch, throw-out bearing and flywheel as well and replace the pilot shaft bushing in the flywheel while it is easy to get to. Motor mounts will also be easy to replace at this time. Good luck, Bob blackwell.<!--QuoteEnd--><!--QuoteEEnd-->

What we (or actually a workshop up north owned by a relative to my co owner, personally I do not have a clue in practical terms) also plan to do is to remove the balance shafts. To take care of potential balance issues of the engine the oil pickup should somehow be strengthened and we may also balance the moving parts of the engine.

/T

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[flash]

having driven a couple of cars with the balance shafts disconnected, i can tell you that you have a long row to hoe ahead of you - it was amazing at how much power was robbed by the engine "fighting itself"

with a DMF, this is mitigated a great deal, because it smoothes out a lot of the balance by means of the seer mass of that thing

but with a lightweight flywheel, it becomes painfully evident - the car immediately ran so differently that i thought i had broken something else

if i had to guess, there was a good 20hp lost while the engine was trying to find balance - it also stalled when dropping rpms quickly coming to a stop - it surged a bit as it went up, and did not have the urgency it did when things were connected

not a fun weekend for me

you will need to remove a LOT of crank weight to make this up, and at that point you might run into other balance issues - the higher order harmonics are tricky - i had planned to do something similar, but it is going to take a lot to get that right - i will have to spend a lot of time at the machinist and the balancer, as well as a LOT of time crunching the numbers on the harmonics - not sure i really want to go through that - i'm guessing at least 2 engines before i got it right

i think you would be better served by leaving the balance shafts in there, and boring out to 3.2 liters - you will more than make up the power loss from the balance shafts, and gain a good amount of torque on top of that - you will also spend a LOT less money

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[968gene]

If replacing the rod bearings...Porsche recommends new rod nuts! very cheap insurance.

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[Torbjorn968]

<!--quoteo(post=79695:date=Sep 8 2009, 08:26 PM:name=flash)-->QUOTE (flash @ Sep 8 2009, 08:26 PM) <{POST_SNAPBACK}><!--quotec-->having driven a couple of cars with the balance shafts disconnected, i can tell you that you have a long row to hoe ahead of you - it was amazing at how much power was robbed by the engine "fighting itself"<!--QuoteEnd--><!--QuoteEEnd-->

Swedish reports on this are all positive, not having a clue myself it would be interresting if there is a US consencus on the matter. Appart from the weight saving and the perceived power benefit from not having the balance shafts the bearings for it are bad in the engine in question.... so a delete option would be a simple way out.

T

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[flash]

make sure they are talking about a 968 engine, or at least the S2 and not a smaller engined 944 - the increased mass and stroke force of the larger engine, change the harmonics a lot

also, the flywheel weight is critical to how bad it feels - as i said, with the DMF it was hardly noticeable, but with the 12 lb aluminum one, it was a train wreck

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[Torbjorn968]

<!--quoteo(post=79773:date=Sep 10 2009, 12:35 AM:name=flash)-->QUOTE (flash @ Sep 10 2009, 12:35 AM) <{POST_SNAPBACK}><!--quotec-->make sure they are talking about a 968 engine, or at least the S2 and not a smaller engined 944 - the increased mass and stroke force of the larger engine, change the harmonics a lot

also, the flywheel weight is critical to how bad it feels - as i said, with the DMF it was hardly noticeable, but with the 12 lb aluminum one, it was a train wreck<!--QuoteEnd--><!--QuoteEEnd-->

So keeping the DMF and removing the balance shafts might not be a bad idea? There are plenty of reports of problems with balance shafts wrongly oriented due to the teeth of the belts jumping over. I have driven at least part of a season with the balance shafts 90 degrees of.

//TL

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[flash]

i can't say it isn't a bad idea, but i can say it's really ugly with a light flywheel - i think the problem is just masked by the DMF

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