M97.21 Engine Rebuild

[TimeAttack]

Hi guys,

I am sending out my IMS to LN for upgrading and since the engine is already dissembled, I will be doing a few minor upgrades to the internals. I have the service manual but I don't see any info. on main/rod bearing clearances. I went into PET and it seems that there's only one standard size for both main and rod bearings. However, when I inspected the old bearings taken out of my engine, there were different sets of 5 digit numbers stamped on them. My questions are, what's the tolerable bearing clearances for this engine, and are there different sized bearings from the factory?

[BYprodriver]

Originally Posted by TimeAttack

Hi guys,

I am sending out my IMS to LN for upgrading and since the engine is already dissembled, I will be doing a few minor upgrades to the internals. I have the service manual but I don't see any info. on main/rod bearing clearances. I went into PET and it seems that there's only one standard size for both main and rod bearings. However, when I inspected the old bearings taken out of my engine, there were different sets of 5 digit numbers stamped on them. My questions are, what's the tolerable bearing clearances for this engine, and are there different sized bearings from the factory?

Porsche only supplies standard bearings & they don't supply the info you seek to authorized Porshe dealers.

[TimeAttack]

Even authorized dealers don't know the bearing clearances? Wow

[BYprodriver]

I don't think dealers were authorized to see or touch the bearings until a year or two ago.

[mikefocke]

Internal engine parts were not available nor were classes for the dealer techs as it was standard practice just to swap an engine ... I presume given the price of 911s it was assumed that this would satisfy. No one ever though of 12 year old cars or $8k price points for the cars.

And yes, it was about 2-3 years ago this policy supposedly changed. But I know dealers today without a single tech capable of entering the engine internals.

[TimeAttack]

Very interesting info! I guess the only option for me is to purchase the bearings in standard size and hope that they work!

[Sil40sK]

Originally Posted by mikefocke

Internal engine parts were not available nor were classes for the dealer techs

Not sure where you heard this. To answer your question every dealer with access to PIWIS WSM should have access to these numbers. Unfortunately due to the architecture of the IDS-engines it's just not common practice to machine the crankshafts or crank-cages, if I'm not mistaken Clevite does make over/undersize engine bearings and a little simple math will dictate the size needed. LN should have access to any info needed to get clearances within factory spec.

[mikefocke]

Where did I hear it...a Porsche press release. I'm sure I posted about it at the time though exactly when that was is lost in the mists.

[BYprodriver]

Originally Posted by Sil40sK

Not sure where you heard this. To answer your question every dealer with access to PIWIS WSM should have access to these numbers. Unfortunately due to the architecture of the IDS-engines it's just not common practice to machine the crankshafts or crank-cages, if I'm not mistaken Clevite does make over/undersize engine bearings and a little simple math will dictate the size needed. LN should have access to any info needed to get clearances within factory spec.

We are talking about M97 engines. What is a IDS engine?

[Sil40sK]

IDS = Integrated dry-sump. Also P10W is the dealer class for rebuilding the water-cooled sports car engines. I took it 3 years ago.

[TimeAttack]

Originally Posted by Sil40sK

N it's just not common practice to machine the crankshafts or crank-cages.

I guess this is why the main bearings are only sold in standard sizes?

[BYprodriver]

Originally Posted by Sil40sK

IDS = Integrated dry-sump. Also P10W is the dealer class for rebuilding the water-cooled sports car engines. I took it 3 years ago.

So Porsche refers to this engine family as IDS instead of M96/97? I thought the IDS was just a marketing term. Interesting this P10W class seems to have started around the time Jake Raby was revealing info on IDS engine internals.

[Sil40sK]

The class was around long before 3 years ago, I just happened to take it 3 years ago. The IDS thing is indeed pretty much just a marketing term, I usually only use it when making comparisons between the GT/Turbo engines and the regular Carrera engines. And yes that's why the bearings are only sold in standard sizes, I'm sure some aftermarket company makes bearings for it, only thing is you'd have to retreat the crank after machining it.

[TimeAttack]

Sil40sK, thanks for sharing such useful info!

[TimeAttack]

Just an update. I purchased the standard main and rod bearings based on my VIN and after fitting them, their clearances are as follows :

Mains +.0023-.0025"
Rods +.0018-.0020"

Do they look ok to you guys?

[kuehjo]

TimeAttack,

I'm VERY interested in your progress, as i may be close behind you in trying to recondition my 2001 2.7 with a rod knock...

Any pointers????

Thanks!

Jonathan

[TimeAttack]

Originally Posted by kuehjo

TimeAttack,

I'm VERY interested in your progress, as i may be close behind you in trying to recondition my 2001 2.7 with a rod knock...

Any pointers????

Thanks!

Jonathan

I'm no expert but will be glad to share any info. should I have them.

[BYprodriver]

Originally Posted by kuehjo

TimeAttack,

I'm VERY interested in your progress, as i may be close behind you in trying to recondition my 2001 2.7 with a rod knock...

Any pointers????

Thanks!

Jonathan

If you have a rod knock you must have spun rod bearings. The rods are not rebuildable but I have good used rods available.

[kuehjo]

Originally Posted by BYprodriver

If you have a rod knock you must have spun rod bearings. The rods are not rebuildable but I have good used rods available.

PM sent!

[tomk]

hi curious as to how you took your measurement of clearance? 0.002 sounds like a reasonable value but i dont have specific numbers to offer