Engine and Transmission Rebuild Specs

Please correct me if I'm wrong: the only place to find engine and transmission rebuild procedures and specifications is the official Porsche Factory Workshop Manuals - the ones that cost $2000? I have a subscription to ALLDATAdiy but I have no way of comparing the info offered there to the official workshop manuals and know if they contain the same data. They have torque values and assembly procedures but I can't find any of the clearances for the bearings, etc. Any help or direction is appreciated.

For some unknown reason the specs are more top secret than NSA files. Jake Raby has these and from what I heard will be including them in his book. I have several of the service manuals but I dont think the bearing clearances are in there. Give me a little and I will check.

They have to be available somewhere, else how are all these folks rebuilding engines, machining parts, checking wear and clearances, etc?

maybe you can get them from Edward Snowden?? haha on clearances, if you have built motors before, esp race motors, you know that the book don't really mean anything.. go on feel for just about everything. Loose is fast..to loose is someones problem..ha ha

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Seriously? Good luck with that...

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see your not a builder then. NP I didn't go on clearances on my motor in my yellow car.. we could take it to any track or road coarse and see how well it does against your "specd" motor.. I'm just saying..

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Yes, everyone knows "builders" do not follow clearance specs, torque specs, wear specs, etc - they just wiggle things around till they feel "right", then tighten 'em down. All the professional race teams do it that way, especially when you get to the really advanced builders, like Formula 1. And don't forget the manufacturers save millions every year by not following those silly specs when developing their products...LOL

I have many of the manuals as well in electronic format. What exactly are you looking for and I can see if I have the right ones to share?

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im not quite sure how to take that.. that is 100% true but i feel like you believe its not.. at any rate.. motor is a motor is a motor.. unless you have something else besides a block with holes in it and a piston that goes up and down.. its all the same..specs are for people that don't do it normally. Which I understand people are always scared to do something they may not have done in the past. I was trying to say that its not rocket surgery and if you know the tq numbers, the rest would be fine.. I think i'm going to go out and do a little bit of racing this weekend if you want to meet up..

HAH! He got you on that one Josh. The M96 defintely does not have pistons that go up and down, unless you rolled the car. Just kidding! I think hes just looking for the stock bearing specs for a normal rebuild.

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Well, the workshop manuals and a number of updates/appendices that completes the workshop manuals is my info. I've not found any engine bearing sizes, clearances, etc. in my set of factory manuals. IIRC in Bruce Anderson's book he lists the info for the air cooled engines and maybe the 1st year of the water cooled engines, but beyond that, unless he has a new printing out that's it. Jake Raby was going to put a book out that I think was going to supply these numbers but I've not heard much about the book. An experienced engine builder would know the range from other engines. There might even be a formula in say the Bosch Automotive Handbook that will give the ideal bearing clearance given the size of the bearing journal, speed, and so on.

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Since even these engines have TDC and BDC, the pistons ARE actually going up and down.

Looked through what I have and it's only the torque values and assembly procedures, as you mention you already have. Nothing on clearances.

OK guys, here is an example of what I'm looking for taken from "How to Rebuild and Modify Porsche 911 Engines 1965-1989" "How to Rebuild and Modify Porsche 911 Engines 1965-1989" cover.pdf spec_1.pdf spec_2.pdf The guy who puts out a book like this for the M96 engines will be a hero and make a lot of money. I thought about the reasons for the lack of info last night and concluded that Porsche obviously has all this data and a set of procedure manuals for rebuilding the engine and transmission. But, since they only replace engines from abroad and ship the cores back home for tear down, analysis, and rebuild, the relevant info is not disseminated to other Porsche entities. At least that's my reading. Others may be devised and I may be completely wrong, but it sounds reasonable. If this is actually the case then the scary part is everyone who is rebuilding these engines, with all due respect, is "winging it", whether based on trial and error, experience with previous engines, etc. Not to imply that some are not perfectly capable and do excellent work even with no support from Porsche (which is commendable on their part and reprehensible on Porsche's part), but it leaves the field of opportunity wide open for, shall we say, substandard workmanship, misinformation, and frustration of Porsche owners with boundless enthusiasm but limited means, myself included.

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There is not a large market for this info for the water cooled engines as there was for the air cooled. The air cooled engines -- there were exceptions there always is -- needed rebuilding at some really low (relatively speaking) miles while for the most part the water cooled engines do not need rebuilding. There are of course those engines that the owner would want to be rebuilt but these cases are small in number. Very small. A relative handful. The engines are warrantied for 50K miles and with CPO up to 100K miles. Very few dealers are staffed by a tech that can do an engine rebuild. None as far as I know have the machinery, highly specialized machinery/equipment that is required to help bring the engine parts (blocks, etc.) to their final form suitable to make a good engine rebuild the outcome. As I'm sure you know, an engine rebuild is more than just swapping parts. Often machining is involved. Thus the dealer has to rely upon the quality of a contractor -- automotive machine shop -- and thus this complicates things. The process is time consuming and the risk is higher (not high but higher than a factory new engine or even a factory replacement engine) that something may go wrong and the car with its engine could be right back in the shop. The engines supplied by Porsche are assembled at the engine factory by people who do that day in and day out. They have all the parts which may be binned based on their size/clearance, or weight, proper well tested supplies, up to the minute assembly procedures, etc. The engines can be subjected to engine test stand running to verify some level of acceptable performance, perhaps with additional instrumentation to more precisely know the engine is operating ok. The engine is rebuilt efficiently and in an environment that is very conducive to an engine that will deliver thousands and thousands of miles and years and years of trouble free service. Thus when the engine is installed in the car the odds are very good, as high, maybe higher that the engine will be ok going forward compared to the original engine. From Porsche's point of view, it is bad enough the engine failed in the first place. But to have the rebuilt engine fail... well, that's just not acceptable at all. As for the engine rebuilders winging it... there is some truth to that. I'm assuming of course they have not acquired the info you seek. Some may have paid the money to get this from Porsche. But with a rebuildable core the odds are the engine is not totally worn out. I've rebuilt a few engines -- no Porsche engines -- and upon teardown and checking for wear have found limited wear. In on case one main journal was worn a bit tapered. It was still in tolerance -- I had the tolerances -- while the other main journals and rod journals showed no wear. If one is building an engine for the street there is enough info available from the existing engine coupled with experience to do a good job. The engine would be as good as, maybe even a bit better if the engine builder used say tighter weight matching than the factory. If the engine builder is seeking to build a high performance engine then he's going off the reservation and really on his own. At this point then he's got his experience, accumulated from probably years of experience (and probably a few busted engines too) to fall back on. No way Porsche would share with him any of its high performance (race) engine building secrets.

I agree with much of your post, but eventually, ALL engines will need to be rebuilt (or replaced), water-cooled or otherwise. The more time that goes by the numbers will increase from a handful to - well it'll never stop increasing. I don't know about others but I certainly can't afford or justify spending 25k on a new engine purchased and installed by Porsche - it'll never happen. But I don't need one - yet. That's what I'm trying to prevent by maintaining my existing engine and replacing worn internals before they fail and destroy the entire engine. This seems like common sense to me. All I want to do is tear down the engine, inspect the pieces for wear and functionality, replace the wear surfaces, and put it back together for hopefully another 100k miles. To do this one needs something to compare the existing engine specs to the design operating specs. I'm not talking about "high performance (race) engine building secrets", just bearing clearances, end play, tolerances, etc. How would one know if a part is worn beyond its service tolerances if one doesn't know what that those service tolerances are? Sure, we can all make assumptions based on experience and measurements from existing engines - but that's not definitive. I work in engineering and I guess I take access to this type of info as a given, a no-brainer when one works with mechanical equipment. But if Porsche refuses to provide the info, what can I do? I can say I resent being held hostage, regardless of their reasons. Still, nothing I can do about it. It's a real bummer cause I love the car and I just want to take care of it so it lasts as long as it lasts - without a rebuild and refreshing that will be less than it would be if the applicable service info were available to end users. I don't see Chevy or Ford losing any sleep because folks are restoring and rebuilding old Mustangs and Corvettes. Maybe someone will compile and publish a book like the one I referenced for the M96 engines. Sure would be nice...

Because it isn't done yet. I stopped referencing it because I was getting 2 dozen PMs a week asking when it would be done. Getting the IMS Solution in the parts supply system with major retailers took many months of my time. I will go into the final stages with the book after mid July when we return from summer shutdown. Since this is 100% real information compiled from only my findings it has taken years to get as far as it is.