TCallas

M96, M96 vs. MA101 and MA102

There has basically been two naturally aspirated (non turbocharged), water cooled, flat 6 cylinder engines since the introduction of the 1997 Boxster. These two engines were classified as the M96 and the M97. In a very basic simpleton explanation, the M96 engine was installed in the 1997-2005 986’s/987’s (Boxster’s) and 1999-2005 996’s/997’s (911’s). The M97 was installed in the 2006-2008 987’s, 997’s and all Cayman’s. The M97 is superior and has many upgrades over the M96 but these upgrades mainly lie in the IMS (intermediate shaft) bearing area and above all, design. The M96 IMS bearing has been to blame for many of the engine failures hence the larger IMS bearing and cradle in the M97 engine. I would choose the M97 over the M96 when purchasing a 997.

Having said that, I would also stay away from the 2009 997-2 (997 facelift and version 2). The 997-2 engine appears and is quickly proving to be mechanically superior to both the M96’s and M97’s and is classified as the MA101 for the 3.8 liter and MA102 for the 3.6 liter. Eliminating the IMS and even one more timing chain, the engine is left with just the two camshaft timing chains simplifying the water cooled modern flat 6 engine design even further.

The reason I have reservations about the new MA101-MA102 engines is because of the Direct Fuel Injection (DFI). All manufacturers are having issues with DFI implementation. This is due to the fact that the fuel injector nozzle sprays directly into the combustion chamber (Cylinder and piston area) and not on the intake valve as with earlier models. Spraying fuel before and on the intake valves helps keep the intake valves cool and clean.

So in a nutshell, I would recommend only purchasing the 2006-2008 997’s.

ADias

Really?

"The M97 is superior and has many upgrades over the M96". Really? The only significant upgrades/fixes on the M97 only appeared in late MY06 models and they are just that - temporary fixes. So watch out for '05s, early '06s and good luck with all the others.

You forgot the chronic RMS problems of the M96/M97 engines and chain failure which yields IMS failure.

BTW... the proper designation of the 997.2 DFI engines is 9A1. These engines have been out for close to 18 months and minimal issues have arisen. There are cars with over 50k miles with no issues.

Thanks for your advice, but no thanks.

At Law

Since I have an '06, I think this is fine advice.

Now, if I had an '09, I would strongly disagree.

ADias

But the question is... is your '06 a late '06?

Even more so if you have a '10.

MLindgren

The change was implemented midway through the '05 MY. ALL 2006 cars and later production '05 cars had the change which minimized the IMS failure (I personally have never seen/read of a failed IMS on an '06 or later car).

RF5BPilot

There are refinements and changes across model years some individuals value.

But it seems that the major change started with the 997-2 (direct injection/no IMS).

The 996 MK II (with VarioCam Plus) through the 997-1 are quite similar and have about the same hp....so, choose among those for the style/price you want. The old adage holds true to get the most recent one you can afford. If you're going to stretch at all, it only makes sense to do so for a 2009 & onward -- which is hopeful, but relatively unproven as to how it will hold up in the long run.

Note -- The RMS issue is only an irriation...nothing more. The hysteria about the IMS can be solved with an $800 bearing upgrade. Figure maybe $2000 if you want to upgrade the RMS & put in a new clutch at the same time. So....if you see a 2003 onward that really flips your switch -- and is priced $20-$50k less than a 2009+ -- just do the upgrade and you're fine. You can save a Lot of money on the purchase -- as well as a lot of money in depreciation over time.

With the current stock/real estate markets -- you can Make money with that $20-$50k over the next 5 years instead of putting it in a depreciating asset.

At Law

Yes, based on my readings here, I intentionally bought a very late '06 production. It's basically a '10 GT3 (Yeah right).

JM993

Thanks Tony. A few questions from a would-be 997S purchaser (as my DD).

1. I've heard conflicting information as to when Porsche switched to the M97 engine. Do all 2006 997 cars have the M97 engine? If not, is there a way to externally identify the updated engine?

2. Have you seen engine failures in the M97 engines? I know they are still relatively new, but it concerns me somewhat that Porsche chose to redesign the engine just 2 years after they supposedly "fixed" the problem in 2006.

3. Are there any other mode of failures to watch out for with the M97?

4. In what other areas were the M97 engine improved? I've read about issues with timing chain rails, intermix issues (head cracks) and rod issues with the M96. Were these areas improved on the M97?

TIA,
Joe

TCallas

Joe,

These are indeed excellent questions. I will definitely compile the answers but have been very busy working with my business partner Tom Prine writing the technical articles for Excellence, PCA and various other periodicals. Please be patient and I will get back to you as soon as I can.

Tony Callas

PS Nice 993, is it Aventurine Green?

JM993

Thank you Tony. It's really great to have you on board at Excellence and to be able to tap into your expertise here. I love the 997, and can certainly live with minor niggles, as long as the major engine components generally stay in one piece.

Yes, my 993 is adventurine green on classic gray. A few personal touches - RS g50/31 gearbox, RS LWF and OBD-1 VRAM conversion. A keeper for sure

Cheers,
Joe

f4 plt

I am not an engineer but have played with cars and planes all my life. As to the DFI engines, I have a 997.2 that I have driven over 12,500 over the last year and I am impressed. It was the replacement for a 997 GT3 that was in for its 4th or 5th RMS in less than 11 months and 3500 miles. Granted RMS is an irritant but Porsche clearly and in bold print states in the owners manual that if any oil leak occurs you should take the car at once to your dealer. Gee lawyer warranty stuff. I can not say enough good things about the 3.8 DFI engine, yes it does use a little oil, but it revs freely, has plenty of punch and provides fantastic gas mileage. As to DFI being troublesome .... well the factory used DFI in the RS Spyder and it did quite well. As I said, not an engineer just a long time (well over 40 years) Porsche owner and driver who is very happy with the evolution of the make.

ADias

The M97 engine is the flat6 in the 997.1 series introduced in late 2004 as MY 2005.


Over the years PAG improved the M96/M97 manufacturing and more so in late 2006, but yes there are M97 failures. It's inherent in the engine design.


Same as M96 failures.

Mostly RMS seal and IMS bearing.

vizcarra44

Mr Addict,

You are incorrect in stating that the correct engine designation for Gen II engines is 9A1. This 9A1 is the first part of the reman engine part number. The correct PAG internal engine designation is MA1.01 or MA1.02, as Tony stated.

Regarding issues with these engines, Hmm, how would you really know? Do you work on these cars?

The issue with DFI engines does carry the inherent problem with carbon/gunk buildup on the back of the valves. This will cause driveability issues and smog failures in the future. The RS spyder is a race car with no check engine light for emissions, and I dont think they used the DFI engine for more than 1 year without a rebuild.

In any case, there are problems arising with these engines and the fuel injection system along with timing chains busting, misfire issues and of course the DFI pump along with Variable oil pump issues. There's also a campaign for replacing all the injectors on some lucky 997's. So the Gen II 997 is far from being fault free.

Want to talk about the 970

ADias

Welcome to rennlist, as I note the above as your 1st post.

PAG/PCNA has always referred to the 997.2 engines as 9A1 series. I care less for other arcane nomenclature.

Re. DFI engines. These engines have 18 months of life on the field with excellent results. Nothing is fault free, but the 9A1 architecture has been remarkably uneventful. I raised the intake valve gunk issue on this forum, a year ago, as a question. The consensus of many Porsche specialists I discussed this with is that, if it would become an issue in the 9A1 series, it should not be a big deal. Cayenne DFIs have been driven a lot longer and we do not see any reports regarding this issue.

Why the fervor to defend the inherently weak M96/M97 architecture and cast doubts on the 9A1 reliability?

vizcarra44

If you had a copy of the factory training manual or service manual for this engine, you'd see that this engine is MA1.01 or .02 not 9A1, but this only matters for technicians who need to order a new engine, or do repairs on one.

Regarding my dislike for this engine, I do not feel like this at all. Anything that has problems has a place in my heart. As a State Smog tech and Porsche technician I do know for a fact that the 970 has a new Air-oil mist separator that will minimize the sludge buildup. Valves with sludge buildup will eventually cause problems, why? It wont stop building up, and it will cause misfire issues as it does on the Audi's. DFI is very delicate when it comes to airflow into the cylinder. If it gets disturbed on its way past the valves, guess what will happen?

Oh, and since this engine is still mechanical, I suggest that anyone who is going to want to own a Gen II for the long term, would do themselves a favor by doing an induction cleaning service to help clean the gunk off the valves. At least once a year would be good preventive maintenance.