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    Jul 25, 2005 10:39:20 PM

    911fan
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    M96 engine versus previous air cooled engines

    So I was reading about the M96 and someone said it is really cheap to build compared to previous engines like in the 993 or earlier. I'm wondering if it was just designed to be a modular engine with less emphasis on unique techolology in mind, but I dont know. Can someone shed some light on this?

    Jul 25, 2005 10:44:49 PM

    Grant
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    Reply to: 911fan

    Re: M96 engine versus previous air cooled engines

    Quote:
    911fan said:
    So I was reading about the M96 and someone said it is really cheap to build compared to previous engines like in the 993 or earlier. I'm wondering if it was just designed to be a modular engine with less emphasis on unique techolology in mind, but I dont know. Can someone shed some light on this?


    Yes, it's much less expensive than the air-cooled motors were. The top line 911's (GT2, GT3, Turbo) still use motors that share a block with the aircooled cars from 1989 (964). These are much more robust and have a dry sump so they can be driven with racing tires without suffering oiling problems on the track.

    In fact the M96/97 motors are exchanged rather than rebuilt when they have a significant problem, just like the gearboxes on the 996 and 997 (unlike the older ones). The M96/97 motors are also more prone to leaking oil from their rear main seal - a problem that has been know since the first Boxsters in 1997, but apparently not yet corrected.

    The main reason for the develpment of the M96 was economic (improves the bottom line for Porsche), AFAIK, and allowed them to offer the Boxster at a lower price than the 911 (993 was the current model then).

    Jul 25, 2005 11:00:40 PM

    JimFlat6
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    Reply to: 911fan

    Re: M96 engine versus previous air cooled engines

    Maybe this will help. This is the simplest way of explaining it.

    Previous 911 motors were Air Cooled and used a block and heads that were precision machined from forgings. The cylinders were actually like lttle finned barrels that were bolted to the block. The oil lines were external and it had a dry sump lube system.It is also more expensive to build and assemble than a M96 engine.

    The M96 engine has a investment cast block with its cylinders intergal to it. The heads are made from
    castings also. The oil lines are internal as are its
    coolant passages. It does not have a dry sump lubrication system.

    I am not a fan of investment castings for engine use. No matter what the hardening procedures used are, they seem to develop a wierd metallurgical half life of their own.

    You can Google up the diagrams for M96 and other Porsche engines and also for details about their parts.

    Jul 26, 2005 1:42:43 AM

    WAY
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    Reply to: JimFlat6

    Re: M96 engine versus previous air cooled engines

    You mean the RMS issue is still around with the 997 and 987??? Boy that is not good news. I was hoping not to have to hear those 3 letters again with the Cayman, but doesn't sound like that would be the case. RMS is all you hear with us 986/996 owners.

    Jul 26, 2005 1:46:47 AM

    LowPolarMoment
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    Reply to: JimFlat6

    Re: M96 engine versus previous air cooled engines

    What's an "investment casting"? I"m not familiar with that term. Thanks.

    Jul 27, 2005 2:38:58 AM

    911fan
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    Reply to: LowPolarMoment

    Re: M96 engine versus previous air cooled engines

    Jim do you kow where these diagrams can be found? I tried Goggle but couldnt find any.

    Jul 27, 2005 3:29:48 AM

    JimFlat6
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    Reply to: 911fan

    Re: M96 engine versus previous air cooled engines

    Here is a diagram of a M96 Boxster engine:

    http://content3.us.porsche.com/prod/boxster/boxster.nsf/usaenglish/performanceengine_diagram

    This how investment casting works.A wax is coated with colloidal silica, followed by a dry powder mix. This process is repeated until several layers are built up and dried. The wax is melted out and molten metal is poured into the resultant mold to form the final metal product.

    With a machined part,they basically take a metal block and mill out the needed dimensions with cutting machines.

    Porsche contracts its M96 motor investment castings from Thyssen.So far they have made Thyssen switch plants twice because of quality issues due to imperfect dimensions and cast in air bubbles.

    Audi has the most advanced and most repeatedly precise way to make a engine and heads. They have created a UV Laser system to replace machine milling and investment castings.

    Audi TDI Engine blocks are rotated on a turntable at 120 rpm around the laser head. The cycle time for a complete engine block including handling is just 184 seconds, and the exposure time for each cylinder bore is 20 seconds.
    Machining the surface of the cylinder bores with the beam of ultra-violet light also reduces engine oil consumption by up to 75 %, and wear to the cylinder bores and piston rings by as much as 90 %.

    Hopefully Porsche will adapt the Audi UV Laser system soon. If they do,the M96 RMS issue will probably dissappear.

    Jul 28, 2005 5:16:56 PM

    DaveC
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    Reply to: JimFlat6

    Re: M96 engine versus previous air cooled engines

    Great post Jim! Thank you. Despite the problems, it's worthwhile to recall that had the Boxster and its M96 engine not been a financial success, it's likely that Porsche would have either ceased to exist or more likely been purchased by another, larger, manufacturer. Jim what is your sense of the service life for the M96 engine? I had a 99 986 with oil leaks that seemed to have been solved in the first year, but I kept the car only 4 years and 31,000 miles. It also seems that some of these engines have managed to reach high milage without problems. Could this reflect variations from individual casting to casting? The issue, at least for me, is whether my next Porsche will be a "keeper" or another lease car.

    Jul 28, 2005 11:18:21 PM

    JimFlat6
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    Reply to: DaveC

    Re: M96 engine versus previous air cooled engines

    There is no doubt that the M96 engine seems to have helped rescue the company, it does cost a lot less to make than a 964 style air cooled engine.

    Yes their can be variations in casting from unit to unit, not only in dimensions but in material. Any problems can show up early or develop later. Their is no way to accurately and precisely predict servicelife.

    I am sure that Porsche has engineering durability standards and predictions, but they do not share that information. Porsche makes a best faith effort to produce a quality product and you takes your chances.

    In general, the problem with investment castings in motor blocks is that they do seem to have a wierd half life of their own. It could be 5 years and 30,000 miles or 5 years and 180,000 miles until any catastrophic failure if at all.

    If you look at a piece of cut investment cast steel under a industrial microscope,its molecular structure is random. If you look at a piece of cut forging, it has a uniform molecular structure. Investment castings weigh less, but thats because they are more porous. Their friction surfaces can also wear faster and the hardening process, if any, sometimes can actually make them very brittle over time.

    One thing that is different between the M96 engine and the 964 and earlier flat 6 engines is that block failure was virtually unheard off, even when they used magnesium in the blocks.They had parts failures, but never had catastrophic failures due to materials and factory new dimensions. But they were never cheap to fix or overhaul.

    In the mid eighties some porsche 6's were known to last for up to 250,000 miles before needing pistons, cylinders and head work, and those parts and labor would have probably cost you the same as a Porsche factory rebuilt M96 engine does now. I have not heard of anyone putting 250,000 miles
    on a M96 engine yet.

    Get what you like. If you are looking for a new Porsche to get as a keeper, just do it and look at the engine as a inevitable line item expense after the warranty is up.

    Jul 29, 2005 12:03:18 AM

    911fan
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    Reply to: JimFlat6

    Re: M96 engine versus previous air cooled engines

    Jim you really kow your stuff. I wonder if the M96 is a step up or down from the air cooled motors in all areas. Obvioulsy this investment casting seems to have problems.

    But I would think the DOHC and 4 valve heads make for an engine that is superior to the Air cooled ones in some ways.

    Its funny about how people say the M96 has lost the Visceral feeling of the air-cooled engines, b/c when I drove one a few months ago I thought it made some cool sounds.

    Jul 29, 2005 2:01:39 AM

    JimFlat6
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    Reply to: 911fan

    Re: M96 engine versus previous air cooled engines

    The M96 is both a step up and a step back.

    M96 step up .....

    Liquid cooled. Runs cooler, makes less noise and is easier to meet emission and noise regs. The DOHC and 4 Valve per cylinder is as much there for emissions reasons as it is for performance.

    M96 step back.....

    The M96 was engineered for consumer application only and is built to a certain price. It has no cross over endurance racing capability and is not certified for use with racing tires because its lack of a dry sump lube system can allow oil starvation when under high G's.

    964 engine, as also used in GT3 and TT....

    Air Cooled. No radiator, no water pump, no coolant lines running back and forth twice to the engine. Noisier and runs warmer. Owns most of the FIA endurance racing records in the world for a production car engine. Originally designed during the post war industrial craftsmanship era when labor and materials were no cost no object.

    M96 Boxster and 996 applications ..

    When Porsche announced the M96, they said that the 964/GT1 engine was DOA for street cars because it could not meet noise and emission laws. Then "miraculously" the GT1 engine appears in the 996 GT3 and 996TT. The actual strength of the M96 engine and its parts simply cannot take the added HP and sustained use needed for those cars performance requirements.

    There is no doubt that Porsche needed the M96 engine to meet the 986's retail price, but the 996 had a retail price point starting at almost 75% more than a 986 and Porsche has stated that the 996 cost them only 10% more to make than the 986, so they had plenty of margin to have included the 964/GT1 engine in the 911.

    But by not doing so, they created the first 911's ever that are incapable of being tracked on racing tires, basically they emptied a part of the 911's soul to make extra, extra profit.

    Part of the more "visceral" feel you noticed in a older 911 is that pre 89 911's use a single mass flywheel, motor mounts that are not hydraulic and use a simple cable to connect the accelerator to the intake linkage. Also, the angle of the floor hinged pedals seem to encourage your right foot to press further and further down on the gas.

    I left out that the 996TT engine does have liquid cooled heads.

    Jul 29, 2005 2:05:02 AM

    W8MM
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    Reply to: JimFlat6

    Re: M96 engine versus previous air cooled engines

    Quote:
    JimFlat6 said:
    When Porsche announced the M96, they said that the 964/GT1 engine was DOA for street cars because it could not meet noise and emission laws. Then "miraculously" the GT1 engine appears in the 996 GT3 and 996TT.



    Huh???

    How come my 996TT has a water temp gauge, then?

    What did I miss?

    Jul 29, 2005 2:07:31 AM

    JimFlat6
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    Reply to: W8MM

    Re: M96 engine versus previous air cooled engines

    Quote:
    W8MM said:
    Quote:
    JimFlat6 said:
    When Porsche announced the M96, they said that the 964/GT1 engine was DOA for street cars because it could not meet noise and emission laws. Then "miraculously" the GT1 engine appears in the 996 GT3 and 996TT.



    Huh???

    How come my 996TT has a water temp gauge, then?

    What did I miss?



    I inadvertantly left out that the 996TT has liquid cooled heads. You didnt miss anything! My haste, my error.

    Jul 29, 2005 2:35:11 AM

    911fan
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    Reply to: JimFlat6

    Re: M96 engine versus previous air cooled engines

    Thats really sad the M96 is basically a cost cutting measure. When the 996 debuted, I thought the new engine was this awesome new modern powerplant, far better than the air cooled ones. Also, it seems funny the TT and GT3 are using engine pieces from such an older engine. One would thikn with its massive profitablitiy, Porsche could develop some newer stuff.

    Hey Mike that interior is really nice.

    Jul 30, 2005 10:37:59 PM

    fritz
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    Reply to: JimFlat6

    Re: M96 engine versus previous air cooled engines

    Quote:
    JimFlat6 said:
    964 engine, as also used in GT3 and TT....

    Air Cooled. No radiator, no water pump, no coolant lines running back and forth twice to the engine.

    When Porsche announced the M96, they said that the 964/GT1 engine was DOA for street cars because it could not meet noise and emission laws. Then "miraculously" the GT1 engine appears in the 996 GT3 and 996TT.


    If you check your facts, you'll find that what was said was that air-cooled engines would not be capable of meeting new emission reqirements, prompting a move to liquid-cooled engines.

    Quote:
    JimFlat6 said:
    I left out that the 996TT engine does have liquid cooled heads.



    You also left out that the 996 TT, GT2 and GT3 engines also all have liquid-cooled cylinder blocks, making them liquid-cooled engines. Otherwise they wouldn't need to carry around 25kg/55lb of coolant!

    But just sticking to the facts would inconveniently have made much of your above rant baseless and redundant.

    Jul 30, 2005 10:48:26 PM

    JimFlat6
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    Reply to: fritz

    Re: M96 engine versus previous air cooled engines

    Fritz, you are right on the liquid cooling. I got so far into the M96 problems that I bypassed it from thinking of the 993 series too much. My error.

    That aside, The method of manufacture and materials used in the TT,GT2 and Gt3 engines are not the same as in a M96 engine at all, and the M96 engine has substantially cheaper components and assembly process than a 993 or earlier series Porsche flat 6 engine.

    Jul 31, 2005 2:05:31 AM

    911fan
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    Reply to: JimFlat6

    Re: M96 engine versus previous air cooled engines

    Hey Jim,
    Hate to keep picking your brain, but could you tell us about the difference in the manufacturing and componenets differences between the M96 and the GT3, TT ?

    Jul 31, 2005 9:58:19 AM

    fritz
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    Reply to: JimFlat6

    Re: M96 engine versus previous air cooled engines

    Quote:
    JimFlat6 said:
    ... the M96 engine has substantially cheaper components and assembly process than a 993 or earlier series Porsche flat 6 engine.



    That's rationalisation. My PC is not built like IBM used to build mainframes back in the '60s - thank God!
     
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