What Reliability Improvements in 9A1 vs M97?
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Thread: What Reliability Improvements in 9A1 vs M97?

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    What Reliability Improvements in 9A1 vs M97?

    I've searched around and have found almost nothing on the differences between the 9A1 engine vs the M97 engine, except the the obvious IMSicon deletion, and the DFI on the S versions of the 9A1 (and on base and S after a few years). The only information I see on this forum are an unanswered thread asking the same question, and a link to an article on difference in the heads between m96, m97, and 9A1, which is no longer available on the internet (links to each below).

    Does anyone know of reliability improvements in the 9A1 over the m97? I'm trying to work out whether it's worth the extra $10k to get a 987.2 vs a 987.1. The major engine problems that I know of with the 986 and 987.1 were below, so I wonder which of those were fixed on the 9A1?:

    Cylinder scoring
    Cylinder chunks cracking out
    IMS failure
    heads cracking

    https://www.planet-9.com/987-cayman-...6-m97-9a1.html
    https://www.planet-9.com/987-cayman-...97-vs-a91.html

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    Re: What Reliability Improvements in 9A1 vs M97?

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    Re: What Reliability Improvements in 9A1 vs M97?

    Thanks, that post is a good summary of the potential problems with the 9A1. But it doesn't list the measures taken to fix the M97 issues.
    So maybe it would be safe to assume the 9A1 hasn't had any heads crack (which I understand happened to very few Boxsters anyway) and of course resolved the IMSicon issue. But it looks like cylinder scoring is still a concern.

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    Re: What Reliability Improvements in 9A1 vs M97?

    Only Porsche knows what was done to fix M9X issues. Everyone else is either guessing or logically deducing it via reverse engineering.

    Jake Raby said there were 23 failure modes for a M9X engine. There are only 4 or 5 on a 9A1. It is the better engine. Period.

    V6

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    Re: What Reliability Improvements in 9A1 vs M97?

    A couple things come to mind on the 9A1. Overall it's better suited to track use. Can't recall the details but it has more pickups and oil pumps than the M97. There are cases of oil starvation on track with the M97 but I've not heard of any instances with the 9A1. There is a video of a 9A1 on a articulated test stand. You might try a search for that. Also the M97 has reported cases of rod bolt stretch and some recommend limiting revs to preserve the bolts. The 9A1 bangs off the limiter without issue- at least mine have.

    To the question of whether the cost delta is worth it, that's an individual assessment. For street use an M97 would likely be fine. For track, one could spend on a deep sump, baffles etc and still be money ahead, but overall the 9A1 seems more robust.
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    Re: What Reliability Improvements in 9A1 vs M97?

    Quote Originally Posted by zedcat View Post
    A couple things come to mind on the 9A1. Overall it's better suited to track use. Can't recall the details but it has more pickups and oil pumps than the M97. There are cases of oil starvation on track with the M97 but I've not heard of any instances with the 9A1. There is a video of a 9A1 on a articulated test stand. You might try a search for that. Also the M97 has reported cases of rod bolt stretch and some recommend limiting revs to preserve the bolts. The 9A1 bangs off the limiter without issue- at least mine have.

    To the question of whether the cost delta is worth it, that's an individual assessment. For street use an M97 would likely be fine. For track, one could spend on a deep sump, baffles etc and still be money ahead, but overall the 9A1 seems more robust.
    The cylinders do not use inserts. The bore is the case, although a vendor is going bigger in 9A1 engines via NikaSil inserts.

    Oil pump has five sections that pick up oil from heads as well as sump. It can be partially computer controlled for pressure at RPM. This allows the pressure to be reduced at idle and save fuel via less HP loss.

    The engine has a two range thermostat to heat the water and oil in economy mode (and for emissions) and provide more cooling in Sport/Sport+ modes.

    Water pump was redesigned.

    Better AOS.

    Cracks in the heads that mix water and oil are unheard of.

    Head airflow is optimized that porting gains little (and can hurt).

    Each size of 9A1 has different camshafts for optimization. Camshafts are lighter and have less rotating mass to accelerate.

    Alternator only runs when needed, saving HP and fuel.

    Case does not have the center cradle and less bolts to mess up. Block is slightly less weight.

    Rear Main seal doesn't leak.

    9A1 weaknesses:

    Intake valve guides wear quickly due to carbon on valves due to DFI

    Oil flow in head to cylinder #6 is less than the other cylinders - may have long term lifter/camshaft wear.

    Cam chain could be better quality and runs 2x the speed of a M9X. Case needs split to change (although a vendor is looking into creating a better chain with a master link that would prevent case splitting.

    Cam gear sprockets wear due to being aluminum

    Cylinders can score when new due to cold temperatures and aluminum bore and close clearance, piston to wall.

    None of the above are catastrophic, just long term wear issues. Baby the engine when cold, use good oil/filters and long life will be achieved.

    Note: early GT3s (2014) had factory rod bolt torque issues that caused rods to leave the engine and the oil caught fire. There was a recall and engines were swapped out (~400 world-wide). The #6 oil pressure problem was detected first on GT3s but the lifter design, for a 9000 RPM red line, is different than the non-GT3 engines. Porsche changed the design for later 9A1 GT3 engines to compensate for the cam/lifter wear issue and raised mid-range RPM oil pressures for the cars with the earlier design. The cam/lifter wear issue has not been detected on 'regular' cars.

    V6
    Last edited by Voyager6; Yesterday at 11:15 AM.

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