Knackered old Porsche with loads of miles - 996 content
Discussion
Krikkit said:
Well that was unexpected!
Having got towards the bottom of the condition report I was expecting "put it all back together as standard and away we go", not "chuck a set of forged pistons in and give it a good going over".
At 500kKM that's not bad condition though, be interesting to see if you're the highest-mileage non-Porsche-owned M96.
If the bores still measured up within spec then it would have gone back together as was with fresh bearings, chains, rings and guides but as they didn't there are limited options. Running it further like this just results in the ovality getting worse until you get into ring pack sealing issues or a failure of the bore. It is possible to hone them oversized and the get them back to OE tolerance by Nikasil coating them but then you have taken some mechanical strength out of a component that is already a weak link in this engine. Having got towards the bottom of the condition report I was expecting "put it all back together as standard and away we go", not "chuck a set of forged pistons in and give it a good going over".
At 500kKM that's not bad condition though, be interesting to see if you're the highest-mileage non-Porsche-owned M96.
By biting the bullet and going liners/closing the deck it solves this problem. Fresh pistons at this mileage would make sense regardless and the cost difference between liners and pistons in 96mm or 100mm is essentially zero so 3.7 it is! Capricorn do all our F1 stuff so I'm pretty confident it will do the trick and Autofarm have a lot of experience of this. Plus a bit of extra poke is never a bad thing
Coakers said:
Well it took me a good hour+ but I thoroughly enjoyed that. Makes my mk2 golf build a tad boring 
Are you undertaking the rebuild yourself PPBB? And yes I second the motion for you to provide plenty of details/pictures for the rebuild. Thanks for sharing.
I quite enjoyed your Mk2 Golf Build to be honest! :-) Are you undertaking the rebuild yourself PPBB? And yes I second the motion for you to provide plenty of details/pictures for the rebuild. Thanks for sharing.No Autofarm are doing the building, whilst I would rather like to put it together myself the time required and specialist tools needed make it impractical - plus there is a huge amount to be said for handing it over to an engine builder who puts one or two of these together every week, it's very hard to put a price on that sort of experience especially when you need it to work for the next 1/4 of a million miles. For me this is definitely a case of the more you know the more you have to learn and I'm well aware of the bits where I could f**k this up royally
poppopbangbang said:
Coakers said:
Well it took me a good hour+ but I thoroughly enjoyed that. Makes my mk2 golf build a tad boring Are you undertaking the rebuild yourself PPBB? And yes I second the motion for you to provide plenty of details/pictures for the rebuild. Thanks for sharing.
I quite enjoyed your Mk2 Golf Build to be honest! :-) Are you undertaking the rebuild yourself PPBB? And yes I second the motion for you to provide plenty of details/pictures for the rebuild. Thanks for sharing.No Autofarm are doing the building, whilst I would rather like to put it together myself the time required and specialist tools needed make it impractical - plus there is a huge amount to be said for handing it over to an engine builder who puts one or two of these together every week, it's very hard to put a price on that sort of experience especially when you need it to work for the next 1/4 of a million miles. For me this is definitely a case of the more you know the more you have to learn and I'm well aware of the bits where I could f**k this up royally
Is there any reason for not going for a turbo motor?
chuntington101 said:
Are Capricorn just doing the liners (guess custom one offs?) or more? Have heard their name coming up in the aftermarket world but can't find much on what services they offer.
Capricorn (or rather Capricorn Automotive as Capricorn are a massive group) are doing liners and pistons including the machining of the original block and liner fit, there are also some additional operations required on the original block for coolant flow etc. due to closing the deck. They are mostly an F1/Pro-Motorsport/OEM supplier rather than tuner market but a few do have parts produced by them if they are not cost limited. They also do a lot of parts and service for our VJ/CK/TJ F1 motors.http://www.capricorngroup.net/en/kolben/service/
Autofarms 3.7L Cayman is using the same approach so it's fairly well proven. Just the cost of doing this is many, many times more than banging a Nikasil ally sleeve down there.
chuntington101 said:
Is there any reason for not going for a turbo motor?
I'm not really a fan of a turbo motors power delivery and they are inheriently less reliable and heavier due to the higher component count. Also in my experience the GT1 based motors (Turbo/GT3) have less life than the M96 and generally require a looking at which costs much more than an M96 at 200K miles or so. Used properly a dual row M96 will clear at least 250K miles - this is probably a sore point as my experience of 996 generation 911s seems to be at total odds with the entire internet...... in the real world the difference between 350bhp and 450bhp isn't actually that much, both cars can cruise at 160mph so over several hundred miles being a few seconds quicker to 160mph doesn't make much difference especially when you probably have an additional fuel stop due to running richer mixtures than the NA engine.John D. said:
He said what?! 
Yeah I know 
I'm not trying to be controversal here but this M96 managed well north of 300K miles without the heads coming off. Out of my (Awwww) Porsche Friends a 996 Turbo melted an exhaust valve at 170K miles and a 997 GT3 had a timing chain failure. So out of a sample of four the three GT1 based motors have been the least reliable with one not being opened as yet, while the s
t unreliable M96 has been the most reliable - based on mileage covered for heads off engine repair. I should quantify this, I'm talking about the total mileage before rebuild here (not overall reliability of engine type before it is lifed) and I'm only talking about the early 3.4L M96 with dual row IMS bearing and ferrous coated pistons. Any single row or plastic coated piston engines then the usual caveats apply but an early 3.4 will in my experience run longer than any normal person will realistically need if you feed it the oil that Porsche say, at the intervals they say and don't be a dick from cold or when it's stinking hot having sat in traffic - all those caveats apply to the Turbos and GT3s too though which should do the same thing.
The bottom line as I see it from having done well over half a million miles across two 3.4L 996 is that the issues reported on the M96 are actually to do with the later 3.4L single row cars and the 3.6L cars. These had some pretty major revisions to engine internals which quite frankly didn't work and these cars do have inherrent issues with about a 10% chance of the motor suddenly becoming in need of rebuild. The 3.4s on the other hand are at about 0.7% from Porsches data and the class action data from the states (and that includes some single row engines) but they got tared with the same brush too. On top of this a lot of scaremongering from those with an interest in flogging upgrade bits and half understood information being repeated by owners has really done the M96 a disservice as in it's original, none cost-down form it was a proper unit capable of big miles with minimal power loss and when it does finally wear out it does it gracefully not catastrophically.
John D. said:
He said what?!
I was shocked to see the 996 turbo on 911 forum recently, the oil sump has not been fitted with bolts during the manufacture (friday car). The car has managed to cover 100k of course, which is great but the owner caught it earlier from the oil filter luckily and went for the rebuild. The rebuild cost of turbos are nuclear comparing to m96/m97, that´s a bit of an issue I think.Gassing Station | Readers' Cars | Top of Page | What's New | My Stuff