Going Back to Track

This Month a Manthey prepared  991.2 GT3 RS  was supported by the team at JZM. 

This took place as part of an unofficial lap record attempt at Silverstone Grand Prix Circuit.  The car was driven at a blistering pace by Johnny Cocker

He set the lap time at an astounding 2.07.33.

Gen 2 Bore Scoring: The Smoking Gun?

Everyone loves a ‘whodunnit’. And in automotive terms they surely don’t get much better than the cylinder-bore scoring that seems to have bedevilled so many of Porsche’s flat-sixes these last 20-odd years, since they famously adopted liquid cooling in the mid-1990s. (With IMS-bearing failure a very close second, of course.) We present, then, the latest nerve-jangling, edge-of-your- seat episode: further graphic evidence that even the gen 2 997 is by no means immune to this distressingly expensive condition – albeit for probably rather different reasons than in earlier instances.

Previously – as they say in all the best TV dramas: two years ago, in the July 2016 edition of 911 & Porsche World, I reported on what then appeared to be an isolated and certainly rather odd case of cylinder-bore scoring in a 2009-model 997 Carrera ‘S’ at Porsche-Torque in Uxbridge, Middlesex. It was a gen 2 car, and thus equipped with the largely redesigned (and by inference significantly improved) type MA1 engine, with its so-called closed-deck cylinder design. (Which pretty massive change to the engine architecture tells its own story about the earlier iteration. Porsche would not have made such a radical and costly alteration without a very good reason.) Remarkably, the story elicited only a deafening silence from the wider Porsche community, although as I recorded almost a year later, in the May 2017 edition, I was soon having a long correspondence about it with Barry Hart at Hartech, who I still believe to be one of the most knowledgeable and experienced specialists in the molecular-level metallurgy of these engines outside of the Porsche factory. My own view of that Porsche-Torque case, based on empirical experience of other engines over many years, and the precise location and nature of the damage to the bore and piston – and cautiously endorsed by Barry Hart – was that this particular problem was caused not by the chronic but essentially very localised overheating that was (and I suspect remains) the most likely culprit in the earlier M96 and M97 units, but by good, old-fashioned partial seizure. Back in the 1970s I ran a 650cc BSA Lightning that suffered pretty much identical damage to both (air-cooled) cylinders, probably due to overheating caused by excessively retarded ignition timing. (I got it running again and then sold it, in case you were wondering…) Initially, Barry Hart believed that this seizure might have been the result of the owner driving his car too hard before the engine had reached full operating temperature, with piston profiles and necessarily minuscule piston-to-bore clearances as significant contributing factors. (And a management system that necessarily insulates the modern driver from the way an older, lower-tech engine would naturally behave during that warm-up process. Think 356, 911S, perhaps even 944.They all have an innate resistance to being ‘woken up’ first thing in the morning, such that it is almost impossible to drive them too hard, too soon.) The pistons were expanding faster than the cylinder bores, basically. Eventually, though, and having forensically examined several other similarly failed gen 2 engines, Barry concluded that it was probably due to stresses almost unavoidably formed within the cylinder-block castings during manufacture, and which eventually caused them microscopically to distort and shrink across the bores in the thrust direction. Whatever, as they say. The jury is still very much out on that one, and with no further reports coming in from anguished gen2 997 (and later Boxster and Cayman) owners, out there in the harsh testing ground of the real world, it seemed reasonable to suppose that any problems of this nature were relatively few and far between; just one of those things. No news is good news, and all that.

Meanwhile I was having conversations with both Steve McHale at JZM Porsche in Kings Langley and Phil Ellis down at Watford-based ASNU about the different problems that were likely to a rise in these later engines (and in the V8s, as well), thanks in part to the natural characteristics of their ultra – lean-burn direct fuel injection, or DFI, but also to the fact that –absurdly–so many high performance cars now spend so much of their time in stop start urban traffic, with their massively powerful engines running at little more than idle. And not least because there appears to be absolutely no provision for their necessarily hard-working fuel injectors ever to be serviced. (Perhaps unsurprisingly, this is a particular concern of Phil Ellisdon.) The result was my five-page Danger in the city story in the June 2017 edition of the magazine. I am pretty sure that you will understand, then, my immediate interest in a batch of photos e-mailed to me by Phil Ellisdon in early May this year. They show the inside of the MA1 engine from a 2010 997 Turbo: one careful owner from new, 23,000miles, full service history, and apparently used mostly for long journeys after being warmed up from cold with all due care and consideration. It ended up at JZM for investigation into a loud knocking sound from the engine, especially after a cold start, and at which point there were found to have been more than 60,000 misfires on cylinder number four. Inspection with a borescope showed the unmistakable signs of scoring inside that same cylinder, and so the engine was removed and partially stripped for further examination. And, by the time you read this, for replacement with a new ‘short’ engine from Porsche. Curiously, there was no obvious sign of any oil smoke in the exhaust. ‘The short block costs around£10,500plusVAT,’ says JZ’s Steve McHale. ‘But we priced up our usual alternative–completely stripping the old engine, sending it away to Capricorn for machining and pistons, and then rebuilding it with all them any other new parts that would be needed – and there was so little difference that it would have been a false economy not to use a brand new one. And although Porsche Cars GB told us that it knows of no other failures of this nature, the fact is that the new block and pistons may well have been superseded by subtly improved components. You just never know with something like that.’ Indeed.

But precisely what caused the problem in the first place? And, no less crucially, what is to stop it happening again, perhaps after just another 23,000 miles? For Phil Ellisdon the classic smoking gun has to be the injectors, combined with the relatively poor lubricity of modern ethanol-based petrol (which also contains a not insignificant amount of water, in part for its anti-detonation properties). ‘When we tested them, we found the flow rates and spray patterns were far from ideal– and you can clearly see that from the different witness marks on the piston crowns. And I believe this is due in no small measure to overheating that has affected their electrical resistance. There is a tiny Teflon seal at the lower end of each injector stem, where it enters the combustion chamber. All six from this engine were showing signs of blow-by, with two particularly bad examples, and I think it is inevitable that the very high temperatures will have travelled up the stems to the delicate electronics inside the body of each unit. ‘That, together with a carbon build-upon the six nozzles themselves–the natural product of the exhaust-gas recirculation system, and the engine stop-start function in traffic–will have adversely affected the spray pattern, and the management system, the so-called fuel trim, will have pushed more fuel through them to compensate for what the oxygen sensor tells it is too weak a mixture. That washes the necessarily thin film of oil off the cylinder walls, and there you have it. The perfect storm. Metal-to-metal contact and, very soon after that, bore scoring. It can surely be no coincidence that replacement injectors now have dark-grey, graphite-based seals, presumably better able to withstand combustion-chamber gases, instead of the original off-white Teflon jobs.’
It’s fair to say that Steve McHale is less certain about the bore-wash theory–the scoring is not in quite the right place for that, he argues–but he agrees that the injectors are probably the underlying source of the problem, and with the situation exacerbated by those supposedly high-tech modern fuels.‘ DFI injectors work in a completely different way to the older Motronic-style units,’ he says. ‘Fuel pressures in these later engines can be anything up to 150 bar, and so while the injectors need only five volts to pulse them on and off as rapidly as necessary at anything up to 7000 rpm, they need 60 volts to open them in the first place. So their electrical resistance is, indeed, critical – and the one from cylinder four in this engine was in effect short-circuited. ’

Quite what might be the longer-term answer to this seemingly new and disturbing scenario is difficult to say. Careful, more considered use of your car, perhaps – not using it for a two-mile trip to the shops or the station, for a start, despite its ability to cope with that in the short term– and certainly constant, eagle eyed vigilance. Turning off the stop-start function – while you are still allowed to, anyway. Regular testing of the injectors’ resistance (which can be done by a specialist such as JZM without any mechanical interference), and possibly a full fuel-injector service (and stem-seal replacement) every 20,000 miles – although since that might by definition require the removal of the engine from the car, and then the removal of the induction system from the engine, it’s hard to see that happening too often. Perhaps even–at the obvious risk of contaminating the catalytic converter – giving the engine an occasional dose of upper cylinder lubricant, just like we used to way back in the 1960s. Plus ça change… Either way, cylinder-bores coring seems to have become an unfortunately random fact of 21st-century Porsche life, an unintended consequence of the industry’s frankly misguided drive toward ever more ‘performance’ from ever smaller quantities of fuel (as a nation, perhaps even as a species, we should surely be looking at more sensible ways of using any of our cars than, say, the twice-daily, perhaps 100-mile commute), and I can’t help feeling that we shall soon be hearing about 991s with the same issues, and in time even the still-to-be-launched 992. Perhaps the all-electric 911 won’t be too heavy a cross to bear, after all.

JZM Porsche: the only UK specialist with Porsche PIWIS III

Our new Porsche PIWIS III diagnostics systems and PIWIS III tester arrived at the end of December. We’ve been enjoying the huge increase in speed and agility offered by the latest Porsche systems and reaping the benefits of our Porsche PXN access and daily software updates.

“PXN stands for Porsche (e)Xternal Network,” says JZM technical director, Steve McHale. “This means that our new machines log in to the main Porsche factory network and have access to all the latest technical updates and coding capabilities. It is impossible to work on Porsche’s very latest cars without this technology.”

JZM has invested in factory training and official diagnostic technology since 1973, when Steve did his first official Bosch training course. Since then, we have maintained a close relationship with the technical team at Reading and regularly attend the manufacturer’s courses. Two of our team went for training on the new PIWIS III system.

“Porsche tell us that JZM is the only specialist on the UK mainland using PIWIS III. That’s not a huge surprise when you consider the costs involved,” says Steve. “It’s easy to buy some second-hand manuals, watch a few DIY videos online and start selling yourself as a Porsche specialist, dealing only with air-cooled and early 996s, but the newer cars are so technically sophisticated that it is impossible to do anything without having the proper technology to talk to every ECU. This costs money that small operations simply do not have. Our technical partnership with Porsche goes back decades, so it is something we have always factored into our business.”


A good example of how important this is to JZM was a recent repair to a 991 Turbo. These cars have active rear wheel steering, which is controlled by an ECU: one for each side. A bodyshop repairing damage to a 991 Turbo had changed a damaged rear steering arm, but there was no way to tell the car what had happened, so the car was showing all kinds of errors. We had to recode the entire car to let it know that something had been replaced.

PIWIS III brings serious computing power to Porsche diagnostics, so much so that the older cars including late 997s simply do not talk to the system quickly enough and have to be reset manually. Newer cars have a lightning-fast onboard network, saving valuable hours in diagnostics when problems arise. This new system is incredibly quick and automatically downloads daily software updates from the factory. If something pops up that we’ve not seen before, we can send the data to Reading and on to the factory until we get a solution. We also see at a glance whether a car has had all of its recall campaign updates applied.

We’re delighted with the new systems and are pleased to offer the Porsche PXN service to all of our customers at no extra charge above our regular fixed-price servicing. Contact service@jzm.south.co.uk to discuss your Porsche maintenance needs.

JZM Porsche Pre-Purchase Inspection Service

It’s a big mistake to buy any Porsche without first inspecting it thoroughly, to be assured of proper condition. That’s why you should talk to JZM Porsche about our PPI service (pre-purchase inspection).

JZM Porsche Pre-Purchase Inspections

We carry out many pre-purchase inspections for prospective Porsche buyers every year. Inspection is reasonably priced at standard workshop rates. Cars can be brought to our workshop, where the inspection will be completed by a trained JZM technician while you wait. The technican will compile a report and discuss his findings with you afterwards. The results will either confirm the car as a good one or offer some areas for improvement, which could be a help in price negotiations.

In the most extreme cases, we may advise against purchase, but the final decision rests with the buyer. Whatever happens, you will have the best information at your disposal, to help with the decision and avoid losing money on a bad car. Email the JZM Porsche service department to enquire about our Porsche pre-purchase inspections or call us on 01923 269788.

Don’t forget those Porsche Winter Checks


Winter is just around the corner. The AA said it received over 10,000 calls on the first real day of UK cold weather, so now is the time to book a service and check all is in order for the cold dark months ahead. Essential checks include tyres, battery and charging system, climate control to keep cabins warm and dry with glass demisted, lighting and windscreen wiper systems and weather seals and hood drains on roadster and cabriolet models.

This smart 996 Turbo S Cabriolet seen here was already wearing its factory hardtop when it visited JZM Porsche for a pre-winter service. Danny went through our service checklist (now managed on tablet devices) and found very little to worry about on this excellent example.

Long term storage does more harm than good, so it is always great to see people using their Porsches on a regular basis. That said, daily familiarity with a car makes it easy to miss simple defects that can cause unnecessary upset when the weather turns bad. Contact us today to discuss a pre-winter inspection on your Porsche.


Manthey Porsche wheels sold to Canada

JZM sells only the highest quality Porsche tuning parts – why fit anything less to the world’s greatest sports cars? Alongside our sales of genuine Fuchs wheels, KW Suspension, JZM/Surface Transforms ceramic brakes and Akrapovic titanium exhausts, JZM Porsche is the UK distributor for Manthey Racing. We ship Manthey parts to Porsche enthusias
ts all over the world and we recently sent a very handsome package to Canada, in the form of a set of Manthey Racing BBS forged wheels for a Cayman GT4.

Used to great effect on the Manthey Racing Cayman GT4 Club Sport, the Manthey alloys are a version of the beautiful BBS F1-R forged aluminium wheels. Manthey reports that more than 11 kilos of unsprung weight may be saved when using these rims in place of original wheels. Available in silver, titanium or black, they can also be supplied in a centrelock version to suit the 991 GT3. Email parts@jzm.south.co.uk to find out more.


Rare RHD Porsche 993 Turbo S for sale

Air-cooled 911s continue to be highly regarded by classic car investors. The record-breaking Porsche results at the recent Sotheby’s London sale reinforced interest in high end 993s, so we’re delighted to bring a real 993 rarity into stock.

The iconic 993 Turbo is a popular option for air-cooled 911 Turbo buyers, but our new Porsche 993 Turbo S for sale is a very different beast. Offered for one year only towards the end of 993 production, the Turbo S is a very well-specced Turbo with factory 450 horsepower upgrade and more add-ons than a budget airline booking form.

Just 23 of these cars were made for the UK, making the RHD 993 Turbo S a very rare car. It is an exceptionally comfortable and usable investment, not to mention a beautiful item in rare Cobalt Blue with Grey leather sports trim. Contact us today!


Porsche 991 GT3 RS for sale at JZM

It’s always a pleasure to have the latest, greatest Porsche 911 available from stock, so we’re delighted to welcome this perfect Porsche 991 GT3 RS for sale to the JZM showroom.

Newly arrived from Hong Kong, this perfect Lava Orange RHD example has covered less than 600 miles since manufacture. We’ve completed the import process and the car is ready to be used and enjoyed: the next owner will be its first registered UK keeper.

Cars like this are few and far between. Contact us to arrange inspection at the earliest possible opportunity. Part exchange, finance and export sales are a pleasure.



Track Day setup for a 991 GT3

JZM Porsche is well established as the UK’s premier Porsche GT3 specialist, which means that we get a lot of Porsche GT2s and GT3s in the workshop for tuning and track day setup on our Hunter laser alignment ramp. Before a car goes on the ramp, we loosen and lubricate all of the suspension components, to ensure everything can move freely as part of the setup process, and fit any new parts which our customers have asked for.

No stranger to track days, this 991 GT3 returned to the JZM workshop for setup tweaks including extra front camber. The standard Porsche arms do not permit enough movement for more aggressive setups, so we alter the geometry using a mix of Porsche components. In the case of this 991, we also had to repair and paint the underside of the front bumper, after someone forgot to use the Front Axle Lift when going over a speed hump!

Want a JZM setup on your 911? Email Steve McHale at JZM about all of our Porsche tuning products, including KW Suspension and Akrapovic titanium exhausts.



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