Bore scoring on refurbished engine
Discussion
Its cause and effect,there are other mods that need (idealy)to be carried out around the rebuild to aid the overstretched thermal efficiency,Hartec are the people to see and discuss options.
Basic changes to driving styles in set situations and increased oil changes all also help a lot.
Just a rebuild isn't a long term fix especially the cheap way IE rebuilding only the affected bores,the additional mods don't cost a fortune either IMO.
Basic changes to driving styles in set situations and increased oil changes all also help a lot.
Just a rebuild isn't a long term fix especially the cheap way IE rebuilding only the affected bores,the additional mods don't cost a fortune either IMO.
hartech said:
Bore scoring is known historically to occur mostly at low revs and high torque. The problem started when the variable valve-lift systems increased low speed torque – so there is a clue (although other changes were made at about the same time to coolant flow balance and piston coatings). Tiptronics set of usually in 2nd and this requires more torque to get the same acceleration than a manual in 1st – so if you are going to get away quickly in a tip it would be better to flick it into 1st.
Not sure I understand. Every time i pull away from a stand still or a junction I never accelerate hard I probably use less than 3k rpm. You mentioned bore scoring occurs at low revs and high torque. With the car being in 2nd gear creating the higher torque and me acclerating slow using low revs does that mean my driving style is likely to increase the chance of my engine suffering for bore scoring? should i be dropping the car into 1st every time i drive away and accelerate up to 4k or have i got the wrong end of the stick!!!?I do appreciate the effort youve made to cover what appears to be a technical topic but I can't sign up from your plan until my warranty runs out. my Car is a Cab does the plan cover broken hoods?
tr7v8 said:
Jon Mitchell or JMG
Thanks. 
Here are the details of their maintenance plan:
http://www.jmgarage.co.uk/CMS/index.php/component/...
Alex, you have to first understand that due to the difficulties I tried to explain about testing for specific causes it is not possible to be adamant about any particular issue - but only able to apply good engineering and technical knowledge and experience to highlight those things that might make the problem more or less likely to occur and advise accordingly.
We test drove manuals and tiptronics and found that in a manual car most drivers don't accelerate from below 2,500 rpm (they change down earlier) whereas by contrast tiptronic drivers often accelerate reasonably hard without the gearbox kicking down - from lower revs (and the incidence of scoring seems to occur more with tiptronics).
The variable valve lift and timing technology allows quite high torque at these low revs so it is used more for adequate driving speeds.
All previous research into bore scoring (or scuffing as it is often referred to) has been found to occur at low revs with big capacity engines. It seems that as the speed of the piston moving up the cylinder bore increases the contact between the piston and the cylinder changes and causes less problems.
Typical experiences of this problem were with (for example) Ducati engines).
We have found that manual cars driven largely on track don't seem to suffer and all 4 of our Porsche Club race cars in our Hartech team are still using original Lokasil cylinders (even though we could have fitted our superior Nikasil plated alloy liners) using Lokasil as part of our research program and have so far been 100% reliable (despite leading the team award and winning the last 2 races). Obviously these do not experience any low revs driving.
Furthermore rather than failures occurring for fast aggressive drivers we have found a fair share of quiet passive drivers also suffering scored bores.
We have to weigh up these experiences and try and marry them to technical explanations to advise people and this has resulted in our general advice.
Because of the variable valve lift – even at half throttle say – the engines produce a lot more torque at lower revs than previous designs and hence – I think that – unless you have fine throttle control – if you want to get going quite quickly – it could be beneficial to flick down to first – but you must choose what to do and I am not telling anyone how to drive their car – you choose what advice to listen to and what to do about it – I am just trying to help.
Regarding other Lifetime Maintenance Plans – there are others that basically copied ours – and therefore that provide similar services (that will become more widespread over future years) – but the only difference I see regarding engine repairs is that we have all the equipment (including a fully functional precision machine shop) a professional design engineer of international repute and have redesigned and re-manufactured lots of parts “in house” that form a part of our offering and that no one else can match.
We also operate an efficient and well organised mini production line with investment in storage and handling that is second to none and complete more engine rebuilds than anyone else with more comprehensive on-going research and development into the whole problem.
Most of our customers on the plan are from down South (where I come from) and find no problem at all in coming up to see us once a year for their annual services or transporting their car in the rare event that it stops running. However if there is a similar scheme near you I think it would be worthwhile going on it - the idea behind it does for the first time put the specialist in a position where he only benefits if he does a great job of servicing and repairing your car and fixes weaknesses before they escalate into bigger problems.
The only way we could operate a South East version of Hartech would be at increased prices (due to the higher cost of industrial space and wage levels there). How much extra would you consider it viable at?
Baz
We test drove manuals and tiptronics and found that in a manual car most drivers don't accelerate from below 2,500 rpm (they change down earlier) whereas by contrast tiptronic drivers often accelerate reasonably hard without the gearbox kicking down - from lower revs (and the incidence of scoring seems to occur more with tiptronics).
The variable valve lift and timing technology allows quite high torque at these low revs so it is used more for adequate driving speeds.
All previous research into bore scoring (or scuffing as it is often referred to) has been found to occur at low revs with big capacity engines. It seems that as the speed of the piston moving up the cylinder bore increases the contact between the piston and the cylinder changes and causes less problems.
Typical experiences of this problem were with (for example) Ducati engines).
We have found that manual cars driven largely on track don't seem to suffer and all 4 of our Porsche Club race cars in our Hartech team are still using original Lokasil cylinders (even though we could have fitted our superior Nikasil plated alloy liners) using Lokasil as part of our research program and have so far been 100% reliable (despite leading the team award and winning the last 2 races). Obviously these do not experience any low revs driving.
Furthermore rather than failures occurring for fast aggressive drivers we have found a fair share of quiet passive drivers also suffering scored bores.
We have to weigh up these experiences and try and marry them to technical explanations to advise people and this has resulted in our general advice.
Because of the variable valve lift – even at half throttle say – the engines produce a lot more torque at lower revs than previous designs and hence – I think that – unless you have fine throttle control – if you want to get going quite quickly – it could be beneficial to flick down to first – but you must choose what to do and I am not telling anyone how to drive their car – you choose what advice to listen to and what to do about it – I am just trying to help.
Regarding other Lifetime Maintenance Plans – there are others that basically copied ours – and therefore that provide similar services (that will become more widespread over future years) – but the only difference I see regarding engine repairs is that we have all the equipment (including a fully functional precision machine shop) a professional design engineer of international repute and have redesigned and re-manufactured lots of parts “in house” that form a part of our offering and that no one else can match.
We also operate an efficient and well organised mini production line with investment in storage and handling that is second to none and complete more engine rebuilds than anyone else with more comprehensive on-going research and development into the whole problem.
Most of our customers on the plan are from down South (where I come from) and find no problem at all in coming up to see us once a year for their annual services or transporting their car in the rare event that it stops running. However if there is a similar scheme near you I think it would be worthwhile going on it - the idea behind it does for the first time put the specialist in a position where he only benefits if he does a great job of servicing and repairing your car and fixes weaknesses before they escalate into bigger problems.
The only way we could operate a South East version of Hartech would be at increased prices (due to the higher cost of industrial space and wage levels there). How much extra would you consider it viable at?
Baz
hartech said:
We test drove manuals and tiptronics and found that in a manual car most drivers don't accelerate from below 2,500 rpm (they change down earlier) whereas by contrast tiptronic drivers often accelerate reasonably hard without the gearbox kicking down - from lower revs (and the incidence of scoring seems to occur more with tiptronics).
The variable valve lift and timing technology allows quite high torque at these low revs so it is used more for adequate driving speeds.
All previous research into bore scoring (or scuffing as it is often referred to) has been found to occur at low revs with big capacity engines. It seems that as the speed of the piston moving up the cylinder bore increases the contact between the piston and the cylinder changes and causes less problems.
Thanks Baz. I think I understand what you mean. I take it it's not just from a standstill, if you're cruising at 40mph and then accelerate fast, manual drivers will normally drop down a gear (high revs, less torque) whereas tiptronic will accelerate in the current gear (lower revs/under higher torque) The variable valve lift and timing technology allows quite high torque at these low revs so it is used more for adequate driving speeds.
All previous research into bore scoring (or scuffing as it is often referred to) has been found to occur at low revs with big capacity engines. It seems that as the speed of the piston moving up the cylinder bore increases the contact between the piston and the cylinder changes and causes less problems.
I have a tiptronic with sports chrono. Would driving around with sports chrono on help? my understanding it that it keeps the rev ranges higher and therefore I would assume keep the car in lower gears preventing the low revs/high torque scenerio you mentioned?
hartech said:
Most of our customers on the plan are from down South (where I come from) and find no problem at all in coming up to see us once a year for their annual services or transporting their car in the rare event that it stops running. However if there is a similar scheme near you I think it would be worthwhile going on it - the idea behind it does for the first time put the specialist in a position where he only benefits if he does a great job of servicing and repairing your car and fixes weaknesses before they escalate into bigger problems.
The only way we could operate a South East version of Hartech would be at increased prices (due to the higher cost of industrial space and wage levels there). How much extra would you consider it viable at?
Based on what you've posted and the investment you've made in understanding and identifying solutions for these problems I'd say the monthly cost is reasonable for what you get. You're actually only 3.5hrs away. JMG is probably 2hrs away so not much in it. The only way we could operate a South East version of Hartech would be at increased prices (due to the higher cost of industrial space and wage levels there). How much extra would you consider it viable at?
I drive a Tip C4S 996. I always drive in manual and when i come to a complete stop pull away in 1st. Those that know, unless you get it right (at the right speed and revs) the tip is a bit clunky going into 1st anyway. The tip at the end of the day is a old merc auto gearbox with a manual gear selection added on. Its not a speed focused gearbox in auto so when making brisk progress and lack of ratios compared to manual its going to rely more on the torque capability of the engine rather than its ability to drop down a gear or 2. But as Barry at Hartech has previously said its the higher temperatures that the M96 engine can run at due to its designed cooling system that along with a tip gearbox increases the bore scoring issues.
Rockster said:
If Porsche deals with bore scoring as it has with other serious internal engine issues the engines are not repaired at least not at the dealer. The engine is removed and a factory supplied replacement engine (new or re-manufactured) is installed.
The removed engine is shipped back to Porsche where it may be repaired if it is deemed a good candidate for repair.
With IMS or other serious internal engine problems a few unfortunate owners experienced this twice. Once with the original engine and then again with the replacement engine. One poor soul I believe even had the 2nd replacement engine fail.
Not true. Porsche's favoured method is repair at the dealers - it is very reluctant to replace the engine.The removed engine is shipped back to Porsche where it may be repaired if it is deemed a good candidate for repair.
With IMS or other serious internal engine problems a few unfortunate owners experienced this twice. Once with the original engine and then again with the replacement engine. One poor soul I believe even had the 2nd replacement engine fail.
Don't ask me how I know - suffice to say I had to fight them tooth and nail on a new car that had done 7500 miles. Porsche's attitude was shocking and I vowed to never buy another new car from them. Gone old school since!
Edited by drmark on Thursday 23 May 12:37
drmark said:
Not true. Porsche's favoured method is repair at the dealers - it is very reluctant to replace the engine.
Don't ask me how I know - suffice to say I had to fight them tooth and nail on a new car that had done 7500 miles. Porsche's attitude was shocking and I vowed to never buy another new car from them. Gone old school since!
Yup think things have changed. When I bought mine I was told that they almost always replace the engine for scored bores. Then it happens and you get a rebuild. Don't ask me how I know - suffice to say I had to fight them tooth and nail on a new car that had done 7500 miles. Porsche's attitude was shocking and I vowed to never buy another new car from them. Gone old school since!
Edited by drmark on Thursday 23 May 12:37
I'm probably a low-value client though with a 2006 motor !
Edited by richardrsc on Thursday 23 May 18:58
drmark said:
Not true. Porsche's favoured method is repair at the dealers - it is very reluctant to replace the engine.
Don't ask me how I know - suffice to say I had to fight them tooth and nail on a new car that had done 7500 miles. Porsche's attitude was shocking and I vowed to never buy another new car from them. Gone old school since!
Depends upon the severity of the issue. Noisy lifters for instance get done at the dealer. This was true back in '02. Up to around 06 IMS issues were dealt with by engine replacement. But the car I came across in a dealer's service department in for this was undergoing repair at the dealer. When I asked the tech about this he told me Porsche issued instructions for qualifying an engine for repair, at least for IMSB issues. A gold certified tech is required to perform the repair.Don't ask me how I know - suffice to say I had to fight them tooth and nail on a new car that had done 7500 miles. Porsche's attitude was shocking and I vowed to never buy another new car from them. Gone old school since!
Edited by drmark on Thursday 23 May 12:37
I'm not sure if IMSB issues are still dealt with at dealer. Probably not but this can be explained by more and more of the vehicles that can be afflicted are out of warranty and the owner will likely seek to have the problem fixed elsewhere.
Even for cars still covered under warranty the owner can be asked to fund the engine teardown needed to determine if the engine qualifies for warranty repair or replacement. This is to guard against someone bringing a car in with a sick engine that is not sick due to anything covered by the warranty. Many owners balk at this since the money amount can be in the several thousand dollar range and there is no guarantee the engine will be covered -- it depends upon what is found wrong.
But with newer models engine replacement is still the preferred choice. I've see new Carrera's (one with the X51 engine no less), Panamera's and Cayenne's in the bays with the engine out awaiting a new replacement engine.
That's useful Rockster - sorry about your bill Petop - would have been far less at an independent. It will be interesting to find out how well the new engines perform in time.
For those interested in my views about what may be behind all these problems (if not please stop reading now) it does seem as if the pursuit of performance and modern production philosophy combined with cost reduction and emission control have rendered many new high performance cars less reliable in the engine compartment than they used to be when they could burn plenty of fuel and manufacturing costs were less dominated by labour rates and raw material costs.
It reminds me of something I commented on a few years ago when I worked in Aerospace and the power generation industries where we worked with "factors of safety". These were basically how much over the calculated limit you were going to design the component for. If you thought a part would need to be a certain size or last for a number of operating hours - you designed for that % bigger or longer.
I don't remember anything similar when I worked in the Automotive Industry - designs were largely based on good practice and longevity.
However weight reduces performance, the number of parts increases handling and assembly times, fuel burn has to limit emissions (increasing cylinder head temperatures) oil needs to be as thin as possible (to reduce drag etc) and I guess manufacturers are designing a predicted lifespan into their products and factors of safety reduced closer to known limits.
Furthermore making a car that will last 30 or 40 years may well add value and turnover to all sorts of support businesses over that period but relatively little to the original manufacturer whose need is to simply sell more and more new cars.
With several Countries now stating an end of life period for cars and fashion proving more of a stimulus for change than ever - perhaps the quality of products has reduced accordingly (no point in making it more expensive to make it last longer than demand) and perhaps we should all get used to it.
This is good for those businesses that can fix those products that fail earlier than planned but with manufacturing declining in the West - there may be fewer businesses with the skill and experience to capitalise on that opportunity.
Going back to before I started making racing motorcycle engines, there was no limit on the number of cylinders or gears etc (just the capacity) but when I started making them there were limits to both.
After that they gradually introduced more and more restrictions, superbikes leading the way and I could see that one day they would decide you could only race with sealed engines made by a major manufacturer (which has now arrived even in some racing Porsche Championships with restricted engine rebuild centres).
All this has been a clever manipulation by manufacturers to squeeze out small businesses and in the process keep all the technology “in house”.
I can now see this manifesting itself through the poor level of basic understanding reflected in Forums responses and with most motor racing classes now restricting any engine development – there are going to be fewer and fewer places where engineers have learned enough and tried enough to fulfil this potential new role I can see emerging – all to the detriment of performance car owners with engine problems.
Despite the restrictions in motor racing it is just about the only place left that young technicians can find out about automotive engineering by experimenting and changing things with the additional incentive of results and wins to drive towards – which is why we are participating.
It is a changing World and I think this is as much behind the problems we experience with Porsches as anything else - perhaps we need to develop a different level of expectation and hope there will still be enough independents around with the skills and experience to help owners find less expensive ways to sort their problems out.
Baz
For those interested in my views about what may be behind all these problems (if not please stop reading now) it does seem as if the pursuit of performance and modern production philosophy combined with cost reduction and emission control have rendered many new high performance cars less reliable in the engine compartment than they used to be when they could burn plenty of fuel and manufacturing costs were less dominated by labour rates and raw material costs.
It reminds me of something I commented on a few years ago when I worked in Aerospace and the power generation industries where we worked with "factors of safety". These were basically how much over the calculated limit you were going to design the component for. If you thought a part would need to be a certain size or last for a number of operating hours - you designed for that % bigger or longer.
I don't remember anything similar when I worked in the Automotive Industry - designs were largely based on good practice and longevity.
However weight reduces performance, the number of parts increases handling and assembly times, fuel burn has to limit emissions (increasing cylinder head temperatures) oil needs to be as thin as possible (to reduce drag etc) and I guess manufacturers are designing a predicted lifespan into their products and factors of safety reduced closer to known limits.
Furthermore making a car that will last 30 or 40 years may well add value and turnover to all sorts of support businesses over that period but relatively little to the original manufacturer whose need is to simply sell more and more new cars.
With several Countries now stating an end of life period for cars and fashion proving more of a stimulus for change than ever - perhaps the quality of products has reduced accordingly (no point in making it more expensive to make it last longer than demand) and perhaps we should all get used to it.
This is good for those businesses that can fix those products that fail earlier than planned but with manufacturing declining in the West - there may be fewer businesses with the skill and experience to capitalise on that opportunity.
Going back to before I started making racing motorcycle engines, there was no limit on the number of cylinders or gears etc (just the capacity) but when I started making them there were limits to both.
After that they gradually introduced more and more restrictions, superbikes leading the way and I could see that one day they would decide you could only race with sealed engines made by a major manufacturer (which has now arrived even in some racing Porsche Championships with restricted engine rebuild centres).
All this has been a clever manipulation by manufacturers to squeeze out small businesses and in the process keep all the technology “in house”.
I can now see this manifesting itself through the poor level of basic understanding reflected in Forums responses and with most motor racing classes now restricting any engine development – there are going to be fewer and fewer places where engineers have learned enough and tried enough to fulfil this potential new role I can see emerging – all to the detriment of performance car owners with engine problems.
Despite the restrictions in motor racing it is just about the only place left that young technicians can find out about automotive engineering by experimenting and changing things with the additional incentive of results and wins to drive towards – which is why we are participating.
It is a changing World and I think this is as much behind the problems we experience with Porsches as anything else - perhaps we need to develop a different level of expectation and hope there will still be enough independents around with the skills and experience to help owners find less expensive ways to sort their problems out.
Baz
thanks baz informative as ever.when you think back engines lasted but bodys rusted ie i remember my brother had a 6 year old ford escort with rusty sills and floorpan.nowdays car bodys last a lot longer how many good condition 12+ year old fords do you see?,so i much rather have an engine repair than a rotten chassis and the fact as long as there are companies like Hartech the 996/7 is going to be with us a very long time
hartech said:
sorry about your bill Petop - would have been far less at an independent. It will be interesting to find out how well the new engines perform in time.
baz - that got me thinking. If my ims failed and I sent my car to your place would you replace the failed bearing with the same part or do you fit a stronger bearing that wont fail? would you fit nikosil liners as part of the rebuild to prevent future bore scoring at additional cost or again replace it with like for like? excuse the tone of the question if it's not as simple as that.
hartech said:
We have found that manual cars driven largely on track don't seem to suffer and all 4 of our Porsche Club race cars in our Hartech team are still using original Lokasil cylinders (even though we could have fitted our superior Nikasil plated alloy liners) using Lokasil as part of our research program and have so far been 100% reliable (despite leading the team award and winning the last 2 races). Obviously these do not experience any low revs driving.
Are you the only specialist who rebuild with nikasil plated alloy liners of is it common knowledge to repair them with something other than lokasil? AlexH997 said:
petop said:
My C4S had IMS failure Feb last year which resulted in OPC Guildford fitting a new engine. Bill which is in the glove compartment still is for £16,000.
You paid £16k or was that covered under warranty. what driving experience did you encounter when the ims failed?Gassing Station | Porsche General | Top of Page | What's New | My Stuff