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DucatiRob
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Joined: 22 Jul 2015
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2006 Porsche 997 Carrera 2S

PostPosted: Sun May 12, 2019 2:21 pm    Post subject: Reply with quote

Totally agree with what others have said! Having had a full Hartech rebuild myself, the title of the original thread frightened the life out of me Surprised so pleased this is all sorted now! Looking forward to your post Wattso Thumb
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Kryton
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PostPosted: Sun May 12, 2019 5:12 pm    Post subject: Reply with quote

If I was in the market for a 997 I'd wait until a Hartec car was advertised, either that or try and purchase a cheap a car as possible then take it straight round to them.

They do seem to be a very honest company to deal with and their work must be second to none.
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bazhart
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PostPosted: Mon May 13, 2019 9:58 am    Post subject: Reply with quote

Interestingly if you strip a new rebuild or new engine after a few hours the main bearing and big end shells have shiny narrow lines on them where the parts are running in - but no one would refer to them as shell scoring!

Later on they wear all over but Nikasil is hard enough once a few high spots are rubbed down to last almost for ever especially being oleophilic.

Baz
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jonttt
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PostPosted: Mon May 13, 2019 5:44 pm    Post subject: Reply with quote

oleophilic, so do my chips but SWMBO insists on baking them Hand
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deMort
Dijon


Joined: 21 Mar 2015
Posts: 7433
Location: Brighton


PostPosted: Mon May 13, 2019 6:53 pm    Post subject: Reply with quote

Kryton wrote:
If I was in the market for a 997 I'd wait until a Hartec car was advertised, either that or try and purchase a cheap a car as possible then take it straight round to them.

They do seem to be a very honest company to deal with and their work must be second to none.


Can i just humbly point out ..

It's only a small percentage of cars that suffer from this and not every single one !

Score marks of some degree are not unusual as Baz has pointed out and as i've seen .. its how they are interpreted by the garage that seems to be the issue here .

description of a score mark ..

: a mark or cut that is made in a surface with a sharp object .

Ref .. http://www.learnersdictionary.com/definition/score

No.3

Whether that is at a microscopic level or far larger is not relevant .. the marks are score marks ... this topic does seem to be about what we call them After all so this is what i found and what i will call them ..

Marks in a bore are bore score .

In this case the marks are what i would class as pretty normal and nothing to worry about .

Has the op been told the same ? it doesn't sound like it hence this thread .

Actual bore score is far far deeper marks followed by smoking , noise , oil usage and black tail pipes .

The tread name was never going to be correct and indeed could be very damaging for a company so it had to be altered ... but the op has also been vilified when the blame imho rests with the garage that told him what .. well .. game over basically ? very wrong .

I don't think he covered himself in glory by not changing the title but he has acted on the advice of professionals .

The reality was it's pretty normal marking and under magnification ( which is what these cameras do ) makes it look far worse than it actually is .

i do actually have a question for Baz .. as long as he doesnt have issue with my post .. which i'm happy to discuss if needed but not to argue over ..


the image below ..

I had always assumed the marking far right was the rings bedding in , a high spot if you like .. i would appreciate your agreement or what you consider it is .

EDIT ..

Just to add ..

I consider Hartech to be one of the market leaders in providing an alternative to the original and somewhat flawed porsche design .. their work in this field has saved many owners imho ... i for one am grateful even though i don't actually own one .
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bazhart
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PostPosted: Tue May 14, 2019 10:31 am    Post subject: Reply with quote

These are chatter marks where the rings has in the first ever running touched a few high spots and bounced on its way up and down.

Interpretation of markings is important and every mark must have some depth - but in that case all the cylinders are scored all the way round in an angles plane where you see the honing marks - which are (if you want to be awkward) scores.

The interpretation however of "bore scoring" is different - being deep grooves cut into the surface and not insignificantly microscopically polished areas that were originally minutely high spots where the ring touched those small high spots a little harder when first run and because the load then per unit area is high - managed to polish them down a little to create an even more round bore and better ring to bore fit, higher compression and less blow by - but due to the highly polished nature of Nikasil on reflection - marks the bore where the running in took place.

Baz.
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bazhart
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PostPosted: Tue May 14, 2019 2:22 pm    Post subject: Reply with quote

Actually - on reflection - I would like to dispute that all marks are scores (however shallow).

The polish marks you see come about because on a miniscule level measuring microns, the very round surface of the bore has come into contact with the hard piston ring (to last long enough) on first running and if you think about it this is only happening if the point where the marks are is where the curved surface of the bore and the ring are touching just a little bit more than on either side leading to a typical pressure point (which is what running in is all about).

This means that if a score is a cut "IN" a surface this is not that scenario as it is the opposite and can only occur if the 2 points in contact are actually proud.

What is happening is that the surface is being rubbed until it conforms more to the shape of the ring and the resulting bore is even more round than it was before.

This is why it is in no way bore scoring even on a micro level but rather an improvements on the fit of 2 new parts - like all running in is meant to achieve.

If it was a mark "IN" the surface - how could that happen and this explains why - when we measure our bores we cannot measure any depth where the polish marks are - because there isn't any.

It is just an unfortunate outcome that the highly polished surface of circumferential marks shows up vertical polish marks in contrast so well under a camera light in the same plane that deep scores would be in - leading to the confusion.


Baz
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toohey
Monza


Joined: 22 Jan 2009
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Location: Naarfolk


PostPosted: Tue May 14, 2019 2:45 pm    Post subject: Reply with quote

I know its been said before but.......

..... thank you Baz for your input to this forum and work to dispel the large quantity of drivel that is generated by the internet with regard to the 996 and other engines. When eventually my daily driver 996 gets tired you will have my business for sure.

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spongebob squarepants
Zolder


Joined: 20 Dec 2009
Posts: 5866
Location: Manchester and Iraq


PostPosted: Tue May 14, 2019 3:03 pm    Post subject: Reply with quote

toohey wrote:
I know its been said before but.......

..... thank you Baz for your input to this forum and work to dispel the large quantity of drivel that is generated by the internet with regard to the 996 and other engines. When eventually my daily driver 996 gets tired you will have my business for sure.

thumbsup


+1 but my head hurts Grin
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deMort
Dijon


Joined: 21 Mar 2015
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PostPosted: Wed May 15, 2019 7:02 pm    Post subject: Reply with quote

bazhart wrote:
Actually - on reflection - I would like to dispute that all marks are scores (however shallow).


Baz


Thank you for your answer ..

It's never been my intention to cause offence but only to post what i feel ..

To question something is to learn .. i question things .

I can understand the markings from say File 2 .. they are not in any way anything other than surface colouration ..

my interest and indeed my comment was more based around File 1 .. the last image as there are 2 of them .... this imho is not the same as the others ..

It may well be a trick of the light .. but it does look different ... hence my first post ... its also easier to interpret if you are using the scope as you can move it around to get a better idea .. this is just a static picture .

Either way i think this thread has run its course and no more comments are really needed .
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bazhart
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PostPosted: Thu May 16, 2019 9:55 am    Post subject: Reply with quote

DeMort - you already know that we respect you for your knowledge and contributions - no problem there.

The important point I was making was that two surfaces will only touch if they are proud of the median.

Classic bore scoring is caused by relatively large loose silicon particles trapped between the piston face and cylinder bore and rubbed up and down to form a recess/groove.

The marks we get in Nikasil are not caused by that as the particles not only almost never become loose but are much too small and are always much smaller than the oil film. The only reason for marks is therefore the microscopic touching of two hard surfaces until a minute amount is rubbed back after which the additional surface area is spread over a wider area and insufficient in force to rub against the surface.

These marks therefore are running in marks that make the surface even a better fit than when manufactured.

I think we are the only people that have researched all this thoroughly and tested out our conclusions and so far I still see other qualified contributors not yet understanding it all - which is why we will shortly post our full report on the subject.

I agree with you that most scores are deep but these are not scores and the difference is hard to see - I agree - on a static picture.

The odd one you picked on is cause by ring judder as the 2 surfaces are touching before the are rubbed smoother and no longer touch on such a small ring area. Microscopically rings are not perfectly round either. We could eliminate the polish marks if we chamfer the ring edge with fine emery a little - but then it wouldn't last as long or seal as well - so - as with a lot of engineering - the best compromise is a very round bore of hard Nikasil that holds its oily surface and hardly ever wears but has one small issue when people film the surface and find some running in marks that are not as polished as the original shinny honed surface and in the other direction reflecting light to look similar to actual scoring.

Keep up the very good work!

Baz
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deMort
Dijon


Joined: 21 Mar 2015
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PostPosted: Thu May 16, 2019 7:22 pm    Post subject: Reply with quote

Thank you for your kind comments and taking the time to answer .

Ring judder is new to me .. i saw a car a few months back that had this on almost every cyl .. a bit unusual but i assumed it was rings bedding in .

I had no history on this car .

I've seen cars with proper bore score .. from the we cannot see the road behind us to the we think we have a problem .

The difficulty lies in the very beginnings of a problem .. as the pictures here show .. is it a problem or is it ok ... all but one of the images i would discount other than the last one ..

Your explanation would preclude Nikasil liners from being able to cause this .

The only correct way to diagnose faults like this is to remove the head and have a look ..

Before these cameras were invented then that's what we did .. and the customer had to pay.

These days it's all about using them and making a full and accurate diagnosis with them ... a little tricky as this thread shows .

It's never going to be possible as they magnify , but we are faced with doing what we can with the tools we have and the customers expect us to be correct ...even though this is not the best way to examine faults like this .. hence i grab any info i can even though i've looked at many cars this way .

A static photo doesn't really help .. we move the camera around to get a better idea .. light in different angles can make it look anything from bad to not a problem... but on here a picture is all we have to deal with .

I think this particular post is more aimed at the general owners of these cars than you .. diagnosing problems like this with a camera is difficult at best .

Thank you once again for your time and advise .
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PanozGTR
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Joined: 05 Jul 2017
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PostPosted: Fri May 17, 2019 2:08 pm    Post subject: Reply with quote

BazHart and DeMort discussing this subject is just awesome. Yet another example of why we are so lucky to be members of such a great forum. Owning a 911 is a great experience anyway but to have this knowledge, help and advice if needed is just plain brilliant. Cheers Chaps Thumb
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wot996
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PostPosted: Fri May 17, 2019 3:14 pm    Post subject: Reply with quote

worship Yeah
 
  
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bazhart
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PostPosted: Sun May 19, 2019 2:11 pm    Post subject: Reply with quote

Unlike Alusil or Lokasil (where silicon is embedded in a bigger aluminium matrix) Nikasil forms a solid alloy of very much smaller Silicon particles in Nickle and the result is like a tubular shim well bonded to the aluminium substrate - as a result it does not release harmful or large silicon particles and even after debris might get into a cylinder (dropped valve etc) we can usually recover it without damage.


It does retain oil as well but also the angle of the honing, type of diamond hones used, stroke rate and surface finish are finely controlled by us and reproduce the very best all round result for a bore finish.



While there are many benefits from a Nikasil calloy cylinder (which is why Porsche use it on GT3 and Turbo versions), unfortunately the downside is that it can wear rings down unless they are also quite hard and the resultis that during 1st running in - as the hard rings touch the carefully created honed bore, in some places the contact rubs slightly proud areas to "run-in " the ring and bore. These have no measurable or significant depth and do not penetrate the Nikasil surface at all whereas in a Lokasil or Alusil score the aluminium substrate is gouged out deeply and completely different.

Softer rings rub the ring instead of the hard and well lubricated bore (and cannot be seen by a camera) but most Porsche specialists will have seen 911SC or Carrera rings (that also run in Nikasil but are softer) worn until there is nothing left at the open ends. Harder rings last longer but can polish the bore in a different direction to the circumferential honing marks and reflect light to appear like scoring to the unfamiliar.

Much more available soon on our web site giving full details.


Baz
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Phil 997
Le Mans
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Joined: 05 Dec 2015
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PostPosted: Sun May 19, 2019 3:35 pm    Post subject: Reply with quote

What a great thread, I am late to the party and must admit when reading from the start when the pics of the scoring came up I did think mmmm looks more like borescuff than score then I continued to find everyone pretty much thought the same infact one member liked it so much he brought the car . Floor Floor for those old enough its the Remmington moment Grin Grin

great to see debate between Baz and Ian.
I was late due to the fact I have been making up for lost time and have now done 2600 miles on my Hartech rebuild collected 4 weeks ago. Grin Oh it feels so much more torquey and solid in love all over again.

I honestly dont think the OP was intentionally trying to damage Hartech's rep it was just a case of a poorly worded header.

What was noticeable and very nice to see was an emotive subject like Borescore discussed without it ending up in a locked thread or a torrent of abuse at each other.

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Wattso
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PostPosted: Fri Jun 14, 2019 3:01 pm    Post subject: Reply with quote

I've just put this update in my ownership threat but thought that anyone who's read / contributed to this threat might also be interested to know...

I've just got off the phone to HARTECH who have had the car for a borescope and major service. They've confirmed that there is absolutely no borescoring.

I was confident anyway after the comments from Baz in this thread but wanted to put the issue completely to bed by way of allowing Hartech to use their own people / cameras and equipment. They even commented that the car drives really well and the engine is performing perfectly.

Hugely reassuring to know that all is well, I can now get on with sorting the car out to my standards and lavishing it with TLC. Thumb
 
  
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Hertsdriver
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Joined: 12 Nov 2018
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PostPosted: Fri Jun 14, 2019 3:17 pm    Post subject: Reply with quote

Thumb

I'm happy that my £300 PPI saved you £5k on the purchase price Floor
 
  
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bazhart
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PostPosted: Sun Jun 16, 2019 12:40 pm    Post subject: Reply with quote

This is a photo I just found of a worn softer 3.2 Carerra ring running in Nikasil after 70K and a new one. This is why a harder ring was chosen for the 996/7 engines.


Baz[/img]
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Luddite
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PostPosted: Sun Jun 16, 2019 1:57 pm    Post subject: Reply with quote

Interesting stuff Baz, I ever REALLY enjoyed the sensation of climbing up on to the cam while driving my SC`s not having a clue as to the part worn piston rings played in that..

I note that your pic contained a couple of broken cyl head studs, which from a poor memory of the situation perhaps 30+ years ago, seemed to affect low mileage air cooled Porsches over time, perhaps more so than those more regularly used..? Given even the youngest of air cooled Porsches are getting on quite a bit and perhaps most may have become garage queens in the intervening years, I wonder if they might be more used for an occasional blast and how much that might affect the studs today..?

I appreciate you are a busy man, whereas I am just passing time seeking to learn from the guys here.. worship
 
  
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