When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
These questions are certainly valid in regards to the video I post. Due to the nature of the direct injection systems, it's all about engineering a way to reduce or possibly eliminating carbon deposits on the valves. I'm also very curious how the valves look on the OP's failed engine. What the experts are saying is due to the emission control and regulations, manufacturers had to change the combustion system on their engines to meet the ever so changing regulations. My question is I wonder if Porsche was going to keep the same MY97 engines on their 911 longer if regulations remain the same since then....?
2009 C2S 132K miles
Your concern about our valves is shared... I am curious what those torn down engines looked like too.. However... I know of no one that had problems. One poster said he had a bunch of work done and had his valves blasted but did not respond when I asked him why he did this, what were his symptoms etc... That video is a bit drastic... not that he is wrong about DFI and buildup, but again, I no of no 9A1 owner that had an issue (other than the one I mentioned... but it was a suspect post IMO).
The engines we stripped were all quite high mileage and the valves were little different to M96/7 valves and none exhibited issues that would have created a problem. But that is not to say that if and when we see more we might come across them.
F911 – there is a variability in the distribution of the silicon in the Lokasil you have in your bores that make some engines far more likely to last for years and huge mileages while others do not because the rate of silicon particles that become detached from the bores to impinge on the piston coating under load may be faster or slower.
Then the amount of pressure that is pressing the piston coating against those particles that are released influences the damage that can be done by them to the piston coating.
The only other way to overcome the reduction in the time available for the valves to breathe air as revs rise – is forced induction which introduces a whole new “book”. Anything that increases the pressure between the piston and the cylinder bore surface will shorten piston and bore life if the pistons are not hard iron plated and the bores are Lokasil or perhaps lees of a problem – Alusil. However Nikasil will take the high pressures without failure if everything else is set up right. So M96/7 engines creating more torque benefit from Nikasil bores and so probably will oversized Alusil engines.
We do not re-plate the Alusil or Lokasil bores with Nikasil. We machine out all of the original liner and fit a new wet alloy cylinder plated with Nikasil. The substrate of lokasil that has failed worries us enough to stick to replacing the cylinders which with the tops fixed rigidly with a precision machined location converting the engine to a closed deck construction is beneficial while a thicker wet liner remains more stable and has better heat transfer.
It may be possible to re-plate 9A1 engines with Nikasil but unlike the M96/7 engines the bores have a blind bottom so it would be very difficult to hone to the bottom of the bore to size and to create the right honing angles. That it not to say it cannot be done but we are sticking to our well proven solution for all models.
Baz
Baz, sense pistons consists of aluminum/silicon, cast 8-10% , forged 4032 12%, hypereutectic 16-18% and Lokasil cylinders are also aluminum/silicon Hypereutectic 20-27%, and since Nickasil works well against aluminum/silicon pistons, wouldn't Nickasil coating on the pistons work against aluminum/silicon (Lokasil-Alusil ) cylinders? Seems coating the pistons skirts with Nickasil instead of iron or plastic would be a lot more cost effective... Thoughts?
The engines we stripped were all quite high mileage and the valves were little different to M96/7 valves and none exhibited issues that would have created a problem. But that is not to say that if and when we see more we might come across them.
Baz
Thanx Baz.... that is nice to hear. It appears we seem to only hear bad news!
OK, at the risk of scaring you away.... Why? Everything I read about DFI points to problems. What did Porsche do to mitigate the buildup? I get what you note that it still may happen, but it appears to be mitigated by some special technique(s)... no?
Peace
Bruce in Philly
Last edited by Bruce In Philly; 03-03-2019 at 11:11 AM.
F911 – there is a variability in the distribution of the silicon in the Lokasil you have in your bores that make some engines far more likely to last for years and huge mileages while others do not because the rate of silicon particles that become detached from the bores to impinge on the piston coating under load may be faster or slower.
Then the amount of pressure that is pressing the piston coating against those particles that are released influences the damage that can be done by them to the piston coating.
This pressure of course relating to the amount of throttle regularly used especially in low to moderate rev ranges (less pressures due to the inertia of the piston travel at higher revs).
Finally the piston coating themselves vary. We have pictures of some where the coating had not bonded properly and had peeled off, others where the bonding is good but the rate of silicon release was high and just made the coating wear away and others where larger silicon particles picked spots away from the surface.
All this makes predicting the anticipated life span completely impossible, but as the engines wear the piston clearances increase and this gives more space for the particles to escape but only if the oil viscosity is increased slightly to fill the gap to let the particles float away (especially as more clearance heats up the piston face more as there is more blow by and this makes the oil film protecting the piston surface thinner).
Chwheeler – very good question that requires a longer answer than space and patience allow for here. Considering tuning N/A engines of the same capacity - the problem is that BHP is the multiple of torque * revs (ignoring constants) – so you can achieve higher BHP if you raise the revs more than you reduce the torque. To do this you would usually require hotter cams, bigger inlets and/or exhausts etc and this in turn usually reduces the power band. However if you raise the revs there are 5 counter-productive consequences.
(1) There is less time that the valves are open so less time to move air (hence the need for larger breathing adjustments) but these then also make the mid-range torque reduce (because the tuning is too orientated to high revs breathing).
(2) If you raise the revs say 10% you also increase the “rev drop” by 10% (the revs you drop to from changing gear at max revs to the revs you settle on in the next gear) and this means that you must somehow not only increase the revs but also the “power band” which is usually impossible.
(3) Your car is already geared higher than you would use on road or track flat out in top gear but raising the revs by say 10% also raises all the speeds reached in each gear even further.
(4) It is torque that accelerates the car (not BHP) and the torque at the rear wheels reduces by the same proportion that the gear ratio (and wheel speed) speeds up as you change up in the gears. This means that as you go faster you get less and less torque driving the rear wheels (eventually around a quarter of the torque in top than in 1st).
(5) The consequence of the above is that to exploit the benefits of tuning for higher revs and peak BHP you need to either lower the crown wheel and pinion ratio, fit closer ratio gears inside the gearbox – or both – which is usually outside the remit for this kind of tuning on Porsche’s. F1 engines revving to 18000 rpm would double the top speed they are set for compared to an engine revving at 9000 rpm but reduce the gearing to suit and in so doing increase torque once again.
Fortunately building an oversized engine does the opposite and increases the torque in the range that you drive in when changing gear upwards and also has the added benefit that you can accelerate more quickly from mid-range revs without the need to drop down a gear and rev the engine higher.
This benefit therefore of an oversized engine resultins in (usually) a bigger increase in mid-range torque % than the % capacity increase and is a massive benefit to a great driving experience and performance even though it does not usually increase the measure of peak BHP by the same proportion.
An oversized engine therefore will usually be great to drive and faster but not necessarily have such a high BHP figure to brag about.
Also different dyno’s can provide different BHP results because the larger the porting and valving the longer unsteady gas flow takes to settle down. This means that a dyno run that selects fixed rev breaks and is allowed to settle in each will give much higher results than a dynamic or inertia run. The most representative will be a run set/timed at a resistance similar to the rate the car would normally accelerate in the chosen gear when in use – but will not give the highest BHP result even though it represents the most relevant performance.
To make things worse “engine dynos” can reproduce even different results so you may have seen than while the owner’s manuals for Porsche’s have gradually left out various graphs and figures and made the BHP graph become a simplified set of almost straight lines – independent dyno runs will still reproduce curves. Finally all dyno runs use adjustment factors to alter the results which can be used to try and get closer to the accurate output or to alter the outcome more positively for the guy paying for it.
All the above would take a full sized book to properly explain but frankly it makes discussing BHP – for me – irrelevant and what I would need to see in order to compare performances would probably be timed acceleration runs through say 2nd to 4th gear flat out! And if you did that with an oversized engine you would get fantastic results compared to most other alternatives.
The only other way to overcome the reduction in the time available for the valves to breathe air as revs rise – is forced induction which introduces a whole new “book”. Anything that increases the pressure between the piston and the cylinder bore surface will shorten piston and bore life if the pistons are not hard iron plated and the bores are Lokasil or perhaps lees of a problem – Alusil. However Nikasil will take the high pressures without failure if everything else is set up right. So M96/7 engines creating more torque benefit from Nikasil bores and so probably will oversized Alusil engines.
We do not re-plate the Alusil or Lokasil bores with Nikasil. We machine out all of the original liner and fit a new wet alloy cylinder plated with Nikasil. The substrate of lokasil that has failed worries us enough to stick to replacing the cylinders which with the tops fixed rigidly with a precision machined location converting the engine to a closed deck construction is beneficial while a thicker wet liner remains more stable and has better heat transfer.
It may be possible to re-plate 9A1 engines with Nikasil but unlike the M96/7 engines the bores have a blind bottom so it would be very difficult to hone to the bottom of the bore to size and to create the right honing angles. That it not to say it cannot be done but we are sticking to our well proven solution for all models.
Baz
Hello Baz
Thank you for your answer!
Further to your response,
1. In order to minimize future malfunctions and in order to make the engine a "bulletproof" engine, it is possible to purchase from Hartech Kit "new wet alloy cylinder plated with Nikasil"?
2. As a result it may strengthen / upgrade the M97 3.8 engine?
3. Is it recommended to use 5W50 1M oil in hot countries? Approved by Porsche.
Thanks again! Your knowledge and answers are highly appreciated and this is not self-evident!
Thanx Baz.... that is nice to hear. It appears we seem to only hear bad news!
OK, at the risk of scaring you away.... Why? Everything I read about DFI points to problems. What did Porsche do to mitigate the buildup? I get what you note that it still may happen, but it appears to be mitigated by some special technique(s)... no?
Peace
Bruce in Philly
Paranoia is rampant in these boards to no fault of Raby or Baz. It was nice to hear from Baz that intake valve carbon deposits is not an issue on high mileage 9A1s.
The Porsche mitigation... it probably is the subtended angle between the intake valve and the injector. It is possible to inject some gas while the valve is still open.
Paranoia is rampant in these boards to no fault of Raby or Baz. It was nice to hear from Baz that intake valve carbon deposits is not an issue on high mileage 9A1s.
The Porsche mitigation... it probably is the subtended angle between the intake valve and the injector. It is possible to inject some gas while the valve is still open.
I have seen this picture before. If you notice, the picture is portrayed from an angle. If the picture was shown straight on with the seam between the block and head lined up front to back, one could see that the spray being indicated would not be spraying on the back of the valve or on the stem. The picture is a bit misleading. That does not mean that Porsche has not found a way to minimize entrained oil from being deposited on the intake. I am just not sure this is being achieved via the spray angle. By the way the VW/Audi group ( whose engines were earlier identified to have buildup in the intake areas of their engines ) seem to have also reduced this problem. Many folks are installing catch cans on their later model engines and are collecting little or nothing in them.
Perhaps the dfi injector does spray a small portion of the intake valves. It is my understanding that the intake valves do rotate to some degree while in use ... so this might contribute to cleaning the valves.
Baz, thanks again for the in depth explanation of piston design: profile, ovality and temperature that affect the life of the cylinder bore. This piston design article will complement well with Baz's post above. http://blog.wiseco.com/pistons-arent...lity-explained
Porschetec3 it does seem that to put Nikasil on the piston would be a logical step if it were not for Youngs Modulus of rigidity. People generally are obsessed with tensile strengths but actually in many applications how rigid a part is can be more important (being largely the result of stress/strain)
Nikasil is a brilliant material but needs a stiff material to bond to otherwise it could crack up or chip off. A thick cylinder bore is an ideal surface to bond to (especially if it is a cylinder held more rigidly at the top where the main thrust loads are applied).
Nikasil forms a thin sleeve well bonded to a bore and as long as the substrate is rigid will last for years but if the substrate can deflect (or the material behind the Nikasil can be pushed inwards or can delaminate) then the Nikasil could be compromised. This worry puts us off trying it on a Lokasil bore that has already scored since the variability of the Lokasil material we find combined with the influence of the high temperature and physical damage caused during scoring could influence the rigidity of that inner bore area on which the Nikasil could be plated.
Alusil is stronger and more solid and therefore may well take a Nikasil coating but then the Gen 2 engine has blind cylinder bores and I am not sure how you would hone to the bottom correctly (although I could be entirely wrong and it may be a perfectly reliable process or alternative) I am just not prepared to risk it when our thicker alloy Nikasil plated wet liners do such a great job.
rmstar - thank you for that link which does describe some of the design criterea for a piston. There is however a lot more to it than that. The position of the cross webs (that support the gudgeon pin) influence the flexibility of the curved pressure faces as do all the internal shapes and sections. Pistons do also flex under high load (and are designed to do so - obviously well within their elastic limit).
Linking this to Porschetec3's question - I think that perhaps the reason Nikasil has not been tried by us on a piston is our concern that it would chip off especially at the skirt where the rocking over TDC applies shock loads. Even more of a worry would be BDC because while Porsche made the longer stroke versions they did not make the cylinder blocks any longer so the piston skirts increasingly poke out of the bottom of the cylinder at BDC (and we make our cylinders as long as possible to reduce that problem).
Making an alloy Nikasil cylinder is not difficult but its design and how it is fitted is absolutely crucial to its success. This is so important to us we do not allow just anyone else to do it and invested in our own brand new CNC lathe and mill to ensure we have the best quality machinery that we can use "in house". This combined with diamond tipped tools specifically designed for each process enables us to manufacture to incredibly fine tolerances (as can be seen on the video on our web site www.hartech.org).
The old cylinders are roughed out on one CNC machine and finished on the new one. The bores are then measured to accuracies of less than quarter of a thou and a chart filled in for each bore and the new cylinders are made to an exact fit individually for height and diameters. We even use tools that hold the liner without distorting it under pressure so the resulting roundness of our cylinders is many times better than we have ever seen in new cylinder blocks.
Because the success of this system relies on the quality of the machining we do not sell the Cylinders - that is except that we have undertaken an experiment to supply one North American continent business (Alpine Autoweks Calgary) who impressed us with their approach to quality and readiness to accept our strict quality controls and procedures and to install their own version of our machining system.
They visited the UK and we visited them in Calgary resulting in both training, tooling and supporting them both in the UK and Canada.
I think they would agree that there is a lot more involved in achieving the quality needed than they probably assumed but have managed to successfully carry out some cylinder fitting in their typically methodical way and not rushing into things just for volume sales sakes (and of course their volumes with which to amortise costs in Canada are likely to be much smaller than in the UK).
We have however accumulated a huge stock of cylinder blocks that we intended to use to fit our cylinders to and make available for export complete with pistons etc - the only problem is we have simply been flat out for years supplying our UK and largely European partners (who send their block to us).
The problem for us is that we have 8 employees in 4 different departments operating a balanced production system that allows us to manage one engine/day and to expand that would need to double our size (which we have neither the space nor inclination to do).
We are happy to fit cylinders to blocks sent here or to take out of stock an existing block and supply that with a small added cost (refundable on the return of a useable replacement needing cylinders).
One thing that held us back is that despite having 5 different cleaning machines (including ultra sonic) the blocks always look dark and dirty (even though they are spotlessly clean) and we feel this is unsuitable to sell an expensive product Internationally. However in a week or 2 we will receive a new machine that will bring them up to a suitable appearance after which we will try to get some on the shelf.
The most popular will probably our 996/7 3.6 to 3.9 conversions that come CW pistons but they are also available for 3.2 to 3.7, 3.4 to 3.7, 3.8. to 3.9, and Cayman S to 3.9).
We are also testing a 4.0 Gen 2 9A1 as our next step for the future.
Baz
Last edited by bazhart; 03-04-2019 at 06:48 AM.
Reason: spelling
We are also testing a 4.0 Gen 2 9A1 as our next step for the future.
Baz
Baz (& community), thanks so much for this awesome thread, & specifically Baz's & Jake's transparency into their investigations, commentary & feedback.
I've shut up (here) until now re this matter as I'm just a very interested observer who is (privileged to be) putting some miles, here & there, on a 9A1.
To date, this particular stock engine (2010 C4S) has been properly cared for & has always performed well beyond my capabilities; at 73k+ miles, it seems very much like new (~48k miles are mine). My expectation is that with continued periodic, regular & proper use, & with scheduled maintenance / proactively & JIT replacing consumables, it should continue to perform as the proverbial Dr P prescribed AND as many other 997.2 pilots have reported, while attaining the 120k+ mile mark (which I've seen up close & personally driving / practicing with a number of other member's 997.2 examples...lucky me!).
Seemingly, some engines will not have received the love (properly warming them up & airing them out, in particular) & other 997.2 examples will have been used improperly as daily drivers and/or in adverse environments / conditions without proper maintenance or use. Perhaps others will (just) be engines that were not built to spec and are now, being unearthed??? That would seem like the rare bird but I'm very open to reviewing some rolled-up data if/when it becomes available.
One way or the other, I share the sense with some members that the 997.2 was overly-engineered on account of previous model issues. That said & as we know, time is the great equalizer, therefore for me, my profound interest to read the facts & conclusions (& in-conclusions), & other data, such as actual number of engines that are in the analysis & whether the work was proactive, or occurred post event, etc.
As I suggested, this transparent dialogue (& sharing the pain) around Bronz's engine (@bronz FWIW, I greatly feel for you ), while sharing & analyzing this specific instance of engine failure, as well as all of the other data points that the various engineering businesses are assembling, is at the foundation of this community & I'm appreciative of getting to hang-out here with y'all!
Baz, I'd say that your "We are also testing a 4.0 Gen 2 9A1 as our next step for the future" utterance & budding relationship with a partner in Canada is music to NA's (North America & normally aspirated!) ears! If it ever came to it & my 4s lost a beat or 3 (which it has yet to do...I hope that I didn't just jinx it), the 4.0 option would be awesome!!! Please keep us apprised of further developments and cheers again for the facts, knowledge & wisdom!!!
This post nailed it. This is exactly what has been occurring, and exactly why we’ve kept things under our roof.
You smart man, you. Best thing you could do was to spend more time in the shop and less online. I watched the Jake bashing up close on the 914 boards back in the day. All the questioning and arguing with what he was seeing and how he was attempting to improve the Type IV was annoying.
Sure it’s okay to disagree with someone but the continual bashing was uncalled for. So far I don’t know of any of those guys who have opened their own shops and then progressed through the air cooled engine ranks to being part of a patented IMS improvement to rebuilding/improving the water cooled 911 engines.
You smart man, you. Best thing you could do was to spend more time in the shop and less online. I watched the Jake bashing up close on the 914 boards back in the day. All the questioning and arguing with what he was seeing and how he was attempting to improve the Type IV was annoying.
Sure it’s okay to disagree with someone but the continual bashing was uncalled for. So far I don’t know of any of those guys who have opened their own shops and then progressed through the air cooled engine ranks to being part of a patented IMS improvement to rebuilding/improving the water cooled 911 engines.
I think that's exactly what Jake Raby is going to be doing based on his lone post on the 996 forum yesterday. I was informed that a 997 owner showed up on a different forum only to troll every comment the man made. There was no substance to what the troll was saying. Lots of twisted information only to berate Jake's lifetime work and insult him in order to try to get him mad and lash out. It's obvious that Jake is not going to sugar coat anything or tickle your ear when he offers advice or is asked for an opinion. People that buy these cars without proper inspections, neglect all the advice of the forum, and then end up with a virtual roller are not going to get sympathy from people like Jake Raby. He's going to give you the bitter truth in pill form that's really hard to swallow.
I think that's exactly what Jake Raby is going to be doing based on his lone post on the 996 forum yesterday. I was informed that a 997 owner showed up on a different forum only to troll every comment the man made. There was no substance to what the troll was saying. Lots of twisted information only to berate Jake's lifetime work and insult him in order to try to get him mad and lash out. It's obvious that Jake is not going to sugar coat anything or tickle your ear when he offers advice or is asked for an opinion. People that buy these cars without proper inspections, neglect all the advice of the forum, and then end up with a virtual roller are not going to get sympathy from people like Jake Raby. He's going to give you the bitter truth in pill form that's really hard to swallow.
And I wouldn’t blame him a bit for not showing up.
Bronz, I’m sorry this happened to your engine. This wait while it’s getting worked on will be tough. But I have no doubt that when you get the car back much of the disappointment of this failure and the money spent will fade away after an hour or so of seat time.
I know originally you were hoping that this was a little issue. But as it turned out to be something else you stuck to providing updates. Thanks for that, because we all benefit from the information being presented.
Because the success of this system relies on the quality of the machining we do not sell the Cylinders - that is except that we have undertaken an experiment to supply one North American continent business (Alpine Autoweks Calgary) who impressed us with their approach to quality and readiness to accept our strict quality controls and procedures and to install their own version of our machining system.
03-02-2019, 05:28 PM
