The State of Piston Re-Coating. Anybody successfully doing it?
09-22-2016, 04:39 PM
#1
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The State of Piston Re-Coating. Anybody successfully doing it?
One of these days I'm planning on putting my engine back together. I keep going back and forth on just going ahead with everything as it sits now, or to really dig in and get it factory fresh.
Some of the pistons are a little shinier towards the bottom of the skirts than I'd like. Has anyone reliably been able to re-coat them? Most of the posts on this are pretty old, and there really isn't much follow-up with the folks who've done it.
I'm at work without pics now, but I can post some when I get home.
Some of the pistons are a little shinier towards the bottom of the skirts than I'd like. Has anyone reliably been able to re-coat them? Most of the posts on this are pretty old, and there really isn't much follow-up with the folks who've done it.
I'm at work without pics now, but I can post some when I get home.
09-22-2016, 06:20 PM
#2
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That's really simple and quick to answer.
NO!
And if they tell you they can, get them to put it in writing with a warranty for parts and labor....
NO!
And if they tell you they can, get them to put it in writing with a warranty for parts and labor....
__________________
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
09-22-2016, 06:39 PM
#3
Rainman
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I've heard from a few folks, mostly 944 racers, that the Swaintech PC-9 is working just fine for them.
These are people who have nothing to gain from promoting the product and have been in the game for a long time so I trust their word on it.
Of course, it only takes a little bit of "wrong" to mess up a bore...
If needed Wossner is manufacturing alusil-compatible pistons in whatever size you want with rings and pins. For a 928 it'd be between $1300-2000 a set, depending what you wanted.
These are people who have nothing to gain from promoting the product and have been in the game for a long time so I trust their word on it.
Of course, it only takes a little bit of "wrong" to mess up a bore...
If needed Wossner is manufacturing alusil-compatible pistons in whatever size you want with rings and pins. For a 928 it'd be between $1300-2000 a set, depending what you wanted.
09-22-2016, 07:14 PM
#5
Some people dream of finding the Patiala Diamonds, or maybe lost Imperial Seal of China.
Not me.
I dream of someday finding an old industrial warehouse in Germany, stuffed with dusty crates of blocks, heads, pistons, transmissions......
Not me.
I dream of someday finding an old industrial warehouse in Germany, stuffed with dusty crates of blocks, heads, pistons, transmissions......
09-22-2016, 07:43 PM
#6
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I've heard from a few folks, mostly 944 racers, that the Swaintech PC-9 is working just fine for them.
These are people who have nothing to gain from promoting the product and have been in the game for a long time so I trust their word on it.
Of course, it only takes a little bit of "wrong" to mess up a bore...
If needed Wossner is manufacturing alusil-compatible pistons in whatever size you want with rings and pins. For a 928 it'd be between $1300-2000 a set, depending what you wanted.
These are people who have nothing to gain from promoting the product and have been in the game for a long time so I trust their word on it.
Of course, it only takes a little bit of "wrong" to mess up a bore...
If needed Wossner is manufacturing alusil-compatible pistons in whatever size you want with rings and pins. For a 928 it'd be between $1300-2000 a set, depending what you wanted.
The "Internet" is a really interesting place. There's an amazing amount of people out there, talking about what they do or plan to do. And even more amazing....very few people report back with their failures.
The 944 engine has a zero offset, perfectly centered rod. The side loading is very nominal. There might be a chance...but you are going to have to prove it, to me. Run the **** out of one for 20,000 miles and show me the bores and pistons!
I've taken apart 2 engines with Wossner "coated" pistons, in the 928 application. Neither made it more than a few hours. There's always an excuse...too much clearance, not enough clearance, didn't break it in correctly, wrong oil, got it hot, ran it too rich, ran it too lean, etc.
As many engines as I build, I'd be overjoyed if there was a viable "solution". That would open up a huge alternative market, for me, in terms of pistons. I'm always open to experimenting.....I'm just done doing it on my dollar!
Like I said above, get a warranty (in writing), that covers parts and labor!
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09-22-2016, 07:55 PM
#8
Rainman
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The side loading difference may be the key here then.
Wossners have been used in many dozens if not hundreds of hot 944T (and turned-up 944NA racers) engines over the years. The things take street life and racing abuse with 300-600hp and lots of boost/heat cycles. Not sure what kind of mileage people have run up on them though.
Wossners have been used in many dozens if not hundreds of hot 944T (and turned-up 944NA racers) engines over the years. The things take street life and racing abuse with 300-600hp and lots of boost/heat cycles. Not sure what kind of mileage people have run up on them though.
I've seen people talking about having success with coatings on the 944 engine. I've seen no long term results, nor have I seen anything personally.
The "Internet" is a really interesting place. There's an amazing amount of people out there, talking about what they do or plan to do. And even more amazing....very few people report back with their failures.
The 944 engine has a zero offset, perfectly centered rod. The side loading is very nominal. There might be a chance...but you are going to have to prove it, to me. Run the **** out of one for 20,000 miles and show me the bores and pistons!
I've taken apart 2 engines with Wossner "coated" pistons, in the 928 application. Neither made it more than a few hours. There's always an excuse...too much clearance, not enough clearance, didn't break it in correctly, wrong oil, got it hot, ran it too rich, ran it too lean, etc.
As many engines as I build, I'd be overjoyed if there was a viable "solution". That would open up a huge alternative market, for me, in terms of pistons. I'm always open to experimenting.....I'm just done doing it on my dollar!
Like I said above, get a warranty (in writing), that covers parts and labor!
The "Internet" is a really interesting place. There's an amazing amount of people out there, talking about what they do or plan to do. And even more amazing....very few people report back with their failures.
The 944 engine has a zero offset, perfectly centered rod. The side loading is very nominal. There might be a chance...but you are going to have to prove it, to me. Run the **** out of one for 20,000 miles and show me the bores and pistons!
I've taken apart 2 engines with Wossner "coated" pistons, in the 928 application. Neither made it more than a few hours. There's always an excuse...too much clearance, not enough clearance, didn't break it in correctly, wrong oil, got it hot, ran it too rich, ran it too lean, etc.
As many engines as I build, I'd be overjoyed if there was a viable "solution". That would open up a huge alternative market, for me, in terms of pistons. I'm always open to experimenting.....I'm just done doing it on my dollar!
Like I said above, get a warranty (in writing), that covers parts and labor!
09-22-2016, 11:22 PM
#9
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The side loading difference may be the key here then.
Wossners have been used in many dozens if not hundreds of hot 944T (and turned-up 944NA racers) engines over the years. The things take street life and racing abuse with 300-600hp and lots of boost/heat cycles. Not sure what kind of mileage people have run up on them though.
Wossners have been used in many dozens if not hundreds of hot 944T (and turned-up 944NA racers) engines over the years. The things take street life and racing abuse with 300-600hp and lots of boost/heat cycles. Not sure what kind of mileage people have run up on them though.
Everyone else is completely free to do whatever they want.
09-23-2016, 10:02 AM
#10
Rennlist Member
I've seen people talking about having success with coatings on the 944 engine. I've seen no long term results, nor have I seen anything personally.
The "Internet" is a really interesting place. There's an amazing amount of people out there, talking about what they do or plan to do. And even more amazing....very few people report back with their failures.
The 944 engine has a zero offset, perfectly centered rod. The side loading is very nominal. There might be a chance...but you are going to have to prove it, to me. Run the **** out of one for 20,000 miles and show me the bores and pistons!
I've taken apart 2 engines with Wossner "coated" pistons, in the 928 application. Neither made it more than a few hours. There's always an excuse...too much clearance, not enough clearance, didn't break it in correctly, wrong oil, got it hot, ran it too rich, ran it too lean, etc.
As many engines as I build, I'd be overjoyed if there was a viable "solution". That would open up a huge alternative market, for me, in terms of pistons. I'm always open to experimenting.....I'm just done doing it on my dollar!
Like I said above, get a warranty (in writing), that covers parts and labor!
The "Internet" is a really interesting place. There's an amazing amount of people out there, talking about what they do or plan to do. And even more amazing....very few people report back with their failures.
The 944 engine has a zero offset, perfectly centered rod. The side loading is very nominal. There might be a chance...but you are going to have to prove it, to me. Run the **** out of one for 20,000 miles and show me the bores and pistons!
I've taken apart 2 engines with Wossner "coated" pistons, in the 928 application. Neither made it more than a few hours. There's always an excuse...too much clearance, not enough clearance, didn't break it in correctly, wrong oil, got it hot, ran it too rich, ran it too lean, etc.
As many engines as I build, I'd be overjoyed if there was a viable "solution". That would open up a huge alternative market, for me, in terms of pistons. I'm always open to experimenting.....I'm just done doing it on my dollar!
Like I said above, get a warranty (in writing), that covers parts and labor!
But on this one, I am 100% with him. I have first hand experience from buying coated JE Pistons for my race car. I asked and they actually put it in writing that the super duper secret formula coating will work in the alusil bores. Engine lasted 10hrs. Of course the excuses were out straight away - not enough clearance, wrong ring gap, wrong alusil honing process, wrong engine tune etc. Did not pursue it, given the amount of variables present. All I am going to say is that all 8 pistons lost their coating on the trust faces. Not a coincidence, is it?
Bought another set of clean JE Pistons, installed dry steel liners and have been running a 434rwhp 5.4ltr GTS based engine for years now without issues. Did the same, but with clean Woessner pistons and liners in my 944 Turbo racer. Same outcome - no reliability issues with regards to block/piston assembly.
09-23-2016, 10:34 AM
#11
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My understanding is that 928 pistons are iron plated for use in the Alusil bore. I have zero technical understanding of coatings but something tells me that what works against a cast iron bore might react quite differently in an alusil bore. All ears if anyone can enlighten me.
Side thrust: notwithstanding a perfectly centred rod, there is always going to be side thrust on a piston. Has to be for an engine to work. Rod length ratio is big determinant of that.
The RLR of the 928 is 1.9, but it could be a lot "worse" eg 1.5-1.6, as used in middle to low end torquey engines, where high piston side thrust is the trade-off for lots of torque.
I always thought the 924 motor was 1/2 of a 928 motor, so Greg's comment re rod centering is intriguing, in that implies a difference for the 928 pistons. What was Ferdinand thinking?
Is there a process for replating pistons with iron?
Side thrust: notwithstanding a perfectly centred rod, there is always going to be side thrust on a piston. Has to be for an engine to work. Rod length ratio is big determinant of that.
The RLR of the 928 is 1.9, but it could be a lot "worse" eg 1.5-1.6, as used in middle to low end torquey engines, where high piston side thrust is the trade-off for lots of torque.
I always thought the 924 motor was 1/2 of a 928 motor, so Greg's comment re rod centering is intriguing, in that implies a difference for the 928 pistons. What was Ferdinand thinking?
Is there a process for replating pistons with iron?
09-23-2016, 11:31 AM
#12
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Thread Starter
The bores look gorgeous, so there must be some coating left. Perhaps the plan should be to stuff 'em back in, run it until they trash the block, then re-sleeve at some future date? Running good used pistons seems like it's just delaying the inevitable.
Is it just that Porsche or the OEM supplier won't let anyone know the secret formula? KS still makes and markets Alusil, who's making pistons for those other engines?
Is it just that Porsche or the OEM supplier won't let anyone know the secret formula? KS still makes and markets Alusil, who's making pistons for those other engines?
09-23-2016, 11:42 AM
#13
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Sometimes I disagree with Greg...
But on this one, I am 100% with him. I have first hand experience from buying coated JE Pistons for my race car. I asked and they actually put it in writing that the super duper secret formula coating will work in the alusil bores. Engine lasted 10hrs. Of course the excuses were out straight away - not enough clearance, wrong ring gap, wrong alusil honing process, wrong engine tune etc. Did not pursue it, given the amount of variables present. All I am going to say is that all 8 pistons lost their coating on the trust faces. Not a coincidence, is it?
Bought another set of clean JE Pistons, installed dry steel liners and have been running a 434rwhp 5.4ltr GTS based engine for years now without issues. Did the same, but with clean Woessner pistons and liners in my 944 Turbo racer. Same outcome - no reliability issues with regards to block/piston assembly.
But on this one, I am 100% with him. I have first hand experience from buying coated JE Pistons for my race car. I asked and they actually put it in writing that the super duper secret formula coating will work in the alusil bores. Engine lasted 10hrs. Of course the excuses were out straight away - not enough clearance, wrong ring gap, wrong alusil honing process, wrong engine tune etc. Did not pursue it, given the amount of variables present. All I am going to say is that all 8 pistons lost their coating on the trust faces. Not a coincidence, is it?
Bought another set of clean JE Pistons, installed dry steel liners and have been running a 434rwhp 5.4ltr GTS based engine for years now without issues. Did the same, but with clean Woessner pistons and liners in my 944 Turbo racer. Same outcome - no reliability issues with regards to block/piston assembly.
http://www.westwoodcylinderliners.co...mpany/faq.html
Good to hear you found the power by correct tuned intake length.
Åke
Last edited by Strosek Ultra; 09-24-2016 at 03:08 AM.
09-23-2016, 11:46 AM
#14
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It's not an issue, move on, don't worry about it. The only time this is an issue is building custom engines where non-stock pistons comes into play.
Some claim the coating is only needed when breaking in a fresh bore, which is questionable since Greg doesn't re-coat the 968 pistons he puts in bored out blocks for strokers.
There is a 928 engine running around Green Bay with Swain Tech's skirt coating applied. These were used pistons in old bores, the coating was applied as a friction reducer for power, not "refreshing" the original coating.
Many years ago, Mahle USA claimed to have the same process and many projects were started. It was soon discovered said coating was crap and engines were lost. Very long story short, years later a rep from Mahle claimed they "fixed" the problem and wanted us to try again. Not willing to chance another motor, we didn't take them up on their offer.
Could the issues with motors being discussed here be due to incorrect tolerances and / or rig gap? Maybe, but that means nobody knows the formula for our blocks with these new pistons and it's a very expensive trial and error to figure it out.
So...if you send Greg a briefcase full of money and have Mark Anderson truck over a dozen blocks, I'm sure he could figure out the magic formula.
09-23-2016, 12:13 PM
#15
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I have a bro who is a long-time wrench at Ford. He knows the ins and outs of the Ford product well and I asked him about this a while back. Ford used a coating on some of the SVO engines quite a while back. None of them lasted very long. I think a few thousand made it out into the field in Mustangs or maybe that little 2.3 engine. Anyway, they tried again with the newer Mustang engine, and again - didn't last long. Note - this is just Ford, and just the SVO(SVT now) group with the small V8 and V6 engine, but Ford has a lot of money and they tried several times. So far no luck.
From a chemical standpoint, one can understand the idea. How do you get a non-stick coating(like Teflon) to stick to something - cuz it's non-stick, right? Of course, that's Teflon, and it's not the same as some of the piston coatings out there, but you get the idea.
From a chemical standpoint, one can understand the idea. How do you get a non-stick coating(like Teflon) to stick to something - cuz it's non-stick, right? Of course, that's Teflon, and it's not the same as some of the piston coatings out there, but you get the idea.