Peter M Posted 3July, 2018 Report Share Posted 3July, 2018 11 hours ago, ANF said: For anyone suggesting to "recoat" an Alusil bore they simply do not understand what Alusil is..... I don't disagree but the universal standard practice to recondition air cooled cars with KS brand Alusil cylinders is to have them Nikasil'ed. In fact the KS cylinders are consider better to re Nikasil than the Mahle's themselves that came standard as Nikasil'ed. I think part of this is because the KS cylinders can usually be picked up cheaper than Mahles as engines with KS cylinders are regarded as second best. Link to comment Share on other sites More sharing options...
ANF Posted 3July, 2018 Report Share Posted 3July, 2018 19 minutes ago, Peter M said: I don't disagree but the universal standard practice to recondition air cooled cars with KS brand Alusil cylinders is to have them Nikasil'ed. In fact the KS cylinders are consider better to re Nikasil than the Mahle's themselves that came standard as Nikasil'ed. I think part of this is because the KS cylinders can usually be picked up cheaper than Mahles as engines with KS cylinders are regarded as second best. I can see that Peter and I know people coat the 928 engines as well. I just see it as odd as I believe the Alusil to be better. As always each to their own, just trying to convey that if you have Alusil it is fairly straight forward to repair if needed and from what I have seen unless a foreign object causes some damage they are very long lasting Sometimes people just do things as that is the norm, I am not one of those people Link to comment Share on other sites More sharing options...
81SC Posted 3July, 2018 Report Share Posted 3July, 2018 Some good information about cylinder identification in this pelican thread, I had this one bookmarked from years ago. http://forums.pelicanparts.com/911-engine-rebuilding-forum/453063-nikasil-alusil.html Might be worth shooting these guys an email to see what they offer. Link to comment Share on other sites More sharing options...
Cheshire Cat Posted 6July, 2018 Author Report Share Posted 6July, 2018 On 7/3/2018 at 7:21 AM, ANF said: Wossner and Arias offer forged pistons with a suitable coating. SPS pistons in Melbourne will make you pistons and HPC can coat them for $27.50 each to suit Alusil. I believe one of the best options is to buy some new Mahle Porsche pistons with the original coating already on them. I found new Mahle pistons available for my 928 and in my searches found that there are many more parts available for 911s..... For anyone suggesting to "recoat" an Alusil bore they simply do not understand what Alsuil is..... this in from my 928 Porsche Factory workshop manual (they should know what to do!). The piston and rings run in the Silicon particles giving a perfect low friction surface. Have you got any pistons coated and working experience? Seems like that not that easy to coat pistons... Link to comment Share on other sites More sharing options...
ANF Posted 6July, 2018 Report Share Posted 6July, 2018 2 hours ago, Cheshire Cat said: Have you got any pistons coated and working experience? Seems like that not that easy to coat pistons... No, I bought some N.O.S. original ones. Why do you say that? All the big custom piston brands offer coated pistons. Arias supply 928 Motorsport with coated pistons and they sell a few into the 928 market. The rest offer them and while none would divulge exactly what the coatings were (industry secret) they assured would work with Alusil. I spoke with HPC they seemed fine with coating pistons, check their website out. Link to comment Share on other sites More sharing options...
Cheshire Cat Posted 6July, 2018 Author Report Share Posted 6July, 2018 41 minutes ago, ANF said: No, I bought some N.O.S. original ones. Why do you say that? All the big custom piston brands offer coated pistons. Arias supply 928 Motorsport with coated pistons and they sell a few into the 928 market. The rest offer them and while none would divulge exactly what the coatings were (industry secret) they assured would work with Alusil. I spoke with HPC they seemed fine with coating pistons, check their website out. I`m doing my homework and either it`s a big business stuff or... Not much info about proper coating for Alusil bores (let`s call it Alusil coating), some say dry film (and much more other words) will do just fine, other - won`t last more than 300-400 kms, Neil from Performance Developments said, quoting "Best choice would be to Nikisil cylinders. Piston Vostongs font have to be special but rings cannot be chrome. " I think some of the text was autocorrected but the idea is there - pistons can be coated (which proven by the original setup) but something wrong with the rings. I always thought that rings aren`t made of aluminium thus can`t be a part of the problem... Anyway, so far I`m still thinking of coating pistons rather Nikasil the cylinders but it is 60 to 40 or 65 to 35 chances... Some say Woessner do the trick, other say no, they don`t... My research in CP Carrillo with polydyn (yet another company that does coatings) coat didn`t give me any straight answers... My head will blow up soon.... Link to comment Share on other sites More sharing options...
ANF Posted 6July, 2018 Report Share Posted 6July, 2018 From the Porsche workshop manual the factory pistons are chrome or iron coated, I have only seen the iron coated ones. I contacted Chris Richards at HPC http://www.hpcoatings.com.au/coatings-2/#Engine-Coatings and he confirmed that their Molybdenum Disulfide DF1 coating was suitable for use in an Aluisl bore/ block. Wossner also assured me that their coating is suitable. To say this they must have been used in Alusil with success. Rings are just standard, nothing special needed as you say the materials are different and not interact (gall) Just had a look on Design 911 website, the 911 Wossner piston sets are cheap (compared to 928 ones!!) Link to comment Share on other sites More sharing options...
Cheshire Cat Posted 6July, 2018 Author Report Share Posted 6July, 2018 3 minutes ago, ANF said: From the Porsche workshop manual the factory pistons are chrome or iron coated, I have only seen the iron coated ones. I contacted Chris Richards at HPC http://www.hpcoatings.com.au/coatings-2/#Engine-Coatings and he confirmed that their Molybdenum Disulfide DF1 coating was suitable for use in an Aluisl bore/ block. Wossner also assured me that their coating is suitable. To say this they must have been used in Alusil with success. Rings are just standard, nothing special needed as you say the materials are different and not interact (gall) Just had a look on Design 911 website, the 911 Wossner piston sets are cheap (compared to 928 ones!!) I think you just gave me a night to sleep well... Thank you SO MUCH! Link to comment Share on other sites More sharing options...
StevepGT3 Posted 7July, 2018 Report Share Posted 7July, 2018 Just make sure that the cylinder coating and ring compatibility have been tried, tested and proved long term, I went through hell with supposedly compatible ring/cylinder coatings on my Ducati race bike. The manufacturer replaced cylinders and piston /ring sets 3 times and still no success. I ended up having the pistons machined to fit,of all things modified ford rings from memory. Even though the parts were replaced, my time and gaskets etc. weren`t.I have been very reluctant to stray from Factory ever since, unless there is well known long term reliability. Sometimes paying more for what is known to work ends up cheaper in the long run. Link to comment Share on other sites More sharing options...
944s2cab Posted 2October, 2018 Report Share Posted 2October, 2018 Just a word of warning when things go wrong, An Alusil block honed by proper procedure, pistons designed for Alusil cylinders, Something went wrong within 150Km's 2 out of 4 piston/bores are rooted, other 2 show signs of (very) early wear/galling Link to comment Share on other sites More sharing options...
StevepGT3 Posted 2October, 2018 Report Share Posted 2October, 2018 15 minutes ago, 944s2cab said: Just a word of warning when things go wrong, An Alusil block honed by proper procedure, pistons designed for Alusil cylinders, Something went wrong within 150Km's 2 out of 4 piston/bores are rooted, other 2 show signs of (very) early wear/galling That`s what mine looked like, although not quite as bad as that,and it was ring material that was the problem. Link to comment Share on other sites More sharing options...
ANF Posted 2October, 2018 Report Share Posted 2October, 2018 Thankfully mine will be using factory pistons and rings Link to comment Share on other sites More sharing options...
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