918-S

OK, I just got off the phone with charles Navarro of LN engineering.
(the Nickasil cylinder guy) We had a conversation about pistons. I was asking about having 97mm 16 valve euro S pistons made in 100mm. My goal is to maintain the 10:1 compression. Charles thought the stock piston skirts were iron coated. Anyone know about this?

His thought was to have the block nickasil coated. This would allow the use of aluminum pistons. He told me you can't run an aluminum piston in an aluminum bore. It will eventually start to gall.

Are the stock pistons iron coated? Is that why guys are running 4 cam 100mm pistons instead of having custom pistons made?

SwayBar

If you'll do a search, you'll find that this has been covered in great detail.

BC

Everything your guy said was true 918. Except for one thing - there MAY be a way to run JE-type pistons in alusil (which is what the 944 and 928 engines have as a block material). A heavy duty polymer coating by swaintech is in use right now and seems to be working (on the pistons).

spare time toys

Hi Rick just bumping this up to put it next to the piston thread

918-S

Hi ya Larry!

John, thanks for the input. I did a search but there are too many threads to read. You get a little piece here and a little piece there.

Part of my discussion with Charles walked around the topic of piston coatings. I asked him about using a skirt coating. He looked at the piston coatings used today as a sacreficial wear surface. He was under the impression that the coatings wear away and would eventually loss the protection. He wasn't sure but didn't think this was a long term solution.

I asked if he thought there was a way to Nickisil the pistons. This would be the same as having a nickie bore only in reverse. His reply was he wouldn't have a way to machine the surface of the piston to spec and the piston material may be too hard for the nickie coating cause delamination during use. The Alusil is porous enough to promote a good bond.

With all the advances in piston coatings I would think there is a way to apply a barrier coating. I'm going to look into Swaintech and other companies a little further.

The other part of this conversation is the true savings. The cost of a set of pistons, coating and boring the block may cost the same.

Stan.Shaw@Excell.Net

I am sure I am missing something, since 16v Euro S heads on a 86 shortblock (100mm pistons) result in 10:1 compression or higher, what is it that you want to be different?

918-S

1) The option of using new parts at a substantial cost savings.

2) reuse blocks by boring to get a new surface without the added cost of block coatings.

3) start a dialog on all the options for making the best use of modern methods to extend the life and use of otherwise cast off parts like the 95mm and 97mm blocks sitting in shop and garage corners.

When your talking about sourcing a 5.0 32 valve short block, hoping it's good, notching the pistons to clear the valves, etc. I would think this is the most expense way to get a hybred. How many 1986 motors are out there?

Even sourcing used pistons is not always the easiest. I see guys using pistons that are pitted and others cutting them into pieces to examine them for modifications.

I don't object to this as it needs to be done. But I'm a drag racer from way back. I'm used to being able to pull parts off the shelf not out of the trash. This type of parts sourcing and limited options can only lead to obsolession.

Technology has brought some real gains. Some of them are being used. What else is out there?

Stan.Shaw@Excell.Net

I have five 86 blocks, and haven't seen them as in short supply yet. But your point is understood. I have acquired cars to get the best price on the blocks, but suspect the value of a good 86 short block to be @$1k. Notching the pistons is only a @$100 item, and is essentially un noticed when you consider the cost of engine bearings and gaskets.

I think your standards for parts is higher than mine has been, so perhaps you will find a new way. I know with regards to builing over bored motors (104mm) the cost of coating a block and using after market (JE) pistons seems to be comparable to using used 968 pistons. Of course the condition of the 968 pistons can be an issue to be compared to the issues of being one of the first to use a coated block.

In my loooooonnnnnnnggggg term bored motor build, I sourced used 968 pistons and had them coated by hpcoatings. I did so to address the skirt scuffing with the hoped for benefits the vendor states about the coating. Whether this is a solutions equivalent to what you will find with new parts is unknown (to me anyways). With regard to cost, I have bought 16 968 piston for a total of under $1k with the added cost of coating (one set so far) of @$400. Of course you need to use aftermarket rods due to the different pin placement as well.

Presumably you could coat a set of 85-86 pistons with the same coating, but if your standards are the you want as good as new, this may not be the right approach for you.

Thanks for your response, I better understand what you are looking for now. Sorry I can't really help though

918-S

Stan, actually you have been a great source for info. Based on the pricing you posted the cost of sourcing new pistons, getting them coated and boring a block seems to be running parallel to the cost of sourcing used pistons, notching them, and having the block nickied. This is part of the information we all need to be able to search out in one place. This thread will become a good strong one stop source for info in the future thanks to your posts.

Oh BTW: I know there are several posts on pistons and block coating here but I couldn't find one on comparing used parts to new and the options that are available. So anyone have something they posted in another thread and want to post a link feel free.

Stan.Shaw@Excell.Net

Of course if you get used pistons, you don't have to have the block coated.

The coating I am using on my 968 pistons does not require the block to be coated.

As I recall boring and lapping a block cost me @$500.

Vilhuer

Pistons are either iron or crome oxide coated IIRR. Mahle uses one material and Kolbenscmidt another. Both work about equally well in Alusil bores. Coating wears at run in period but do not wear after that. Pistons can take few run ins before coating gets too thin on two highest wear points on skirt.

mark kibort

personally, ive built two of the hybrid 85 5 liter engines (from a US 85 block and euro S top end)

the only cost, as stan says is really the block itself, and the chance that the bores are not perfect. generally they are. if they are not, the paste process is not expensive at all. then, the only other expense is to notch the pitsons. I have the templates for doing this. you could have the templates and mark the pistons yourself and almost do it yourself with a die grinder.

so, the situation is that you have a 85 block with balanced components and no need to have custom components made, and the quality of even a used mahle piston is top notch.

the only time its worth making pistons is if you are doing a 6.5 liter and have a choise of nicasil for some uncoated JEs or alusil with the 968pistons. (from what ive been told) . otherwise, just take the stock stuff and do the minor mods, re-ring, rebearing and off you go with a 285rwhp min set up for relatively cheap

mk

mk

BC

The point was well made by erkka - the coating is a sacrificial one. Not one that is used past 1000 miles or so. So a plastic coating should work just fine. I may be wishfully thinking, but it sounds feasible.