pistion suggestions and questions...

[IDIoit]

in my tear down thread, ive ran through all of my options.

neither of the blocks were up to par, IMO.

engine #1 which is supposed to be a 94 IDIT, has hairline cracks in the slugs.

the cylinder walls look primo w/ cross hatch hone marks.

so i will be purchasing new slugs.

a couple of questions...

where is the best place to order new slugs?

i guess it depends on the place that coats them,
but how much do the slugs need to be shaved typically before ceramic coating them?

need to get these ordered asap....

 

[icanfixall]

Well my suggestion is to stick with what works. Mahle is the oem piston so why change now. These pistons are 560 to 580 thousands thick in the center. that's the thin area. I'm not sure if you can purchase them without the hard anadoised tops but call and ask them. They are in Tenn. If you are thinking od ceramic coating the tops I suggest buying the Tech Line product I used. Only issue using this is they will not sell to us as a private person. They have a recognized applier base that they send what you buy from them so they know its applied properly.
Now the milling of the pistons... Really not needed but if you want to take some off the tops please don't take more than 15 thousands. Reason for this max amount is the engineers at Mahle I talked with told me any more can make more heat reaching the ring and thats not what we want. I also know some have taken plenty more and nothing happened.... Yet.. But who has removed a piston to check about burning rings. Now if milling some off the top remember you will have to sand blast or media blast whats left in the Richardo cups on the tops. Then send the pistons to be coated. No matter how clean the tops are the better coating company s will still blast the tops and coat immediately. Any oxidation will be like oil and glue.. the coating will not stick is anything is on top. So the company that coated my pistons.
Techline also makes a great piston skirt coating too along with many other ideas to reduce friction. Check out their good web site for more info.

 

[IDIoit]

i have purchased from techline before, thats where i got my turbo x coatings for the hot side.

you sent them your pistons and they did it for you, correct?

 

[icanfixall]

Nope... I purchased their product and they mailed it to a place that was waiting for my pistons. It was a VW shop they knew was doing a good job with their product. That shop is no longer there and this was about 9 years ago. I think the market crash sent them out of business. Peopels toys were not being built as much during that mess.

 

[IDIoit]

Gary, how much did you pay?

 

[icanfixall]

Really too long ago to recall what I paid. I do have many recites from my builds so I will check if I have this for you.

 

[TahoeTom]

http://www.calicocoatings.com/
I sent my pistons to these guys. The machine shop I used recommended them. I had the CT-2 ceramic on tops and CT-3 on skirts. Cost was $322 three years ago. They are in North Carolina, so shipping both ways was $70 or so. Their turn around is fast, 2 or 3 working days. I was told the coating doesn't add a measurable amount to the piston. I didn't cut down my pistons, so stock compression. I found my pistons on ebay.

 

[typ4]

IDIot, you staying stock bore?
Clevite bought Mahle so its hard to get Mahle but my parts guy said he may be able to source some, but I dont know about standard. I have a new OEM ford set of turbo pistons, .020 over with pins and rings.

 

[IDIoit]

the bore im going with is 030 over, with very good cylinder walls, the block was remanned before i over fueled it.


another question,
would shaving my pistons, effectively lowering the compression, .015 like gary said, help out with lowering EGT's?

 

[typ4]

Not likely, mine are 10 shorter and it makes lots of heat. The only way to lower egt is more air, less fuel.

 

[jaluhn83]

I went 0.015" on mine. Would probably have gone 0.020" if I did it again, since the coating adds about 0.005"

I don't think heat reaching the rings is going to be much of an issue since the ceramic coating will reduce the heat flow into the piston. The issue is that by removing materials you're reducing the distance between the piston top and the ring as well as reducing the cross sectional area of the piston in the radial direction. This means more heat will get to the ring because it's now closer to the top and there's less metal in the radial direction for the heat to flow in and down to the cool lower area. The outer most small section of the piston above the top ring is one of the critical sections since heat has to flow in and around the ring groove. But, if you're ceramic coating the top you're reducing the amount of heat entering the piston to begin with - hence less of an issue.

I sent mine to a shop somewhere in the midwest IIRC - cost about $300. Had the local machine shop machine them first, then stuck them in the box and off they went.

IMHO any of the major piston brands should be fine.

Personally, I would check ebay & rock auto - there's a good amount of NOS pistons & sets floating around for reasonable prices. Avoid the 'engine tech' or whatever cheap import stuff there is, but plenty of warehouses and such cleaning out stock of good quality sets.

 

[riotwarrior]

IDIot, you staying stock bore?
Clevite bought Mahle so its hard to get Mahle but my parts guy said he may be able to source some, but I dont know about standard. I have a new OEM ford set of turbo pistons, .020 over with pins and rings.

Really...and I have a turbo e gine core here....hmmm sleeved block vored 020...hmmm whats yer $