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sullydog93 Thu Aug 02, 2012 3:30 pm

Is it worth the trouble, probable high cost?

DarthWeber Thu Aug 02, 2012 7:59 pm

An air cooled piston has different metallurgy, expansion characteristics and dimensions than a water cooled piston...................................then again, maybe Gene Berg was wrong.

Fiatdude Thu Aug 02, 2012 8:17 pm

I have aftermarket chevy pistons in mine --- no problems

Hotrodvw Thu Aug 02, 2012 10:35 pm

I think it's a cool idea, but as the article states, you have to modify them a bit. I'd try it someday!

SRP1 Thu Aug 02, 2012 11:29 pm

DarthWeber wrote: An air cooled piston has different metallurgy, expansion characteristics and dimensions than a water cooled piston...................................then again, maybe Gene Berg was wrong.

Nonsense, they run the same clearances, same material, same expansion rates.
That piston FYI is dirt cheap, made and sold in the after market by NPR of Japan
Same old NPR that sold VW P&C kits back in the 80's. But that dish is a POS! Even machined down it's no good in an air cooled unless it's gone and that can't happen, not enough material there.

I'n working on another piston at the moment from another engine, it's a forged 94mm
Mahle with teflon coated skirts. Pretty much the same thing everyone is used to seeing.
Would be considered a B piston and is a flat top with 4 small valve reliefs (not that it matters in a VW)
I'll have more details to post up at the later end of next week if it looks like a viable candidate, and the parts source shows their readily available.

mark tucker Thu Aug 02, 2012 11:47 pm

ya Ive been looking at that piston too.and thinking about a 4 or 5 valve set of heads to go with it.
there is no mettelergy to it,just about everybody has a different mix,(alloy)it depends on how you set it up and what the cylinder does.the piston dont know or care WTF it is in. I thought about putting a set of my je 4 1/2"bore pistons in one of my scrap motors just fer the hell of it.might have to split a set of heads to do it, but thats not an issue.

luckystiff Fri Aug 03, 2012 7:45 am

there's also the Icon 92mm toyota pistons. forged, no valve reliefs, basiclly C pin height, and fairly reasonable priced. combined with a set of AA thickwall cylinders another very viable option...ken...

ralf Fri Aug 03, 2012 8:58 am

luckystiff wrote: there's also the Icon 92mm toyota pistons. forged, no valve reliefs, basiclly C pin height, and fairly reasonable priced. combined with a set of AA thickwall cylinders another very viable option...ken...

true and i think they do have A height equivalents too?


one of the reason why i orderd a set of AA thickwalls..

u never know when you'd
need em ' 8)

mark tucker Fri Aug 03, 2012 9:05 am

luckystiff wrote: there's also the Icon 92mm toyota pistons. forged, no valve reliefs, basiclly C pin height, and fairly reasonable priced. combined with a set of AA thickwall cylinders another very viable option...ken... I havent seen the icons, hows the forging?light or what?slipper?

tmcdade Fri Aug 03, 2012 10:07 am

mark tucker wrote: luckystiff wrote: there's also the Icon 92mm toyota pistons. forged, no valve reliefs, basiclly C pin height, and fairly reasonable priced. combined with a set of AA thickwall cylinders another very viable option...ken... I havent seen the icons, hows the forging?light or what?slipper?

http://www.kb-silvolite.com/icon/icon.php?action=details&P_id=616

I was looking for a set of forged 88's, and found quite a few with .866"/22mm pins - the hard part is finding them without 4 deep valve reliefs or huge dish. If I could've found some without those 2 issues, I would've ran them. I didn't see that HVW issue, but I say go for it

mark tucker Fri Aug 03, 2012 3:15 pm

looks like a nice piece.my hyd roller cam motor was going to be a small motor(around 2000cc), but things change.I wonder how thick the dome is?it states it is for boosted apps, so it may have some extra under there along with being made right for the app.

udidwht Fri Aug 03, 2012 8:37 pm

SRP1 wrote: DarthWeber wrote: An air cooled piston has different metallurgy, expansion characteristics and dimensions than a water cooled piston...................................then again, maybe Gene Berg was wrong.

Nonsense, they run the same clearances, same material, same expansion rates.
That piston FYI is dirt cheap, made and sold in the after market by NPR of Japan
Same old NPR that sold VW P&C kits back in the 80's. But that dish is a POS! Even machined down it's no good in an air cooled unless it's gone and that can't happen, not enough material there.

I'n working on another piston at the moment from another engine, it's a forged 94mm
Mahle with teflon coated skirts. Pretty much the same thing everyone is used to seeing.
Would be considered a B piston and is a flat top with 4 small valve reliefs (not that it matters in a VW)
I'll have more details to post up at the later end of next week if it looks like a viable candidate, and the parts source shows their readily available.

Nonsense...anything that runs hotter is going to have different expansion characteristics. Lesson learned years ago in Metallurgy 101. Watercooled vehicles won't see the temps that air-cooled vehicles see.

Fiatdude Fri Aug 03, 2012 9:09 pm

That is true -- BUT aircooled engines run completely different tolerances than water cooled --- It is also true there is a completely different set of op temps in a boost engine vs. an NA engine -- -- if you setup a piston to wall clearance for the application you will enjoy success

Lobotomy Thu Sep 13, 2012 10:32 am

Bump. So who here has done this? I read the article, and now I'm really interested in piston alternatives for many reasons beyond them simply being cheaper. I wouldn't really use Toyota 94s in a 1915, due to the high RPMs that it can potentially put out, thus ruining the cast pistons, but what about a Toyota 92mm option for a 2180? You probably wouldn't go over 8k in a well built 2180, so cast pistons are a more viable option. How much machining needs to be done, and where? What cars do the 92s and 94s come out of?

I'm no tuning wizard, but my only fear is that the pistons may expand more than aircooled pistons, in theory, increasing friction, heat and damaging internals faster, but then again, I know dick about this kind of thing, so I'll let you magic men figure it out.

neil68 Thu Sep 13, 2012 5:50 pm

[quote="SRP1"] DarthWeber wrote: An air cooled piston has different metallurgy, expansion characteristics and dimensions than a water cooled piston...................................then again, maybe Gene Berg was wrong.

Nonsense, they run the same clearances, same material, same expansion rates.quote]

Then why do Wiseco's require extra skirt clearance? I see they have gained the nickname: "Seizeco"...

Steve Arndt Thu Sep 13, 2012 5:59 pm

[quote="neil68"] SRP1 wrote: DarthWeber wrote: An air cooled piston has different metallurgy, expansion characteristics and dimensions than a water cooled piston...................................then again, maybe Gene Berg was wrong.

Nonsense, they run the same clearances, same material, same expansion rates.quote]

Then why do Wiseco's require extra skirt clearance? I see they have gained the nickname: "Seizeco"...

It is a matter of being cast vs forged. Forged pistons expand more so they need more clearance.

mark tucker Thu Sep 13, 2012 8:08 pm

nonsence, not because there forged,in reality they run cooler with less hot spots,but some have an isolation slot and some have holes in the oil ring slot.and there are may different types of aluminum, je had a higher silocon content than sieezco's, & Ive seen a lot more wizassco pistons with broken ring lands too. different pistons take different clearances in iferent applications. a car(wattercooler) bored & honed corectly can work at .0015 with some pistons, now the exzact same motor in a boat will seezzee in a hurry. why??? because the pistons run the same temp in both motors. but the cylinders in the boat have a big supply of nice cool water to keep them cool cool is small, so the piston expands as normal but cylinders dont so they grab each other.,but bearing clearances are about (some .001 more on a boat.)the same as they have hot oil keeping all at the same temp. but there isant a "special"piston for any of it aircooled watter cooled what ever the piston dont care it is going to run about the same temp for it's material(cast or forged, then there is the hyperutectic witch run even hotter) the piston dosent know or care what it is in.

AlteWagen Fri Sep 14, 2012 9:01 am

[quote="SRP1"] DarthWeber wrote: I'n working on another piston at the moment from another engine, it's a forged 94mm
Mahle with teflon coated skirts. Pretty much the same thing everyone is used to seeing.
Would be considered a B piston and is a flat top with 4 small valve reliefs (not that it matters in a VW)
I'll have more details to post up at the later end of next week if it looks like a viable candidate, and the parts source shows their readily available.

Any word?

chrisflstf Fri Sep 14, 2012 2:36 pm

The word is... nonsense :lol:

modok Fri Sep 14, 2012 5:48 pm

I think he is looking at a subaru piston probably
The subi piston is very short skirt, the pin is 1mm bigger

the aircooled piston probably does run a bit hotter than some other engines, but not anything that a little extra clearance won't make up for



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