Ok I've been talking to charrlie and ki tom and my machine shop guy about the turbo motor im building I'm kicking the idea around of getting the weisco/rod combo yes i know they are high compression pistons so here comes the question.
Options move the wrist pin to lower compression to somewhere in the 8 or 8.5:1 area this option costs about 350 bucks and wouldn't it affect some kind of piston rod angle?
Copper head gasket to whatever thickness needed to lower the compression
along with adding some cc's to the combustion charmber of the cylinder head. I really need opinions ideas in what direction to go in or what combination of directions to go in and why you would go in the direction you chose thanks guys.
I need your knowledge and different points of view on this one to help me make a decision because my piston/rod order is in limbo.

Kev

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Take the current Wiesco pistons and machine .120 off the tops.
Combine those with a unmilled block, a 60 cc chamber size head and a .045 thick head gasket and you get 8.1 to 1 CR.
DD

Moving the wrist pin seems like an expensive way to go. Why not try another piston? Look in Mahle or Keith Black or other piston catalogs for a forged piston with less comp height and use the K1 rods. Maybe Wiseco has an off-shelf piston with a smaller comp height??

2.0L Ford pistons are 1.41" comp ht, and 3.1L Chev v6 pistons are 1.45" comp ht in bores we can use. Not sure if you can get those in forged. I bet you could get something between 1.3 and 1.5" comp ht and deck block to get whatever comp you want.

Otherwise, I like the milling idea, but I would do less, like 0.080"-0.100" to leave plenty of piston thickness. Copper head gaskets can do up to 0.090" thickness from SCE or Charlie's contacts.

Another way would be to use a 198 crank...

Lou

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Home of Slant6-powered fun machines since 1988

I like your idea doc that was my first thought would it be safe to take that much metal off the pistons?

Lou I actually happen to have a 198 crank sitting aroung this would lower the compression? Wouldn't I lose cubic inches? K1 tom said the only pistons they stock are the high compression ones and they are actaully out of stock for 3 weeks at the moment

Thanks Kev

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Lou is right but Charrlies contact I think can go .120 thick
A 198 crank would just put you back to stock 198 Stroke. Then Bore out to .105 for the wiseco pistons, adjust the thickness of the copper head gasket and you are there.
JMHO
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

Yes, you would have a bored over 198. Just a thought.

I was suggesting you look at Wiseco pistons for another engine with the right bore and a smaller comp ht. They will be list for some other 6 or 4cyl app and not the Slant 6.

Lou

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Home of Slant6-powered fun machines since 1988

I talked to a Wiseco rep at PRI, and they said it wouldn't be much more expensive to make lower compression custom pistons that work with the K1 rods.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

That is what I would think. I sugested to Kev, he check with Wiseco about moving the pin location, and was very supprised, at the pricing.
I like the idea of a good quality rod, and a premium piston & ring package. I am not a fan of a copper gasket on a mainly street driver. I was concerned if cutting the top of the piston would make it too thin.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Cutting the piston crown also "moves" the ring pack closer to the combustion. Also, Wiseco did not have an off the shelf forged piston that was close to the 1.455 comp height I wanted.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

I would not overbore this much. Start with the smallest overbore as possible. Keep the cylinders as strong as possible for less distortion under load. The extra cubes don't matter as much with a turbo. Put an extra .5 psi into it to make up for the .060" overbore to get to .105". Go for strength.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

So far im leaning towards doc's solution except i would try to limit the metal take off the pistons as much as possible i gotta cc the head and see how thick of head gasket I could pop in there .100 sounds like alot of metal to take off the piston. But charrlie has me scared of using a copper head gasket because he said he's heard they have a tendancy of weaping oil and or water

Thanks, Kev

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Talk to Wiseco first and see how much crown is on the piston and how much it is to cut them. I run copper on the street. I do push out some water under boost...20psi+. Use a good sealer like hylomar.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

will do, I've gotta make some phone calls and some decisions but I think I've got the direction I wanna go in figured out.

Thanks guys,
Kev

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According to my spec sheet, the crown on my pistons is .250". I would not recommend cutting .120" off. We don't know the thickness of the shelf piston at this time.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

Ya thats alot of metal i dont want to take off the pistons. What compression would I be aiming for this motor i was thinking somewhere around 8:1 could i get away with maybe 8.5:1 or should i shoot for lower?

Thanks Kev

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