Keith Black pistons question.

SCme

Registered User
Can anyone verify what/if this # is for a 3.8 V6? h820cp Have a great deal if they are. They are suppose to be new pistons that are hyperutectic and have an anti friction coating on them and are .75mm over bore or around a 3.840 bore.

Just wanting to verify before I get with the guy to purchase if they are what he says they are. I checked on KB's web site, but I don't see that part number, and with them being for a larger bore, I wonder its a "special" # that not listed.
 
I'd recomend getting forged pistons for our motors instead of hyperetic. Forged are better for boosted applications.
 
HSKR said:
I'd recomend getting forged pistons for our motors instead of hyperetic. Forged are better for boosted applications.


I just had a rebuild, so they are not directly for my SC. I was just trying to figure out if they are what he thinks they. He's selling 6 new ones for a dirt cheap price, that if will work in our cars, is too cheap to let pass. Also, for doing a near stock rebuild and not upping the boost, hyperutectic sould be fine, since they came stock in our cars. Besides KB's hypers seem to be a little better quality they most kypers from what I remember reading about them sometime ago.
 
I agree the pistons will do excellent in terms of quality and durability. The question is whether or not they actually are correct for our cars. Can you get any pictures and/measurements off them? A picture would tell if they are low or high compression, and if you measure comp. height and pin diameter that will tell the rest of the story. I would be totally comfortable running those up to 400rwhp.
 
HSKR said:
I'd recomend getting forged pistons for our motors instead of hyperetic. Forged are better for boosted applications.
Actually that is not entirely true. A forged piston is less likely to break than a hyper, but a hyper has other advantages such as it's ability to hold heat in the combustion chamber where it belongs and actually, a KB hyper piston is stronger than a forging.
 
for the price he is asking for them, I might just take a gamble and purchase them, and if they are for another version of the 3.8, I can easily get my money back .
 
That number is a Sealed Powered number. You need to make sure that the compression height is same otherwise you will need different rods.

It's a piston for 96+ Ford 3.8L. It has a coated skit. Compression ratio is higher and CD is 1.440

They are $24 new from Summit. STL-H820CP

Here's the info in PDF.

piston info
 
Last edited:
Sealed Power stock replacements for 1989 thru 1995 SC motors is: H675. With coated skirts H675CP.

Stock pistons are Hypereutectic and allow tighter combustion chamber fit compared to a forged unit. For street and moderate power (under 400rwhp) they should be just fine.

According to Federal Mogul's website (parent of Sealed Power)
H675CP
Bore(inch): 3.811
Compression Distance: 1.607
Pin Diam: 0.9122
Pin Offset: 0.03
Ring1: 1.50mm
Ring2:4.00mm

H820CP
Bore(inch): 3.811
Compressoin Distance: 1.440
Pin Dia.: 0.9056
Pin Offset: 0.03
Ring 1: 1.50mm
Ring 2: 3.00mm

That different compression distance makes me think you would need different rods.
 
Hypers vs. Forged

XR7 Dave said:
......but a hyper has other advantages such as it's ability to hold heat in the combustion chamber where it belongs and actually, a KB hyper piston is stronger than a forging.
Dave, Can you explain:

1) Why a hyper' holds the heat better? Different alloy? Thickness? Is that all hypers, or only KB's?

2) Why a KB hyper is stronger than a forged piston?

Curious 68COUGAR
 
cougarsc said:
That number is a Sealed Powered number. You need to make sure that the compression height is same otherwise you will need different rods.

It's a piston for 96+ Ford 3.8L. It has a coated skit. Compression ratio is higher and CD is 1.440

They are $24 new from Summit. STL-H820CP

Here's the info in PDF.

piston info


Thanks all for the answers. I was wondering when I could not find that part # on KB site. So they are more for the 3.8 stang and n/a MN-12 cars, is that correct, or the SC with a different rod?
 
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