C-3, pistons

[D S.]

Anyone had any experience with Keith Black hypereutectic forged pistons? That's what was installed in my 454 engine during the stock rebuild.

Thanks,
Scott

[Joe L.]

Re: C-3, pistons

Scott----

If they're hypereutectic, then they're not forged. Although KB makes both hypereutectic (i.e. high silicon alloy) CAST pistons and the also make forged pistons, I don't think that they use a hypereutectic alloy for the forged pistons.

KB hypereutectic cast pistons are my choice. These pistons offer the best of all worlds. In my opinion, they're one of the best hypereutectic cast pistons available, second only, perhaps, to Mahle.

Most all modern high performance engines use hypereutectic cast pistons (although no PRODUCTION engine that I know of uses KB). These pistons were/are used in the Corvette LT1, LT4, ZR1 (LT5), LS1, LS6, and, soon, the LS7. They're also used in the new 8.1L big block, including SHP versions for marine applications. The Dodge Viper "500/500" uses them, too.

[KEN BUTCHER]

Re: C-3, pistons

Hi Scott,
My original 1974 camaro Z-28 with the L-82 motor had the forged factory TRW pistons before I rebuilt it and I also used the KB piston you mentioned, and it seems to feel right at home.

[D S.]

Re: C-3, pistons

Thanks Joe and Ken. My question actually revealed a possible uh-oh in the rebuild. Joe made a statement that caused me to read the invoices and I found the part number for the pistons. I checked it out and the ones installed appear to be dome tops for pro-street engines. I specifically requested flat tops so I can use pump gas. I'll know for sure tomorrow. I hope the mistake is on the invoice and not in the engine.

SS

[Joe L.]

Re: C-3, pistons

Scott-----

You didn't mention which pistons that you have or the other important information about your engine which would affect compression ratio. However, assuming that you have the original cylinder heads, these heads have a combustion chamber volume of 101 cc, nominal. Likely, you have a .040" thick head gasket and a deck clearance of about 0.020". Also, you probably have a .030" overbore. If so, your compression is going to be about as follows with the described KB pistons:

KB287------------about 8.4:1

KB200, KB202---- about 9.0 to 9.3:1

KB201, KB203---- about 10.1 to 10.6:1

KB207, KB257---- about 12.0:1

KB245----------- about 15.0:1

If you have the KB287, KB200, or KB202, you will be just fine. No problem, at all.

If you have the KB201 or KB203, you will still likely be ok. You will have to use the highest pump premium gas available and you might have to retard the timing a bit. A lot will depend on which camshaft you have installed, too. However, you should be ok.

If you have the KB207, KB257, or KB245, forget it. In that case, you need to tear the engine down and replace the pistons. No two ways about it.