how much of a difference is there between the two? im building a sbc, 357cu in with roughly 400fhp and have the choice between the 2, the engine will never see n20 or boost

main reason is theres 2 kits on summit, the better of the 2 (name brand parts) comes with KB silv-o-lite pistons vs summit brand hypers

which should i go with?

 

hypereutectics, you can run a tighter piston to wall clearance and they're stronger

 

but the kit that comes with the cast is only like $50 more and it comes with all name brand parts and all sealants and timing chain

arent stock ls1 pistons cast aluminum too? and they can handle a butt load of power

 

Both those pistons are cast hypers. Hyper refers to the alloy used not the manufacturing technique in this case.

 

Keith Black products,

in a different league to Summit supplied discount stuff I would think. Unless you know the manufacturer who's supplying the parts to Summit.

Yes LS1 pistons are cast, and it's probably their biggest weak point. Especially the #7.

Regardless, forged is always better for durability.

 

so go with the keith black pistons then?

 

I've had good luck with the Keith Black pistons in other cars. I prefer the better 390 alloy performance pistons. Those are supposed to better than the silv-o-lites, but I don't know by how much. I was just a little nervous about pistons they put in a "claimer" engine kit. Calimer engines are a race series where you are allowed to claim another guys engine if he wins the race, so you build an engine as cheap as possible, but oviously it can't be total junk if you want to win the race.

 

Not even close...the rod bolts are the weakest link in a stock LS1 (they'll have serious issues if you rev much higher than stock, power level doesn't matter, just RPM), and with a proper well done tune on a car, the stock pistons will take a SERIOUS beating...I've seen combustion chambers crack//break/shatter from the cylinder pressure before the pistons gave out...broken pistons are usually a sign of an inadequate fuel system, a shitty tune, or both. I understand #7 tends to run leaner...so tune the engine to an AFR where number 7 is safe...and sacrifice all of 8 horsepower due to the other cylinders being a tiny bit fatter than they really need to be at the power peak.

 

If you know it will never see nitrous or boost, hyper is fine for a performance minded rebuild.

Are forged ones better per say, yes, but if you dont have the expendable $$$ for them than its severe overkill for a 400HP sbc.