Keith Black Pistons

[moper]

Kieth Black hypereutectics use a different alloy and that material makes the top of the piston concentrate more heat in the ring land area. Which is why those particular hypers need a wider ring end gap on the top ring. They experienced failures because like many "everything is bad" reports builders thought they knew and didnt read instructions. Hypers are lighter and much stronger than factory cast. But, they are brittle. Meaning they will take a lot of power safely, but they dont tolerate detonation for long. And if the top rings are not gapped properly, they have been known to pull the tops ott the pistons. not the pistons' fault. It was the builders'. You dont want them in an engine that will run large NOS loads. You dont want them in a situation where the piston speed gets really high. They are not designed or priced for that. As a result of the piston speed deal, I won't ever use them in a longer than stock stroke build. but, I've never had an issue with them. They hold up well, and are great for a budget build. Do not sweat them if you have them. Just dont buy an NOS system for it . Every American auto maker is using them because they are good pistons when spec'd properly. In those applications, the first damages one sees when adding a blower is the explosion of the pistons... because they are not designed for it...lol. They are run much tighter in terms of piston to wall claerance than any forged or cast piston. Which greatly enchances ring seal and both power and longevity, and the heat they retain means it stays in the chamber where it's making power instead of leaching into the components.

[Jim]

Hey Don,

If you ever decide to get a stroker kit from 440 source, you will have no problems as their pistons are quality pieces ols mate.

440 Source pistons are KB pistons. The are KB FORGED pistons (not hypers). They aren't advertised as such, but they have a KB number etched on them.

The KB forged pistons are a little heavier than the counterparts from Ross, Diamond etc (about 50 g on a 10:1 440 piston) and the top ring is a bit higher. They are quite a bit less expensive.

[73EStroker]

A friend a while back had KB Hypereutectics in a BB Chev. One day he gqave a nice 7000RPM squirt on the throttle and boom went the engine. Turned out that the piston stretched enough to hit the open valves. He changed the pistons to forged plus other repiars and no more problems. He changed to forged Diamonds.

Don't chintz out on pistons. Those parts are the most abused parts in an engine. I use Ross and they were expensive but what is $200 difference on a $13500 engine.

[moper]

A friend a while back had KB Hypereutectics in a BB Chev. One day he gqave a nice 7000RPM squirt on the throttle and boom went the engine. Turned out that the piston stretched enough to hit the open valves. He changed the pistons to forged plus other repiars and no more problems. He changed to forged Diamonds.

Don't chintz out on pistons. Those parts are the most abused parts in an engine. I use Ross and they were expensive but what is $200 difference on a $13500 engine.

Exactly what I said abut using them when the piston speed gets too high. They were the wrong choice from the get go on that. And yes, KB manufactures pistons for 440Source, they are all forged, and they are an ok piston. In terms of higher end forged, I use Diamond.

[black71]

here are my Ross pistons for my 543 from 440 source kit....12.5:1 

[hemiken]

I have a stroker kit from 440source here aswell that converts 400 to 500, and the pistons are Ross But i have heard that they have been using different piston manufacturers, depending on what stroker kit you do get. 

440 Source pistons are KB pistons. The are KB FORGED pistons (not hypers). They aren't advertised as such, but they have a KB number etched on them.

What size stroker engine have you seen the KB's used on the 440source kit please 471_M

[Topcat]

Kieth Black hypereutectics use a different alloy and that material makes the top of the piston concentrate more heat in the ring land area. Which is why those particular hypers need a wider ring end gap on the top ring. They experienced failures because like many "everything is bad" reports builders thought they knew and didnt read instructions. Hypers are lighter and much stronger than factory cast. But, they are brittle. Meaning they will take a lot of power safely, but they dont tolerate detonation for long. And if the top rings are not gapped properly, they have been known to pull the tops ott the pistons. not the pistons' fault. It was the builders'. You dont want them in an engine that will run large NOS loads. You dont want them in a situation where the piston speed gets really high. They are not designed or priced for that. As a result of the piston speed deal, I won't ever use them in a longer than stock stroke build. but, I've never had an issue with them. They hold up well, and are great for a budget build. Do not sweat them if you have them. Just dont buy an NOS system for it . Every American auto maker is using them because they are good pistons when spec'd properly. In those applications, the first damages one sees when adding a blower is the explosion of the pistons... because they are not designed for it...lol. They are run much tighter in terms of piston to wall claerance than any forged or cast piston. Which greatly enchances ring seal and both power and longevity, and the heat they retain means it stays in the chamber where it's making power instead of leaching into the components.

Thanks for the info as I wanted to know more on what the differences were. I'm in the market for forged pistons.

[NoMope Greg]

Thanks for the info as I wanted to know more on what the differences were. I'm in the market for forged pistons.

Don't you just love it when someone explains the "why" of a problem or issue and you come away having learned something?  There are a couple of people on here that have an excellent command of the theories of engine design, assembly and repair.  Moper is one of the guys at the top of the list - I always learn something from his posts. 

[71chally416]

Good cast pistons are fine for a N/A street motor, even the low dollar Badger's with the metal thermal expansion limiters. That's the same type every stock 440 and 360 and 340 and 318 had from the factory, and I've never heard about them breaking. Forged pistons require more shirt clearance and they rattle around in the bores until the motor is warm, so they tend to wear rings and bores more and they're noisy. The critical thing is always the ring gaps. If they are too small the rings butt and you lose power. Better to err on the side of too big than too small. An .010" too big of a gap will show no noticeable power loss, but .010" too small can cost you hp when the ends butt and the rings distort in the bores. I'd tell you about one of our race motors we had on the dyno that picked up 40hp when we just opened up the gaps .020", but you wouldn't believe me. Really though, at 6,000rpm the amount of power lost because of ring gaps in a 4"+ bore is a fraction of almost nothing. 

[73EStroker]

My Ross forged set run 0.005" skirt to bore clearance. Virtually same as cast. No rattle.

[hemiken]

Hey Guys,


I found out today that KB pistons are in fact Keith Black pistons.......... They just shortened the name is all.

[Swedefish66/67]

Don't you just love it when someone explains the "why" of a problem or issue and you come away having learned something?  There are a couple of people on here that have an excellent command of the theories of engine design, assembly and repair.  Moper is one of the guys at the top of the list - I always learn something from his posts. 

[AMXguy]

Moper, you say detonation is something the KB's won't tolerate but aren't they designed with relief grooves to help prevent detonation? and the rings lowered to help even more with damage control?  I'm wondering if on normal 8.5-9.5 compression ranges the safegaurds built into them wouldn't take care of most of the issues as long as correct timing and correct fuel are used? if I understand you right what you're saying is what my builder told me, in a street type engine installed correct they're a nice upgrade from standard cast.

[wally426ci]

 

Mine must have backfired about 3 times BADLY  when we first built it. And they're fine so far. 

[71chally416]

It's just an old wives tail that won't die that you have to have forged pistons or you sacrifice performance and reliability. All the Chrysler muscle car motors with 100K+ miles that had them stock (including the new Hemis) are proof of their strength. And if you run your motor into Detonation you might as well just beat on it with hammers. That'll kill your rings and bearings way before it kills a good cast piston.