KB Pistons

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powerwagon

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Wut is the differance betwen Hypereutectic Pistons and forged pistons other than price$$$$$$$im looking at some KB Hypereutectic Pistons for a 360 trying to find a good zero deck 4.00 resonable priced set of slugs!HELP ME
 
Hyper eutectics are more or less cast pistons that have an altered ratio of silica vs Aluminum (if memory serves me correctly) compared to normally cast pistons, it makes them stronger by doing so, but at the same time can make them somewhat brittle - I have heard. Forged pistons are made by stamping the piston from a chunk of hot metal rather than by pouring and casting. The metallurgy of a forged piston is such that the metal grain runs in favorable directions making it a stronger piece than a cast or hyper eutectic piston.

Bottom line - hypers are a compromise on cost vs forged pistons, but they are not as tough a piston. You must also run more piston to wall clearance with forged pistons due to their expansion characteristics. It really depends on what you want to use the motor for. If you want to build a motor for racing and use nitrous you want forged pistons. Street engines are fine with hypers and cast IMO. Forged pistons are more money than cat or hypers. Im pretty sure there are zero deck pistons available from silvolite that will meet your needs.
 
my 69 barracuda had been running KB191 hyper pistons for 5 yrs...

best et is 10.77...so dont sell the hyper pistons short...

they are a very good piston for bracket racing...

there are alot of 360 running KB107 pistons... my 73 duster has them...i am installing another set in a 360 that will probably run mid 11 in vegas.

just following the instructions....tigher clearance...and make sure you gap the top ring correctly..
 
I'm running mid-11's with KB 107 pistons. Third season, starting my 4th season. I hit them with a 125hp shot of nos every now & then. it runs 10.80's with the NOS. No concerns.
 
A good answer...

Another problem is overall strength.

The cast pistons are not designed for high piston speeds. They are good for stock stroke, and engine speeds that keep the pistons below 4000 feet per minute.

Hypers are stronger, but as mentioned, they are like steel vs tool steel. Hit a cold chisel hard, and it fractures because it's tremendously strong, but brittle. hypers are stronger, but can be brittle. hyper alloys are not all created equal. So attention has to be paid when machining to get the right clearances for the brand used. Hypers can handle faster piston speeds than cast. IIRC around 5000FPM. are as such they can handle racing abuse. They are strong enough to take the force of NOS. But, if you go lean, and the engine detonates, they tend to explode because they are so brittle. Also, they are usually lighter than a factory cast piston and are available in a lot of good designs for various heads and uses.

Forged are the strongest, but they also are very flexible. Cheap forged are heavy, and limited in designs. Better forged are more money, but lighter still, and much stronger. Forged can handle piston speeds of over 6000FPM, which are typically generated by a stroke of more than 3.75 and rpms starting as low as 5800rpm. The longer the stroke, the lower the rpm that the safe thresholds are crossed.

I wont use cast or hypers in a 4" small block, or any big block stroker due to the piston speed issue.
 
Used KB's in a 12sec 360 (hardtop/Dart)

Were fine till I had a detonation issue now use forged pistons

Cheers

Benton

KB 107.jpg
 
The Sealed Power H116CP pistons are an alternative to the KB107's. Anybody here tried them with success?
 
SP makes a good piston too. I wouldnt worry about using them either.
 
im loking at some kb191s or kb107s for my 360. im wanting zero deck, wut do i tell my machinest? how much is removed to get zero deck.i will be using some 68 x heads about 65cc.and keeping the 4" bore im guna try some 73 318 rods.i have a crower 282,292/480,503 cam,any ideas or help?
 
I am looking at putting the 11:1 kb pisons in my 318 with small valve j heads so I am looking at getting around 10.5 when I am done. I was looking to see if there was an alternative to the keith pistons. Help and advice would be appreciated. The block and rotating assembly are going to the machinest soon so I need to make a decision soon.



Mopar Jeff
 
If you tell your machinist you want zero deck, it's up to him to set teh height. Because factory blocks are all over in terms of "tall" (and they are always taller than they shold be) it's easy. He totals up the compression height of the piston, the rod length, and 1/2 the stroke and gets a number. then, he measures your block and finds the height it is now. He then removes the difference, and viola! instant zero deck...lol.

Jeff, is there a reason you want to avoid the KB brand?
 
moper said:
If you tell your machinist you want zero deck, it's up to him to set teh height. Because factory blocks are all over in terms of "tall" (and they are always taller than they shold be) it's easy. He totals up the compression height of the piston, the rod length, and 1/2 the stroke and gets a number. then, he measures your block and finds the height it is now. He then removes the difference, and viola! instant zero deck...lol.

Jeff, is there a reason you want to avoid the KB brand?
Click to expand...


There is no specific reason. I was just curious if there was a cheaper option and if there was a better option for the price.


Jeff

Post script: also that is why I was saying I appreciate advice.
 
I'm running the sealed power pistons in my 360 and have had zero issues for about two years now. Very nice piston for the money. They are claimed to be a "matched set".
 
are the kb191s and kb107s mached sets?im also looking at speed pros flat tops, im wanting good compression to suport 400 to 500 hp and still run pump gas like 10.50/1 or 11/1?
 
I was about to ask the same thing, pros and cons... One thing I still need is where to get piston rings for a 30 over 318
 
That one piston looks like it got pulled apart. What was the ring gap and was it juiced at all?

I've never had an issue with KB's. My friend has a set of 107's in a 360 making about 585hp and running up to 7500 rpm. Been that way for a few years now.
 
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