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Do you guys like KB pistons for a street motor....

bandit67

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Guys, found myself needing to rebuild a 440 , a 76 block, for my 73 B body. Time to purchase internals and looking at KB 237 flat tops. Plan is to use the 452 heads for a mild rebuild. So, having not yet ran any KBs, I understand they are a decent replacements rather than twice the price custom pistons....any opinions.....thanks....
 
These are what I put in my 383. Just as an FYI you will need to use a ring file to expand / adjust the top ring end gap for the Hypereutectic aluminum.
 
I've got over 20,000 miles on mine so far, second time using them.. no complaints. They may not be as durable as forged but for a street car they don't have to be, the tighter clearances I would think would cut down on wear over time as well.
 
Hyperutecic’s are good slugs. Pay attention to ring gap.
The tighter clearances will make it a quieter engine.
I’ve used them 3 times. Twice from KB and once from Speed Pro.
 
I've got those pistons in my .040" over 440 and so far so good. Great choice for a naturally aspirated motor. If you intend to boost or use nos I would go forged.
 
I've had hypereutectic pistons in my charger for 23 years now almost 35k miles.
They've been perfect.
 
What are you guys using for piston rings? I am going to be following
this thread. I've used Hastings Rings before.. there piston rings Manufacturing
plant is only 30 minutes from our shop.
 
With stock open chamber heads use the quench dome pistons
I helped design these pistons specifically for your application and they really work
I use ductile top rings
Flat top forged-no quench do not solve the big problem
 
Tom Hoover, “father of the 426 Hemi,” told Hot Rod that he had discussed the Elephant Engine’s design with new-Hemi engineers.
Three of his major suggestions — raising the camshaft (to shorten the pushrods, reducing valve-train inertia and simplifying the rocker arms), using twin spark plugs, and adding squish area (for more light load/low speed efficiency and reduced emissions) were adopted.

Squish and cam (reduced overlap and opening ex later and closing earlier (closing the lca and reducing ramps)
can reduce EGT by 800 degrees
 
One Mopar book says the 452 heads are about 90 cc heads. The KB book shows the KB 237 flat top piston with 90 cc head coming in at about 9.7 comp. The quench dome piston, KB 236, with 90 cc comes in at about 9.9 comp. The quench dome is listed to .075 in height and side notes say that to achieve effective quench , head milling is usually required. I m not sure how much quench is effective quench and how much trouble would be to ensure and achieve that....so , thinking the 237s were the easier choice. thanks wyrmrider.....
 
One point only a little off track, a basic "pocket port" on the 452's will gain a lot more power & torque no matter what you use for pistons or a cam. Mill the 452's to be flat, if not for a bit more CR.
 
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wyrmrider, I have not yet pulled the trigger and ordered pistons yet. Been seeking a bit more info as you led to, using the quench dome pistons. The 452s are huge open chambers and may support 'effective quench" as is , but not sure how much that needs to be. Can you share any more info you have .......thanks....
A bit of pocket porting is in the works, but first , as I have no info on these heads, must wait and see if the machine shop notes any problems after clean up and inspections. If any thing prove the heads unusable, then other heads would be needed. If smaller chambers are used, then quench deck milling would be needed.....we love it simple, but sometimes not.....thanks all...
 
I’ll just say the more quench the better. Be it squeeze distance (less) or area.
 
I'd like to hear how much difference there is between the quench dome style piston is compared to a flat top (HP & torque) with a 906 or 452 style head with minimal milling (84-86 cc).
 
The quench dome pistons have their place, and if limited to using an open chamber head can create a bit of quench to help prevent pinging/detonation. Depending on design may increase compression too. I found that they do take a bit more planning/inspection machine work to get the most out of them. First the block decks should be machined so all the pistons have the same deck height. Some blocks are off (different deck heights) front to back and side to side.
Then the open part of the cylinder head chamber needs to be the same depth from the heads deck. Again one head can be different than the other.
Then need to figure just how tall the quench dome needs to be, or how much to mill the block and heads to achieve the correct quench distance.
If you plan to use a 0.039-0.040" head gasket, then the quench dome should be at about zero clearance with the heads on and no gasket.

I usually just run a flat top piston (or D-Dish) where the block can be milled for about zero deck with the piston, and then use a closed chamber head.
 
ok451
What 451 said without closed chamber head here
"The 452s are huge open chambers and may support 'effective quench" as is , but not sure how much that needs to be."
open has no quench period without more milling than they can take and 0 deck with ft pistons still takes some milling
you can run some more compression, not as fussy on the timing or the gas you will drop many degrees of EGT if you keep overlap and exhaust opening down
I've seen 30-50ft lbs but most at low and mid rpm
below torque peak
top end hp may not change much but compression helps
 
I'd like to hear how much difference there is between the quench dome style piston is compared to a flat top (HP & torque) with a 906 or 452 style head with minimal milling (84-86 cc).
What the two guys said above but there’s more to this than an easy, “It’s an easy *** more hp and TQ.”

You would have to equalize both pistons to use one head and that alters the game with the head altered. Even if you had two heads modified to accept a flat top and then a dome, the test results could not be considered equal. Nether piston can not take advantage both heads.

The best way you can call this is to say the domed piston will give X amount more compression (Lets pretend 1 point.) which would equal 3% on most builds of a high performance nature. But only that narrow window. That number percentage changes with each build. The weaker the build, the less difference in power and the reverse, more power in a stronger higher HP build.

The question is splitting hairs in the wind while at full gallop. And your cutting tool is a baseball bat.

If you have open chambered heads and need a high compression ratio, then get the domed slugs and be done with it.
 
What the two guys said above but there’s more to this than an easy, “It’s an easy *** more hp and TQ.”

You would have to equalize both pistons to use one head and that alters the game with the head altered. Even if you had two heads modified to accept a flat top and then a dome, the test results could not be considered equal. Nether piston can not take advantage both heads.

The best way you can call this is to say the domed piston will give X amount more compression (Lets pretend 1 point.) which would equal 3% on most builds of a high performance nature. But only that narrow window. That number percentage changes with each build. The weaker the build, the less difference in power and the reverse, more power in a stronger higher HP build.

The question is splitting hairs in the wind while at full gallop. And your cutting tool is a baseball bat.

If you have open chambered heads and need a high compression ratio, then get the domed slugs and be done with it.

I think you mis-read type of piston? Not a Dome piston for compression, but a "quench dome" piston which is more for resistance to detonation than to raise compression. I built my 360 LA engine with the KB-232 pistons. Really designed for the Magnum 360, but these pistons have 0.050" raised "Quench Dome" to fill the void of the stock open chamber heads, even though the pistons are a 18cc Dish design.
 
I think you mis-read type of piston? Not a Dome piston for compression, but a "quench dome" piston which is more for resistance to detonation than to raise compression.
Ummm, well yes to a degree. My reply was more geared to the OP. But after reading your post again,
:thumbsup:

I built my 360 LA engine with the KB-232 pistons. Really designed for the Magnum 360, but these pistons have 0.050" raised "Quench Dome" to fill the void of the stock open chamber heads, even though the pistons are a 18cc Dish design.
I had to go to Summit to be on the same page.
I see what your getting at.
upload_2020-8-19_8-51-2.jpeg


Getting back to the big block.... LOL..

The open chambered heads need a bit of dome to fill the void. The on line calculators will help with the math to find out what the new ratio will be.

What are you guys using for piston rings? I am going to be following
this thread. I've used Hastings Rings before.. there piston rings Manufacturing
plant is only 30 minutes from our shop.
I, at least, like a moly top ring.
 
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