i am building a 400 stroker motor with open chamber 452 heads, stock 440 rods, and a stock stroke 440 crank. i am aiming for around 500 hp, maybe a little more. will hypereutectic aluminum pistons work? if they do i would get the KB280 pistons, or do i need forged pistons? the forged piston i was looking at is the KB icon 837 step dish. is the step dish head the same as a quench dome like on the KB280 piston? will the KB icon 837 be okay with open chamber heads?
400 stroker piston help
- Thread starter mopar1994
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The hypers will work fine as long as you set them up according to KB's top ring gap specs. It's all on their web site.
moper
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The 3.73 stroek is a factory 440 so hypers will be fine. However, I would not plan to use a quench dome design as the setup alone is much more expensive to get any benefit from. Either plan to have the domes completely milled flush with the flat top, or upgrade to a set of forged flat tops (the Icon823s). The flat tops at .010 down in the hole will be around 9.9:1 static so you'll want a cam around 230°@.050 to run well on pump unleaded. You'll also want to make sure teh shop sets the deck height... Not just "cleans up" the block's decks. 383/400 are typically taller than blueprint spec by a bit.
Call Marco at United Engine and Machine. He will help you. He told me that the KB280 will a LOT of times actually work with a stock unmodified open chamber head and give the correct quench unmodified. They tell you on the site that the head must be machined just to cover their butt. Marco is da man. He will help you. Why mill the head off the piston and lose compression when you can run it effectively? If you're gonna take somebody's advice and mill the heads off, at least measure your engine and see what you need to set up a good quench. If you're gonna pay for milling pistons, you might as well set it up right cause the cost will be the same to mill them flat or for quench....and the thing is, you might be just perfect for quench without machining a thing. You never know til you measure. Call Marco. You'll see.
moper
Well-Known Member
I disagree with Marco. There's a differnce between "working with", and working as designed. My KBs didnt need machining to get the proper quench distances I use. But the heads sure as hell did. Chambers polished and re-shaped to get depths and volumes equalized, then milled .040 on one and .045 on the other to get .035" quench. And that was measuring 3 heads before I gave up and said I'll just make it fit right instead of checking more heads. I know of no-one who actually checked and set them up that didnt require a lot of blueprinting type work. Yes, milling domes off is the same as milling them down. But the end result of trying to get the engine to have effective quench and squish makes the open chamber design much more expensive to get right. Not working, but working effectively.
Ok.
needsaresto
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At least the "blueprinting "work can be done at home if you know what to do. I would go this route if using the dome piston.
Of course 40 year old heads will need a lot of work to make fit right in just about any domed piston app.
JoeDust451
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Get some good forged pistons like Ross/Diamond FTs, there a bit pricey but well worth it in the long run. Thats what i ran in my 400/451, its still going strong after 6 yrs. of racing & over 250 passes.
today i stopped by mancini racing to talk to them about pistons. they recommended diamond pistons and they said i could use flat top pistons and an open chamber head to get about 9.5 to 1 compression. i will be running it on 93 octane.
JoeDust451
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Good choice 8) This way if you ever want, you can blow some nitrous through it with peice of mind. I spent alittle extra & ran the Z-Gap rings along with Wave-Lock rod bolts, like i said, its still being raced today with 2 660 carbs, the new owner just install 4.56 gears & now shifts it at 6800 & traps at 71-7200 :-D.
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