how much boost can KB hyperutetic pistons take generally? I have a 9.2 comp 496 BBC (stock rod length) now but with my cylinder head (Brodix race rite) change that will go down to 8.5 comp. I have gapless rings in it so ring butting isnt an issue. I plan on running roughly 8 psi (no intercooler)and am going to get a wideband air/fuel ratio gauge so I can keep it from running lean. I think if I am careful with timing and fuel mixture I can get by. but I have heard horror stories off hypereutics shattering and letting the rod go instead of just melting.
I have saved enough to put forged pistons in and other mods but would rather put my money in other places if possible.
To make a long post short should I upgrade to forged pistons or can I use my money elsewhere?
Thank you!!

If you keep it out of detonation you should be fine. The problem is (at least in many cases) you end up wanting more and more! Boost is addictive and those pistons don't give much protection if you do detonate the engine a bit. Some good quality forged pistons are some extra insurance.

Jody

How much $$$ would the new pistons be.If it's more than $300, how about a Boost Cooler setup.Control detonation and pick up some free HP with some windshield washer fluid.............

Check it out here:
http://www.snowperformance.net/default.htm
graemlins/thumbsup.gif

I have kb pistons in my bb with a weiand 177, closed chamber heads, and around 9.2-9.5 cr, 6-8 #'s boost, msd boost timing box, no probs. Been running this for about 2 years now. Least no probs yet.She doesn't like regular though.

thanks for your input guys!!!
any one else have opinions? I am looking for as many point of views as possible.

As Jody said, if you don't detonate it you should not hurt it. My preference would be forged also,, but I do have a question.

Why do you think ring end gap isn't an issue??
I would not run less than .007/ inch on the top ring with the KB's & boost.

I am by no means an expert but I though that the gappless style rings had enough of a gap in the top and bottom part of the ring that ring expansion and butting wouldnt be an issue. I know it would with a standard ring.
Please correct me if I am wrong.

forgot to add. Please give me ring gap specifications for the first and second ring, so if I do put in different pistons I set them right.
Also if I put pistons in I was thinking about longer connecting rods. what are your views on this.
Thank you.

Originally posted by greasefire:
I am by no means an expert but I though that the gappless style rings had enough of a gap in the top and bottom part of the ring that ring expansion and butting wouldnt be an issue. I know it would with a standard ring.
Please correct me if I am wrong. =
What brand of gapless rings are you referring to?
Second groove or top?
Most are second groove & the top ring is a standard type gap.
The C&A gapless which is the only one I use is a step gap second & the end gap for this is a non issue but you still need to gap the top ring.
The Total two piece second still needs checking & again the top is a standard type gap.



===

Originally posted by greasefire:
forgot to add. Please give me ring gap specifications for the first and second ring, so if I do put in different pistons I set them right.
Also if I put pistons in I was thinking about longer connecting rods. what are your views on this.
Thank you. =

I would recommend .018-.020 top & .014-.016 second.
You can run them tighter but if it does detonate & they butt it will probably not end your day real good.
I am not a fan of gapless rings as I have not seen the "magical horsepower" claimed. Great cold leakdown numbers though & they do help keep alcohol out of the oil :D
If you are going to use gapless I would recommend C&A as they are one piece & I have taken apart too many engines with Total Seal where the gaps have lined themselves up rendering them kinda useless as a
"gapless"

My opinion of rod length for almost any engine we are discussing here is to use enough rod to get enough counterweigt into the engine for internal balancing :D
I have built & seen "short rod" engines that make good power & "long rod" engines & there are good & bad arguments for both.
It was summed up at the last ATEC conference by some of the top cup team engine builders at a roundtable discussion about like this
"You decide on a stroke. decide on a piston design & put a rod in that connects the two together & puts the piston where you want it" :D
Not a direct quote but you get the idea.
I do like a "longer rod" in higher rpm performance deals as it makes the piston lighter.
For a 496 I like a 6.385 rod & for 383/400's a 6" for the above reasons but if you already have a 6.135 crank the longer rod will not do much good except for the piston weight which isn't a huge deal in a 6000 RPM engine.

Just my opinions along with a few "excerpts" from some folks a lot smarter then I ;)

thank you for your valuble information
I plan on tearing the motor down and putting in a good set of forged pistons and longer aftermarket rods. Because I know if I dont I will regret it later. thank you once again. graemlins/thumbsup.gif

Originally posted by Wolfplace:
I would recommend .018-.020 top & .014-.016 second.
You can run them tighter but if it does detonate & they butt it will probably not end your day real good.
[/QB]Exactly right. Thanks for bringing up a little talked about tip. I've made the mistake of not running enough gap on the top ring. I wasn't even detonating, just building enough heat in the cylinders to butt the ends... Yes, my day did not end good. I broke the rings in three cylinders. I've run .020 ever since and have not had a problem.

My cousin had the KB's in a Pontiac 455, broke the top of the piston off - traced back to not enough ring gap. Motor was barely broken in and never really ran hard.

i use the kb pistons in my 454. i emailed them about nitrous. they told me i should be safe up to about 250 hp. but also stated the set the top end gap accordingly. i have a old cheater system i entertained using. either way I would be absolutley certain of proper ring end gap, timing pulled out and fuel delivery and quality. i don't think there would be much room for error. mike