ddn

My current situation dictates that the only piston I can find for my application is a Keith Black Hypereutectic. What's everyones opinion on these? I know they don't like detonation, but who plans for detonation?

The motor will be a 500-550HP 454, with a 100-150HP shot of nitrous. Nothing radical.

corvgreg

With that level of power and the nitrous on top of it, I'd recommend a forged piston. A little noisy when cold, but your piston will take the abuse. If TRW doesn't do it, then Sportsman Racing(part of JB Piston), Ross, or Wiseco would work. I put Wiseco's in my 6" rod 383, and the quality is very high.
Without the nitrous, the KB's should be okay.

mountainmotor

There are some quality issues with the KB's.Some motors get flogged and last while a Farm truck spits it's guts out at a city intersection.I personally don't like the idea of running a performance motor with such tight piston clearances anyway. Especially a 454 with it's rod stroke ratio.Clearances like that warrants 10/30 motor oil to lube properly but you have cam and springs that need 20/50 or straight weight racing oil to survive.Another mismatch of components for sure.For long term reliability nothing can beat a forged piston .I think you should check to see if that block will hone to size"4.314-4.316" and in the mean while I will check on some .070 pistons for you.
Later Gator

ddn

mountainmotor: I'm not hot on the KB idea at all, not for this engine, and I think you've pretty much solidified it for me. I called JE and they have nothing available with a small dome. Huge domes abound. I also called Competition Products and he couldnt help me much other than the KB.

I just called the machine shop, the guy's pretty helpful. He said he'd measure everything up, check it out, and see if it would be alright to go with the .060 over pistons honed out. He says that generally the extra tolerance is built into the forged piston, so you don't have quite as much extra as you'd think. Hopefully we can do that.

Otherwise I'm afraid I either need another block, or bend over while Ross gives it to me for a custom set.

I don't see any other alternatives.

norvalwilhelm

Hypereutectic pistons are stronger then you think. They have a higher tensile strength then forged. There only problem is they don't bend. They are not forgiving if overloaded. Forged bend. A hundred horse shot of nitrous will do them no harm. Detonation kills, rpm kills the nitrous will not if used in moderation. I don't know about KB pistons but alot of very fast car use hyper pistons. A few recently in hot rod magazine running in the 10s on cast.
Keep the rpm reasonable and nitrous at 150 max and they will live.

ddn

Problem Solved.

Machinist just called. Very helpful guy. He said that it looks good for just honing it and sticking with .060. I have a feeling this motor was rebuilt, the cam lobe went flat (and let me tell you it is FLAT) and they just said to hell with it. So it had very few miles. He said it'll rattle a little at startup, but forged do that anyway, and hey, it has character.

Crisis averted - I can run the TRW-2465 - I am a happy camper.

VegasJen

ok, this subject hits close to home for me. i'm building a 350 and was planning on running the kb hyper pistons. i was not aware of any problems with them. admittedly, my engine will be "mild" in comparison. .030 over 350 with 2.02 open chamber heads (shaved) with about a 284 duration cam at about 9.5:1 compression. i was not anticipating any problems with this and thought i would be more than capable of long term durability even when i may run into some mild detonation problems. occasionally, i can get some detonation in my original motor when the ambient temp is about 115*, just gotta love las vegas! :cool:

Flareside

David, the forged pistons you need are definitely available from SRP. Have you talked to them? They list 4.320 and 4.350 in flat tops, small domes (9:1), and large domes (10.25:1). The three popular rod lengths are all available in each piston.

-Joe


[Modified by Flareside, 7:21 PM 1/21/2002]

The Dude

Can't comment on KB directly, but hypereutecticc sure do make a cool tinkling sound when they shatter.

ddn

clutchdust: You should be just fine with Hyper pistons on that engine. From all I've read (especially today) the problem lies in the fact that Hyper pistons are TOO hard, and don't flex or deform as much as forged. I hear the top ring land loves to shatter. I wouldn't worry about it in your buildup unless you plan on running nitrous. Although the price difference is small, and forged ARE better.

SprintCarDriver

clutchdust, I just built a .030 350 using KB 11.5 dome pistons. I had a problem during install as I was running a longer rod (6.25) which put the oil ring up higer on the wrist pin. Other than that I have not had any problems.

mountainmotor

David,
That is good news your block has another lap left in it.More money to save for other parts like broken half shafts ect :D

Have they checked the crank yet?

Jason Staley

I've been running KB hypereutectic pistons in my big block Oldsmobile for 9 yrs now. They've seen 6000 rpm regularly at the drag strip with some runs up to 6500 rpm. I'm not sure exactly how much power I am making (never been to a dyno), but I run 12.0 @ 115 mph in the 1/4 mile. I have about 10,000 miles on the engine with no problems. If your not using nitrous or making loads of power, then I don't see any problems with using hypereutectic. Just my experience.

mountainmotor

Some have run for a long time w/o trouble.
Something is up with them though.At first the finger was pointed at insufficient top ring gap being the cause for broken lands.That does not account for the domes cracking though.Something about they draw heat to the center of the piston.I don't know for sure.
Another thought would be that the pistons are wrongly accused of failure when a head snaps off a valve or there was a gross over rev of the motor with a hydraulic cam with insuffcient valve to piston clearance ect
Too many variables
I see there is a huge price difference between the KB's and and Speed Pro.I guess that they are cast differently.

edited to add that a friend had a Jeep with a 350 Chevy set up for Sand Drags.7 years of abuse with missed shifts,blown clucthes and the GM cast pistons hung right in there.The motor was 10.3 compression.Go figure.

Oh Yeah,it was doing short wheel stands with a Comp HE 268 Cam :cool:


[Modified by mountainmotor, 7:51 PM 1/21/2002]

63Banshee

All I ever hear about around here is KB or TRW... anyone ever consider Ross, Wiseco, or JE? You want more rpm? Lose weight. You want quicker revs? Lose weight. You want more horsepower/torque at the flywheel? Lose weight. Yes, you will pay a bit more, but good Lord what a difference!

DeenHylton

I'm running KB's with a blower...the only thing I don't like about "hyper" pistons is you have to run a very large top ring gap compared to what you'd run on a forged or even stock piston...you end up with more blow-by from the very start. This could explain why some guys are breaking top ring lands, they are probably not reading the directions when they install the piston and don't set the top gap properly. You can't just buy a set of rings and install...you have to gap-em. I've stated this in another post, I called KB and asked about running nitrous with my blower. They said the piston will live as long as I maintain the proper octane level and pull back the timing as you increase the NOS shot (all to eliminate detonation). They said they sponsored a racer for a few years that was running a blower on alcohol making 1,200HP...he ran hyper pistons with no piston failures. As far as cost goes there is a big difference, about $230 for a set of KB's and upward of $550-650 for a set of Ross or J&E's...then again what's a few extra hundred when your building a $6,000-10,000 engine :lol:

Tom454

Ditto on the gapping issue... you have to read all of the instructions for BOTH the piston manufacturer and the ring manufacturer. There are "multiplication factors" & tables that come into play, and you MUST follow their directions. If not, then you deserve to have your rod bent. :)