[chappy_692000]

like i said in a previous post i'm looking for a 15cc D dish piston. the only way i see getting a forged piston is having it custom made with custom prices i'm sure. so in looking i see that keith black makes a hyper with a 15cc D dish. here comes the questions. how many rpm's are "safe" on these pistons and what are the pro's and con's with them? i'm lookin for a piston that will stand up to the abuse of my pulling engine i'm tryin to piece together. i would like to see 8k out of this thing and would like to not have to tear down every other week. also are these pistons floating or pressed pin? if popular rule says they won't last then i guess i wil have to loosen the pockets up a little but i really don't want to have to take that route. thanks daniel

 

[jpierce55]

I can't speak for the safety of your application here is my two cents: They are better than some say!

I ran a 2.3L from 95-96 with 13.5 compression and KB's. Everybody said they are crap and stay away from them. The engine shifted about 5800rpm's. It was no serious power maker by any means. Later I sold the engine to a guy who drove it everyday in a Ranger truck. He used high octane fuel with booster. The last I heard of the engine was in 99 or 2000 when he sold the truck. The 4 banger had an easy 20,000 by then from what I was told.

So they aren't all bad, but I can't speak for your 8k.

 

[rmcomprandy]

Some experiences.

If they are used in a well tuned engine, then they can be good for any kind of competition.
If there is ANY detonation then say good-bye to the top ring land; if they are made to withstand the forces of DEceleration then say good-bye to the piston top; if they are run too hot then say good-bye to the skirt; and be CERTAIN to run enough ring end gap that the rings can NEVER butt together at any time.
Other than that, you can expect good service from the KB hyperutectic cast pistons.

 

[DaveMcLain]

I've had excellent results from the KB pistons when I've used them but like any parts they are not without their strengths and weaknesses. They fit the bore closely and they expand very little when they warm up and these are both good properties when it come to having a long lived engine. They are avaliable for many applications, also a plus. The machine work on them is nicely done and the manufacturer gives you lots of good information.

They are less forgiving if your tuneup is out of whack or if you use cheap gasoline for your compression ratio. They do not like detonation and the ring gaps must be done properly as specified in the instructions. They are heavier than many forged pistons and they can be noisy if not fitted to near the minumum recommended bore clearance esspeically in applications where the pistons are "tall" like a 440 Chrysler or something similar.

If you think their features appeal to you and fit your application then I would use them, I have a set in my 1979 Ford 1 ton's 460 and they have been excellent over the past 30,000 miles. I've used them in circle track engines making 500 horsepower turning around 7200rpm with great results too.

 

[CarsByCarl]

8,000 rpm in a pulling application and hypers? No way. I wouldn't risk it. Maybe they'd work, but I think in the long run a set of forged pistons would give you peace of mind.

Maybe you can find another way to reach your desired compression? Weld up the chambers? Thinner head gaskets?

 

[jpierce55]

Chappy how much compression are you going to run? What fuel limitations? I ask because people tend to say that ring around the Probes helps a little when running a tight quench.

I take it the customs are out of your price range?

I hope things work out for you.

 

[chappy_692000]

i'm shootin for between 10.5-11:1 compression on 93 octane pump gas max

 

[chappy_692000]

the custom pistons aren't completly out of the question as i said if they will work great if not we will go custom

 

[ByronRACE]

NO

I say definitely not. If you'd like to look at broken hypereutectic pistons of all brands, pay shipping and I'll send you a big box full.

Granted, most of these died in supercharged applications with idiot owners that didn't know what detonation sounded like (or had the stereo up too high to hear it). However, the same idiots (save a few) were unable to break a forged piston in the same application after the rebuild...so what does that tell you.

I would never spend the money to build a race engine and not spend a few hundred extra bucks to put Forged pistons in it, whether custom or not. And, when making your selections...don't miss cp pistons when you're looking. Great product, great people, great prices...the finish on the stuff looks like fine jewelry and they are tough as nails.

Byron