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  #1  
Old 07-05-2003, 11:26 PM
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Default kb-silvolite piston feedback?

Any feedback from mopar land?


I've heard they are having problems with thier 408 pistons.

I'm more interested in the big block ones, anyone has tried.

Consistant weights(relatively, of course)?

Heights and stuff seem to be as specified?

Durability?(Not collabsed after a year or what?)

All feedback welcome.
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  #2  
Old 07-05-2003, 11:44 PM
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I have heard of three guys breaking the head of the piston ....... and then that takes the whole motor with it.

The pistons I hear are very brittle.

I would never use that type of piston....ever.
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  #3  
Old 07-06-2003, 12:30 AM
Tarrbabe Tarrbabe is offline
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Cool Never used them but.......

The ring clearance is very critical. You MUST gap the rings according to suggested specs. A lot of broke pistons when they first came out because of that. I have seen a set out of a sbc that was ran for 2 years on the dirt track and they were in great shape. You must get the proper end gap or else broken pistons with these.

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  #4  
Old 07-06-2003, 01:45 AM
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I build several 400 plus hp engines every year with them. Very close in weight and sizes. Very happy with them. As mentioned before top ring gap is critical. It's up closer to the surface than most. The upper should be gapped about 18 and the second ring can be stock to like 16 at the most. Never lost a piston yet. Never had a brittle problem with them either. Course we dont have det problems on 110 race fuel either. But over all great pistons.
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  #5  
Old 07-06-2003, 01:45 AM
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Confused

I have never used them either............

BUT you are saying that butting end gaps of the rings will break the piston ??

Now that is a fragile piece .......... IMO.
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  #6  
Old 07-06-2003, 01:48 AM
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A lot of cast or hyper pistons with the upper grove up high like these will bust if the gaps butt. Too close to the top I think. They should be lowered some. Some pistons have a heat sink and then a ring land. I might try some r&d and move the ring land and leave the top one as a heat sink and see what it does.
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  #7  
Old 07-06-2003, 04:07 AM
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Due to the thin face, they will blow through if you have detonation (ping).
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  #8  
Old 07-06-2003, 07:39 AM
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I have a friend who runs 13:1 KB's at the track for 3 years now and no problems at all. The ring gap is critical as they say in their web page. The piston is a good cross between cast and forged at a low price. Not as strong as forged but better than cast. I just bought a set for my +.30 400 big block.
Bob
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  #9  
Old 07-06-2003, 10:30 AM
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custom880; Glad you mentioned there web site. Most people over look the sites.

Anyway. I have run them in the street for a while now. No problems at all. And, I'm not kind.
The biggest problem I have seen is 1 of 2 being;

1.) Ring end gap
2.) abuse understress in example of poor timing, and or fuel quality/octane issue that leads to pinging.

They tell you that the piston can fail under detonation. Which should never happen no matter what piston you have anyway.

The ring gap issue. If you didn't read the instuctions to a piston they tell you needs a critical gap, well, you got what you deserved.
The silicone makes it stronger but brittle is a catch 22.

I can understand when Mr. Fiberglass says he would never use them when you read all these people braking them. He ethier will use a cast piston for stock to mild build or he steps up to the plate and drops the coin on a quality forged unit.
Sometimes, it just makes good sense. Overkill? Maybe. Long life from overkill? More than likely. (LOL)

Also, theres allways a group of people tring to push 600 HP (from 300 cubes for example) , out of these things at crazy abuse levels. Ethier drag or dirt track. Right piston for the right application.
For the street, I say no problem.
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  #10  
Old 07-06-2003, 11:35 AM
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i've got kb-107's flat tops in my 360. there have been no problems with mine.
i think it all comes down to attention to detail.

the manufacturer doesn't have instructions about assembly written for nothing you know.
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  #11  
Old 07-06-2003, 12:23 PM
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Just finished a 451 for a customer. Don't care for the Micky Mouse roll pin oil ring locating setup. All were same weight to a gram. The long Mopar rods will probably let the KB's live longer under adverse conditions. Large top ring end gap is a little scary but doesn't have a lot of blowby.
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  #12  
Old 07-06-2003, 06:58 PM
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Hay......some(MOST !!) of them have to be OK - they must have sold thousands of sets.

Does anyone have a spec on where the top ring is on these pistons? ........... vs a same application forged or OEM cast piece?
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  #13  
Old 07-06-2003, 07:57 PM
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I use KB237's in my 440 with about 450HP. The motor was really beat before I built it and it had the stock cast pistons with no problems. The KB's were about 110 grams lighter per piston with the pin. The ratio is about 9.5 to 1 and I run pump gas (92 Sunoco) with 906 heads. I've run the Cuda hard, over 6 grand and it runs great. You can really tell with the lighter piston. The motor rev's much guicker with a lot less strain on the stock rods. Everyone is right about the ring gap. Put in the proper gap and don't worry if you go a little bigger. Just like every thing else about engine building, if you do job right you won't have any problems. If you don't, you will.
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  #14  
Old 07-06-2003, 08:16 PM
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Quote:
Originally posted by JoeGrapes
I use KB237's in my 440 with about 450HP. The motor was really beat before I built it and it had the stock cast pistons with no problems. The KB's were about 110 grams lighter per piston with the pin. The ratio is about 9.5 to 1 and I run pump gas (92 Sunoco) with 906 heads. I've run the Cuda hard, over 6 grand and it runs great. You can really tell with the lighter piston. The motor rev's much guicker with a lot less strain on the stock rods. Everyone is right about the ring gap. Put in the proper gap and don't worry if you go a little bigger. Just like every thing else about engine building, if you do job right you won't have any problems. If you don't, you will.

I have the flat top KB's for my 400 B block with a set of Eagle rods, sealed power rings, and a huges cam (should have gotten the Racer Brown but oh well) stock 452's and a Performer RPM with a Demon850. Ready to plop into a very heavy 73 Charger. I am interested in what it will be able to do. The converter is a 3800 stall Dynamic hooked up to a torqueflight with 8 3/4" 4:10's. Should be interesting.
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  #15  
Old 07-06-2003, 10:39 PM
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Well, with Comp X-treme Energy cam, Performer RPM manifold, 750 Holley, roller rockers, MSD ignition, headers, 3.91 sure grip and 2500 stall slightly reworked 727, the Cuda will run 13 in the quarter. Traction is a little problem but I think with more practice I should be in the high 12's The weak link is the stock 906 heads. I have a pair Edelbrock Performer RPM aluminum heads planned in the future. That should get me in the mid 12's, I hope.
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  #16  
Old 07-06-2003, 10:50 PM
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ring end gaps should be .004 per inch.that will never let you down
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  #17  
Old 07-07-2003, 12:52 AM
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That is safe for a lot of things, but I don't know about a KB. Personally, I would go for a Forged stock replacement piston, because they are much stronger, and not a whole lot more expensive. You do give just a little on the weight (forged are a touch heavier), but to me, the strength of the product outweighs the little bit of throttle response and power I lose with a forging. Plus I know I can set my gap at .003 or .004" per inch of bore (depending on purpose of the engine), and be safe.

KBs are brittle, there is no doubt about that. I would never do anything to a KB hyperutectic casting that I would not do to a standard hypoutectic cast piston in an engine that I cared about. That includes: no more than 125 shot of nitrous, no more than 8 lb. of cooled boost, and no more than 11:1 compression. The reason for this is the fact that a hyper-u piston will run hotter on the crown than any other type, due to the fact that heat is not transferred as well through hyperutectic alloy as is low silicon aluminum alloy. This causes the crown to swell and thus close the ring gap more and more as the heat collects at the top of the piston. That is why they tell you to set the gap looser than you would on a forged piston. The gap is supposed to close to the same thing once the engine is at operating temp, but under extreme heat as encountered with a performance engine the piston continues to swell until the gap closes, the ring ends butt together, and the top gets yanked off of the piston. As stated by the other gentlemen, they are brittle and the crown is thin as well, so they are not detonation ready, which happens in any drag engine, so that makes them a no-no for me. I couldn't say about circle track--dwc43 is a speedway man, I believe so apparently he can use them in his application with no problem.

A few real life experiences:

A friend with a Ford 460: KB flat tops, 13:1 compression, alu. Cobra Jet heads, put a 4300 pound Galaxie at 7.90 in the eighth. Went into the engine to fix a leaky copper head gasket and found he had broken a chunk off of the crown in the first year of the engine's life. Got Jeg's to break a set and got a single for $50, replaced it, went back through and set his ring gap for KB's ring end gap spec for Nitro Blown Mudboggers, which worked out to .080" for his bore. Put it back together, ran worse due to the increased blowby, and he has never been satisfied since, but the engine is safe now for the most part.

Another friend with '75 Duster, 360 with KB domes, again 13:1 , but with iron heads, ran 8.20s in a 3200 lb car. The engine has been together for eight years, and who knows what his ring gap is because he is too lazy to check it. Removed the engine from that car and put in a Dart with 100 hp of Nitrous sprayed on it, again not a peep from the KBs, just blew a head gasket. That engine now resides in a '66 Belvedere, and who knows what he is trying to spray, but I would say he has had good service from his KBs.

Personally I have never run them. I have only installed forged pistons in the whole two engines I have built, and I will continue to do so when I start from scratch. For the extra (small amount) of money I spent on the forgings, I can sleep well at night knowing that the engines can take abuse. Next project: a recently freshened 383 with a set of hypoutectic Badgers (I think) that I scored for 200 bucks that had dropped a camshaft lobe. I can feel safe on the street/strip with no more compression than I have, and I will be out a whole 350 bucks or so if the engine goes south, but I think that my cheapos are just as strong and a lot more cheapo than the KBs, and I would pick them first for my type of application. It is about economics and reliability. If you want to push it, go forged IMHO. If you want something mild, go with a cheap stock replacement casting.

Just my $.02
--deadhorse
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  #18  
Old 07-07-2003, 01:19 AM
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Damn dead....food for thought !

...and then there are some hypers for a 360 on ebay for 108$...FOR a set of 8 pistons.....doesn't THAT tell you something?
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  #19  
Old 07-07-2003, 01:27 AM
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Used? What brand?
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  #20  
Old 07-07-2003, 01:30 AM
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They were NEW and I believe that it was a buy-it-now price !!
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  #21  
Old 07-07-2003, 01:40 AM
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I might do that. I just have a problem with buying internals off of e-bay because you never know if someone found a problem with the stuff and decided to resell it. But if I could get them at that price from a reputable distributor, and I could trust the brand, sure I would buy some for a budget build. I don't think they are bad, just overpriced (when you buy them new from somewhere like Mancini's or Summit or Jeg's) for what you are getting.
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  #22  
Old 07-07-2003, 01:58 AM
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kb silvolites in a 68 sport fury edel heads .557 purple shaft performer rpm intake and 750 demon 4500 stall converter
4400 lbs race weight 12.51 @ 104
motor survived only a short time due to faulty oil pump =(
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  #23  
Old 07-07-2003, 07:07 AM
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Quote:
Originally posted by JoeGrapes
Well, with Comp X-treme Energy cam, Performer RPM manifold, 750 Holley, roller rockers, MSD ignition, headers, 3.91 sure grip and 2500 stall slightly reworked 727, the Cuda will run 13 in the quarter. Traction is a little problem but I think with more practice I should be in the high 12's The weak link is the stock 906 heads. I have a pair Edelbrock Performer RPM aluminum heads planned in the future. That should get me in the mid 12's, I hope.

Joe sounds like a fun ride. You might want to go with a bigger carb. I thought a 750 was good enough for mine but I was told 850. I didn't think the motor could take it but it does.
Hey you are from NT I used to live in Lancaster just outside of Buffalo
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  #24  
Old 07-07-2003, 10:46 AM
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Thumbs up Would buy them again......

I ran them in my 10:1 383 '69 Coronet. Love them, never a problem.
I MIGHT have had major problems if I didn't follow the instructions to the letter. There are pictures in the instructions of a mis gapped rings and the top of the piston broken out. Ring gap is critical as stated before. There is a complete list of different applications and suggested ring gaps. I found that very helpful.
I could see if someone setup his engine as a mild street car then later decided he wanted to run nitrous and then breaks a pistons, that is a major problem because NOS takes a different ring gap. How many people would pull the pistons out to change the gap?? (Very few)
EVERY failure I have heard of was from improper setup.
Plan to buy them again for my 360
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  #25  
Old 07-07-2003, 12:17 PM
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Just an FYI post. It was mentioned in an earlier post that the KB's were lighter than "forged". The KB's for the 451 are 550gr and 191gr for the pin. Both Ross and JE list their 451's at 524gr and the pins are lighter as well.
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  #26  
Old 07-07-2003, 05:29 PM
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They are lighter than stock which requires rebablancing even for factory parts, grandma's grocery getter. They do require speical top ring gap, do to the higher ringland being higher in the water jacket, they wont take lots of detnation, any could be cause engine failure, they dont reccomend NOS but says 100 shot should be ok, sound like russian roulett to me. I have run then in a few engines 107's for a 360 and 237's in a 440 there, ok for a hot street car/racer but for a car that will see mostly or all track, pistons, isnt were you want to skimp, I can do without tht fancy vavle covers/breather, and cool trick braided hoses, when it comes to a high quality race piston. I reccomend Ross. I have had NO failures from the KB's, but for the same cost I would go with the TRW's 6 pack pistons in a race engine, there a little cheaper through Summit I belive.
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  #27  
Old 07-07-2003, 06:24 PM
JoeGrapes JoeGrapes is offline
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Hay Custom, you know where NT is ha? That's GREAT. I go to Lancaster all the time. Your right about the carb. I really should have an 850. One thing everybody should keep in mind about the pistons is that it all depends on what your going to do with the motor. KB has been making them for a long time with great success. As long as you use them for the right application. I wouldn't go woodchuck hunting with a shotgun any more than I would go deer hunting with a .22
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