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#1
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keith black hyperutectic
ok, i have to ask, has anyone besides me have trouble with these? i have seen more of these things break tha any cheep cast piston, even one of our own motors (350 chevro), just wondering, cause i helped a friend with his big ford and he called this morning and said it broke a piston last night pulling a hill. this is like the 10th time ive heard this story. (our 350 chevro popped a piston pullin a hill). ive never used these in my dodges, ive always use cast or forged.
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#2
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So Far no problems with the #232 pistons in my truck, and I have been hard on them. I did pay special attention to gap the top ring as they recommend. it has alot more gap than standard. Also the small end of the rods needed to be narrowed to 1" to use this piston.
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#3
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No problems at all. I have them in my 440 and I've run them at the strip to about 6500 rpm. My motor is not stock with around 450+hp. There're stronger than cast but not quite as strong as forged but a lot lighter. So as long as your not using nitros you'll be fine. 451MOPAR is right about the ring gap. VARY IMPORTANT! You must follow KB's directions. I would use them again for a hot street car. As for pure race I'd probably feel better going with forged pistons. I have to think that your friends are installing them with to tight of a ring gap.
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#4
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No problems here with them
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#5
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mus be a brand X thing, the 350 and the 460 gaps were set exactly what they were spose to, i dont know bout the otrhers. ill run forged thank you. there not that much more money.
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#6
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I only have about 500 miles on mine, but no problems. KB 107+.020. Sealed Power rings, custom filed by me.
Jay |
#7
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We've used them in our dirt track engines for years. Never had a problem with them. Just set the top ring gap to 18 adn the second one in the 16 range and your good to go. Weve used them in 360's making well over 400 hp.
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#8
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So, the rods have to be machined to fit these pistons, does that go for all engines?
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#9
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I did not have to machine anything to use them. We also used them on '68 or '69 full floating pin 318 rods. The 318 rods are a little litghter than 360 or 340 rods and hold up just as good. Run them as high as 6800 with no problems.
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#10
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Thanks for that, dwc43.
Mine is a 340 ('72) and I have been eyeballing them over forgings, to up the C/R in this smogger. I did obtain a used set of +.030" (I think factory replacement) pistons made for a 70-71 engine that look to be about 10.5 to 1 C/R, and I am thinking about going ahead with those. They are probably cast, but would be a nice cost saver if they won't break. It will be a street/strip engine. Opinions? How much HP are they safe for? |
#11
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Welcome, anytime. KB's? Well, I know we get way over the 450 mark with them just fine.
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#12
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Thanks again.
I guess my text was a bit "busy", what I meant was: how much HP are those "factory original" high compression castings safe for? Are they worth using or should I bite the bullet and buy, as a minimum, the KBs? We are slowly acumulating parts for this street/strip project. |
#13
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I'd most likely buy the KB's cause you don't know how they have been abused. I just don't like using some used engine parts.
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#14
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Good point, thanks!
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#15
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Welcome, anytime.
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#16
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The machining of the rods is only needed on some of the pistons. The #232 "D-Cup / Quench" pistons require it, but most of the other pistons do not require the extra machine work. although the D-Cup / quench pistons seem to work well, Keith black could have done a better job designing them.
At least they put taller quench pads on the newer #372 pistons so the heads don't need to be milled as much. When I checked the #232's for clearance, the quench pad needed to be slightly modified to clear the ridge around the intake valves (Just more work to consider when building a quench type engine.) |
#17
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kb pistons
I have a buddy who lost motors due to KB piston failure. big block fords. pistons broke off in chunks.
I run a set of KB in a 360 once. held up but was noisey . they'll hold up for street duty.
__________________
Sapporo Man |
#18
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yup, thats what these did , ill use forged thank you>
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#19
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THAT is a bit scary.... Just exactly what is "hyperutectic", not cast, not forged, but???
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#20
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I believe hypereutectics are still cast - the difference is the high silicon content. It's supposed to make them less prone to thermal expansion and wear, but doesn't necessarily make them stronger. It started to be used in piston construction so auto manufacturers could run tighter clearances, and not have piston slap while engines are warming up. I guess that's why you're supposed to run the ring gap wider - less room to expand, and the top ring is placed a little higher and runs hotter. Strength still depends on good design, and reading the previous posts that might not always be the case, I guess.
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#21
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i stat my forgies at 30 below, slappin pistons never hurt nothin
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#22
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Never had any problems with piston slap or rings poping the tops off. If your having problems with KB's your not setting your engine up correctly. With proper ring gaps and clearances they work great. Only thing I would not use them in is a N20 engine.
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#23
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thought I would chime in here on this as it seems people have made a lot of mistakes with these pistons....
as some have stated...YOU MUST set the ring gap according to KB instructions..if you have any doubts call them...they will tell you what you will need to do with your application, but for the hypertechtonics (mind my spelling).... They are actually good light pistons. The thing is with these, you cant set the normal gap settings becuase when they get hot, they expand, and if your ring gap is too tight, BAM, broken motor...I ahve seen over a dozen motors run on these pistons on show, and street hot rods, I am not sure as to what their max hp and RPM is, but I do know that never have seen a problem with them. They do have down side and that is you CAN NOT run N20 on them, if you do, kiss those pistons goodbye. They have too high of a silicon diet in them that they jsut cant hang. anyways, hope that clears up a few things....just my 2 cents. |
#24
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Quote:
I cant say what there max level is, but I know we have run them in dirt track engines with over 450 hp and turned them as high as 6800 without any problems so far. It's all in the preperations. |
#25
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Street parts for street RPM and Race parts for race RPM
Quote:
The 429, 460 can't take much over 5500 rpm with street parts. Pistons chunks kind of sound like to much timing and way over RPM. |
#26
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Actually i used to have a KB catalog and it said the hyperutetic piston were designed around use in nitrous engines,it just with nox you need to increase the ring end gap even more,waynebo
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#27
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kb pistons
I have seen KB's break at the wrist pin twice in big block fords.
__________________
Sapporo Man |
#28
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since I posted this, A guy I know, who had his engine professionaly built, blew a KB at 70,000 after rebuild. (440)
No thanks still....I'd use OEM pistons first. |
#29
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KB's pistons will NOT take any kind of detnation at all, I have a run a few sets in the past, and never go there again. I never had engine failer, but I like a good forged piston in my hot rod engines, or heavy tow type engines, for reasons mentioned. They do require correct top ring gap, just follow manf reccomendations.
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