Hypereutectic pistons and failures related..

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1wild&crazyguy

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Who has had failures with Hypereutectic pistons?
weather it be installation failure or otherwise.
any body scuff a skirt, break a land, melt the tops etc...?:read2:
 
1wild&crazyguy said:
Who has had failures with Hypereutectic pistons?
weather it be installation failure or otherwise.
any body scuff a skirt, break a land, melt the tops etc...?:read2:
Click to expand...

Mine are about 3 years old,no problems yet but I only drive the car 6-7 months a year.8)
 
I have 62k miles on the KBs in my 360. Virtually all new cars have them and I have put close to 300k on the in daily drivers.
 
I had a problem with them. I wish i knew where the pictures were at. There was a rod sticking up threw the top of the intake.

i would rather run heavy trw forged pistons than kb hypers. I think they have went the way of menards and walmart products. brand name but cheapened up to sell.

In a motor that will never turn over 5500 i think they "might" be alright. Over that rpm is just dancing with the devil. imo
 
Ironic how many people run a Chinese crank and ***** about pistons from Carson City.

The main failure I have seen or heard about has been due to top rings being too tight. The Keith Black pistons are a really nice cast piston, but a cast piston nonetheless.

Are you looking for an excuse not to run them?
 
Its looking like I be having to run K.B. Hypers :sign10:

Manici is telling me Speed Pro no longer makes .040 over 340 forged pistons. Seems like K.B. hypers are about it, if it was .030 over be a different story but my shop is saying no way, has to be bore out to .040 over.

I am going to ask for .003 wall clearance and .032 ring gaps
 
In a stock stroke small block with the correct ring gap they will work well. Strokers should go forged due to the excessive piston speeds.
 
ran them and beat them to death for years in stock and super stock, stock car racing, they wont take a hit, hit the valve and you'll break one, too tight a ring gap and you'll seized the piston land and seperate the piston into pieces....however, i would run them again in a stock or super stock class anyday, cheap reliable power on a budget, i wouldnt hesitate to use them.......however there is a hp limit to them, under 7k and under 500 hps they will live, once you get pass that point, time for real pistons and real rods, unlike most people I believe a cast crank will take more punishment than a steel crank, a steel crank will not twist, a stock cast crank proved to be reliable for many years in 450/500hps stock car motors, however they have a fatigue point, about 2000 laps we would throw away.....take a hard hit, seem like a cast crank would survive a steel one would crack or snap in half.....

it is a double edge sword, pass the 7k rpm point and 450/500hps, and you better have good stuff if you want it to live and be reliable....

speed cost money how fast do you want to go

Dodge29
 
I've been running KB 243's in my .030 340 for yrs.
I had the same no.5 piston weld itself to the cylinder twice.
the cause was cap rotor phasing in my poorly made mopar distributor.
I was frukin pissed to find this out on the second build.
I started .020 , scuff'd, then went .030, scuff'd, sleeved the no.5 hole & bought 1 new piston ground it to the weight of the rest BTW this is when I found they started making them in mexico cause the new piston weighed 8 grams more than the usa made.
SO right before fire up of the .030 set I checked into some theorys and found the dizzy was crap, so I bought an MSD pro billet and fixed 7200rpm all day no issues.


Next the 410.....
KB356 which I told the machinist to hone for 3 1/2-4 thou skirt clearance, he said huh??
I told him I punish my stuff which is why I run mopar to begin with, he says 'uhhh ok' built into the piston right..
Being tuned in as I am to my motors perfomance I decided to do a leak down on it and found 22% on all cylinders.....
so I get into the motor and pop some valves out[due to hearing air leak out the pipes during the test] and find all the out of the package ferrea valves were out of round...owner of the shop says I ran it too lean, BUT the mix was not that lean..I mean stainless distortion point is like 2200* and the pistons melt at over 1200* so...nope to being too lean, it was a valve manufacture issue.
Well...then I get to the drivers side and find 3,5,7 all had the beginings of scuff but didn't smear or ruin the skirts and barely scrathed the upper exhaust side of the cylinder which is odd being I'm running the same oil I have in every other engine of mine for yrs now, the same oil petty driving experience runs in all their cup cars...
Even funnier is when I dropped the no.1 piston rod on my foot and then onto the shop floor...I dead blowed the skirt back into shape and installed it.....well guess what?
The no.1 piston is the only piston not to scuff on that bank....

I've had machine shop failures before, it's hard to find a good one and that makes a lot of people resort to the highest dollar shops they can find since it makes them feel like the are deffinitely getting the best.
But really it's about them knowing what you want and doing it.

Unfortunately even though I know this machinist pretty well, he's trying to find every excuse under the sun to say it was my fault, which I would except if the reasons made any sense...

I'll be sticking a bore gauge in it and see where it really is, then a hone, new rings, re grind on the exhaust valves and back together it go's

ran good for being that fruk'd up...

anyways I had a feeling I would hear good things mostly about these hypers
it's when you use them out of app that they show weakness.
this 410 motor spins 6500rpm regularly.

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1wild&crazyguy said:
Next the 410.....
KB356 which I told the machinist to hone for 3 1/2-4 thou skirt clearance, he said huh??
Being tuned in as I am to my motors perfomance I decided to do a leak down on it and found 22% on all cylinders.....
so I get into the motor and pop some valves out[due to hearing air leak out the pipes during the test] and find all the out of the package ferrea valves were out of round...owner of the shop says I ran it too lean, BUT the mix was not that lean..I mean stainless distortion point is like 2200* and the pistons melt at over 1200* so...nope to being too lean, it was a valve manufacture issue.
Well...then I get to the drivers side and find 3,5,7 all had the beginings of scuff but didn't smear or ruin the skirts and barely scrathed the upper exhaust side of the cylinder which is odd being I'm running the same oil I have in every other engine of mine for yrs now, the same oil petty driving experience runs in all their cup cars...
Even funnier is when I dropped the no.1 piston rod on my foot and then onto the shop floor...I dead blowed the skirt back into shape and installed it.....well guess what?
The no.1 piston is the only piston not to scuff on that bank....

I'll be sticking a bore gauge in it and see where it really is, then a hone, new rings, re grind on the exhaust valves and back together it go's.
Click to expand...

All valves out of the box are not concentric to the stem. Maybe they forgot to grind them. Some of us are anal enough to even mark the valve stem where it comes out of the valve guide inside the bowl and index that when you chuck the valve into the valve grinder. Anyway, I always check a couple intakes and exhaust valves in each head by hand lapping the valves to check seal and seat width. Anything bad shows up real quick and easy to see.

As for the cylinder scratches, maybe it is the rings? Who gapped them, and what gap? Look for shiney spots on the ends where they may have butted at temperature.
 
had a 360 with kb191 pistons with hundreds of 1/4 passes on them..the 360 ran in the high 10 with J heads out in Vegas...

got a set of kb107 in 73 duster for 5 yrs now...

got another 360 with kb107 .020 but it is on engine stand waiting for something...
 
Never had any problems with them in mine just over a year. We also put them in two others with no problems.
 
66fs said:
All valves out of the box are not concentric to the stem. Maybe they forgot to grind them. Some of us are anal enough to even mark the valve stem where it comes out of the valve guide inside the bowl and index that when you chuck the valve into the valve grinder. Anyway, I always check a couple intakes and exhaust valves in each head by hand lapping the valves to check seal and seat width. Anything bad shows up real quick and easy to see.

As for the cylinder scratches, maybe it is the rings? Who gapped them, and what gap? Look for shiney spots on the ends where they may have butted at temperature.
Click to expand...

the top rings were at .028
 
.028 is still "tight" for K.B.

Check out their guild for ring gaps.

For Circle Track - Unrestricted .0080" per inch so a stock 360 bore should be .032

For Marine - Normally Aspirated .0080" -same gap as Circle Track

Street - Towing is .0080"

I don't know why they say for Street - Normally Aspirated .0065", guess that is for "normal" people. (those are the ones in the far right lanes on the freeway we go zipping past, ha ha)

The Wall Clearance is what really changes. Goes from Street - Normally Aspirated .0015" - .0020". Circle Track is .0030" - .0045". Marine .0030" - .0045"

Why Marine use is so much higher than "normal street use" IDK but like I said, we aren't "normal street" I guess.

I am asking for min Marine spec's (good point if the shop will listen thou)

KB Pistons for Automotive Applications:
http://www.kb-silvolite.com/kb_car/clearance_pop.php
 
Quote from the K.B. web page I just posted the link.

"Excessive spark advance, lean fuel mixture or too much compression for the fuel and cam used will make heat sufficient to butt piston rings with as much as .060" ring end gap"
 
My 360 has Speed Pro hypers in it, they say to use normal end gap spec's for their pistons. This thing sees 7500 RPM on a regular basis with 12.7 compression. I had to cut the valve reliefs way deeper too, in fact it's so deep that the piston top is only .090 thick where the exhaust valve relief is. Been running like this for over 10 years now without a problem.
 
Are the pictures the passenger side? 4" stroke and shorter pistons will side load and leave marks where the std stroke and tall pistons rarely do. What I see might being issues are too much piston to wall, possibly contaminants in the oil, and the cylinder wall finish looks too rough.
I'd be looking at piston to wall of .0015-.0025 and the finish should be a lot smoother. This will help with giving the skrts a smoother surface so there is no material transfer and let the limited oil do a better job of protecting against the skirt contacting the wall. See attached.

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dodge freak said:
.028 is still "tight" for K.B.

Check out their guild for ring gaps.

For Circle Track - Unrestricted .0080" per inch so a stock 360 bore should be .032

For Marine - Normally Aspirated .0080" -same gap as Circle Track

Street - Towing is .0080"

I don't know why they say for Street - Normally Aspirated .0065", guess that is for "normal" people. (those are the ones in the far right lanes on the freeway we go zipping past, ha ha)

The Wall Clearance is what really changes. Goes from Street - Normally Aspirated .0015" - .0020". Circle Track is .0030" - .0045". Marine .0030" - .0045"

Why Marine use is so much higher than "normal street use" IDK but like I said, we aren't "normal street" I guess.

I am asking for min Marine spec's (good point if the shop will listen thou)

KB Pistons for Automotive Applications:
http://www.kb-silvolite.com/kb_car/clearance_pop.php
Click to expand...


My 340 w/KB243's has .029 top ring gap, 7000rpm and no issue.
I've run KB's at .008 just teetering in the bore, besides noise, no issue.

I've only scuffed no.5 in a 340 before with the kb's due to spark jump/cap& rotor phasing, once I changed the distributor & sleeved the hole..no issue.

as for the finish...I run your basic hastings single moly top rings.

I tell you this....this is the 1st block I have had done at this shop....
I'm thinking it's the last as well, I might go back to hds or ricks machine in sante, though the customer service guy is a douche bag...at least rick does excellent work and has family generations in experience.

I have not had a chance to speak with Brian yet, but will and 1st consider his shop before making a move.
It just sux that he is an 1 1/2 away.

I was thinking too tight a wall moper, cause theres no sufficient oil there, thats a lot more swept and side thrust. jmo
But I am all ears to any idea's and thank you all giving them.
 
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