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Discussion Starter · #1 ·
I just purchased a 55 Chevy 2 door post and I'm contemplating installing a 383 stroker engine in it. I have been reading the spec's from the various engine builders who are selling 383 stroker engines on Ebay. I notice that some of the 383 engines being sold on Ebay have was called: Hypereutectic pistons installed. Has anyone had any type of problems with this type of pistons? Thank you for your support.
 

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I just purchased a 55 Chevy 2 door post and I'm contemplating installing a 383 stroker engine in it. I have been reading the spec's from the various engine builders who are selling 383 stroker engines on Ebay. I notice that some of the 383 engines being sold on Ebay have was called: Hypereutectic pistons installed. Has anyone had any type of problems with this type of pistons? Thank you for your support.
I've been running SpeedPro hypereutectic (flat top) pistons in my very warmed up 355 since I built it in 1990. The block hasn't been out of the frame since. I did change the heads from L98 aluminum "Vette" to AFR 190's that I had milled to achieve 64cc chambers. This combo yields out about 10.25 to 1. I'm running a flat tappet comp "292" Magnum cam. No issues with the pistons.
 

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Hypereutectic pistons

Hypereutectic pistons offer better tighter piston fit on cold starts than forged ones and increased strength over cast pistons. They are a compromise, they have good thermal expansion characteristics of a cast piston yet they are stronger than cast. They are however not as ultimately strong as a forged piston. A forged piston however has a looser fit in the bore and sometimes produces cold piston knock and diminishes ring life slightly. Side sensitive pistons help with this due to differing pin offset directions on right side and left side pistons as opposed to piston sets that are centered and fit both sides. Hypereutectic pistons do work well in most applications except those requiring the absolute most abuse and stress.
:anim_25:
 

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Hypereutectic pistons have their place.

One thing you must do with them is follow the mfr's recommendation on ring end gaps. They do not follow the usual rules that you'd use on either cast stock type pistons, or forged pistons.
 

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Some people think they are not a cast pistons. They are cast but use a modified alloy stronger than stock cast but not as strong as forged.. They are ok for low to midrange budgets.

Don
 

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Discussion Starter · #7 ·
Awesome! That is what I wanted to hear. You have been a big help. Yes, just normal street stuff. No nitrous, turbo or blower. Thank you very much for your support.
 

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wikipedia says ...

A hypereutectic piston is an internal combustion engine piston cast using a hypereutectic alloy–that is, a metallic alloy which has a composition beyond the eutectic point. Hypereutectic pistons are made of an aluminum alloy which has much more silicon present than is soluble in aluminum at the operating temperature. Hypereutectic aluminum has a lower coefficient of thermal expansion, which allows engine designers to specify much tighter tolerances.

The most common material used for automotive pistons is aluminum due to its light weight, low cost, and acceptable strength. Although other elements may be present in smaller amounts, the alloying element of concern in aluminum for pistons is silicon. The point at which silicon is fully and exactly soluble in aluminum at operating temperatures is around 12%. Either more or less silicon than this will result in two separate phases in the solidified crystal structure of the metal. This is very common. When significantly more silicon is added to the aluminum than 12%, the properties of the aluminum change in a way that is useful for the purposes of pistons for combustion engines. However, at a blend of 25% silicon there is a significant reduction of strength in the metal, so hypereutectic pistons commonly use a level of silicon between 16% and 19%. Special moulds, casting, and cooling techniques are required to obtain uniformly dispersed silicon particles throughout the piston material.

Hypereutectic pistons are stronger than more common cast aluminum pistons and used in many high performance applications. They are not as strong as forged pistons, but are much lower cost due to being cast.
 

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Discussion Starter · #9 ·
A hypereutectic piston is an internal combustion engine piston cast using a hypereutectic alloy–that is, a metallic alloy which has a composition beyond the eutectic point. Hypereutectic pistons are made of an aluminum alloy which has much more silicon present than is soluble in aluminum at the operating temperature. Hypereutectic aluminum has a lower coefficient of thermal expansion, which allows engine designers to specify much tighter tolerances.

The most common material used for automotive pistons is aluminum due to its light weight, low cost, and acceptable strength. Although other elements may be present in smaller amounts, the alloying element of concern in aluminum for pistons is silicon. The point at which silicon is fully and exactly soluble in aluminum at operating temperatures is around 12%. Either more or less silicon than this will result in two separate phases in the solidified crystal structure of the metal. This is very common. When significantly more silicon is added to the aluminum than 12%, the properties of the aluminum change in a way that is useful for the purposes of pistons for combustion engines. However, at a blend of 25% silicon there is a significant reduction of strength in the metal, so hypereutectic pistons commonly use a level of silicon between 16% and 19%. Special moulds, casting, and cooling techniques are required to obtain uniformly dispersed silicon particles throughout the piston material.

Hypereutectic pistons are stronger than more common cast aluminum pistons and used in many high performance applications. They are not as strong as forged pistons, but are much lower cost due to being cast.

Very good explanation. I viewed the 383 engine that Skip White sells on Ebay. I'm not an engine builder, however, I'm impressed with the quality and workmanship that goes into building their engines. They use a 2618 aircraft alloy to fabricate their pistons which is suppose to be much more resistant to detonation. It would be nice if I could afford a 383 engine from them. In any case for me, just a street driver, the Hypereutectic pistons should work out just fine. Thank you for your support.
 

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Some people think they are not a cast pistons. They are cast but use a modified alloy stronger than stock cast but not as strong as forged.. They are ok for low to midrange budgets.

Don
I have had a lot of calls over the years about broken HYPER pistons as they are just a glorified cast piston.

Do a search on hyper pistons.
 

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Correct (for hypereutectic) piston ring gap is very crusial! Hyper pistons has their place in mild performance applications but I wouldnt gample with detonation....actually I wouldnt with ANY piston.
 

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Got it right

You just have to be absolutely sure the engine does not go into detonation or you can kiss your whole engine goodby in one heartbeat. Owner of a company I worked for rebuilt the engine in the company delivery and put standard pre-gapped rings into it. First time it got hot with a load on it BOOM. Bye Bye motor.
 

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K-B (Keith Black) hypers require larger top ring gap (around .0065" per inch of bore) due to the ring's proximity to the top of the piston. However, this is not applicable to Speed Pro hypers. Unless you are running nitrous or very high compression, they work fine for a street/strip engine. But, no, they are not as strong as forged pistons, which, by the way, don't need as much cold clearance as back in the day.

I have run K-B and SpeedPros for years with zero problems. Anyone who tells you hypers are problem-prone did not install them (or gap the rings) correctly. I'd put my money on the engineers at K-B and SpeedPro before betting on any old wives tales.

I'd be very leery of any products from Skip White. I'd bet most of of the engine internals are Chinese, as are the heads. Why are so many hot-rodders drawn like moths to a candle by too-good-to-be-true prices?
 

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K-B (Keith Black) hypers require larger top ring gap (around .0065" per inch of bore) due to the ring's proximity to the top of the piston. However, this is not applicable to Speed Pro hypers. Unless you are running nitrous or very high compression, they work fine for a street/strip engine. But, no, they are not as strong as forged pistons, which, by the way, don't need as much cold clearance as back in the day.

I have run K-B and SpeedPros for years with zero problems. Anyone who tells you hypers are problem-prone did not install them (or gap the rings) correctly. I'd put my money on the engineers at K-B and SpeedPro before betting on any old wives tales.

I'd be very leery of any products from Skip White. I'd bet most of of the engine internals are Chinese, as are the heads. Why are so many hot-rodders drawn like moths to a candle by too-good-to-be-true prices?
Had calls about over heating an engine with hyper pistons which killed them. The y work good in GM engines which are computer controlled which have knock sensors.

Over the years I have had calls about replacing broken HYPER pistons with a forged piston, but never a call to replace a broken forged piston with a HYPER

I build a lot of high end engines and have and good luck with forged pistons why would I switch?????

Check this link out
https://www.google.com/#q=broken+hyper+pistons
 

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Over the years I have had calls about replacing broken HYPER pistons with a forged piston, but never a call to replace a broken forged piston with a HYPER

I build a lot of high end engines and have and good luck with forged pistons why would I switch?????
Very true if you are talking about engines that see abuse. All I'm saying is they are stronger than cast and work fine in a street/strip car. There's lots of bad info out there that hyper pistons are somehow flawed and worse than cast pistons. I think much of it is due to folks not reading the instructions that come with K-Bs.
 

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Very true if you are talking about engines that see abuse. All I'm saying is they are stronger than cast and work fine in a street/strip car. There's lots of bad info out there that hyper pistons are somehow flawed and worse than cast pistons. I think much of it is due to folks not reading the instructions that come with K-Bs.
From what I have seen even reading the instructions they are not as dependable as a good forged piston and dependability is key when building a street and strip engine.

For mild street built a HYPER would probably work fine but if I spec out an engine I either use a 2618 or a 4032 alloy material and have had great luck but I don't build any mild street engines either. I use quality pistons with thin ring packages and seem to work fine.

Quality parts equals reliability.

I probably get a few phone calls on this subject then most people and have a good idea what works.

HYPERS are a true budget piston for sure if your building budget engines.
 

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" I think much of it is due to folks not reading the instructions that come with K-Bs."
SO TRUE! You'd think the way some people talk that cast pistons hadn't served well in some pretty stout factory performance builds over the years. I also think KB is the only hyper that specs a larger #1 ring end gap and that's more due to #1 ring land placement than composition of aluminum. They have some street and price advantages and if you detonate an engine to the point where you break one, you need to get into another line of work. :)
 

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" I think much of it is due to folks not reading the instructions that come with K-Bs."
SO TRUE! You'd think the way some people talk that cast pistons hadn't served well in some pretty stout factory performance builds over the years. I also think KB is the only hyper that specs a larger #1 ring end gap and that's more due to #1 ring land placement than composition of aluminum. They have some street and price advantages and if you detonate an engine to the point where you break one, you need to get into another line of work. :)
I have never used KB HYPERS in any of my builds but sure have sold a lot of forged pistons to replace the broken HYPERS LOL.

So far the forged pistons have worked very well:congrats: Do it once right or it will cost in the long run!!!

I would never use a budget piston in my performance builds LOL
 
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