Hyper vs Forged
06-07-2007, 10:33 PM
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Hyper vs Forged
I have been reading tons of debates over this. I know forged are generally accepted for power adders and very high HP. I came across some reading about some direct experience and was wondring if anyone else with direct experience maybe could shed some insight. I mean from general surfing you will generally hear about how brittle hyper pistons and to avoid them then you hear how its just proper ring gap that keeps them alive. I came across a builder with direct experience and found he had the exact opposite experience with various pistons and was shocked. Please add any info you may have and please try to keep direct experience rather than theory.
Just want to point something out----------------
I have had a total of 5 boat motors come to me within the last year with motors ranging from 468 to 540 with forged and hyper pistons, all the motors had #2 hole with no or low compression. All the motors (3) with forged pistons had melted pistons and the other (2) motors with hyper pistons had burnt valves. The hyper pistons have the ability to disapate the heat better than the forged because they are less dense. Out of the 5 engines 2 had dual plane manifolds the rest had single plane manifolds.
All these guys have the same story (they had no problems with these motors until the held it wide open for longer than they normally do). All these engines were carbed and all these engines had non modified marine carbs on them. Most carbs are calibrated for a wide open A/F ratio of 13/1. This is fine on making good power, but for a boat motor to run wide open for a long duration this is a recipe for disaster.
The moral of the story---If it's your first time building a boat motor make sure you check your A/F ratio with a wide band O/2 sensor or check the plug the proper way to get a wide open reading. This is not done by running your boat hard and idling to your dock to then pull the plug, this is done by running the boat wide open then clicking it off at max RPM, then pull the plug. I would always check the #2 plug first because this is the leanest running hole on standard BB chevy heads.
I have had a total of 5 boat motors come to me within the last year with motors ranging from 468 to 540 with forged and hyper pistons, all the motors had #2 hole with no or low compression. All the motors (3) with forged pistons had melted pistons and the other (2) motors with hyper pistons had burnt valves. The hyper pistons have the ability to disapate the heat better than the forged because they are less dense. Out of the 5 engines 2 had dual plane manifolds the rest had single plane manifolds.
All these guys have the same story (they had no problems with these motors until the held it wide open for longer than they normally do). All these engines were carbed and all these engines had non modified marine carbs on them. Most carbs are calibrated for a wide open A/F ratio of 13/1. This is fine on making good power, but for a boat motor to run wide open for a long duration this is a recipe for disaster.
The moral of the story---If it's your first time building a boat motor make sure you check your A/F ratio with a wide band O/2 sensor or check the plug the proper way to get a wide open reading. This is not done by running your boat hard and idling to your dock to then pull the plug, this is done by running the boat wide open then clicking it off at max RPM, then pull the plug. I would always check the #2 plug first because this is the leanest running hole on standard BB chevy heads.
Last edited by shaggy56; 06-07-2007 at 10:39 PM.
06-07-2007, 10:52 PM
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Re: Hyper vs Forged
well a boat engine is a very very different animal than a street engine... they are using sea/fresh water cooling so maybe 70-75 degree coolant temps all the time... they are mostly a continues RPM machine not very much accel deccel... and run in extremely hot intake temps do to being run in a confined almost non ventilated space...
sorta a apples and oranges comparison both engines but a boat engine isn't in the best operating conditions ever...
and a boat engine is normally run "wide open" at about 5200 rpms for 2,3,4+ hours..not talking about your old fart boat here... i mean a formula with 2 L98 tpi engines...
if they are having problems like that with pistons and valves it is because the owners played with something they know little about and screwed it all up
----
sorry didn't really give you any input... the forged pistons are a good piston and will out live a hyper under detonation for a short time but forged isn't worth the price for a N/a 350 putting out 350-450 hp but forced induction i would say that it would be worth it
and yes hyper pistons are more brittle hence the problems detonation i believe it is do to the high silica content in the hypers but that is also what gives them strength...
proper ring gap is necessary with any piston hyper, forged or cast... all can be damaged do to improper gapping but then the proper gap isn't going to save a piston from detonation...
sorta a apples and oranges comparison both engines but a boat engine isn't in the best operating conditions ever...
and a boat engine is normally run "wide open" at about 5200 rpms for 2,3,4+ hours..not talking about your old fart boat here... i mean a formula with 2 L98 tpi engines...
if they are having problems like that with pistons and valves it is because the owners played with something they know little about and screwed it all up
----
sorry didn't really give you any input... the forged pistons are a good piston and will out live a hyper under detonation for a short time but forged isn't worth the price for a N/a 350 putting out 350-450 hp but forced induction i would say that it would be worth it
and yes hyper pistons are more brittle hence the problems detonation i believe it is do to the high silica content in the hypers but that is also what gives them strength...
proper ring gap is necessary with any piston hyper, forged or cast... all can be damaged do to improper gapping but then the proper gap isn't going to save a piston from detonation...
Last edited by SpitotRs305; 06-07-2007 at 11:04 PM. Reason: forgot to type words
06-07-2007, 10:58 PM
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Re: Hyper vs Forged
From what was said these were completely random engines so I would think the data cant be because of one owners mistake. I dont see why it being a boat engine makes it any different. Its still putting the pistons under extreme stresses whether its a street engine or a boat engine.
06-07-2007, 11:15 PM
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Re: Hyper vs Forged
you must not know any rich boat owners....they love to buy things and play...
and from the quote you gave it seems that those engines where built buy the owners not a company... if they were the failures would be from defects in manufacturing
and a boat engine is under way more stress then any street engine do to the high intake temps gobs of timing and constant high rpm for long periods
take a look at the older mercury outboards specificaly the roller V6s they came stock with roller bearings on the rods and crank for the specific purpose of extreme duty... those engines but down around 240-260 horse and 1-2 degrees of timing out of spec and you will melt every piston in the block
and from the quote you gave it seems that those engines where built buy the owners not a company... if they were the failures would be from defects in manufacturing
and a boat engine is under way more stress then any street engine do to the high intake temps gobs of timing and constant high rpm for long periods
take a look at the older mercury outboards specificaly the roller V6s they came stock with roller bearings on the rods and crank for the specific purpose of extreme duty... those engines but down around 240-260 horse and 1-2 degrees of timing out of spec and you will melt every piston in the block
06-07-2007, 11:20 PM
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Re: Hyper vs Forged
Well the information is still up and valid from my point of view. Even if they are different the comparison is between each material being under severe conditions whether its street or boat use. Btw my friend has boat and hes not rich.
I will all together ignore this statement as it doesnt come from direct experience and shows an assumtion.
and from the quote you gave it seems that those engines where built buy the owners not a company... if they were the failures would be from defects in manufacturing
Last edited by shaggy56; 06-07-2007 at 11:25 PM.
06-07-2007, 11:30 PM
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Re: Hyper vs Forged
okay good point then just look at the material then why did the hypers burn valves and the forged pistons were "melted" what does that tell you about the seperate engines... as they werent all from the same engine.
someone built the engines and didnt properly tune the carb as i have never heard of a carb that will plop on any engine and automaticly give you a 13/1 AFR
each engine experienced a failure just at a different degree those hypers would have melted eventually too and there is no way to know how long each engine was run after they started experiencing the symptoms
but it is correct about hypers dissapating more heat than forged usually why you run wider clearances with forged than hyper cause forged pistons will expand more
other than that i dont think there is any clear assumptions you can draw from that info
someone built the engines and didnt properly tune the carb as i have never heard of a carb that will plop on any engine and automaticly give you a 13/1 AFR
each engine experienced a failure just at a different degree those hypers would have melted eventually too and there is no way to know how long each engine was run after they started experiencing the symptoms
but it is correct about hypers dissapating more heat than forged usually why you run wider clearances with forged than hyper cause forged pistons will expand more
other than that i dont think there is any clear assumptions you can draw from that info
06-07-2007, 11:42 PM
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Re: Hyper vs Forged
Those engines rain too lean, simple as that. Hypers dissipate the heat better, hence why they only had burnt valves and the pistons weren't melted.
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