FORGED vs CAST vs HYPEREUTECTIC PISTONS

what is up people today we're talking about the differences between forged cast and hypereutectic business I decided to make this video because when I worked up the differences between forged and cast business online I honestly noticed that there's quite a few misconceptions out there and also there's a lot of oversimplification that usually goes along the lines of forged pistols are good because they're strong and gas business are bad because they're weak now reality is almost never that simple and making the decision on what kind of piston to put inside your engine based on these oversimplified statements is almost never a good idea so today we're going to dive deeper into the whole cast versus Forge thing we're going to look at the fact we're going to talk in the manufacturing processes we're going to see what are the advantages of each of these types of pistons because they all do have significant advantages and at the end of the day we're going to make an informed decision on what kind of piston is best for your engine belt understanding the differences in the manufacturing process of caste and force business is key to understanding how they differ from each other in terms of strength so it starts with caste Pistons how are they made well as their name tells you their caste and what does that mean it means that you take an alloy of mostly aluminum and a few other metals and you melt it until it's completely liquid then you pour that liquid into a mold and once it cures and solidifies the mold which is usually made of three parts is going to retract and you're going to have your basic piston shape after this the cast piston needs very little machining and you can basically pop it into your engine and be done with it this manufacturing process explains why almost all cars and motorcycles come with cast pistons in them from the factory cast pistons are great for a large-scale mass production once you make the large initial investment in the complex and expensive casting machinery you can actually produce cast Pistons in large quantities quickly and at all costs on the other hand the manufacturing process of forged pistons doesn't involve any melting of any aluminum alloys what you do for forged pistons is that you take a long aluminum alloy rod that you cut up to the size of the billet you're going to need for the piston you didn't take that billet and heat it up once it's heated up sufficiently you will place it in a large forging press that forging presses a is going to apply a tremendous pressure onto the billet and shape it into the basic piston shape you need after this the forged piston is going to require significantly more machining than the cast piston because the mold for a cast piston can be made as complex as the manufacturing needs basically you can encode valve reliefs and domes into the mold itself which is something you cannot do when it comes to the forging press dies this is why the basic shape the comes out of the forging press is a lot more simple and rough and the valve reliefs and the domes and other stuff needs to be machined in and this is why forged pistons take more time to make and are significantly more expensive than cast pestis the manufacturing process of pistons doesn't just determine their price it also determines their grain for what is grain flow grain flow is the directional orientation and distribution of metallic grains within the piston you want your grain flow to be coherent uniform and rounded off for maximum strength if your grains are randomly distributed you are going to have a weaker material so here's a look at the grain fall of cast Pistons as you can see they are pretty random and in some cases you can even find some air pockets trapped in the grain flow of the cast Pistons and this is because you aren't applying any pressure in the manufacturing process of cast pistons you're just pouring in an hour and letting it cool that's pretty much it but when it comes to the forged pistons their grain flow is very different and as you can see it's much more uniform it's much more coherent and this is why they are stronger it's more coherent because the significant pressure applied in the forging press eliminates all possibility of any sort of porosity and it basically forces all the grains together in this uniform shape but saying that forged business are simply stronger than caste business is actually misleading what we should be saying is that forged pistons are more ductile than cast pistons what is dr. D ductility is the measure of how much a material can resist deformation before it breaks apart or ruptures forged pistons are significantly more ductile than cast pistons but this ductility comes at a price and the price is that forged pistons expand more when exposed to heat when compared to cast pistons as you know pistons are exposed to high temperatures during the engines combustion process this of course heats up the piston and this heat causes it to expand and as we said the forged piston is going to expand more and this is not necessarily a good thing and in the long run it actually hurts the engine and here's what because the piston expands more you have to account for this when you're preparing the engine for a forged piston you will have to leave more clearance between the piston and the cylinder wall to account for the Pistons expansion now this is okay when the engine is warm the piston is going to expand and it's going to seal properly and the Rings are going to seal properly and it's going to fit nice and snug inside the bore of the engine but while the engine is cold they this large clearance between the fourth piston and the sunder wall is going to often cause something known as piston slap because of this large clears the piston sort of slaps in the ball and it hits the cylinder wall as it moves up and down this happens only until the piston heats up but before it heats up the slapping of the forged piston in the bore causes increased cylinder wear and of course you don't want that on the other hand the cast piston expand significant to us this means that you need to leave a smaller clearance between the cast piston and the cylinder bore and this means that there is no piston slap and no increased wear with cast pistons during cold starts and this means that ultimately a cast piston engine is going to survive many more cold starts and lasts longer than a forged piston engine you can I forgot about hypereutectic pistons didn't you well I have now hypereutectic used to be a big buzzword in the 80s and the 90s and nobody really knew what it meant what you having about hypereutectic is that it has everything to do with the amount of silicone inside a piston every piston that has more than 12 and a half percent silicone in it it's gonna be called hyper eutectic why do you want silicon in a piston because it does a bunch of good things for the piston number one it increases the Pistons resistance to wear number two it makes the piston harder by being harder manufacturers can make the piston wider by using those alloy to cast it but the most important feature has to do with expansion under heat hyper eutectic pistons expand even less when exposed to heat compared to a typical cast piston that has around 8 to 10 percent of silicon in it and this is something that every modern engine designer wants because a hyper eutectic piston means that really tight piston to all currencies can be used and this is really good because tight piston to all currencies reduce emissions they improve efficiency they improve performance and ultimately this means even better fuel economy and these are all features that every modern engine designer wants and this is why most modern engines design in the last decade or so actually have hypereutectic Pistons in them but hypereutectic Pistons are still cast Pistons they just have a lot of silicon content in them and at the end of the day this means that they are less ductile then a forged piston while they are a step up from your low silicon cast piston they will still never be as resistant to extreme conditions and abuse as a forged piston will be now here's a good question what about the silicone content in forged pistons now when it comes to forged pistons we have two main hours the 40-32 and 2618 now the 40-32 has around 11% of circum in it this means that it isn't a hyper eutectic piston but it means that it does expand the less than your content era such as the 2680 which usually has around one to two percent of silicon in it but the main difference between between these two is that the 26:18 is the ultimate option when it comes to extreme racing application you can take a 2618 forged piston and get a hammer and you can hit it as many times as you want this piston will not break apart it will just deform from all the hammer impacting but this also means that the 26:18 expands the most when it comes to exposure to heat and this means that the 2618 also has to have pretty hard piston to wall clearance and this means that it also has the most increased wear when it comes to cold starts on the other hand the 40-32 is sort of a compromise it's trying to give you the benefits of the forged piston while trying not to expand too much under heat and trying to minimize piston slap so what you're basically doing here is trading on jelly for maximum power potential the more maximum power potential you have though as longevity you're going to have so here's a little chart that's meant to help us put things into perspective and a little chart is going to help us understand what kind of piston should we use for all different kinds of engine building possibilities that we have now we live in a day and age when we turbocharged pretty much everything and often you are going to hear the word forged piston in the same sentence as the word turbo and many people today decide to go for Ford Pistons when building a turbocharged engine and then they also end up daily driving that car and having multiple code starts per day I'm going to work with the car going shopping and they only occasionally go to the racetrack or to the drag strip and while it's really cool to be able to say I have forged pistons in my engine using them in a daily driver can mean that you're actually harnessing more of the disadvantages of the forged pistons instead of harnessing their actual advantages if you have some of the some of the greatest turbocharged engines that came turbocharged from the factory you will see that many many many of them have cast Pistons in them and while the internet may try to convince you that cast pistons are actually made from wet biscuits they're not cast Pistons modern good cast Pistons made in the last two three decades especially OAM ones are made using very modern very complex casting methods that result in really good and products and if your tune is good on your turbocharged engine if you have knock monitoring if if you do everything to ensure that your tune is safe and done properly then cast Pistons might be the right choice for you if you're gonna be driving this thing on the street most of the time and if you're not looking for extreme power potentials on the other hand if you are building an engine that you're going to drive on where you're occasionally and it's going to spend most of its time on the racetrack on the drag strip or in error or say extreme conditions then forged pistons might be the right things for you because increased wherefrom forged pistons doesn't really play an important role in an engine that isn't trying to rack up big pipes and another important fact that modern forged pistons actually use advance skirt designs as well as some really good advanced coatings that help them mitigate the increase wear effects of a forged piston now all of this means that engines are just like shoes shoes are about the occasion you are going to wear casual shoes to a formal dress event engines are the same way but they're all about application how often are you going to drive the engine and what kind of ultimate power potential are you looking for these are the two questions you have to ask yourself before deciding which person you should chuck into that engine because using something that has large power potential and is race oriented and putting it and something you're going to daily drive isn't really getting the most out of that particular part in a sense you might be wasting it and those are pretty much the basics when it comes to 40 versus cast distance I hope this information helps shed some light on the matter and it helps you make an informed decision on what kind of piston is the best for your engine if you have any other questions don't hesitate to ask in the comment section so that's pretty much it for today I hope you enjoyed watching this video thanks a lot for watching and I'll be seeing you soon with more fun and useful stuff on to be for a child

Channel: driving 4 answers

Views: 683,151

Keywords: forged vs cast pistons, best forged pistons, disadvantages of forged pistons, benefits of forged pistons, hypereutectic pistons and nitrous, do i need forged pistons, forged pistons turbo, wiseco, mahle, je pistons, k20 forged pistons, k24 forged pistons, b16 forged pistons, do forged pistons expand, forged pistons 350z, billet pistons, 4032, 2618, sr20, 2jz, 4g63, 3sgte, hypereutectic pistons, cast pistons, forged pistons, rb26, k24det, boost, how are forged pistons made, piston slap

Id: rN2ND_FPnUA

Length: 15min 14sec (914 seconds)

Published: Sun Feb 16 2020