What are SEMI FORGED PISTONS?
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- Опубликовано: 28 сен 2024
- www.mrpltd.co.nz/
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What is up engine heads! Today we're talking about semi-forged piston and we will try to clear away some of the miscronceptions surrounding semi-forged pistons, and even other semi-forged stuff like semi-forged wheels.
To understand what semi forged pistons are we first have to understand how they're made. So how are they made? Well...they aren't. There's no such thing as semi-forged pistons. It is physically impossible to semi-forge something. It's impossible to forge things half-way. A piston, just like pretty much anything else, is either forged or cast.
In many cases when people speak about semi-forged pistons they actually speak about hypereutectic cast pistons. The term semi forged is common in the Subaru community and many people also like to call the 2JZ-GTE oem stock pistons semi forged. In reality they're cast hypereutectic pistons. Hypereutectic pistons are usually a step up from the more common gravity cast eutectic pistons because they do have a higher silicon content (more than 12.5%) which gives them better wear resistance, enables a tighter piston to bore fit and reduces emissions and blow-by). Although hypereutectic pistons need high pressure casting to be made properly, there is still zero forging going on during their manufacturing process. A molten aluminum alloy is fed under pressure into a mold. So the term semi-forged, although used often is definitely unjustified in the case of high pressure cast hypereutectic pistons.
So what about semi-forged wheels? Well, in their case the semi forged term is sort of justified. A semi forged wheel starts as a cast wheel with a thinner than specified rim. After it's cast it's set into a special machine that rolls the rim section into the final width of the wheel. This gives the rim section forged-like properties, however the segment of the wheel where the spokes are remains fully cast with cast mechanical properties.
What about pistons where the semi forged term is sort of justified? Well, the OEM 4AGZE Toyota pistons are one such case. These pistons aren't made using conventional low or high pressure casting methods. Instead, they are made using semi-solid casting. Semi solid casting relies on thixotropy, a property of certain fluids to be more viscous when agitated and less viscous when at rest. Aluminum is also thixotropic at certain temperatures and the semi solid casting process relies on this property to create parts of very high quality, great surface finish and excellent mechanical properties. Because aluminum is forced into the mould when semi solid there is no slushing or slurring of the liquid which results in zero porosity for the final product. On top of this semi solid parts have an excellent grain flow and a very fine micro structure, similar to that of forged pistons. The process also creates parts with a very smooth finish that don't shrink as they cool. This is why the undersides of semi solid cast pistons look very similar to that of forged pistons, without any parting lines or crosshatches.
This makes semi solid cast pistons excellent all-rounders giving them properties of both cast and forged pistons. They are usually made from a hypereutectic alloy with around 17% silicon in it, so they have low thermal expansion, but are strong thanks to their excellent micro-structure. Of course. a fully forged piston made from the 2618 alloy will still take more abuse and be stronger and more ductile, but semi solid cast pistons are much better all rounders.
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Isn't MAHLE the biggest OEM piston manufacturer?
I thought it meant forged then machined.
How lame that they're embarrassed to admit bc we won't like "the words."
Great my semi-machined-titanium-hypereutetic-cast-aluminium alloy engine head cover just arrived
Tough luck! 🤣
Semi machined 3D printing, aka "drill the holes where they're supposed to be!"
@@bryanst.martin7134 too hard, lemme get my 672 axis diamond welding mill
What do you have valves in block or something?
@@aterack833 i have 16 valves in my exhaust header
Yes I remember the time I got my girlfriend semi pregnant.
😂😂😂🤣
She was actually hypereuknockedup.
🤣🤣 good my friend
Yea.. +1.... And now I'm a semi father. The kid is mine so she claims 😁😂😂😂 and my job is a semi truck driver. So everything just interconnects.......
What happened was it half a baby
man! I've learning so much in this channel. This is very helpful to me specially I'm having a automotive class
I've been 'playing' with engines about 50 years and this is the best video explanation I've seen.
Any time I learn something new is always good.
I had never heard of semi solid casting before although I had an idea of high pressure die cast parts due to various places my father worked.
I thank you and wish I was in a better position so I could send some cash your way
Don't worry, no need for cash, words like that are more than enough 😉
The growth you’ve done with your channel is amazing asf I’ve learned so much over the years
Can you explain SHOT PEENED gears please?
I love the channel, you're a pioneer.
I think this guy knows so much about cars, that he can start his own automobile company.
Dude I cant believe you only have 200k subs... you're gonna blow up soon, I can tell.
Mrp is a great. Have bought from them a number of times. Excellent communication as well! Also they price match. Makes it hard to justify shopping anywhere else.
Congratulations man!!!! what a master piece of video haha, great information and explanation!!!!!
Great video, I didn't know such terminology existed. Keep up the good work my friend.
Same pistons I have on my 7AGE. Perfect video
I'm very disappointed, I really loved your sword fairy tale! :-D
Excellent, brilliant, clear as always!
Great work my Dear 👍🏻 Greetings from Unkel ,Germany
I thought it was a cast piston with a forged steel head
Do a video on polishing heads. There are still people that do thet on intake part and believe that increase performance when in reality it does opposite.
Perfect channel for a car nerd and for me
Really good stuff man! Dropping a comment to help out the algorithm.
High pressure casting of an oversized part "blank" that is subsequently pressed to final size in a secondary mold similar to the wheel analogy. This process reduces the size of the voids in the cast blank and creates some strengthening grain flow. In other words, semi-forged/thixotropic. Semi-forged is easier for layman to understand than thixotropic.
"Once upon a time!, sir!
start the vids with that!
As always, i enjoyed it, found it useful, and entertaining man! Never knew the difference but now I do, cheers!
learned a lot again, thank you Professor D4A!
You should do a video on magnesium engines
ultrasonic welding or sonic welding can be used to connect forged and cast part but i know they don't use it in engines yet but could be possible
I always learn something from your videos, generally even when I revisit them.
And yeah, semi-forged sounds like marketing hype. I kept thinking of a "semi-forged cheque".
And I have to admit I was befuzzled at first, going, "Huh?" Then I remembered you did this sort of hoax before....
Very impressive video, informative and entertaining.
All die cast hyperutectect pistons are strong and might be marketed as semi forged. Truly semi forged possums are really also semi die cast pistons. Thanks for providing great technical information.
lots of great new information, thanks!
The trick piston almost fooled me but I saw the undercuts in it then I was pretty sure it was cast! Forging is something that 99% of the world believe has an almost supernatural quality when it's more like it's man behind the curtain in the Wizard of Oz. Forging was a necessary evil that man had to do when we first discovered metals alloys and came out of the stone age. Impurities in the alloys caused numerous problems and forging helped minimize those issues but centuries later you can now get alloys straight from the foundry that are as strong and far stronger than what any forge smith could ever have produced 50 years ago hell 20 years ago. Forging steel and other alloys today has far less to do with the part being stronger than it has to do with the how much it cost to forge it vs machining it from a blank billet. As for forging vs casting here to is less an issue with which one is stronger but which way is cheaper and I've been out of the forging business for over a decade now I still believe that forging is the cheapest way to get a high quality highly complexed automotive part to the market but I could be wrong I am bias to forging! Forged piston/wheels have the mythical status to car guys today that Ninja's and Bruce Lee had to martial arts enthusiast during the 1970-80s. But who knows I could be wrong
Still waiting on that video about valves and valve included angles
thanks next 2 piston rings vs 3 piston rings ??
I swear I had never missed my single class if he was teacher ❤
I actually know a situation where semi-forged is actually a justifiable term. If you cast a piston blank and then hammer or press forge it too spec.
I’m using this toyota piston in to mivec 4g92 turbo with 480hp at 1.8bar no issue..
Worth for budget
i chose a subaru engine with hyperutectic pistons = ej207 spec c ra sti jdm = instead of forged pistons - just a street 300hp .
Hypereutectic = Pressure injection molded piston machined finished.
Semi forged wheels = Cast wheel with Cold rolled alloy rims.
Forged wheel = stamped billet machined.
IMO semi-cast pistons can be made by firs casting a rough piston shape, then putting it in a press and forging it to almost the perfect shape needed. This method may be better than basic forging since the part coming out of a press will need less machining than a piston cast from a solid chunk of metal.
Spanked Castings? Hot isotactic pressing?
15:55 what about 4032 forged vs semi-solid cast?
Damn buddy, can you explain your research procedure?
It's pretty simple 😊
Step 1. Get on the PC
Step 2. Spend an eternity combing through everything and fact checking.
Semi forged means they drove over it with a semi truck in order to forge it.
True story
Great piston
Yeah, but how do they make the pistons,
That make high pressure- cast- pistons?
Those are semi-forged
Ok, up until 1:51 I was like ... Ww... wot... wwwwot the phawk?! :))
That was the goal 😂
Is hyper piston the same as semi forged pistons??
Where can I buy pistons like this?
Is your video auto detecting where I am from and displaying the price in NZD?
Yes, my video is equipped with artificial intelligence. It's definitely not a still screen shot image of the mrp website.
What are some semi- solid pistons brands??
So, yes, a wheel can definitely be semi-forged. Here are two ways: 1) you cast a wheel face with a heavy rim that you then attach to a spinning lathe and draw out the barrel. This is a form of forging, and it is done both hot and cold industrially. The end product is a single-piece wheel with a cast face and a forged barrel... SEMI-FORGED. 2) a peculiar process from Japan where a roughly finished shape wheel casting still in its semi-liquid phase is then struck with high force to refine the grain structure. The shape of the wheel was cast, but it was treated via a form of forging... SEMI-FORGED.
Perhaps we need to look at the purpose of forging and determine if that goal has been met in any product purporting to have been forged. I know you can buy a wheel made by cutting a shape out of a forged aluminum billet and it's called a forged wheel. Same for a forged piston. But in the same vein you can grind a knife out of a bar of (definitely by any measure forged) hot or cold rolled mill steel and nobody would call that a forged knife. Semantics, maybe?
I bought a set of 302 Icons that said Forged Tops?
I got 1 question. My car has aluminum engine block, and my original piston is eutectic piston. Can I swap my eutectic piston with forged piston? Do i need smaller size forged piston to fit in my engine block?
If the forged pistons you want to use are designed and made for your engine they likely already are of the correct size or oversize if you'll be overboring.
@@d4a Thanks for the reply! Im just afraid forged piston expand more than my original eutectic piston, so Im thinking of using 0.5mm smaller forged piston to avoid any fricton inside my engine when its running. Thank again for the reply 😄
The process described on "semi forged" wheels is called work hardened.
I was semi-fooled...
Semaphore, a musical reference. So these pistons sound better?
I don't get it... But I'm curious to understand
so basically you can use a hyper eutectic piston for daily driving?
Some motors come from the factory as hypereutectic. There's no reason you couldn't.
@@donaldgminski8621 ah ok, but i guess there are different kinds of "quality". i guess researching about your engine is an option to become clear
Aren't semi forged wheels just flow formed wheels?
So basically we car builders want to know if there worth to buy or not
Another name they use is liquid forged
When did your head got semi forged, bro?🤣🤣🤣
If you forge the blade of the sword but leave the tallon "unforged" wouldn't that be a semi-forged sword?
There for stage 2.5 builds 😒
😂🤣😂🤣
Thiccotropy is how it should have been spelled
😂
Pressure Die Cast - simple's
Not that simple 😉
@@d4a Pressure Die Cast - which is what we would call the process you describe, here in the UK - The metal is in the Thixotropic (pseudoplastic) stage between solid and liquid and injected under great pressure - The pressure and sheering of ionic bonds in the alloy causes the viscosity to reduce - its possible by careful mold design and selection of flow directions to manipulate the grain similar to extruding to enhance strength, wear resistance, weight, finish while avoiding voids - I suspect the word "semi forged" was used not out of ignorance but rather a short cut to imply that the grain has been manipulated like forging
I believed you until the blacksmith story...
That could have been described in like 5 minutes....
Bet! Part of it is forged, then they cast the rest directly to the forged piece? Just guessing
Wrong! Guess you can't make a 2pc piston lol. But, wtf? No forging at all? How can they get away with false advertising?
есть хороший поршень ,а есть плохой других названий НЕТ !!!
Semi-eutetetic
I dont like coated piston,s period, Asian pistons use a barrel faced top ring, Go figure).
Whoever coined the term definitely consumes soy lattes.
Alright I have to ask, what's this guy's background? He's got to have at least a BS in... what, mechanical engineering? ME includes materials science right?
You are wrong about the metallurgy of hypereutectic alloys, I hope you realise. May be you are over simplifying for your chosen audience?
When you say someone is wrong it's common sense to explain why you think they're wrong.
@@d4a I really like your work, I was not trying cause offence. My comment was from the perspective of someone who used to work in high pressure die casting a while ago.
But, since you ask, here are a couple of points that may be relevant.
The eutectic of the aluminium-silicon alloy system is close to 11.8% silicon.
Both hypo-eutectic and hyper-eutectic alloys can be high pressure diecast. That is, below and above 11.8%. Typically 8-9% or above 14% in my experience.
The mechanical properties of high pressure die castings are determined by the runner design. That is, the passage design that feeds the metal from the piston in the machine to die cavity in which the casting is formed. The gate design.(As in the orifice which feeds metal into the cavity from the runner. The gate velocity . (Usually around 50 m/s or above.) You are correct when you state that the cavity fill time should be around 50 milli seconds. If a partial vacuum is applied or not. The temperature of the die and metal. And so on.
What I am trying to illustrate here that its a fairly complicated process and there is lot that can go wrong. The process control must be pretty damned good. But then the technology of high pressure die casting changing rapidly the whole that I was in that industry.
You refer to smaller silicon rich particles in the cast metal.
This due to metal solidifying rapidly while it is still being injected under a very turbulent flow. This refined grain structure gives better fatigue resistance and other improved mechanical properties.
I am surprised that the die casting process is used for this application. Process control must have improved. But then, engine bocks have been die-cast for many years.
Of course, you are correct when you state that an high pressure die casting is not a forging of any kind.
They're junk.
Another one down, another one down, another misconception hits the floor.
Man, you have a damn talent for this. These videos are reference material grade. I mean, intro level in a lot of cases. However a good spring board to launch from is invaluable in a topic as vast as engines. I learn so much from these videos.
Thank you.
+1 My thoughts exactly
I couldnt say it better
The term “semi-forged” was probably coined by the same marketing goons that came up with “CAN Bus LEDs”. People who like buzzwords without understanding what they’re actually trying to describe.
Just like "99% fat free"
It's actually 0% fat free, because it still has fat in it.
No, there is a valid point here. Both semi-sold casting and high pressure hyper-eutectic casting involve a slurry, so a mix of molten phase and solid phase. Semi-solid casting starts with a slurry, hyper-eutectic alloys turn into slush before they solidify as they cool. Proper forging involves forming a soft solid phase. If you're dealing with a mix of liquid phase and solid phase, and it behaves like very high viscosity liquid, then there is some truth in calling it semi-forging.
@@Hydrazine1000 sounds half-assed to me...
Or like "dipped in Chrome"!
No such thing. How bout if pistons are run over by a "semi"! Does that make them "semi pistons"?
Ah, I remember learning about thixotropic metal forming many years ago - nice to know more about its applications. Curious to know more about the coatings that pistons get!
I'll do a video on coatings soon
For the wheels, "semi-wrought" is probably a much more accurate description than "semi-forged".
Forged generally implies high temperatures above the recrystallisation temperature of the alloy, whereas wrought is a more generalised word to describe any time you're shaping a metal by using brute force to deform it below the melting temperature. More specifically in industry you'd typically call a lump of material shaped whilst red-hot "forged" and a piece of metal shaped while cold (like stamping car bodywork out of sheet) "wrought". Although to add even more confusion "cold-forged" is a term that also exists.
Engineering speak can be very messy sometimes, with words going back hundreds or even thousands of years. And then the Germans have an entire dictionary of their own engineering terms which don't translate well into English at all.
Thanks for the info.because of my poor performance in my English vocabularies and grammar I really don't understand the term "forged" .for me (incorrectly) it meant more towards cheating and/or producing something in a bad way.thanks again.
@@hermanman8235 Well, if you forge banknotes or paintings then your interpretation of the meaning is absolutely correct.
So 'forged' has come to mean two very different things in English. One, something fake (also known as a forgery). Two, a metal item produced by hammering in a forge (and usually of higher strength than a cast one).
It's called roll forging, edumacate yoseff
Saying your engine has "hypereutectic pistons" sounds much better when bluffing you are an expert.
I really fell for it at first 😅,
I remember when Honda was introducing pressure cast Aluminum. It was similar in strength to forged. Not bad for Aluminum. This would probably be where the the diffusion began.
So you are saying a semi forged piston is a forgery. That is advertisers being evil, mu ha haha haaaa.
Honda K series can also take over 500hp with stock oem pistons, just wondering if these really are "just" cast?
I follow all your programs from Iran. Excellent and informative.
Easy: they're semispherical.
Badum-ts
😂
🇵🇷 💘 ur teaching methods,great job
Just plain old pressure die casting with the wheels its just metal spinning on a casting - thank you very well presented
This video really good, simple explanation...
Likely will buy your stickers to put on my tuning laptop and tool boxes :)
This video is amazing man! You're an absolute asset to the greater car community. :)
Injection molding casting has been a thing for decades in plastics, it's even been a thing for metals for many years. Most compacted grey iron engine blocks for diesel engines are cast under injection pressure because they are mechanically stronger than your typical gravity cast block.
I just subscribed to the channel..
In ww2 the Allies looked at a German downed fighter plane and where shocked to realize they couldn't make some of the parts. The main strut was lighter and stronger than anything the Allies had and made in one piece. This was something they didn't even know how to do. Germany had developed manufacturing technique using 15,000T presses. The Russians and the Americans both took presses home as war prizes. Then came the heavy press program and well still use these 50,000T presses today in forging structural parts.
Nice one, love pieces of information like this.
Don't care about cars or motorcycles, I don't even change oil in my car by myself, but I watch your videos just because they are really entertaining. And while I won't be disassembling any engines or repairing vehicles in nearest future, it's a cool bonus to learn something while enjoying good video. Thank you!
its just a simple die casting process nothing more improves massproduction rate and give semi finished product quality is modrate air pockets are to be emilinated by controling temp. n flowability of molten metal reduce oxidation in manufacturing process clean n give better repeatability through out production so implimented by manufacturer for cutting cost and improve production rate n quality parts with less machining trust mi i am certified mechanical engineer☺☺☺
there is no term called semi-forged its HOT METAL DIE CASTING just like plastic molding its slang just used by noobs n non technical persons or mechanics😂😂😂😂😂😂😂😂
My first guess is a combination of casting and forging.
Something that I would probably do try to do (and I wouldn't call it sem-forged) is start off with a combination of advanced casting processes, and then utilize a combination of ultrasonic frequencies and aerogel-based thermal insulation within the mould/die to maximize the evenness of the entire alloy and crystal structure. I would follow up with some precise machining, and finish off with a combination of inductive heat treating and surface treating.
STOP!!!
1:50 lucky I watched further than this point before calling out your bullshizzle.
CARRY ON!!
Never heard of semi forged, in america they're just called hypereutectic
Nothing beats an engineer who loves cars when it comes to explaining anything related to a car. The quality of the information is next level. Most of this stuff you teach took me years of gaining parcels of information here and there to learn properly.
👍