cas piston vs forged
- Thread starter kidmtn
- Start date
L
longhairfreak
Well-known member
No.
T
TARI
Well-known member
Forged wiseco pistons are lightweight, which could give you more acceleration or rev quicker with a lighter piston, but should be used for race applications. If your tearing down your motor every couple races or so to check it out. Keep it stock.
what kind of 1000 are we talking about?
what kind of 1000 are we talking about?
I always understood just the opposite. Forged pistons are made by heating a block of metal to almost liquid and then stamping them into shape, thus compacting the metal making it more dense and therefore heavier, which is why forged pistons usually aren't desired because they expand and contract with heat and cold more than a cast piston simply because there are more molecules in the piston and more mass. Cast pistons are made by heating the metal until it is a liquid and pouring it into a mold. Since the liquid doesn't fill every single little void in the mold and because there is no pressure compacting the metal into shape it is lighter. A piston that is spin cast may be comparable in weight since after pouring the liquid metal into the mold it is then spun to force it into all the voids within the mold. Am I right or am I wrong? That's how they were expalained to me. Someone here will know for sure.
Not as many differences these days between the two styles of pistons. I don't know that terrible much about it, but here it goes.
Cast is a pour mold type of piston. OEM style and has been the the most preferable over the years for 2-stroke applications. As they would typically exhibit less expansion and tighter tolerances could be used.
Forging is what I believe to be best explained as a compressed metal. Typically stronger, but thought to have more expansion. This metal is then machined to the desired shape and tolerances. This process often times provided a piston that was lighter and stronger than cast, but would have a higher expansion rate. Many people found that they had to run more clearance with these.
Now with todays technology, both styles share the ability to either mix or impregnate different materials (metals, alloys, etc) into thier base material. This is done for better heat tolerance less friction and to minimize expansion of the metal so tighter tolerances can be maintained. Less expansion of the metal will obviously improve longivity.
The next thing is that both tend to share different low friction heat tolerant coatings. Despite what most people believe, it is not intended to wear off during break in of the motor. It has been applied to the piston to reduce friction and wear as well as reduce operating temperature of the piston.
With todays standards, I have seen a switch between the two styles of pistons. I have actually seen forged pistons sucessfully run tighter tolerances than their cast brothers.
Which one is better will always be up for debate.
Is there an advantage in your motor? Hard to say. The high compression will demand a stronger piston where the forging may be desireable. It will also likely generate more heat. Some will tell you to stick with the cast for that reason.
Gees, I'm no help at all.
Cast is a pour mold type of piston. OEM style and has been the the most preferable over the years for 2-stroke applications. As they would typically exhibit less expansion and tighter tolerances could be used.
Forging is what I believe to be best explained as a compressed metal. Typically stronger, but thought to have more expansion. This metal is then machined to the desired shape and tolerances. This process often times provided a piston that was lighter and stronger than cast, but would have a higher expansion rate. Many people found that they had to run more clearance with these.
Now with todays technology, both styles share the ability to either mix or impregnate different materials (metals, alloys, etc) into thier base material. This is done for better heat tolerance less friction and to minimize expansion of the metal so tighter tolerances can be maintained. Less expansion of the metal will obviously improve longivity.
The next thing is that both tend to share different low friction heat tolerant coatings. Despite what most people believe, it is not intended to wear off during break in of the motor. It has been applied to the piston to reduce friction and wear as well as reduce operating temperature of the piston.
With todays standards, I have seen a switch between the two styles of pistons. I have actually seen forged pistons sucessfully run tighter tolerances than their cast brothers.
Which one is better will always be up for debate. Is there an advantage in your motor? Hard to say. The high compression will demand a stronger piston where the forging may be desireable. It will also likely generate more heat. Some will tell you to stick with the cast for that reason.
Gees, I'm no help at all.
A
AdrenalineAddict
Well-known member
You're right on about the forged piston having a higher density. The forged piston is machined substantially thinner over most all areas of the piston such as the skirts and dome therefore being lighter than the cast counterpart.
C
clutch man
Well-known member
The difference between a cast and forged piston is the way it is made. A cast piston is made by pouring or injecting molten aluminum into a mold and letting it cool. A forged piston is made by ramming a die into a hot but not quite molten ingot of aluminum in a mold under great pressure (20+ tons!) The extreme pressure created in the forging causes the metal to be denser and have a uniform grain, making it much stronger and less brittle. There is more to making forged pistons than just the different manufacturing process, they often start with a stronger alloy such as 4032 or 2618 aluminum. Cast pistons are high in silicon content, which makes them dimensionally stable under high temperatures, but brittle. Forgings have a low silicone content and thus "grow" (expand) more when hot, but offer much improved strength and resiliency
T
TARI
Well-known member
Mjunkie, most wisecos are lighter weight in the reason there are more denser, so can be made lighter, such as thinner piston skirts and less material in the dome of the piston
Then as mentioned above ^^^^ cast pistons having silicon content making the piston harder but more durable, at 18-27% where wisecos are around 2% ?? being soft once heated. Piston skirts can push in making more clearance where the piston rocks and eventually damage happens catching the exhaust port.
The cast pistons today such as cat (suzuki Japaneese) are hard anodized as well. being very durable but are made light weight also with thinner piston skirts. so some of these motors we see such as the 860 big bores in the ski doos are finding broken skirts or cracks on them. So piston clearance is critical as is "break in"
I have seen quite a bit of pistons, testing over the years. I perfer the cast pistons. stock.
Then as mentioned above ^^^^ cast pistons having silicon content making the piston harder but more durable, at 18-27% where wisecos are around 2% ?? being soft once heated. Piston skirts can push in making more clearance where the piston rocks and eventually damage happens catching the exhaust port.
The cast pistons today such as cat (suzuki Japaneese) are hard anodized as well. being very durable but are made light weight also with thinner piston skirts. so some of these motors we see such as the 860 big bores in the ski doos are finding broken skirts or cracks on them. So piston clearance is critical as is "break in"
I have seen quite a bit of pistons, testing over the years. I perfer the cast pistons. stock.
M
manowar
Well-known member
Ok bottom line is piston clearance. The horror stories come from the fact that you need correct piston to cylinder wall clearance with a sleeve you can simply hone and spec the thing but most people don't. Next is a nic cyc is a re plate job to get it right and the company doing the work needs to know what the exact piston diameter is and how much clearance u want or need. So if you have a sleeve liner then go for it if not do some checking on how much it cost to have the work done before you leap. But u can't just toss forged pistons in and go you will be like others saying they are "bad,junk, not worth a crap, and other things " cuz they will expand more than cast this makes them cease if the clearance in to tight.
O
Yes but the Wiseco`s are machined smaller so the extra clearance is already done in the piston, close anyways. It still might need to be honed. my 85mm wiseco`s are just 84.8 or someting. i guess the cast is 84.9 because i can switch between the forged and cast and still have the right clearance. Wiseco`s are the tough ones! If you detonate, Run wiseco`s!
Break it in good.
Break it in good.
Similar threads
