Cast Piston vs Forged Piston

[Triple_B]

There seems to be interest in the strength of Forged vs. Cast Pistons. I didn’t have a cast piston to crush in the press for a demonstration, but we’ve all seen enough carnage and know how cast pistons fly apart.

I did find an old forged Wiseco to give a substantial push demonstration. I put this old Trooper Wiseco in my 60 ton press and gave it a shove. The piston didn’t start to fail till around 40 tons. I took these photos at 50 tons of pressure.

2 Views of the same Piston after a 50 ton push

CAST PISTON:

My large press was a little over kill for the Yamaha piston. The piston started to crack almost instantly. I wasn’t able to get any kind of pressure reading


The pair: Small, Yamaha Cast
Large, Forged Wiseco.

Not much needs to be said after a look at the pics. This is a total guess but it seems as though the forged piston is 5-10 times stronger than the cast piston. This shows you folks the true story between Cast & Forged pistons.
I give Wiseco Piston a Thumbs UP.


Credit for the write up goes to John Tice

 

[Motocrossguy17]

Awesome Man! iv got a wiseco in mines as i had a cast in it and it was starting to crack. i took my head of to just check and luckily i did as if i didn't i would of had a bill of £300 instead of £70 for a wiseco piston

 

[blasterBruce]

Nice Little Test there , I Had to beat The H*** out of a Wiseco .10 over piston out of a fresh bore that was left outside after a fresh rebuild , Killed the piston rings crank bearings clutch plates as well as more damage

 

[brandoz28]

that's pretty cool.....i like seeing broken parts lol

 

[Surfrjag]

very good demonstration!

 

[JareeB]

Its been awhile since I have been on here. You know forged pistons expand more then cast. Cast shouldn't crack if you arnt detonating. Plus pistons arnt under that much side press. Try a horizontal press.

 

[Blaaster]

Detonation will cause failure in cast and forged pistons, mainly to the crown and rings.

Detonation can be held responsible, for skirt breakage, if is causes the piston to expand enough that the skirt grabs the bore.

Worn cast pistons, slopping around in a loose bore, suffer extreme side stress, from slapping back and forth thousands of time a minute.

Although it is not a constant pressure, it is a constant hammering, which cast products hate. Forged pistons hold up a lot better under hammering.

The wear which causes piston slap is generally caused lack by of lubrication, or by poor warm up proceedure, causing excessive piston/bore wear, due to uneven component expansion.

Or by plain everyday running and old age = wear.

 

[89blaster89]

Wiseco ftw!!!!!!!!!!!!!