Stihl ms 460/660 Hybrid. 469e

[NateSaw]

Alright we're back in the saddle. I got a call from Doc yesterday morning. He had a grand idea to shave weight off this slug without weakening. He said to drop the bottom ring and cut the windows higher into the land. So with that goal in mind, I chucked up a new cs900evl unit, cut the top to @Ketchup 's recommended (and proper) squish of 0.022". I had nipped the skirt on the other one to time intake and block less port, so I just turned them both up to that height. Still sitting pretty at 80* intake. Put it on a healthy diet and it's a few grams lighter yet. Minus a ring, and plus an oem tapered pin, this is nothing but improved, and stronger.
This is the original echo slug, 2 rings, and lrb pin.

Improved Doc(tored) unit, 1 ring, oem pin. Over 7 grams lighter.
Tonight after work, it goes back in the hole, saw goes back together, and tommorow I'll run it and we'll see if the intake port is doing the trick!

 

[Powerstroke Cowboy]

We need a side shot of the piston Nate!

 

[NateSaw]

Yes! So you can see how it'll free port! (another doc realization)
Got windows? I'll clean it up nicer with the diamond egg before I install it when I get home.

 

[NateSaw]

No dice fellas. I'm fairly certain the free porting killed it. Not worth a video.
Last two, if you look close, are illustrating how much upper is still blocked at bdc.

 

[Ketchup]

Anybody got a 500i piston to measure? Probably has a short skirt, but it’s 54mm, 12mm pin. And light.

 

[NateSaw]

Anybody got a 500i piston to measure? Probably has a short skirt, but it’s 54mm, 12mm pin. And light.

We're still good! I gotta whip up another one on the lathe, and get it to where I was on the first one, minus the @Mastermind condemned super thin struts. However I'll still take those measurements please

 

[Loony661]

We're still good! I gotta whip up another one on the lathe, and get it to where I was on the first one, minus the @Mastermind condemned super thin struts. However I'll still take those measurements please

I vote you run the first slug and see what happens. I’ll bet it’s stronger than you think.

 

[NateSaw]

I vote you run the first slug and see what happens. I’ll bet it’s stronger than you think.

Don't think I ain't thinkin it. Trouble is, Randy's gonna be right. And I'll be an a**hole for ruining a good oem case against his far more experienced judgement. Doc agreed it's sketchy. That's 2 experienced votes against 1 experienced vote and 1 not experienced squirrelly monkeys itchy fingers

 

[NateSaw]

I vote you run the first slug and see what happens. I’ll bet it’s stronger than you think.

I was actually thinking I'd run that sketchy slug for piss revving and high jet tinkering. Tells alot. But I guarantee it'd Grenada unda da load.

 

[Loony661]

Don't think I ain't thinkin it. Trouble is, Randy's gonna be right. And I'll be an a**hole for ruining a good oem case against his far more experienced judgement. Doc agreed it's sketchy. That's 2 experienced votes against 1 experienced vote and 1 not experienced squirrelly monkeys itchy fingers

Well keep in mind, I don’t have a dime in it!

But in all seriousness, I think it would be fine for quite some time. It is thin in places, but unless it had a LOT of piston rock, I don’t think it would be stressed enough to come apart. I think you have enough meat to hold the pin.

 

[Loony661]

I was actually thinking I'd run that sketchy slug for piss revving and high jet tinkering. Tells alot. But I guarantee it'd Grenada unda da load.

I disagree: RPM is what would stress it the most. In the cut it wouldn’t be coming to so many starts and stops. And compression wouldn’t kill it, but the stretching action as the crank head back down would be the hardest in the aluminum IMO.

 

[Loony661]

At 14,000 rpm, the piston is coming to a complete stop 466 times a second…

 

[NateSaw]

Well keep in mind, I don’t have a dime in it!

But in all seriousness, I think it would be fine for quite some time. It is thin in places, but unless it had a LOT of piston rock, I don’t think it would be stressed enough to come apart. I think you have enough meat to hold the pin.

Welllll, ya seeeee, that's just the thing... These lrb slugs come in small @ 53.92mm, coupled with the flat Intake floor I gave it.... Ehhhhhhh
I also forgot to mention early in this thread... I'm grateful I'm ocd about checking ring gap. I almost forgot to... These lrb rings had a healthy gap of 0.00000000001".

 

[Maintenance Chief]

I'm not trying to pizz in anyones cornflakes, but isn't there an am 54mm cylinder? For the 460.

 

[NateSaw]

I disagree: RPM is what would stress it the most. In the cut it wouldn’t be coming to so many starts and stops. And compression wouldn’t kill it, but the stretching action as the crank head back down would be the hardest in the aluminum IMO.

I see your point. And it's valid. Anyone else wanna vote on this?

 

[NateSaw]

I'm not trying to pizz in anyones cornflakes, but isn't there an am 54mm cylinder? For the 460.

I have one. It's Supa fly.
It's got chitty ports, chitty plating, chitty honing. Chitty chitty bang bang.

 

[NateSaw]

At 14,000 rpm, the piston is coming to a complete stop 466 times a second…

It's side load I'm concerned about. That big fat strut connecting the pin bore to the crown is beefy.

 

[NateSaw]

I'm not trying to pizz in anyones cornflakes, but isn't there an am 54mm cylinder? For the 460.

Plus, that'd be too easy!

 

[Maintenance Chief]

I have one. It's Supa fly. View attachment 411682View attachment 411683View attachment 411684
It's got chitty ports, chitty plating, chitty honing. Chitty chitty bang bang.

That is a chitty one!

 

[NateSaw]

That is a chitty one!

I'm sure there are better. Soon I'm going to fab the mount for clamping the straight hand peice to my compound, so I can diamond grind plating from squish areas of meateor cylinders. That'll open up some am options.