A little help please top end 97 xp

[Aagesen26]

Wanting to rebuild top end. Was thinking it was standard at 82mm cylinder but apparently its not. Inside of piston reads sbt which is aftermarket. Cylinder Measures 3 1/4" which is 82.55mm. Was wanting to buy a top end kit to give to the machine shop while they bore for specs and all but here I was thinking it was standard. Whats the biggest you can goe on these. For a minute thought I could get away with standard size and throw it in because sleeves look and feel good. But you would definitely throw up if you looked at the pistons that came out

 

[mikidymac]

Please post a picture of the pistons.

Is compression low? What is the reason for a new top end?

Pistons should say 025 or 050 for oversize.

Piston sizes are available to 1.0mm over in 0.25mm increments.

 

[Aagesen26]

 

[Aagesen26]

No need for compression numbers now right

 

[Aagesen26]

 

[mikidymac]

Bad news is you are going to have to do the crank also.

Something went through that engine.

You can see the wear on the piston pin so the connecting rod will be bad also.

T

 

[Aagesen26]

 

[Aagesen26]

Thats a better picture. Definitely gotta be some shrapnel in there though.

 

[mikidymac]

Full top to bottom rebuild.

Is it a SBT reman engine?

 

[Aagesen26]

Crankcase was put in by dealer in 2007 two days after I bought it. Something went wrong in there and was covered under warranty. Assuming its bombardier. The sleeves have no gashes or scratches witch is unbelievable. And no up down slop and very little side to side on rods. Not sure what tolerance is for side to side but its very little

 

[mikidymac]

If the pistons were SBT I would be surprised if the bottom is OEM but could be.

It really looks like a lot of wear on the piston pin and something let go but the piston skirts look surprisingly good.

It’s hard to tell if that eroded piston is from mechanical damage or detonation. I would really check squish closely when it goes back together.

 

[Aagesen26]

Does say sbt on the rod.

 

[Aagesen26]

Dropping a brand new one in is starting to sound better

 

[mikidymac]

You have a full SBT reman it sounds like so I wouldn't bother rebuilding it as they weld the cranks so they can't be used as a core, they cut the heads to lower compression and typically bore the cylinders pretty large.

Your easiest path would be another SBT reman and send them that complete engine as a core.

 

[Aagesen26]

Thanks for all the pointers and knowledge. I called sbt and they are like six weeks out at the moment for 787s. Little by little