MattHDSM
5+ Year Contributor
- 113
- 71
- Oct 20, 2018
-
Ottawa,
ON_Canada
I’ve got my motor apart, the crank is currently at a machine shop getting spec’d and polished. I figured there’s no point in buying or boring anything until I know the crank is good.
In the mean time, a little bit about the motor.
7-bolt with 200k km (~124k miles), no fuel upgrades (yet), no bigger turbo (yet), balance shafts are getting tossed when I put the engine back together. Basically, it came apart as a factory 7-bolt.
Bearings all looked healthy, even wear on the surfaces. Thrust clearance was at its service limit, so it’s probably a good thing I took it apart when I did.
Why take it apart? Compression. My compression across the board sat below the service limit, with cylinder #4 sitting at a measly 100psi dry, 120psi wet. A leak down test showed no sign of compression leaking past the valves or into the cooling system so I’m pretty sure my rings are dead or piston #4 is bad.
I’m on a tight budget (surprise ) so I need to make sure I do this right. My number one goal here is to get the motor back up and running with good compression. I’ll chase more than 200 horsepower after I know my motor is alive and healthy. After I know it’s all good, I’ve got a small 16g I’ll slap on with the hopes of pushing it towards 300 whp, maybe, we’ll see.
I’m thinking about going with some .020” overbored NPR pistons and rings. I heard they originally manufactured the OEM pistons so I figure it’s a safe bet. Are cast pistons like these safe to take to 300whp?If anyone has experience with these I would love to know how they faired and what power levels they were pushed to.
In the mean time, a little bit about the motor.
7-bolt with 200k km (~124k miles), no fuel upgrades (yet), no bigger turbo (yet), balance shafts are getting tossed when I put the engine back together. Basically, it came apart as a factory 7-bolt.
Bearings all looked healthy, even wear on the surfaces. Thrust clearance was at its service limit, so it’s probably a good thing I took it apart when I did.
Why take it apart? Compression. My compression across the board sat below the service limit, with cylinder #4 sitting at a measly 100psi dry, 120psi wet. A leak down test showed no sign of compression leaking past the valves or into the cooling system so I’m pretty sure my rings are dead or piston #4 is bad.
I’m on a tight budget (surprise ) so I need to make sure I do this right. My number one goal here is to get the motor back up and running with good compression. I’ll chase more than 200 horsepower after I know my motor is alive and healthy. After I know it’s all good, I’ve got a small 16g I’ll slap on with the hopes of pushing it towards 300 whp, maybe, we’ll see.
I’m thinking about going with some .020” overbored NPR pistons and rings. I heard they originally manufactured the OEM pistons so I figure it’s a safe bet. Are cast pistons like these safe to take to 300whp?If anyone has experience with these I would love to know how they faired and what power levels they were pushed to.