Who has a pic of stock LNF pistons? Specificaly the top of the bowl.

 

sub'd

 

Small, but here it is:


Effectively the same as the wiseco pistons:

 

well thats not good. lol we pulled apart a blown LNF yesterday and the piston has another set of valve reliefs next to the bowl valvetrain looked okay though. i'm wondering if there really was piston to valve contact

 

What was the red line on the car you pulled apart, was it factory or did he have it moved up?

 

no idea. he was running a trifecta inifiniboost tune. so whatever he requested to redline it at

 

I need to see a picture of this.

 

i wanna see pics of what josh is talking about lol

 

lol i'll see if i can get joe to take a picture.

 

Sounds like a mis-shift. Too much boost wouldn't cause contact between valves and the piston.

 

I don't see how a mis-shift would either. I've pushed my motor to 8500RPM without issue. There would have to be some kind of mechanical issue prior to the piston-valve contact.

 

matt every single piston has these recesses in them for the exhaust valves. its a little strange since the other LNF pistons i have seen dont have these recesses(neither do the wiseco's that he bought). any chance you can get me a close up picture of a stock piston you have lying around?

 

With stock valvetrain, or did you have a spring upgrade? I wouldn't be surprised if valve float occurs at that RPM.

 

Dunno if you can see them there. They are even on every piston and don't really look like valve contact IMO, just odd that they aren't there on the wiescos. I'll try to get closer pics next time i'm out there with the camera.

 

Nothing better than looking at the internals of a beautiful ICE...

 

Nothing pretty about a broken one. I'll post up a pic of another build i'm doing in a bit.

 

I see 4 valve reliefs per piston, like the picture that IsItFast? posted. Doesn't look like contact to me, unless it's one of the pistons at BDC.

Kinda looks like the exhaust side is gunked up. Is that just the pic?

 

Look at the top of the bowl area, where the other side of the exhaust valve would be (near the spark plug). There are 'reliefs' there as well. They look factory to me, just wondering.

 

The Wiescos are machined differently but it looks like there are 4 valve reliefs in the pic above.

 

Also, yes, everything is quite dirty. Blown piston on #4 sucked a ton of oil through the whole motor.



Now that's a pretty motor.

 

I'm gonna bet on ring lands. I don't see any valve to piston contact in your pics. Gettinausername sucks proposed that the ring lands cracking is a result of too small a ring gap for the boost level. The same problem that Evo X's are facing in the 4B11.

Regarding the flat top piston, all I see is unoptimized flame path in my mind.

 

It's a dish. How is it not optimal with a centrally located spark plug and 4 valves?

I know it has bad ring lands. There was no compression on that cyl and damage to the sleeve. I want to see pictures of other stock LNF pistons for verification, i'm not trying to figure out what happened to this motor, just making sure what i'm seeing is normal.

 

thats mine i have the stock rev limiter..

 

Yep. You got my e-mail, right?

 

I was running over 7000 RPM on stock springs, but yes, not as high.