Valvetrain chatter on KW SC FRS
 

14k miles, boosted approximately 4k. Running the Kraftwerks C30 supercharger (10.5 lbs boost max) and oil cooler on a Delicious dyno tuned e85 setup (now running the Delicious flex fuel kit). DW 550 injectors. Running fresh redline 5w30 oil.

Tracked the car 3 days with the SC kit but a few more days previously with the electric SC kit.

Recently I heard what I thought was rod knock. I only hear it when the engine oil is between 120 and 170 degrees. Too cold or warm and the noise isn't there. After taking it to Infamous Performance, it looks like the noise is valve chatter coming from the passenger side head. Here is an audio clip I captured using a powered mechanical stethoscope. You can really hear the chatter starting around 15 seconds.

https://www.dropbox.com/s/y2r8jblxuz...20frs.m4a?dl=0

I'm not sure what exactly is wrong so I decided to have the engine pulled and completely rebuilt with forged rods (Manly turbo tuff) , pistons (custom CP @ stock 12.5:1 compression), valves (supertech) and valve springs (supertech). Outfront Motorsports will be doing all of the machining and engine work since they have a lot of experience with Subaru engines.

Any thoughts on the audio clip and the potential cause of the valve chatter? I figure I'll know more when they tear it down in ~5 weeks (that's how long the custom CP pistons take). I want to make sure that this thing is solid and built/fixed right so I don't have too many (or any!) other engine issues (fingers crossed).

I am no expert but it does sound like the valves to me, but also sounds normal to my ear. IMO these engines are prone to issues in their stock form especially with spirited driving , so all bets are off if you modify them.


You're smart to beef up the internals...that's the only way to go if you go FI

Rockers have shown up broken and i think Evasive had one come apart. Hard to say without taking it apart though.

Yeah, I was worried about the rockers but there's not much to do to strengthen those right? Just replace OE?

Ask the FullBlown guys they'd know.