Valvetrain chatter on KW SC FRS - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

nlowell · 05-03-2015, 12:59 AM

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).

BRZnut · 05-03-2015, 08:22 AM

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

FirestormFRS · 05-03-2015, 10:40 AM

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

nlowell · 05-03-2015, 11:58 AM

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

FirestormFRS · 05-03-2015, 12:20 PM

Ask the FullBlown guys they'd know.

05-03-2015, 12:59 AM	#1
nlowell Senior Member Join Date: May 2013 Drives: 2013 Scion FRS Location: Dallas, TX Posts: 443 Thanks: 105 Thanked 409 Times in 173 Posts Mentioned: 51 Post(s) Tagged: 0 Thread(s)	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). __________________ Complete Part Out: http://www.ft86club.com/forums/showthread.php?t=125688 Last edited by nlowell; 05-03-2015 at 01:53 AM.

05-03-2015, 11:58 AM	#4
nlowell Senior Member Join Date: May 2013 Drives: 2013 Scion FRS Location: Dallas, TX Posts: 443 Thanks: 105 Thanked 409 Times in 173 Posts Mentioned: 51 Post(s) Tagged: 0 Thread(s)	Yeah, I was worried about the rockers but there's not much to do to strengthen those right? Just replace OE? __________________ Complete Part Out: http://www.ft86club.com/forums/showthread.php?t=125688

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Valvetrain noise	Gixxersixxerman	Engine, Exhaust, Transmission	23	01-05-2021 04:44 PM
FS: Ported & Polished Heads with Ferrea +1mm Valves and Valvetrain, Ready to Install	Dustin@Dynosty	Engine, Exhaust, Bolt-Ons	8	02-21-2015 12:21 PM
Flywheel Chatter	samisons	Issues \| Warranty \| Recalls / TSB	13	12-05-2014 10:30 AM
Clutch, LW flywheel and chatter....	wootwoot	Engine, Exhaust, Transmission	20	11-17-2014 04:50 PM
Odd Chatter Noise?	Chrisposey	Forced Induction	5	05-05-2014 10:37 PM

05-03-2015, 08:22 AM	#2
BRZnut Senior Member Join Date: Oct 2012 Drives: BRZ DGM Limited Location: USA Posts: 1,237 Thanks: 5 Thanked 431 Times in 250 Posts Mentioned: 8 Post(s) Tagged: 0 Thread(s)	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

05-03-2015, 10:40 AM	#3
FirestormFRS Senior Member Join Date: Jul 2012 Drives: 2013 FR-S Location: Anytown Posts: 920 Thanks: 73 Thanked 643 Times in 302 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	Rockers have shown up broken and i think Evasive had one come apart. Hard to say without taking it apart though.

05-03-2015, 12:20 PM	#5
FirestormFRS Senior Member Join Date: Jul 2012 Drives: 2013 FR-S Location: Anytown Posts: 920 Thanks: 73 Thanked 643 Times in 302 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	Ask the FullBlown guys they'd know.

User Name		Remember Me?
Password