Snapped valve on dyno - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

kleenS14 · 01-21-2015, 09:35 AM

So, just wondering if anyone has had an experience with snapping the bottom of the stem of a valve effectively grenading the cylinder. Had my car on the dyno making great power for what it is (tomei arms turbo kit, the bigger t2 one, 256 cams, stock bottom end with springs and retainers and ras, all tomei) then at about 395 whp and 273 wtq on a dynojet @22psi, one of my number two intake valves (it appears) decided it had enough. I know, it's was too much for the oe bottom end, but it wasn't like a rod let go. Really kinda sad because it would have been stupid fun with that much power on that small frame turbo with my nismo x 6 speed. I guess my main question it's, had anyone else snapped a damn valve stem before? Pretty anticlimatic way to pop a motor. [emoji29]

PoorMans180SX · 01-21-2015, 10:18 AM

Sounds like a rocker arm broke or came off and held the valve open.

kleenS14 · 01-21-2015, 10:23 AM

Yea, I wanted to rip the vc off to see, but was a little pissed by that point. Guess it could have broken a rocker. Don't think it would have thrown one past the ras.

Croustibat · 01-21-2015, 10:23 AM

Quote:

Originally Posted by PoorMans180SX

Sounds like a rocker arm broke or came off and held the valve open.

That is exactly what a rocker arm stopper does when a rocker arm breaks or get loose.

I can't figure why people install these things. I'd rather have a loose rocker in the cover than a stuck valve kissing a piston (actually i don't have rockers, CA18 rules

)

the whole engine and trans was a grenade waiting to explode anyway. 22psi on stock bottom end, + 6spd trans ... that really is looking for trouble.

I feel sorry for you OP. But you kind of did everything you could for something like that to happen.

Dboyizmlg · 01-21-2015, 10:44 AM

Dual rocker arm guide conversion from Mazworx!!!

iRONDONkey · 01-21-2015, 10:45 AM

SR's motor.... not so great. Lol

kleenS14 · 01-21-2015, 10:47 AM

Yea, knew I'd be cutting it real close. Was more going to chuck a rod and have a little more of a spectacle, but meh, it happens.

Yea, dual guide will deff be next. Already have new valves, and forged bottom end waiting. Just time to bite the bullet and get it done. Didn't expect this one to last long, just wanted it to at least make it off the dyno lol

Tom N · 01-21-2015, 10:36 PM

You don't need Mazworx to do a dual guide conversion. Any idiot with a grinding wheel can do it.

TheRealSy90 · 01-21-2015, 10:57 PM

Quote:

Originally Posted by Tom N

You don't need Mazworx to do a dual guide conversion. Any idiot with a grinding wheel can do it.

This. It's so easy to do. I made a how-to video on you tube also. sr20 dual guide shims or something like that.

Dboyizmlg · 01-21-2015, 11:25 PM

Quote:

Originally Posted by Tom N

You don't need Mazworx to do a dual guide conversion. Any idiot with a grinding wheel can do it.

Can you lead me in the direction of an idiot with a grinding wheel so I can get it done...?

5280VertDET · 01-22-2015, 08:53 AM

***S14DB*** · 01-22-2015, 09:05 AM

Clean break or is the shaft bent?

Ramonesfreak2010 · 01-22-2015, 09:36 AM

VVL time! You'll thank me later.

01-21-2015, 09:35 AM	#1
kleenS14 Zilvia Member Join Date: Sep 2006 Location: NoVa Age: 37 Posts: 204 Trader Rating: (6) Feedback Score: 6 reviews	Snapped valve on dyno So, just wondering if anyone has had an experience with snapping the bottom of the stem of a valve effectively grenading the cylinder. Had my car on the dyno making great power for what it is (tomei arms turbo kit, the bigger t2 one, 256 cams, stock bottom end with springs and retainers and ras, all tomei) then at about 395 whp and 273 wtq on a dynojet @22psi, one of my number two intake valves (it appears) decided it had enough. I know, it's was too much for the oe bottom end, but it wasn't like a rod let go. Really kinda sad because it would have been stupid fun with that much power on that small frame turbo with my nismo x 6 speed. I guess my main question it's, had anyone else snapped a damn valve stem before? Pretty anticlimatic way to pop a motor. [emoji29]

01-21-2015, 10:18 AM	#2
PoorMans180SX Zilvia.net Advertiser Join Date: Nov 2005 Location: Michigan Age: 36 Posts: 5,574 Trader Rating: (16) Rides Gallery: PoorMans180SX Feedback Score: 16 reviews	Sounds like a rocker arm broke or came off and held the valve open. __________________ Build: http://zilvia.net/f/showthread.php?t=643065 Friends don't let friends buy knock-offs.

01-21-2015, 10:36 PM	#8
Tom N Zilvia Addict Join Date: Oct 2012 Location: SW Florida Posts: 746 Trader Rating: (1) Feedback Score: 1 reviews	You don't need Mazworx to do a dual guide conversion. Any idiot with a grinding wheel can do it. __________________ 98 240sx w/ S15 SR20DET, T2 20g, 11.22 @ 124.98

01-22-2015, 08:53 AM	#11
5280VertDET Nissanaholic! Join Date: Aug 2013 Location: Denver Age: 40 Posts: 2,052 Trader Rating: (14) Feedback Score: 14 reviews	__________________ S13 Vert \| SR \| PE1420 \| 5-Speed \| 15x9.5 - 0 \|

01-22-2015, 09:05 AM	#12
*S14DB* AFC #1 Join Date: Oct 2003 Location: 昨晩あなたのお母さんの家 Posts: 20,181 Trader Rating: (3) Feedback Score: 3 reviews	Clean break or is the shaft bent? __________________ Comments should be taken as Opinions not as Statements of Fact

01-21-2015, 10:23 AM	#3
kleenS14 Zilvia Member Join Date: Sep 2006 Location: NoVa Age: 37 Posts: 204 Trader Rating: (6) Feedback Score: 6 reviews	Yea, I wanted to rip the vc off to see, but was a little pissed by that point. Guess it could have broken a rocker. Don't think it would have thrown one past the ras.

01-21-2015, 10:44 AM	#5
Dboyizmlg Nissanaholic! Join Date: Aug 2011 Location: SoCal (I.E.), San Berdino, Colton, Redlands Posts: 1,675 Trader Rating: (18) Feedback Score: 18 reviews	Dual rocker arm guide conversion from Mazworx!!!

01-21-2015, 10:45 AM	#6
iRONDONkey Zilvia Junkie Join Date: Sep 2007 Location: in yo mailbox! Posts: 463 Trader Rating: (1) Feedback Score: 1 reviews	SR's motor.... not so great. Lol

01-21-2015, 10:47 AM	#7
kleenS14 Zilvia Member Join Date: Sep 2006 Location: NoVa Age: 37 Posts: 204 Trader Rating: (6) Feedback Score: 6 reviews	Yea, knew I'd be cutting it real close. Was more going to chuck a rod and have a little more of a spectacle, but meh, it happens. Yea, dual guide will deff be next. Already have new valves, and forged bottom end waiting. Just time to bite the bullet and get it done. Didn't expect this one to last long, just wanted it to at least make it off the dyno lol

01-22-2015, 09:36 AM	#13
Ramonesfreak2010 Zilvia Addict Join Date: Jul 2008 Location: Silver Spring, MD Age: 32 Posts: 963 Trader Rating: (11) Feedback Score: 11 reviews	VVL time! You'll thank me later.