Sr20det Billet Rocker Arms - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

juiced305diesel · 01-04-2019, 01:45 PM

If you come to love the sr20det you have probably come to realization on how much we hate the Oem rocker arms. I been waiting for an aftermarket billet or reinforced rocker for the past 10 years. It doesn't matter if you have solids , dual guide conversion rockers were always the weakest link. Well Alpha and omega have finally answered the call. I should be testing these soon as i can.
http://alphaomegaracing.com/p/202/c/...nd-SR20DE.html

https://ibb.co/h7cm1ky
https://ibb.co/hK2dZxf

*brndck* · 01-04-2019, 02:45 PM

ooooooh nice! didn't know you were still active on here!

juiced305diesel · 01-04-2019, 02:57 PM

Quote:

Originally Posted by brndck

ooooooh nice! didn't know you were still active on here!

Not to much anymore. But this brought me out from the shadows.

*brndck* · 01-04-2019, 03:44 PM

those look pretty rad, esp since they're already sized for dual guides. I'd still want to get them WPC treated just to be EXTRA extra.

Kingtal0n · 01-04-2019, 03:58 PM

opinions

I believe the material oem rockers are made from is brittle to keep the rocker from doing more damage if and when it dislodges.

Brittle materials like cast iron can work in environments where sudden changes to stress indicate some kind of system wide failure, in those situation the cast immediately gives way, as opposed to a ductile material which will merely deform first, and sometimes not break at all. I'd prefer my rockers as extremely stiff when properly installed, and for all other situations I'd like them to behave like large fragments which are easy to collect afterwards, after giving way to other moving objects.

Splatter a rocker and nick the cam. Instead of break the cam.

Rocker isn't expensive or difficult to replace.

Surely many 500-600hp sr20s run oem rockers.

There maybe an application I am not seeing, but

Kind of as an aside. The oem engineers may have designed the rocker with a specific angle in mind. Stress in 3 dimensions is often given as a 'stress tensor' in mechanics and there is a very specific angle at which the material will initially fracture that may be considered in the design. It may be that they have 'beefed up' specific area of the rocker, or even lessened them, with hopes of reducing damage.

The rocker design in and of itself will always be a challenge because in order to be successful with it one must know many things, such as damping and natural frequencies of valvetrain parts, what the stress in every part will be at each frequency, stress concentrations in the design of valve related parts, the list goes on and on. So most enthusiasts are forced to blindly trust manufacturers when buying things like valve springs and valves, and such a seemingly insignificant feature of one of those parts can dislodge a rocker at some specific rpm from causing a valve to bounce on it's seat because the single spring had a resonant frequency which wasn't dealt with properly at that specific rpm. Now you blame the rocker arm for coming off, but the real problem was the spring and cam selection was mis-matched, and maybe it wouldn't have been if the right valve was used, etc... So, That is one reason I recommend buying the spring from the same manufacturer as the cam (Tomei, Greddy, and similar, the Japanese companies surely test their spring/cam combos for such things as resonance, that is the hallmark of their compatibility and one of the things that makes true "JDM" parts high quality)

RalliartRsX · 01-04-2019, 06:51 PM

The issue with a DE/DET is not rocker arm strength. It is the fact that the rocker arms are essentially floating. This is an inherent design deficiency. Unfortunately, the billet rocker doesn't address the inherent flaw and just moves the failure node to another component (cam, piston, etc)

Most (if not all) manufacturers have since gone to shaft (or similar) mounted rocker arms.

*TheRealSy90* · 11-12-2020, 01:15 PM

So i'm going to guess you never actually tried these by this point.

01-04-2019, 01:45 PM	#1
juiced305diesel Zilvia Junkie Join Date: May 2007 Location: Dade County Age: 36 Posts: 595 Trader Rating: (11) Feedback Score: 11 reviews	Sr20det Billet Rocker Arms If you come to love the sr20det you have probably come to realization on how much we hate the Oem rocker arms. I been waiting for an aftermarket billet or reinforced rocker for the past 10 years. It doesn't matter if you have solids , dual guide conversion rockers were always the weakest link. Well Alpha and omega have finally answered the call. I should be testing these soon as i can. http://alphaomegaracing.com/p/202/c/...nd-SR20DE.html https://ibb.co/h7cm1ky https://ibb.co/hK2dZxf __________________ "Being a SSR wheel nude model is NOT easy, I just make it look like it is!"

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01-04-2019, 03:58 PM	#5
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 38 Posts: 4,649 Trader Rating: (17) Feedback Score: 17 reviews	opinions I believe the material oem rockers are made from is brittle to keep the rocker from doing more damage if and when it dislodges. Brittle materials like cast iron can work in environments where sudden changes to stress indicate some kind of system wide failure, in those situation the cast immediately gives way, as opposed to a ductile material which will merely deform first, and sometimes not break at all. I'd prefer my rockers as extremely stiff when properly installed, and for all other situations I'd like them to behave like large fragments which are easy to collect afterwards, after giving way to other moving objects. Splatter a rocker and nick the cam. Instead of break the cam. Rocker isn't expensive or difficult to replace. Surely many 500-600hp sr20s run oem rockers. There maybe an application I am not seeing, but Kind of as an aside. The oem engineers may have designed the rocker with a specific angle in mind. Stress in 3 dimensions is often given as a 'stress tensor' in mechanics and there is a very specific angle at which the material will initially fracture that may be considered in the design. It may be that they have 'beefed up' specific area of the rocker, or even lessened them, with hopes of reducing damage. The rocker design in and of itself will always be a challenge because in order to be successful with it one must know many things, such as damping and natural frequencies of valvetrain parts, what the stress in every part will be at each frequency, stress concentrations in the design of valve related parts, the list goes on and on. So most enthusiasts are forced to blindly trust manufacturers when buying things like valve springs and valves, and such a seemingly insignificant feature of one of those parts can dislodge a rocker at some specific rpm from causing a valve to bounce on it's seat because the single spring had a resonant frequency which wasn't dealt with properly at that specific rpm. Now you blame the rocker arm for coming off, but the real problem was the spring and cam selection was mis-matched, and maybe it wouldn't have been if the right valve was used, etc... So, That is one reason I recommend buying the spring from the same manufacturer as the cam (Tomei, Greddy, and similar, the Japanese companies surely test their spring/cam combos for such things as resonance, that is the hallmark of their compatibility and one of the things that makes true "JDM" parts high quality)

01-04-2019, 06:51 PM	#6
RalliartRsX Post Whore! Join Date: Apr 2006 Location: Maryland Posts: 4,753 Trader Rating: (32) Feedback Score: 32 reviews	The issue with a DE/DET is not rocker arm strength. It is the fact that the rocker arms are essentially floating. This is an inherent design deficiency. Unfortunately, the billet rocker doesn't address the inherent flaw and just moves the failure node to another component (cam, piston, etc) Most (if not all) manufacturers have since gone to shaft (or similar) mounted rocker arms.