Pro-Billet Rocker Arms: SR20DET and SR20DE
*All prices exclude GST(Tax) and will be calculated during checkout. International customers do not pay tax*
*Pictures are for illustration purposes only and may differ to your order*
"Final Version" PRE-ORDER OPEN
Depending on the feedback from the Pilot Program we may or may not make changes, then we get straight into production, and then ship out to you. There is currently no ETA on the shipping date, but the earlier you order, the lower the price - check back in a few weeks and the price will go up.
International customers please email us to place your order - our website isn't set up for international orders yet.
PILOT PROGRAM CLOSED
Final date to submit results: End of January 2019
Include photos, measurements, fit and finish, general comments
Download feedback forms here (PDF)
Pro-Billet Rocker Arms for the Nissan SR20DE and SR20DET
Don't want broken bits of rocker arms?
The Weak Link In The SR20DE(T)
Alpha Omega Racing's Pro-Billet Rocker Arm
Pro-Billet Rocker Arms are engineered from the ground up to work perfectly with the factory OEM set up - or aftermarket set ups - without needing modifications, including:
- Hydraulic lifters + hydraulic cams
- Solid lifters + solid cams
- Single guide + single shim
- Dual guides (no shim)
Everything including weight, rocker ratio, critical dimensions, clearances, have all been modelled off brand new OEM genuine Nissan rocker arms. Keep this in mind because we have found - and you too may find - that during installation, old/used/worn parts and their clearances need to be adjusted to suit brand new rocker arms.
Alpha Omega Racing Pro-Billet Rocker Arm (top left)
Brand New OEM Nissan Rocker Arm (top right)
This is the first and most obvious theory on why rocker arms break. They're simply too weak in material and design.
We have carefully analysed the OEM rocker arms, trialling a range of new materials and testing them over a 15 month period, finally selecting a tough steel for this part. Notice we didn't say a hard steel or a stiff steel...
Definition of Tough: In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing... Toughness requires a balance of strength and ductility.
Think of it like a really really really really really really really strong spring - instead of snapping into bits like the standard part, the Pro-Billet Rocker Arm is specifically engineered to absorb and soldier on like a boss.
LEFT (Alpha Omega): FEA-Optimised Support Structure
RIGHT (OEM): ... nothing
Our tough material is both stronger and more ductile than the OEM part - it starts out in the form of a billet block of secret steel, carefully CNC machined and undergoing multiple stages of stress relieving, malleability, and heat treatments (this is where the "Pro" in "Pro-Billet" comes from) before finally being polished to be the most beautiful rocker arm in the world. Just kidding! - aesthetics is the lowest priority on our list - the polishing is done primarily to remove stress risers, lower friction, and aid in the flow of oil, and you may notice that the oil channels have been optimised too.
When you flip the Pro-Billet Rocker Arm over you'll immediately notice extensive webbing in an area that is hollow in the OEM part. This support-structure is CAD-engineered and FEA-optimised to find the ideal number, locations and angles, all aimed to increase toughness whilst balancing the weight. With the FEA-optimised support structure in place, the weight is still the same as the OEM part which means harmonics and balance are just like factory: the Pro-Billet Rocker Arm is ready to mix-n-match, plug-n-play.
FEA-Optimised Support Structure = No Stress
Harmonics and loads.
When upgrading cams you will go with longer duration along with higher lift. The higher lift makes more power by keeping the valve open wider, and this allows more air and fuel to enter for a bigger bang for more power, but in doing so the rocker arm fingers are now loaded on an area that was never intended to be loaded - just the tip.
The is (part of the) second theory on why rocker arms break.
Tomei Instructions To Remove The Tips
Tomei recommends that the tips of the OEM rocker arms be removed, but there's a catch22; by grinding the OEM rocker arm you have now removed the hardening, altered the molecular structure, introduced microcracks and inadvertently weakened the OEM rocker arm. The Pro-Billet rocker arm have CNC machined radiused tips from the factory, so now you can safely run super duper high lift camshafts without any worries... except maybe for your valve-to-piston clearances.
OEM Tip (Black / Behind)
Pro-Billet Tip (Polished / Front)
Hydraulic lifters and unmatched valve springs.
These have nothing to do with the rocker arm design itself but have a direct influence on its life.
The hydraulic lifter heights are controlled by oil pressure; if the oil pressure spikes or drops - say you launch the car for a drag race or you're attacking an S-corner at 150km/h - then the lifter height can drop, then the rocker arm will fall, then you say good bye to your rocker arms, or of the pressure spikes then it can add more load than the rocker arm can take and break. The easiest solution is to eliminate the oil pressure variable altogether; upgrade to Tomei solid lifters.
On the other end of the rocker arm are the valve springs; if their harmonics and rates are not matched with your camshafts, turbo, boost, RPM, etc or they wear out then they may not keep the valve/guide/rocker arm/camshaft controlled within tolerance, the rocker arm / guide / shim can become unseated and once again, say good bye to your rocker arms. The solution is to upgrade the valve springs.
Note that valve spring rate / pressures / max lift / coil bind are the things people compare because they're factual figures. We don't manufacture our own camshafts but if we did we'd also consider the harmonics; things like the coil width, coil spacing style (linear or beehive or something else), single or dual springs (dual springs aren't just for additional spring rate - the two springs can rub onto each other and cancel out harmonics), material, treatments, coatings... all of this should be taken into consideration. We recommend you choose a reputable camshaft manufacturer and use their recommended valve springs.
Same Weight As Brand New OEM (±5%) = Same Harmonics
Dual guides and the shim/guide pad.
In the OEM set up Nissan uses one guide and one flat shim. The flat shim is to - as the name suggests - shim the rocker arm so that it is horizontally parallel to the cam lobe, and the guide is there to keep the rocker arm in position. Without the one little single guide, the rocker arm will literally slip out of place.
This is the third theory on why rocker arms break.
To address this issue you can introduce more stability; instead of using one guide + one shim, you can (sort of) replace the shim with a second guide of the correct height with the standard Nissan rocker arm. BUT! The catch22 here is you had to decide between having the stability of dual guides VS a weakened standard Nissan rocker arm. Why? The OEM rocker arm did not allow for a guide to fit on the shim finger - the shim finger was too wide - so you had to grind down the shim finger to fit the guide and in the process removed the hardening, altered the molecular structure, introduced microcracks and inadvertently weakened the OEM rocker arm.
Alpha Omega Pro-Billet Rocker Arms have both fingers designed to fit either a shim or a guide without any modifications - no modifications means the strength of the finger and the rocker arm is never compromised. We recommend dual guides for twice the stability and twice the reliability but if you want a quick easy fix then simply take out the old standard stuff and drop in the new Pro-Billet stuff.
LEFT: OEM factory set up = one shim + one guide
MIDDLE: OEM set up not compatible with dual guides (without modifying) - note the gaps
RIGHT: ALPHA OMEGA Pro-Billet rocker arms are dual guides ready
Additionally we went as far as analysing the guide/shim pad. Notice that the Pro-Billet Rocker Arm pads are wider to spread the load, and they are polished silky smooth for less friction. Finally, the tolerances are smaller, meaning the fit is tighter than OEM. There is a high chance that you can't notice a 0.01-0.02mm difference - which is a fraction of the size of human hair - but it's there.
The wider and tighter contact patch has more stability for more time for more of the radius.
Bigger, Wider, Smoother, and Tighter Tolerances: Guide/Shim Pad
FEATURES AND BENEFITS
- Direct plug-n-play
- Dual guides ready / double the reliability
- Solid lifters ready
- Solid cams ready
- Tougher base material CNC machined from billet + the treatment works
- The most beautiful rocker arm in the world =)
- Reduced friction
- Increased stability
- Improved oil control and lubrication
- FEA-optimised support structure
- Limiter bash for days
- 1x SR20DE(T) rocker arm
Alpha Omega Racing's Pro-Billet Rocker Arm (SR20DE and SR20DET)
You must check and adjust all clearances, lash, and parallelism of the rocker arms to the cam lobes.
Can be mixed and matched with standard parts.
This product is a direct replacement for the part number “13257-53J03” and suits the Nissan SR20DE(T) in the following vehicles (excluding RNN14 GTiR): S13, S14, S15, B14, C23, M11, M12, N14, N15, N30, R10, R11, W10, W11, P10, U13.
Does not suit RNN14 Pulsar GTi-R engines.
Sold in single pieces, 8 required per engine.
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