After performing many tests through competing in D1GP, SR20DET head systems are now available to extract maximum power at high rpm. SR20 engines feature a Y shaped rocker arm which is unseen in most other engine types and reducing rocker arm trouble has become the key in SR20 tuning.
SR Engines, Problems and Solutions
Hydraulic lash adjusters
The stock engine uses a hydraulic lash adjusting system which uses oil pressure to press the cam against the rocker arms. This means that there are no tappet clearances to worry about. As the engine ages and wears, the hydraulic system can absorb the increasing tappet clearance and so engine noise is reduced but this is not necessarily a good thing to extract performance on a tuned engine.
When strengthen valve springs are combined with continuous high revving, the load from the rocker arms can be too much for the lash adjusters causing the clearances to open too much and cause eventual damage to the engine. In order to prevent this, HKS recommend that the hydraulic system is replaced with mechanical tappets using the HKS Lash killer kit.
Rocker Arm Damage
A lot of problems from SR engines come from the rocker arms. If the rocker arm breaks it can often lead to further problems causing complete engine failure.
Valve Float can make a rocker arm come loose and stronger valve springs are usually used but this did not completely solve the problem. HKS has developed a spring retainer that prevents shims from falling off the upper part of the valves. This prevents engine damage if the engine should be accidently over revved and the valves float. On the other hand, using high strength double valve springs increases pressure and load on the cams and rockers causing other issues.
The black coated rocker arms overcome this issue by reducing friction where it contacts with the cam whilst increasing surface strength
●SR20DET Head System (SR20DET Head Systems do not include
Camshafts)
Engine
Type
Kit
Contents
Part
Number
Retail
Price
Remarks
STEP2
SR20DET
・ Outer Valve Spring
22010-AN002
£962.50
・ Black Coated Rocker Arm Set
・
Valve Spring Retainer Set
STEP3
SR20DET
・ Lash Killer Kit
22010-AN001
£1,633.50
Due to
increased valve spring strength, NVCS unit may make noise at low rpm.
・ Outer Valve Springs
・ Inner Valve Springs
・ Black Coated Rocker Arm Set
・ Valve Spring Retainer Set
・ Stem Seal
Set
Product
Engine
Code
Part
Number
Retail
Price
Remarks
Lash Killer Kit
SR20DE(T)
2499-RN001
£ENQUIRE
Not Compatible with RNN14
Rocker Arm Stopper
SR20DE(T)
2299-RN005
£90.20
Modifications
to cam cover necessary when fitting to S14/S15
