SR20 Forum - View Single Post - The JDM/USDM Roller Rocker SR20DE Info Thread
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post #110 of (permalink) Old 06-25-2006, 10:21 PM Thread Starter
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Hell yeah, thanks Mike...

here is a copy of the email that was sent to JWT: (06/25/06)
To JWT Research & Development, To Whom it may concern:

A team of friends from and I had been doing some work on finding information on the Roller Rocker SR20DE Engine. The main cause was to raise awareness in the differences of the roller engine and the regular highport/lowport spraybar engines, and to clear the misconceptions being thrown around. We have most of the differences nailed aside from the true camshaft/valvetrain information. We had a few questions and we were wondering if the people at JWT could help (considering the experience, knowledge, and development your company has provided with this motor).

Here is the information that we have gathered.

-------------------Here are our questions pertaining to the SR20-------------------

1) The main question that we were pondering was - What is the main difference between these stock camshaft profiles besides the duration and lift? Are their differences in the lobe base radius? This is what we know.

Stock Spraybar Stamped Rocker SR20DE Camshaft Information
Intake: Duration = 248* / Lift = 10.0mm (Highport)
Intake: Duration = 232* / Lift = 8.66mm (Lowport)
Exhaust: Duration = 240* / Lift = 9.2mm

Stock Non Spraybar Roller Rocker SR20DE Camshaft Information
Intake: Duration = 232* / Lift = 10mm
Exhaust: Duration = 240* / Lift = 9.2mm

2) We understand that the cams from a spraybar sr20 & a RR SR20 are from a different grind... We were told that this was because the valves for the RR engine were a little bit shorter that the spraybar engine. Do you know the length specs of the different valves?

3) There has been an occurence where a stock spraybar highport intake cam has been afitted into a roller rocker SR20. The car has been driving with no problems for over a year. The engine was pushed hard and driven everyday. Can you provide some feedback on this? Why did this work? Could this yield any damage?

4) Is there a difference in height of the stock stamped rocker arm and the stock roller rocker arm? If so, how does this effect cam design?

5) Was there a difference in the development for the S3 & S3R camshafts? In other words was their testing done on the cams individually, or was the S3R's design the same as the S3 with just the valve heights taken into account?

The following are the specs for the S3 & S3R series cams provided per your website...
Intake/Exhaust S3 cams = .442" lift, 260 degrees duration
Intake/Exhaust S3R cams = .450" lift, 262 degrees duration

This yields a 0.008" lift difference in lift & two degree duration...

6) Lastly we understand that the SR20 motor is no longer in production, but, is there going to be any more research and development for another roller rocker camshaft in the future?

Please let us know if we need to be more elaborate with these questions... Please let us know if you can be of assistance.

Thank you for your time and patience,

Ameen Bakare (SN: xxtokesxx at
James Weintz (SN: 98sr20de(t) at
Here is where the answers to these questions will be posted: Will be updated (__/__/06)
"The profile and specs of the cams are different because of the physical differences between the two different (roller vs. non-roller,) type valve trains. The roller rocker engines have shorter valves due to the roller rocker taking up more space and the valve covers are different. The rocker arm pivot is different. The combustion chamber design is different. The way that the rocker arm works against the cam is different. You only run the correct cam in each application."
-Technical Support @ JWT
Currently Receiving Information... Will Update as necessary...

Please disregard specification information in this post, as it may not be totally correct... that is why I am asking...

1993 B13 SE-R!!!! | SR20VE Daily
1996 D21 4x4!!!!!!! | KA24E Bike Hauler
1998 200sx SE-R | SR20DE S3R'd For Sale!!!!
1991 NX-TuRBO | SR20DET Parted Out
1993 NX2000!!!!!!!! | SR20DE Sold
1993 B13 SE-R!!!! | SR20DET Parted Out
1995 240sx BaSe | VQ30DET Sold
1991 240sx SE!!!!! | KA24DE Sold

Shift_Buy Broken & Build...

Last edited by XxToKeSxX; 06-28-2006 at 08:21 PM.
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