The dark art of cam design

Valve timing is everything with cams as it determines what RPM and range an engine makes torque.  The single most important camshaft event is when the intake valve closes.  Fluid inertia and compressibility dictates optimal intake valve closing to maximize cylinder filling in a particular RPM range.  We spent a lot of time getting the timing right using adjustable cam gears. 

The next most important camshaft parameter is intake cam duration.  Intake cam duration is optimized based upon manifold pressure and the primary engine operating range.  Intake duration along with lift determines the maximum amount of air an engine can consume and ultimately the torque that can be made at each RPM. 

Exhaust cam

Exhaust valve duration and lobe separation angle are the next most important camshaft timing events that define camshaft overlap which dictate fluid momentum and pressure bleed.  Intake valve closing and duration determine how much power cams can make, and exhaust timing events adjust the range and peak of the torque curves.

We studied hundreds of torque curves and flow charts to understand what size exhaust cam we should pair with our intake cam to maximize torque gains across the largest RPM range possible.  The S2000 OEM head has a unique IN/EX flow ratio unlike other Honda or popular motors.  Many camshaft designers try to use K Series IN/EX cam sizing (we know as we were recommended this repeatedly) however the S2000 EX flow is much stronger than K series and we knew any gains would be over a narrow RPM range if we had listened.  

Performance

The S2000 is a highly optimized engine achieving 120 HP per liter and we didn’t want to deliver a relatively modest camshaft at price point needed to cover high quality materials, precession manufacturing and low wear profile design.  5-10 HP is typically what you see in the S2000 after-market cams with a tune.  We achieved >10 HP over tuned motor.  Other dynos show gains from tuned camshaft over an untuned motor.  Since we know an S2000 can easily make 5-10 hp with a proper tune alone, it brings into question how much of the gains were from the tune vs the cams.  All our camshaft testing is a tuned OEM cam motor vs our tuned camshaft motor meaning all gains are attributed to the camshafts and not tuning gains. 

Here’s our straightforward approach to ensuring transparent results:

1. Tune the motor
2. Dyno
3. Install part
4. Dyno
5. Launch product because it’s awesome OR back to the drawing board and apply what we learned

Our testing protocol pits a tuned OEM cam motor against our tuned camshaft motor, so any observed gains are due to the camshafts alone, without any confounding from tuning improvements. Consistently, our camshafts have demonstrated remarkable increases of 15-20+ horsepower between 5000 and 9000 RPM when compared to a tuned AP1 model without any additional modifications. When installed on a tuned AP2 model with an intake, header, and exhaust, gains of 12-17 horsepower were realized in the 5000 to 8500 RPM range. We believe no other camshafts on the market have shown to exceed 10 horsepower gains over a tuned S2000.

When evaluating our products against competitors, it is critical to compare tuned versus tuned outcomes. Additionally, if a company artificially inflates their dyno numbers with questionable testing methods, it casts doubt on their overall integrity. URGE guarantees that any product we release has been validated through transparent and verifiable testing.

Tune is required

We understand the desire for a drop-in camshaft that doesn’t require tuning.  However, the stock ECU can only compensate for a small increase in air limiting power to 10-15 HP.  These gains can easily be achieved by intake or exhaust, so we had no desire to design a camshaft with limited gains.  Bottom line, Jerk Camshafts are a significant improvement in airflow over OEM camshafts and tuning is required to install and maintain optimized air fuel rations and spark timing. 

Jerk

Another key focus of Jerk Bumpsitx is reducing jerk or the rate of change of valve acceleration.  Higher jerk increases valve train wear and the potential of valve, spring, or retainer failure.  Despite having ~10% more lift than OEM, our Type R cams have reduced valve jerk vs OEM.  All Jerk Camshafts profiles were designed via advanced camshaft software to unsure as low cam jerk as possible while optimizing valve lift and duration. 

Tool Steel

Jerk Camshafts use S7 tool steel alloy which is harder and stiffer than typical cast steel camshafts.  Stiffer material reduces the axial twist along the cam during higher RPM use reducing cam deflection between cylinder 1 closest to where the cam is driven and cylinder 4.  This will improve torque consistency between cylinders providing a more balanced and tuned motor freeing up a few HP. 

CNC Machined

Jerk Camshafts are ground using computer numerical controlled (CNC) machines to create precise copies of our computed added design (CAD) camshaft profiles.  Camshaft dimensions on checked on a computer-controlled cam gauge to ensure millionth of an inch accuracy! 

Ultra Valve Spring Kit

The URGE designs Ultra-Valve Spring kit is a single spring design custom wound to use OEM base locators combined with Ti-17 alloy retainers designed to use OEM keepers.  Eliminating custom bases and new keepers reduces cost vs. other high end spring kits.  High strength CrSiV spring alloy and thicker wire diameter reduce the number of coils needed supporting higher valve lift (0.650” or 16.5mm), while reducing weight capable of >10,000 RPM.  Additionally, URGE Ultra-Valve springs are heat treated and shot pinged reducing stress risers and potential crack initiation points significantly increasing longevity and reducing spring rate degradation.  Finally, the Ultra-Valve Spring kit uses Ti-17 Titanium alloy, which is 30% stronger and 7 points harder on HRC scale vs typical Ti6Al4V improving durability. 

Ultra Valve Spring Kit

Adjustable Cam gears are NOT needed for URGE Jerk camshafts.  We have set the cam centerlines in a conservative position for OEM bottom ends accounting for high mileage S2000s that have stretched timing chains and loose timing chain tensioners.  There is potential for more power by adjusting the cams for built bottom ends and upgraded or new timing systems.  If you are looking to squeeze more mid-range out of our cams, adjustable cam gears may be an option for you to advance the intake cam with proper piston to valve clearance. 

Timing Chain and Tensioner 

The S2000 timing chain system is a known weak point with the OEM TCT having a notice for the timing chain tensioner wearing out prematurely and/or not applying enough chain tension potentially causing valve timing issues or failures.  Additionally, most S2000s are over 100,000 miles likely have chain stretch also causing timing issues.  With more aggressive cams, both concerns could worsen.  For high mileage S2000s, we recommend upgrading replacing the timing chain to a longer lasting heavy duty Toda timing chain.  For any S2000, upgrading the TCT is a must to apply consistent tension.