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JERK CAMSHAFTS

GET 10% OFF WHEN YOU BUY 2 OR MORE ITEMS, EACH PRICED AT $750 OR MORE!

The dark art of cam design

The development of Jerk Bumpstix has been an extensive journey spanning over six years. Throughout this period, we’ve collaborated with numerous camshaft designers and manufacturers to fulfill our criteria for the right profile design, material quality, and precision manufacturing. Our initial partnerships were untenable as they fell short of our stringent standards in one or several aspects, leading us to continue our search. We have meticulously measured, dyno-tested, and quality-inspected a multitude of camshafts, confronting various issues such as porous metal castings, high-stress lobe profiles, and inaccuracies in timing.

We had the option to proceed to production with any of these manufacturers or designs. However, doing so could have resulted in subpar performance, increased wear profiles, or the risk of manufacturing defects—issues that are unfortunately not uncommon in the industry. But in line with our commitment to excellence, as demonstrated with our header design, we chose to discontinue our investment with any designer or manufacturer whose product failed to meet the URGE benchmark.

At last, we have achieved camshaft profiles that optimize performance and minimize valvetrain wear. These are produced on quality-controlled CNC machinery, employing the finest materials available and backed by industry-leading test results.

Intake cam

Valve timing is a pivotal aspect of camshaft function, dictating the RPM range and the specific band where an engine produces torque. The most critical event in camshaft timing is the closing of the intake valve, which is influenced by fluid inertia and compressibility. These factors determine the optimal point of intake valve closure to maximize cylinder filling at a targeted RPM range. We dedicated considerable effort to perfecting this timing, utilizing adjustable cam gears for precise adjustments.

Following the intake valve closing event, the next key parameter is the intake cam duration. This duration must be finely tuned based on manifold pressure and the engine’s primary operational range. The combination of intake duration and valve lift is crucial as it defines the engine’s air intake capacity at any given RPM, which in turn dictates the potential torque output.

Exhaust cam

Exhaust valve duration and the lobe separation angle are critical camshaft timing events that establish camshaft overlap, which in turn influences fluid momentum and the bleed-off of pressure. While the closing and duration of the intake valve are primary determinants of a camshaft’s power-generating capability, the exhaust timing events refine the torque curve’s range and peak.

In our research, we analyzed hundreds of torque curves and flow charts to determine the optimal size for the exhaust cam that would complement our intake cam, with the aim of maximizing torque gains across the broadest RPM range feasible. The S2000’s OEM cylinder head features a distinctive intake-to-exhaust flow ratio that sets it apart from other Honda engines and popular motor designs. Despite recommendations to adopt K Series intake-to-exhaust cam sizing — a suggestion we encountered frequently — we recognized that the S2000’s exhaust flow capabilities far surpass those of the K series. We knew that adhering to such advice would likely result in performance gains confined to a limited RPM band.

Performance

As we have previously discussed, the S2000’s engine is exceptionally efficient, delivering an impressive 120 horsepower per liter. To achieve this level of performance, we committed to a camshaft solution that incorporates superior materials, precise manufacturing, and a design profile that minimizes wear. In contrast to typical aftermarket camshafts that offer modest gains of 5-10 horsepower for the S2000, our camshafts yield a significant improvement of 15-20 horsepower within the VTEC range on a tuned engine — and this distinction is crucial. Competitors may present inflated “gains” by measuring from a baseline dyno run, then installing their parts and tuning the engine with those new components installed (noting that an S2000 can gain 10-15 horsepower from tuning alone). Therefore, it’s vital to discern whether horsepower gains are due to the new parts or the tuning itself.

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.

13 hp gains over a tuned motor, all gains attributed to the camshaft

Tune is required

We recognize the demand for camshafts that can be installed without additional tuning. Yet, it’s crucial to grasp the inherent constraints of the stock engine control unit (ECU) when it comes to adapting to increased airflow. Without tuning, the ECU can only marginally enhance air intake, with potential power gains restricted to about 10-15 horsepower—gains that are similarly accessible through basic modifications like upgraded intakes and exhaust systems. Furthermore, without recalibration, the ECU cannot optimize the engine’s performance to take full advantage of the increased airflow provided by our camshafts.

The Jerk Bumpstix camshafts are engineered to substantially augment airflow beyond what OEM parts can offer. To harness their complete performance benefits, meticulous tuning is essential to fine-tune the air-fuel ratios and ignition timing. Such precision tuning is critical to achieving the best engine performance by capitalizing on the significant airflow improvements of the camshafts. As much as the convenience of a plug-and-play camshaft is appealing, the importance of comprehensive tuning should not be underestimated for those aiming to maximize the performance enhancements afforded by the Jerk Bumpstix camshafts.

Jerk

An additional key goal of the Jerk Bumpstix camshafts is to minimize jerk, which is the rate of change of valve acceleration. High levels of jerk can lead to accelerated wear in the valve train and increase the likelihood of component failures, including valves, springs, or retainers. Our Type R camshafts, while offering roughly 10% more lift than their OEM counterparts, actually demonstrate lower valve jerk rates in comparison to the OEM cam profiles. The design process for all Jerk Bumpstix profiles involved the use of sophisticated camshaft modeling software to ensure we achieved minimal cam jerk, while also enhancing valve lift and duration. This focus on reducing jerk is intended to bolster the durability and reliability of valve train components, thereby contributing to superior engine performance and longevity.

URGE Bumpstix Intake VTEC Jerk Graph

OEM Intake VTEC Jerk Graph

URGE Jerk Bumpstix have lower and smoother valve jerk vs OEM meaning lower valvetrain wear, despite a >10% increase in lift and >10 degrees of duration.

Tool Steel

Jerk Bumpstix camshafts are crafted from a tool steel alloy, a material that is harder and more rigid than the cast steel typically used in camshaft production. This increased stiffness mitigates the axial twist experienced by the camshaft during high-RPM operation, which in turn reduces the deflection between the first and fourth cylinders—those closest and farthest from the camshaft drive, respectively. This reduction in deflection ensures more consistent torque across all cylinders, resulting in a more balanced and finely-tuned engine. The enhanced uniformity in performance can liberate additional horsepower.

CNC Machined

Jerk Bumpstix camshafts are manufactured using computer numerical controlled (CNC) machines, which meticulously replicate our computer-aided design (CAD) camshaft profiles with high precision. The dimensions of each camshaft are verified with a computer-controlled cam gauge, ensuring accuracy to the millionth of an inch. This rigorous process guarantees that each camshaft meets our exacting standards for precision and quality.

Ultra Valve Spring Kit

The URGE Designs Ultra-Valve Spring kit features a single spring design, custom-wound for use with OEM base locators and paired with Ti-17 alloy retainers compatible with OEM keepers. This design choice eliminates the need for custom bases and new keepers, offering a cost advantage over other high-end spring kits. The springs are made from a high-strength chromium-silicon-vanadium (CrSiV) alloy and utilize a thicker wire diameter, which reduces the number of coils necessary. This supports higher valve lifts of up to 0.650 inches (16.5mm) while concurrently reducing the spring’s weight, thereby facilitating operation beyond 10,000 RPM.

Moreover, the Ultra-Valve springs undergo heat treatment and shot peening, processes that diminish stress risers and potential points for crack initiation, thereby greatly enhancing their longevity and maintaining consistent spring rates. The kit’s springs are crafted from Ti-17 titanium alloy, which boasts a 30% increase in strength and a higher hardness on the HRC scale compared to the commonly used Ti6Al4V alloy, enhancing the overall durability of the springs.

Pricing

Type R Jerk CAMSHAFTS

$1400

  • Stock bottom engines w/ bolt-ons, 270-300+ HP @ 8500 RPM peak power
  • ~13.5mm IN & ~11.6mm EX valve lift (no need for EX rocker notching)
  • S7 tool steel billet cores
  • Strongly recommend URGE Ultra Valve Spring Kit

Stroker Jerk CAMSHAFTS (In development)

$1500

  • 95mm+ Stroked Motors, 330-380+ HP @ 8000-8500 RPM peak power
  • ~14.5mm IN & ~13mm EX valve lift (MUST notch exhaust rockers for clearance)
  • S7 tool steel billet cores
  • Must use URGE Ultra Valve Spring Kit

ready to order?

2 + 14 =

10K Jerk CAMSHAFTS (In development)

$1500

  • 9500+ RPM motors, 330-380+ HP @ 9000-9500 RPM peak power
  • ~14mm IN & ~12.5mm EX valve lift (MUST notch exhaust rockers for clearance)
  • S7 tool steel billet cores
  • Strongly recommend Titanium valves to support 10K RPM
  • Strongly recommend URGE Ultra Valve Spring Kit

Ultra Valve Spring Kit

$600

  • Uses OEM bases and AP1 keepers for simpler install (don’t need to remove seals) and reduced cost
  • High strength CrSiV with large wire diameter providing 341 lbs/in spring rate
  • Reduced spring coils supporting higher valve lift of 0.650” or 16.5mm
  • Single spring design reducing spring weight ~10% vs OEM raising redline support
  • Spring surface and heat treatment maximizes lifetime with no pressure degradation
  • Strongest Titanium alloy (Ti-17) retainers @ ~30% higher strength vs typical Ti 6Al4V retainers

Found something you like or just shopping around?  Feel free to send us an email and a consultant will follow up to answer any questions you may have.

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