{"id":139745,"date":"2026-02-11T09:28:53","date_gmt":"2026-02-11T14:28:53","guid":{"rendered":"https:\/\/kinsler.com\/Shop\/?p=139745"},"modified":"2026-03-30T13:54:47","modified_gmt":"2026-03-30T17:54:47","slug":"get-the-racing-advantage-with-a-kinsler-k-140-high-speed-bypass-valve","status":"publish","type":"post","link":"https:\/\/kinsler.com\/Shop\/2026\/02\/11\/get-the-racing-advantage-with-a-kinsler-k-140-high-speed-bypass-valve\/","title":{"rendered":"Get the Racing Advantage with a Kinsler K-140 High-Speed Bypass Valve"},"content":{"rendered":"

If you know anything about racing, then you understand that a high-speed bypass is needed to obtain maximum horsepower. Otherwise, your engine will experience a loss of volumetric efficiency at RPM above the peak torque<\/a>. At this higher RPM, the inlet valves are open for such a small amount of time that the cylinders just don\u2019t have enough time to fill with fresh mixture.<\/p>\n

But a high-speed bypass also benefits the mid-range performance. After all, if an engine is jetted to obtain maximum horsepower at a high RPM without a high-speed bypass, it will be lean around the peak torque RPM. Unfortunately, jetting rich enough for the best mid-range power will cause your engine to run rich and lose power at a higher RPM. And nobody wants that.<\/p>\n

With a high-speed bypass valve<\/a>, however, it\u2019s possible to gain separate control of the mid-range and high RPM fuel rates. The main jet can be run richer for best mid-range performances, while the high-speed leans the system for best power at a high RPM. And the Kinsler K-140 high-speed bypass valve<\/a> is the champ for hurtling you toward the finish line.<\/p>\n

The Kinsler K-140 High-Speed Bypass Relief Valve Advantage<\/h2>\n

In case you\u2019re unfamiliar, the Kinsler K-140 high-speed bypass valve<\/a> is a pressure-sensitive valve<\/a> in a mechanical fuel injection system that releases excess fuel back to the tank at high RPMs, leaning out the fuel mixture to match your engine’s reduced volumetric efficiency. This prevents it from getting too rich and thus optimizes power for peak performance.<\/p>\n

Opening at a pre-determined set pressure to manage fuel flow when your engine needs less fuel per revolution at higher speeds. \u00a0This is crucial for engines running on methanol in drag racing and sprint cars. \u00a0The K-140 has the highest flow capacity with the lowest pressure rise of any valve on the market. \u00a0For most applications, the rise is under 1-PSI, since the total bypass flow for most systems is 600 lbs\/hr or less.<\/p>\n

This high-speed bypass valve also allows for superbly smooth operation. It maintains a flow curve within 0.3 (3\/10) PSI at any flow point on the opening curve. \u00a0All of the moving parts are hard-coated, then micro-lapped to ensure that the pressure in the fuel system stays close to the set point on both the rising and falling engine RPM.<\/p>\n

While it\u2019s not uncommon to hear a buzzing sound from the hydraulic vibration of other valves, the Kinsler K-140 is much more stable. It\u2019s the only IRL valve<\/a> on the market with a unique spring arrangement designed to control that buzz. The diaphragm has a swiveling \u201clive\u201d center pintle that closes down on the seat, resulting in smooth operation. Plus, both the pintle and the seat are lapped for bubble tight close-off.<\/p>\n

The hard-anodized aluminum<\/a> housing components and compact design make this piece lighter (only 0.45 lbs) and easier to install in the vehicle. Components are compatible with gasoline and methanol.<\/p>\n

Plus, the K-140 comes complete with a 6 AN male flare inlet fitting, #3161 restrictor jet holder, and vent breather filter. \u00a0Seven different spring combinations are available for a total adjustable range of 17 – 230 PSI. Custom buildup service is also available from the fuel-injection experts<\/a> at Kinsler.<\/p>\n

Tuning Tips and Basic Adjustments<\/h2>\n

It\u2019s important to note that when properly adjusted, you, as the driver, should not feel the high-speed bypass\u2019s engagement. \u00a0If you do feel it because your engine\u2019s power increases dramatically, then either the main jet is adjusted too rich, or the high-speed bypass is opening at too high an RPM.<\/p>\n

Either condition will cause your engine\u2019s output to be lower than optimum. There should be no sudden burst of power. You should feel only a steady, strong pull.<\/p>\n

Troubleshooting<\/h3>\n

If a high-speed jet is installed on a fuel system when it is calibrated by Kinsler<\/a>, the main jet and high-speed bypass setting should be very close for optimal power. However, consider the following:<\/p>\n

1. If the fuel curve seems too rich throughout the RPM range, you should go to a leaner main jet.<\/p>\n

2. If just the top end seems rich, go lower on the high-speed pressure setting until the high RPM mixture is correct.<\/p>\n

A) If the system has a restrictor jet, try going .004\u201d – .010\u201d larger per run.\u00a0 (Note: The calibrated pressure settings of the high-speed valve should not require a major adjustment if the original main jet is being utilized.) \u00a0Compare this with the results obtained by going lower on the valve pressure setting.<\/p>\n

B) If the system still seems rich after step A above, lower the opening pressure of the high speed by approximately 3 PSI. \u00a0The experts at Kinsler strongly recommend you reinstall the original restrictor jet before lowering the pressure setting.<\/p>\n

C) If your engine still seems rich with the lower pressure setting, repeat step A. \u00a0While this method may require several runs of your engine, it\u2019s been found to be a safe way to tune the system while avoiding engine damage from going too lean.<\/p>\n

3. If the system is adjusted to give a proper fuel curve, but the overall curve needs to be richened or leaned due to changes in your engine displacement, air density, weather, altitude, etc., adjust the high-speed pressure for each main jet step you adjust.<\/p>\n

4. And finally, always tune your engine for best performance, not just what appears to be good plug readings.<\/p>\n

How do I set the K-140 High Speed Bypass Valve?<\/h2>\n

The Kinsler K-140 High Speed Bypass Valve has many features and the video below explains the function, servicing, and how to set the valve.<\/p>\n