Bourne HPP: Motorsport Engineering for the Honda K-Series

When it comes to building a Honda K-Series engine, there’s no shortage of aftermarket parts to choose from. But there’s a big difference between simply manufacturing performance parts and developing components through real-world motorsport experience.

That’s what makes Bourne HPP interesting.

Based in the UK, Bourne High Performance Powertrains is an engineering and engine development company with experience reaching into some of the highest levels of motorsport. The company specializes in competition engines, engine development, electronics, calibration, and trackside support, with a particular focus on Honda’s K20 and K24 platforms.

In our latest video, we took a closer look at Bourne HPP, their background, and several of the components they’ve developed for Honda K-Series engines.

From Formula 1 Experience to Honda K-Series Development

Bourne HPP was established by Terry Radbourne in 2019, but the experience behind the company goes much further back.

According to Bourne HPP, its team brings experience from Formula 1, Le Mans, the World Endurance Championship, and other forms of professional motorsport. Today, that knowledge is applied to everything from complete competition engines and component development to wiring, ECU calibration, power distribution systems, and trackside support.

Honda's K-Series has become one of the company's specialties.

Bourne describes the K20 and K24 as engines that combine performance, reliability, availability, and an enormous aftermarket ecosystem. Their K-Series engine programs cover everything from relatively straightforward naturally aspirated builds to heavily developed competition engines. Bourne states that its K-Series programs can be configured for applications ranging from circuit racing and hill climbs to drifting and time attack.

More importantly, these aren't components being developed purely on paper.

Bourne HPP engines and engineering have been used successfully in competition. The company cites championship-winning applications including UK Time Attack, while its more recent work includes the turbocharged K22-powered Tegiwa Honda NSX that competed successfully in Time Attack.

That motorsport background is ultimately what makes the Bourne catalog worth looking at.

Bourne HPP K20 Cylinder Head

One of the most serious components we looked at was Bourne HPP's K20 cylinder head.

Rather than simply rebuilding a factory Honda cylinder head, Bourne offers a performance-prepared K20 head featuring beryllium-copper valve guides and seats.

The material choice is particularly useful in demanding high-RPM and forced-induction applications because of its thermal properties. Bourne's goal is to transfer heat away from the valve more effectively while maintaining stable valve-guide and valve-seat geometry as temperatures increase.

Better thermal management becomes increasingly important as cylinder pressure, exhaust temperature and engine speed increase.

Bourne also highlights improved valve sealing, reduced wear and resistance to galling as advantages of the Be-Cu configuration. It's a solution aimed at serious naturally aspirated, forced-induction and competition K-Series engines rather than simply being an aesthetic or bolt-on upgrade.

K20/K24 Performance Valves

Naturally, once airflow and RPM increase, the rest of the valvetrain becomes equally important.

Bourne HPP offers its own performance intake and exhaust valves for K20 and K24 applications. These components can be combined with the company's cylinder-head preparation, valve springs and camshafts to create a complete valvetrain package rather than treating each component independently.

This is also where Bourne's engine-building background becomes valuable. The company isn't simply offering isolated components—it uses its own valves, springs and related hardware in complete K-Series engine combinations. Its JDM K20 engine package, for example, uses Bourne HPP performance valves and upgraded valve springs as part of the finished assembly.

For anyone building a higher-RPM K20 or K24, that's an important distinction. The valvetrain needs to operate as a system.

Bourne HPP 21S Drop-In Camshafts

Not every K-Series build needs an all-out race cam.

For street cars and dual-purpose builds, Bourne offers its 21S Drop-In Camshaft for the K20 and K24.

This is probably one of the more interesting products in the lineup because it sits between an OEM camshaft and a dedicated race profile.

The 21S is designed to work with the standard valvetrain without requiring cylinder-head machining or upgraded valve springs. Bourne lists the operating range at approximately 1,500–9,000 RPM and specifically designed the profile to improve usable midrange torque in addition to peak power.

That makes it an appealing option for the type of K-Series build many enthusiasts actually have: a naturally aspirated street car that sees occasional track use but still needs good drivability.

You aren't necessarily trying to build a 9,500-RPM race engine. You just want more out of an otherwise relatively conventional K20 or K24 combination.

That's where a drop-in cam makes a lot of sense.

Stepping Up to the 32R Race Cam

At the other end of the spectrum is Bourne HPP's 32R race camshaft.

This is a much more aggressive profile intended for purpose-built engines.

The 32R uses considerably more lift and is designed around high-RPM airflow. Bourne offers the profile in both chill-cast and billet versions, with the billet 32R receiving an additional super-finishing process intended to reduce valvetrain friction.

Unlike the 21S, this isn't intended to simply drop into an otherwise stock engine.

Bourne specifies supporting modifications including upgraded valve springs, appropriate cam timing hardware, increased fueling capacity and professional ECU calibration. The billet version of the 32R is also the specification used in Bourne's own K22-powered Honda NSX program.

It illustrates the range Bourne is trying to cover with its K-Series program.

On one side, there's a street-friendly drop-in cam. On the other, there's a dedicated motorsport profile for engines where maximum airflow and high-RPM performance take priority.

Lightweight Chromoly Flywheel

Moving outside the cylinder head, another component we featured is Bourne HPP's lightweight chromoly flywheel for K-Series applications.

Reducing rotating mass can make a noticeable difference in how quickly an engine responds to throttle input. A lighter flywheel requires less energy to accelerate, allowing the engine to gain and lose RPM more quickly.

For a performance street or track-oriented K-Series build, that sharper response can make the engine feel significantly more eager—particularly during downshifts and transitions where engine speed needs to change quickly.

It's another relatively simple component that fits into Bourne's larger philosophy: improve the response and performance of the complete powertrain rather than focusing exclusively on a peak horsepower number.

K-Series Exhaust Studs

Some of the least exciting parts of an engine build can also become some of the most frustrating when they fail.

Bourne HPP also offers upgraded K20 exhaust studs intended for performance and motorsport applications.

Exhaust hardware lives in an extremely harsh environment. Repeated heat cycles, vibration and removal during engine service can eventually take their toll on factory hardware.

For a street car that rarely comes apart, that might not be a major concern. For a competition engine—or simply a K-Series build that's going to see frequent service—upgraded hardware becomes a much more worthwhile consideration.

Aluminum Radiator With Integrated Oil Cooler Mount

Bourne's engineering isn't limited to internal engine components.

We also looked at the company's aluminum radiator featuring provisions for mounting an oil cooler.

For track cars, packaging is always a challenge. Cooling systems, oil coolers, ducting, intercoolers and other components all compete for space at the front of the car.

Integrating the oil cooler mounting solution into the radiator assembly helps create a cleaner package while addressing two of the biggest concerns for a track-driven K-Series: coolant temperature and oil temperature.

As power increases and track sessions become longer, managing temperature becomes just as important as making horsepower.

Race Parts Developed Through Race Experience

That's really the recurring theme throughout the Bourne HPP catalog.

These aren't simply shiny parts designed to fill another space in the K-Series aftermarket.

Bourne's core business includes engine building, component design and manufacturing, engine dyno services, wiring, ECU calibration and trackside support. That means the company gets the opportunity to develop components, assemble them into complete engines, calibrate those engines and then see how the entire package performs in competition.

That feedback loop matters.

It's one thing to design a camshaft.

It's another to design the camshaft, build the engine, put it on the dyno, install it in a race car, calibrate it and then see what happens after repeated laps at full load.

And the results are there. Bourne reports championship-winning engines in multiple applications, while projects such as the K22-powered Tegiwa NSX demonstrate just how far the company's Honda engine development can go.

Another Option for Serious K-Series Builds

One of the reasons the Honda K-Series platform remains so popular is the enormous range of ways you can build one.

You can keep things simple with a mostly stock K20 and a few bolt-ons. You can build a high-compression naturally aspirated K24. You can create a high-RPM circuit engine. Or you can build a turbocharged combination making several times the power Honda originally intended.

Bourne HPP's catalog reflects that same range.

Components like the 21S drop-in cams provide an approachable upgrade for a street or track-day engine, while the company's cylinder heads, valvetrain components and 32R race cams provide a path toward much more serious competition builds.

And that's why we're happy to announce that we've partnered with them to offer their products to US customers and use the engine in our upcoming 2027 GLGT Accord Touring car!