tech overview

Let us try to answer some of the typically broad questions that people have in deciding to  turbocharge their motorcycle engine. Hope it helps or call us: 0118 977 6755

how does turbocharging work?

Turbocharging a motorcycle is the process of using exhaust pressure to drive an impeller that in turn on the same shaft drives another impeller that pushes air into the engine & creates a forced pressurisation of the inlet air for which a reciprocal fuel ratio has to be achieved . The sizing & choice of those impellers & their reciprocal housings & other turbo features such as boost control determine many aspects of power potential & power delivery which can be tailored to a specific application.

Certain standard motorcycle engines can add 50-100% power increases. Certain modified motorcycle engines can increase their power with racing fuels by over 500%! Big CC Racing are world leaders in motorcycle turbocharged horsepower.

When you upgrade a bike with a turbo the entire fuel system will need redesigning to feed the increased air flow. Most engines will need to be strengthened not just to get to the correct compression ratio but to add strength in parts.

Some electronics may need to be added to give both fuelling ignition & power control. Some electronics may require a complete change of ECU according to racing applications . Most street systems do not need anything too complicated.

why choose turbocharging V supercharging?

Turbocharging uses exhaust gas compared to Superchargers that suffer reciprocal losses driving the supercharger off the crankshaft so turbo’s have no real loss in energy by comparison.

Turbocharging is load or throttle reactive. Supercharging is crank speed reactive in boost. This means the rpm determines the boost not the throttle position thus in turn a supercharger generates much more heat. A turbo by comparison can be ridden successfully without creating any boost if desired by simply using low throttle openings.

Typically a turbo bike will create in positive pressure per psi of boost between 8 & 14hp where as a supercharger will struggle to create 5-8 hp per psi of boost without other enhancements.

Superchargers due to creating boost by rpm will need to be enriched much more with fuel reducing fuel economy .

Because a supercharger creates boost by rpm & not load it will be positive in boost not just on acceleration slow or fast but at a constant cruise or even on deceleration. The turbo only creates boost when you load the engine with more throttle. Less heat & more economy.

Turbocharging offers easier & variable boost control via its wastegate. You can choose the power to ride at according to road or race conditions etc.

what power level can i get?

The power potentials of your turbo package depends on many factors. Here are a few below

• The Turbocharger’s claimed power potential by the manufacturer (not always accurate especially in motorcycle applications)
• The Turbo systems actual potential. This is not the same as above as restrictions may exist in the fuel system such as pump or injector size or filter flow rate etc or the air flow through intercoolers, airboxes air filters etc. Typically Stage 1 Turbo systems are restricted in fuel ability to give affordability.
• The engine type. Certain engines can only handle a certain amount of power. Think about the loading per con rod in the power you seek to realise easier the stress certain engines like 2 or 3 cylinder motors may be under compared to 4 cylinder etc.
• The engine work carried out to strengthen your engine. Using stronger conrods special turbo pistons, stronger & larger engine studs/bolts etc power potentials can be dramatically increased.
• Fuel type. Boost pressure dynamically increases the compression ratio of an engine. Super unleaded fuel reaches its limit before 14:1 with a turbo especially with the increase in air inlet temperature. So it is important for you to find from your turbo system supplier & tuner what your boost limit is on regular pump fuel & also what the limit is on high octane racing fuels.
• The air inlet temperature. Running air to air intercoolers or liquid to air chargecoolers will reduce air inlet temperature which in turn will help prevent detonation. The size of the turbo will also determine air inlet temp as larger turbos will move more air with less heat & less exhaust back pressure. Added bonus of colder air is more power for the same boost as the air is denser yet equates to the same boost pressure.
• The tuning. Work carried out in so far as keeping the engine safe such as enriched air fuel ratio & ignition timing etc.

A simple example: A Stage 2 street turbo system non intercooled could run 12psi boost = 320hp max on pump fuel providing the engine compression ratio has been dropped sufficiently . On a fully built motor using high octane fuel it may run up to 450+hp but it would need a fully strengthened engine for this. If people choose to risk turbocharging a stock engine then the dynamic compression under boost is the restriction. A Hayabusa with stock compression at 11:1 cannot use more than 7psi boost safely on pump fuel.

So when asking what power your bike will make it depends upon the package that you can afford to go with in so far as engine compression & strength, turbo size & turbo system choice intercooled or not & the safety of the tuning work. Big CC Racing are happy to go in depth with you to help select your best turbo package to your budget.

ok what is involved price wise?

There are 4 main cost factors to turbocharging a bike. They are as follows….

• Type & choice of turbo system that fits your needs. We offer several stages from basic street use to full blown drag or land speed.
• What engine work is required to sustain your power level you want reliably. Inc removal strip inspect modify rebuild & refit etc. The choice of vehicle you have & the power you want will determine the mods required to achieve reliability in your application.
• Installation & Dyno. The cost including bracketry welding mods & other modifications to the vehicle required & a full rolling road set up.
• Electronics & other ancillaries. This may be power commanders or Stand alone ECU’s, boost controllers, full exhausts instead of dumps, scavenge pumps, oil cooler / radiator upgrades, lock up clutches & so on. Not all bikes need them but some do & your application will determine your options or requirements.