Four-stroke power valve system

Last updated
2007 Honda CBR600RR exhaust power valve 4.jpg
The exhaust power valve of a 2007 Honda CBR600RR.
2007 Honda CBR600RR exhaust power valve 3.jpg
The servo motor controls the valve via two cables. Shown removed.

A four-stroke power valve is a device fitted to four-stroke engines that constantly adjusts the internal diameter of the exhaust system to better suit the speed of the engine. Yamaha was the first to develop such a system, called the Exhaust Ultimate Power Valve (EXUP). [1] It first appeared on the Yamaha FZR EXUP and was later used on many other Yamahas.

Contents

Later versions from Honda went by the names Honda Titanium Exhaust Valve (HTEV) and Honda Variable Intake/Exhaust (H-VIX), [1] appearing on the CBR600RR and Honda CBR929RR. Suzuki's version is called Suzuki Exhaust Tuning (SET). [1] The system is also used on the Triumph Daytona 675 triple.

Operation

At low engine speeds, the wave pressure within the pipe network is low. A full oscillation of the Helmholtz resonance occurs before the exhaust valve is closed, and to increase low-speed torque, large-amplitude exhaust pressure waves are artificially induced. This is done by partial closing of an internal butterfly valve within the exhaust where the primary pipes from the cylinders join. The alteration of the pressure at this point controls the behavior of reflected waves at this sudden increase in area discontinuity. Closing the valve increases the local pressure, inducing the formation of larger-amplitude negative reflected expansion waves. A servo motor controlled by the ECU opens and shuts the valve. [1] The valve goes from being almost fully closed at idle speed, through to fully open at higher engine speeds. This ensures low to mid-range performance, more linear power output and reduced exhaust noise levels while the valve is in its reduced opening position.

See also

Notes

  1. 1 2 3 4 Coombs, Matthew; Haynes, John; Shoemark, Pete (2002), Motorcycle Basics (2nd ed.), Haynes, p. 2.28, ISBN   1-85960-515-X

Related Research Articles

<span class="mw-page-title-main">Two-stroke engine</span> Internal combustion engine type

A two-strokeengine is a type of internal combustion engine that completes a power cycle with two strokes of the piston during one power cycle, this power cycle being completed in one revolution of the crankshaft. A four-stroke engine requires four strokes of the piston to complete a power cycle during two crankshaft revolutions. In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with the intake and exhaust functions occurring at the same time.

<span class="mw-page-title-main">VTEC</span> Automobile variable valve timing technology

VTEC is a system developed by Honda to improve the volumetric efficiency of a four-stroke internal combustion engine, resulting in higher performance at high RPM, and lower fuel consumption at low RPM. The VTEC system uses two camshaft profiles and hydraulically selects between profiles. It was invented by Honda engineer Ikuo Kajitani. It is distinctly different from standard VVT systems which change only the valve timings and do not change the camshaft profile or valve lift in any way.

<span class="mw-page-title-main">Variable valve timing</span> Process of altering the timing of a valve lift event

In internal combustion engines, variable valve timing (VVT) is the process of altering the timing of a valve lift event, and is often used to improve performance, fuel economy or emissions. It is increasingly being used in combination with variable valve lift systems. There are many ways in which this can be achieved, ranging from mechanical devices to electro-hydraulic and camless systems. Increasingly strict emissions regulations are causing many automotive manufacturers to use VVT systems.

<span class="mw-page-title-main">Exhaust manifold</span> Structure collecting an engines exhaust outlets

In automotive engineering, an exhaust manifold collects the exhaust gases from multiple cylinders into one pipe. The word manifold comes from the Old English word manigfeald and refers to the folding together of multiple inputs and outputs.

<span class="mw-page-title-main">Honda CBR900RR</span> Sport bike

The Honda CBR900RR, or FireBlade in some countries, is a 900 cc (55 cu in) sport bike, part of the CBR series introduced in 1992 by Honda. It was the first of a series of large-displacement Honda models to carry the RR suffix. The development of the first generation CBR900RR was led by Tadao Baba.

<span class="mw-page-title-main">Inlet manifold</span> Automotive technology

In automotive engineering, an inlet manifold or intake manifold is the part of an engine that supplies the fuel/air mixture to the cylinders. The word manifold comes from the Old English word manigfeald and refers to the multiplying of one (pipe) into many.

Manifold vacuum, or engine vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere.

<span class="mw-page-title-main">Expansion chamber</span>

On a two-stroke engine, an expansion chamber or tuned pipe is a tuned exhaust system used to enhance its power output by improving its volumetric efficiency.

Homogeneous Charge Compression Ignition (HCCI) is a form of internal combustion in which well-mixed fuel and oxidizer are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction releases energy that can be transformed in an engine into work and heat.

The two-stroke power valve system is an improvement to a conventional two-stroke engine that gives a high power output over a wider RPM range.

<span class="mw-page-title-main">Motorcycle engine</span> Engine that powers a motorcycle

A motorcycle engine is an engine that powers a motorcycle. Motorcycle engines are typically two-stroke or four-stroke internal combustion engines, but other engine types, such as Wankels and electric motors, have been used.

<span class="mw-page-title-main">Suzuki RGV250</span> Suzuki sport motorcycle

The Suzuki RGV250 was a Suzuki high performance sport bike which had a great number of its features and design cues based on Grand Prix technologies and ideas. It is a race-replica based on Suzuki's 250 cc (15 cu in) GP bikes from 1987 to 1998, the RGV V-2 racer. This motorcycle replaced the RG250 Gamma, which employed an alloy frame with a two-stroke parallel twin engine. The bike produced over 60 bhp in a narrow power band between 8,000 and 11,000 rpm. The dry weight ranged between 128 kg (282 lb) (1989) to 140 kg (309 lb) dry weight.

<span class="mw-page-title-main">Honda CBR600RR</span> Sport bike

The Honda CBR600RR is a 599 cc (36.6 cu in) sport bike made by Honda since 2003, part of the CBR series. The CBR600RR was marketed as Honda's top-of-the-line middleweight sport bike, succeeding the 2002 Supersport World Champion 2001–2006 CBR600F4i, which was then repositioned as the tamer, more street-oriented sport bike behind the technically more advanced and uncompromising race-replica CBR600RR. It carried the Supersport World Championship winning streak into 2003, and on through 2008, and won in 2010 and 2014.

Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve their air flow. Cylinder heads, as manufactured, are usually suboptimal for racing applications due to being designed for maximum durability. Ports can be modified for maximum power, minimum fuel consumption, or a combination of the two, and the power delivery characteristics can be changed to suit a particular application.

<span class="mw-page-title-main">Honda CBR1000RR</span> Superbike

The Honda CBR1000RR, marketed in some countries as the "Fireblade", is a 999 cc (61.0 cu in) liquid-cooled inline four-cylinder superbike, introduced by Honda in 2004 as the 7th generation of the CBR series of motorcycles that began with the CBR900RR in 1990.

<span class="mw-page-title-main">Yamaha FZR1000</span> Motorcycle model produced by Yamaha

The Yamaha FZR1000 is a motorcycle produced by Yamaha from 1987 to 1995. Classed as a sports motorcycle.

<span class="mw-page-title-main">Formula 1000</span> Open wheel class of Formula car racing

Formula 1000 (F1000) is an open wheel class of Formula car racing, with professional and amateur series worldwide. Formula 1000 gets its name from the 1000 cc super-bike engine used to power a single seat, open wheel race car with fully adjustable wings and suspension. Currently, in the United States, F1000 is run in SCCA under the FA class or under SCCA Pro Racing with the North American Formula 1000 Championship.

<span class="mw-page-title-main">Yamaha FZR600</span> Type of motorcycle

The Yamaha FZR600 is a sports motorcycle produced by Yamaha between 1988 and 1995. It was the successor to the FZ600 and was replaced by the Yamaha YZF600R in 1996. It had a steel Deltabox frame and swingarm, similar in appearance to the alloy Deltabox frame introduced three years earlier on the 1WG FZR400.

<span class="mw-page-title-main">Honda CBR400</span> Type of motorcycle

The Honda CBR400 is a Japanese domestic market small-capacity sport motorcycle, part of the CBR series introduced by Honda in 1983. It was the first Honda motorcycle to wear a CBR badge.

<span class="mw-page-title-main">Yamaha OX66 engine</span> Racing engine

The Yamaha OX66 is a four-stroke, naturally-aspirated, 30-valve, V6 racing engine, designed, developed and built by Japanese manufacturer Yamaha, in 1984.