Redline

Redline

Overview
This article discusses the term "redline" as it applies to internal combustion engine technology. For other uses of the term, see Redline (disambiguation)
Redline (disambiguation)
Redline may refer to:* Redline Magazine, a monthly automotive tuning magazine based in the UK.* Redline, the high level of an engine speed at its maximum safe RPMs* Redline Tire, a popular style of tire for muscle cars in the 1960s and 1970s...

.

Redline refers to the maximum engine speed
Speed
In kinematics, the speed of an object is the magnitude of its velocity ; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as...

at which an internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

or traction motor
Traction motor
Traction motor refers to an electric motor providing the primary rotational torque of a machine, usually for conversion into linear motion ....

and its components are designed to operate without causing damage to the components themselves or other parts of the engine. The redline of an engine depends on various factors such as stroke
Stroke (engines)
Reciprocating motion, used in reciprocating engines and other mechanisms, is back-and-forth motion. Each cycle of reciprocation consists of two opposite motions: there is a motion in one direction, and then a motion back in the opposite direction. Each of these is called a stroke...

, mass of the components, displacement
Engine displacement
Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top dead centre to bottom dead centre . It is commonly specified in cubic centimeters , litres , or cubic inches...

, composition of components, and balance of components.

Engines with short strokes can handle higher rpm because there is less force in reciprocating motion
Reciprocating engine
A reciprocating engine, also often known as a piston engine, is a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types...

.
Discussion

Encyclopedia
This article discusses the term "redline" as it applies to internal combustion engine technology. For other uses of the term, see Redline (disambiguation)
Redline (disambiguation)
Redline may refer to:* Redline Magazine, a monthly automotive tuning magazine based in the UK.* Redline, the high level of an engine speed at its maximum safe RPMs* Redline Tire, a popular style of tire for muscle cars in the 1960s and 1970s...

.

Redline refers to the maximum engine speed
Speed
In kinematics, the speed of an object is the magnitude of its velocity ; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as...

at which an internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

or traction motor
Traction motor
Traction motor refers to an electric motor providing the primary rotational torque of a machine, usually for conversion into linear motion ....

and its components are designed to operate without causing damage to the components themselves or other parts of the engine. The redline of an engine depends on various factors such as stroke
Stroke (engines)
Reciprocating motion, used in reciprocating engines and other mechanisms, is back-and-forth motion. Each cycle of reciprocation consists of two opposite motions: there is a motion in one direction, and then a motion back in the opposite direction. Each of these is called a stroke...

, mass of the components, displacement
Engine displacement
Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top dead centre to bottom dead centre . It is commonly specified in cubic centimeters , litres , or cubic inches...

, composition of components, and balance of components.

Variation of redline

Engines with short strokes can handle higher rpm because there is less force in reciprocating motion
Reciprocating engine
A reciprocating engine, also often known as a piston engine, is a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types...

. Lighter components can increase the redline as well, since they have less inertia
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...

and decrease forces present in the engine.

Redlines vary anywhere from a few hundred revolutions per minute
Revolutions per minute
Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...

(rpm) (in very large engines such as those in trains and generators) to more than ten thousand rpm (in smaller, usually high-performance engines such as motorcycles and sports cars with pistonless rotary engine
Pistonless rotary engine
A pistonless rotary engine is an internal combustion engine that does not use pistons in the way a reciprocating engine does, but instead uses one or more rotors, sometimes called rotary pistons...

s). Diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

s normally have lower redlines than comparatively-sized gasoline engines, largely because of fuel-atomization limitations. Gasoline automobile engines typically will have a redline at around 5500 to 7000 rpm. The Ariel Atom 500 has the highest redline of a piston-engine road car rated at 10,600. The Renesis in the current Mazda RX-8
Mazda RX-8
The Mazda RX-8 is a sports car manufactured by Mazda Motor Corporation. It first appeared in 2001 at the North American International Auto Show. It is the successor to the RX-7 and, like its predecessors in the RX range, it is powered by a Wankel engine. The RX-8 began North American sales in the...

has the highest redline of a production rotary-engine road car rated at 9400 rpm.

In contrast, some older OHV
An overhead valve engine, also informally called pushrod engine or I-head engine, is a type of piston engine that places the camshaft within the cylinder block , and uses pushrods or rods to actuate rocker arms above the cylinder...

engines had redlines as low as 4800 rpm, mostly due to the engines being designed and built for low-end power and economy during the late 1960s all the way to the early 1990s. One main reason OHV engines have lower redlines is valve float. At high speeds, the valve spring simply cannot keep the tappet or roller on the camshaft. After the valve opens, the valve spring does not have enough force to push the mass of the rocker arm, push rod, and lifter down on the cam before the next combustion cycle. Overhead cam engines eliminate many of the components, and moving mass, used on OHV engines. Lower redlines, however, do not necessarily mean low performance, as some skeptics sometimes assume. For example, a Supercharged Buick 3800 V6 with a redline anywhere from 5500-6000 has a torque curve that peaks at 2600-3600rpms, yet the engine is a strong performer from takeoff all the way through to the redline.

Motorcycle engines can have even higher redlines because of their comparatively lower reciprocating mass. For example, the Yamaha YZF-R6
Yamaha YZF-R6
Yamaha's YZF-R6 is a 600 class sport bike motorcycle, first introduced in 1998, updated in 2001, 2003, 2006, 2008 and revised in the years in between.-History:...

has a redline of about 16,200 rpm. (Yamaha heavily advertised the engine as having a 17,500 rpm redline, though for reasons of marketing and/or tachometer error, the engine was not actually capable of that speed.) Higher yet is the redline of a modern Formula One
Formula One
Formula One, also known as Formula 1 or F1 and referred to officially as the FIA Formula One World Championship, is the highest class of single seater auto racing sanctioned by the Fédération Internationale de l'Automobile . The "formula" designation in the name refers to a set of rules with which...

car. Regulations in 2010 limit the maximum engine rotation to 18000 rpm http://www.formula1.com/news/features/2010/3/10487.html, but during the 2006 season, engine speeds reached over 20000 rpm on the Cosworth
Cosworth
Cosworth is a high performance engineering company founded in London in 1958, specialising in engines and electronics for automobile racing , mainstream automotive and defence industries...

engine.

Rev limiter and implementation

The actual term redline comes from the red bars that are displayed on tachometer
Tachometer
A tachometer is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine. The device usually displays the revolutions per minute on a calibrated analogue dial, but digital displays are increasingly common...

s in cars starting at the rpm that denotes the redline for the specific engine. Operating an engine in this area is known as redlining. Straying into this area usually does not mean instant engine failure, but may increase the chances of damaging the engine.

Most modern cars have computer systems that prevent the engine from straying too far into the redline by cutting fuel flow to the fuel injector
Fuel injection
Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....

s/carburetor
Carburetor
A carburetor , carburettor, or carburetter is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom....

or by disabling the ignition system until the engine drops to a safer operating speed. This device is known as a rev limiter
Rev limiter
A rev limiter is a device fitted to an internal combustion engine to restrict its maximum rotational speed. This is usually carried out to prevent damage to the engine, however sometimes these devices are fitted to prevent an engine reaching the point at which it develops maximum power...

and is usually set to an RPM value at redline or a few hundred RPM above. Most Electronic Control Unit
Electronic control unit
In automotive electronics, electronic control unit is a generic term for any embedded system that controls one or more of the electrical systems or subsystems in a motor vehicle....

s (ECUs) of automatic transmission
Automatic transmission
An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...

cars will upshift before the engine hits the redline even with maximum acceleration
Acceleration
In physics, acceleration is the rate of change of velocity with time. In one dimension, acceleration is the rate at which something speeds up or slows down. However, since velocity is a vector, acceleration describes the rate of change of both the magnitude and the direction of velocity. ...

(The ECU in a sports car's automatic transmission will allow the engine to go nearer the redline or hit the redline before upshifting). If manual override
Manual override
A manual override is a mechanism wherein control is taken from an automated system and given to the user. For example, a manual override in photography refers to the ability for the human photographer to turn off the automatic aperture sizing, automatic focusing, or any other automated system on...

is used, the engine may go past redline for a brief amount of time before the ECU will auto-upshift. When the car is in top gear and the engine is in redline (due to high speed), the ECU will cut fuel to the engine, forcing it to decelerate until the engine begins operating below the redline at which point it will release fuel back to the engine, allowing it to speed operate once again.

However, even with these electronic protection systems, a car is not prevented from redlining through inadvertent gear engagement. If a driver accidentally selects a lower gear when trying to shift up or selects a lower gear than intended while shifting down (as in a motorbike sequential transmission
Sequential transmission
Sequential transmission may refer to:* Semi-automatic transmission, a method of mechanical power transmission used in motor vehicles* Sequential manual transmission, a type of mechanical power transmission often used in motorbikes...

), the engine will be forced to rapidly rev-up to match the speed of the drivetrain. If this happens while the engine was at high rpms, it may dramatically exceed the redline. For example, if the operator is driving close to redline in 3rd gear and attempts to shift to 4th gear but unintentionally puts the car in 2nd by mistake, the transmission will be spinning much faster than the engine, and when the clutch is released the engine’s rpm will increase rapidly. It will lead to a rough and very noticeable engine braking
Engine braking
Engine braking is where the retarding forces within an engine are used to slow a vehicle down, as opposed to using an external braking mechanism, for example friction brakes or magnetic brakes....

, and likely engine damage.

Examples of performance automobile piston engines

• Ariel Atom 500 V8 10,600 rpm
• Audi R8 V8 8000 rpm (rev limiter 8250 rpm)
• Audi Q7
Audi Q7
The Audi Q7 is a full-size luxury crossover SUV unveiled in September 2005 at the Frankfurt Motor Show. Production of the Q7 began in autumn of 2005 in Bratislava, Slovakia. It is the first SUV offering from Audi and went on sale in 2007. Later, Audi's second SUV, the Q5, was unveiled as a 2009...

6.0 V12 diesel 4750 rpm
• Bentley Azure
Bentley Azure
The Bentley Azure is a large, four seater convertible built by Bentley Motors Limited at its factory in Crewe, England. The model debuted in 1995 on the Continental platform and was produced in its original guise until 2003. A completely new version powered by a significantly updated engine and...

'T' 6.75 V8 4500 rpm (is a petrol, but low redline)
• BMW E46 M3 I6 8000 rpm
• BMW E90 M3 V8 8400 rpm
• BMW E39 M5 V8 7000 rpm
• BMW E60 M5 V10 8250 rpm
• BMW F10 M5 V8 7200 rpm
• Bugatti Veyron
Bugatti Veyron
The Bugatti Veyron EB 16.4 is a mid-engined grand touring car. The Super Sport version is the fastest road-legal production car in the world, with a top speed of . The original version has a top speed of...

turbocharged W16 6500 rpm
• Chevrolet Corvette C6 ZR1
Chevrolet Corvette C6 ZR1
The Chevrolet Corvette C6 ZR1 is a high performance version of the Chevrolet Corvette C6. Both the C3 from 1969–1971 and C4 Corvettes from 1990-1995 had ZR-1 models...

supercharged V8 6500 rpm
• Ferrari 348
Ferrari 348
The Ferrari 348 is a mid-engined, rear wheel drive V8-powered 2-seat sports car by Ferrari S.p.A., replacing the 328 in 1989 and continuing until 1995.- Overview :...

V8 7500 rpm
• Ferrari F50
Ferrari F50
The Ferrari F50 is a mid-engined range-topping sports car made by Ferrari. The F50 was introduced in 1995 to celebrate the company's 50th anniversary. The car is a two door, two seat convertible with a removable hardtop...

V12 8500 rpm
• Ferrari Enzo V12 8000 rpm (rev limiter 8250 rpm)
• Ferrari F430
Ferrari F430
The Ferrari F430 is a sports car that was produced by the Italian automaker Ferrari from 2004 to 2009, as a successor to the 360. It debuted at the 2004 Paris Motor Show...

V8 8500 rpm
• Ferrari California
Ferrari California
The Ferrari California is a grand touring sports car that was launched by Ferrari at the 2008 Paris Motor Show. It is a two door "2+2" hard top convertible. The California is powered by front-mid mounted gasoline direct injection V8 with...

V8 8000 rpm
• Ferrari 458 Italia V8 9000 rpm
• Ford Mondeo
Ford Mondeo
The Mondeo was launched on 8 January 1993, and sales began on 22 March 1993. Available as a four-door saloon, a five-door hatchback, and a five-door estate, all models for the European market were produced at Ford's plant in the Belgian city of Genk...

V6 6750 rpm (rev limiter 7000rpm)
• Ford Mondeo
Ford Mondeo
The Mondeo was launched on 8 January 1993, and sales began on 22 March 1993. Available as a four-door saloon, a five-door hatchback, and a five-door estate, all models for the European market were produced at Ford's plant in the Belgian city of Genk...

ST TDCi 4500rpm (rev limiter 4900rpm)
• Honda NSX
Honda NSX
The Honda NSX, or Acura NSX, is a sports car that was produced between 1990 and 2005 by the Japanese automaker Honda. It is equipped with a mid-engine, rear-wheel drive layout, powered by an all-aluminium V6 gasoline engine featuring Honda's Variable Valve Timing and Lift Electronic Control ...

V6 8000 rpm
• Honda Integra Type R
Honda Type R
Honda automobile Type R models are special performance editions of their respective model families.The design of Type R models was originally focused on race conditions, with an emphasis on minimizing weight, and maximizing performance potential . Thus, Type R models were first conceived for...

I4 8400 rpm
• Honda Civic
Honda Civic
The Honda Civic is a line of subcompact and subsequently compact cars made and manufactured by Honda. The Civic, along with the Accord and Prelude, comprised Honda's vehicles sold in North America until the 1990s, when the model lineup was expanded...

Si I4 8000 rpm (rev limiter 8400 rpm)
• Honda S2000
Honda S2000
The Honda S2000 is a roadster that was manufactured by the Japanese automaker Honda Motor Company. It was launched in April 1999 and was created to celebrate the company's 50th anniversary. The car was first shown as a concept at the Tokyo Motor Show in 1995, following which it was launched in...

I4 9000 rpm (2.0L) (rev limiter 9200 rpm)
• Honda S2000 I4 8000 rpm (2.2L) (rev limiter 8200 rpm)
• Lamborghini Gallardo
Lamborghini Gallardo
The Lamborghini Gallardo is a sports car built by Lamborghini. The Gallardo is Lamborghini's most-produced model to date, with over 10,000 built in its first seven years of production...

V10 8100 rpm
• Lamborghini Gallardo V10 LP560-4 8500 rpm
• Lexus LFA
Lexus LFA
The Lexus LFA is a 2-seat exotic sports coupe produced by Lexus as a concept car, "halo" vehicle, racing prototype, and production model. It is the second model in the F marque line of performance vehicles from Lexus, following the IS F...

V10 9000 rpm (rev limter 9600 rpm)
• Lotus Elise
Lotus Elise
The 1996 Lotus Elise weighed . Because of its relatively low weight, it was able to accelerate 0- in 5.8 seconds despite its relatively low power output of...

I4 8000 rpm (rev limiter 8500 rpm)
• Mazda MX-5 Miata I4 7200 RPM (7500 rpm for some markets)
• McLaren F1
McLaren F1
The McLaren F1 is a supercar designed and manufactured by McLaren Automotive. Originally a concept conceived by Gordon Murray, he convinced Ron Dennis to back the project and engaged Peter Stevens to design the exterior of the car...

V12 7500 rpm
• Mercedes-Benz SLR McLaren
Mercedes-Benz SLR McLaren
The Mercedes-Benz SLR McLaren is an Anglo-German grand tourer car jointly developed by Mercedes-Benz and McLaren Automotive, built in Portsmouth and the McLaren Technology Centre in Woking, Surrey, England and sold from 2003 to 2009...

supercharged V8 7000 rpm
• Mitsubishi Lancer Evolution X 2.0 turbocharged I4 7000 rpm (fuel cut off at 7600 rpm)
• Nissan GTR turbocharged V6 7000 rpm
• Nissan Micra K11 I4 7000 rpm (rev limiter 7300 rpm)
• Nissan 370Z
Nissan 370Z
The Nissan 370Z is a sports car manufactured by Nissan Motors. It was announced on October 29, 2008 and was first shown at an event in Los Angeles ahead of the 2008 Greater LA Auto Show, before being officially unveiled at the show itself...

V6 7500 rpm
• Peugeot 309 GTI16
Peugeot 309
The Peugeot 309 was a small family car manufactured between 1985 and 1993 in England and France.The 309 was originally intended to be badged as a Talbot and, as development progressed, to be called the Talbot Arizona...

1.9 16v 7300 rpm
• Porsche 911 Carrera (2012 991) B6 7800 rpm
• Porsche 911 GT3 4.0 (2012 997) B6 8500 rpm
• Porsche Carrera GT
Porsche Carrera GT
The Porsche Carrera GT is a mid-engined sports car that was manufactured by Porsche in Leipzig, Germany.- History :The development of the Carrera GT can be traced back to the 911 GT1 and LMP1-98 racing cars. Due in part to the FIA and ACO rule changes in 1998, both designs had ended. Porsche at...

V10 8400 rpm
• Suzuki Swift
Suzuki Swift
The Suzuki Swift is a subcompact car produced by Suzuki in Japan since 2000. Prior to this, the "Swift" nameplate had been applied to the Suzuki Cultus in export markets such as Australasia, Europe, India and North America.- Predecessor :...

GTi 16v 1.3 8000 rpm
• Volkswagen Golf
Volkswagen Golf
The Volkswagen Golf is a small family car manufactured by Volkswagen since 1974 and marketed worldwide across six generations, in various body configurations and under various nameplates – as the Volkswagen Rabbit in the United States and Canada , and as the Volkswagen Caribe in Mexico .The...

GTI 2.0TSI I4 6500 rpm
• Toyota RunX (Matrix) RSi (XRS) 1.8 (2ZZ-GE) 8200 rpm
• Williams Cosworth V8 F1 19000rpm (limiter 20100rpm)

Examples of production rotary engines

• Mazda RX-8
Mazda RX-8
The Mazda RX-8 is a sports car manufactured by Mazda Motor Corporation. It first appeared in 2001 at the North American International Auto Show. It is the successor to the RX-7 and, like its predecessors in the RX range, it is powered by a Wankel engine. The RX-8 began North American sales in the...

1.3L twin rotor 9000 rpm (rev limiter 9400 rpm)

Examples of motorcycle engines

• Honda CBR250RR: 19,000 rpm
• Yamaha FZR250
Yamaha FZR250
The FZR250 motorcycle was a Japan only 250cc learner legal race replica. However it was grey-imported to other countries around the world. The FZR250 was produced from 1986 to 1988...

: 18,500 rpm
• Yamaha YZF-R6
Yamaha YZF-R6
Yamaha's YZF-R6 is a 600 class sport bike motorcycle, first introduced in 1998, updated in 2001, 2003, 2006, 2008 and revised in the years in between.-History:...

: 16,200 rpm
• Honda RVF400
Honda RVF400
The Honda RVF400R is a motorcycle introduced by Honda Motor Company in 1994, powered by a V4 16 valve double overhead geardriven cam 400 cc engine and known for its supreme handling capabilities. There were two models, the R and the T, which differed only in their paint schemes...

: 14,500 rpm (With HRC ECU 15,500 rpm)
• BMW S1000RR
BMW S1000RR
The BMW S1000RR is a sport bike initially manufactured by BMW Motorrad to compete in the 2009 Superbike World Championship, that is now in commercial production...

: 14,200 rpm
• Honda CBR 600F-P
Honda CBR600F
The Honda CBR600F, known as the 'Hurricane' in the US market, is a sports motorcycle made by Honda from 1987-1990, with an all new model of the same name released in 2011. The original CBR600F was Honda's first inline four-cylinder, fully faired sport bike. It had a liquid cooled DOHC 16-valve...

: 14,000 rpm
• Kawasaki ER-5
Kawasaki ER-5
The Kawasaki ER-5 is a naked commuter motorcycle produced in Japan by Kawasaki. The bike is powered by a liquid cooled 4-stroke DOHC 498 cc engine based on the design used in the Kawasaki GPZ500, producing around . It is capable of a top speed of around...

: 10,500 rpm