In car tuning culture, an engine swap is the process of removing a car's original engine and replacing it with another. This may be a like-for-like replacement, or to install a non-factory specification engine. Typically, an engine swap is performed for performance, swapping-in a more powerful engine; however, an engine swap may also be performed for maintenance, where older engines may have a shortage of spare parts, and so a modern replacement may be more easily and cheaply maintained.
Swapping the engine may have negative implications on the car's safety, performance, handling, and reliability. For example, the new engine's different weight balance over the axles and the overall weight of the car can adversely affect the vehicle dynamics. Existing brakes, transmission, and suspension components may be inadequate to handle the increased weight and power of the new engine with either upgrades being required or premature wear and failure being likely.
Insurance companies may charge more or even refuse to insure a vehicle that has been fitted with an engine that is different from its initial configuration. For instance, in jurisdictions such as California—with its strict smog rules—it may not be possible to register a late-model vehicle with an engine swap.
Swapping to a diesel engine for improved fuel economy is a long established practice; with modern high-efficiency diesel engines, this does not necessarily mean a reduction in performance associated with older-version diesel engine swaps. For the particular application of off-road vehicles, the high torque at low speed of turbo diesels (combined with a fuel economy advantage) makes these conversions particularly effective. However, older non-electronic fuel injection diesel engines were well known for their reliability, especially in wet conditions.
An engine swap can either be to another engine intended to work in the car by the manufacturer, or one totally different. The former is much simpler than the latter. Fitting an engine into a car that was never intended to accept that engine may be more laborious and costly; modifying the car to fit the engine, modifying the engine to fit the car, and building custom engine mounts and transmission bellhousing adaptors to interface them along with a custom-built driveshaft. Some small businesses build conversion kits for engine swaps, such as the Fiat Twin cam into a Morris Minor or similar.
A common anecdote among tuners in the United States is that the easiest way to make a car faster is to drop in a more powerful engine, such as the General Motors small-block engine as used in the Corvette. The Chevrolet Vega (and its Astre, Monza, and Skyhawk sisters) is a candidate for a small-block swap; some have seen big blocks as well. Chevrolet engines have been used in such cars as Toyota Supras, BMWs, RX-7s, Mazda Miatas, Jaguar sedans, Corvairs, and Datsun 240s, 260s, and 280Zs.
In the Honda world, engine swaps include the Civic Si (B16A), the Civic Type R (B16B), Integra GSR (B18C), and the Integra Type R (B18C5) engines. More recently, swapping larger displacement Honda engines (such as the J-series V6) has become more popular. Swapping any of these motors into a lightweight 1988–2000 Honda Civic chassis can achieve greater performance.
Chrysler made many turbocharged vehicles in the 1980s, and these engines share much in common with the mass-produced naturally aspirated vehicles. It is quite common to obtain an engine from a vehicle such as a Dodge Daytona and swap it into a Dodge Aries. The Mopar Performance arm even offered a kit to upgrade the Dodge Daytona to rear wheel drive with a Mopar V8.
Engine swaps are also somewhat common within the Volkswagen tuning scene, often placing Type 2 (Bus), Type 3, and Type 4 (Squareback) engines in the Type 1 (Beetle). Water-cooled engines, such as the GTI 16-valve four, VR6, or 1.8 T are commonly swapped into the Mark II GTI, Jetta, and Corrado. Less common is the swap into a Mark 1 Golf or Cabriolet, giving an amazing power-to-weight ratio, even with minimally modified powerplants. Porsche engines are also very popular. One of the most popular options is to take the engine from a Porsche 911 super 1600. Vintage VW's also take very well to the Subaru EJ "flat four" engine, which also has a factory turbo-charged variant.
In the Super GT racing series, engine swaps can be considered a way of life for the upper tier GT500 cars, most of which are provided with specially modified racing engines from the manufacturers. GT500 class rules themselves allow for any engine to be swapped into a car as long as it is from the same manufacturer. Notable examples include Toyota swapping in highly tuned 4-cylinder engines originally from the Toyota Celica into their Toyota Supra GT500 race cars.
British sports cars (such as MGs and Triumphs and Sunbeam Alpines) from the late 1960s and early 1970s were attractive and light-weight cars that had excellent suspensions. However, they were known for troublesome electrical systems, modest power levels and a certain amount of unreliability. It is popular to take one of these small classic sports cars and add a more powerful engine. The original manufacturers did this when the vehicles were current with the MGB GT V8 and the Sunbeam Tiger. The all-aluminum 215cid Buick and Oldsmobile V8 engines are a traditional choice for these cars. Swapping the stock MGB all-iron 1.8L 4-cylinder engine and 4-speed transmission for a Buick 215 V8 and a modern 5-speed transmission actually improves both cornering and acceleration because it reduces the overall weight of the car by about 40lb. Power is approximately doubled. Derivatives of that classic General Motors engine, the 3.5L, 3.9L, and 4.2L Rover V8s are also frequently used. (The original Buick / Oldsmobile, the Rover, and the related Morgan-licensed V8, are simple bolt-ins.[1])
Although the more recent "narrow-angle" 60-degree Ford and GM V6 engines—notably the GM 3.4L "L32"—are more compact than the Rover/Buick and Ford V8s, they usually do not equal the power-to-weight ratio of the popular 90-degree V8s frequently swapped into smaller cars. These V6s can, however, be very cost-effective and easier to fit into a variety of car bodies.
The Ford 302 (5.0L) V8, with its cast iron block, results in spectacular power-to-weight ratios for straight-line acceleration. If the Ford 302 is fitted with aluminium heads, intake, and water pump, the resulting engine only adds about 40lb to the front of an MGB, and is substantially more powerful and lighter-weight than the iron-block six-cylinder found in an MGC or TR6. An aluminium 302 performance block is available that weighs 60 lb (27 kg) less than the common iron version, and can be found in displacements of 331 and 347 ci, but those are significantly more expensive than using the common 302 internals.
The Nissan SR20DET is an all-aluminium fuel-injected DOHC turbocharged 4-cylinder. This compact engine, along with the very compact, light, and powerful Mazda 13B rotary engine, have both been transplanted into too many different cars to assemble a complete list.
Note: These are the most common examples and are not an exhaustive list, just a representative cross section.
| Original engine | Common donor engines | Notes | |
|---|---|---|---|
| Chevrolet small-block V8 engine (SBC) (1955—2002) | Hot Rods, Chevrolet Vega and S10, Nissan S30, Pontiac Fiero, Austin-Healey, kit cars, light aircraft, Jaguar XJS and Jaguar XJ6, Suzuki Sidekick/Vitara, Datsun 240Z-260Z | When this engine was introduced, it was designed for a wide range of displacements in a compact package. Its external format has been available from 265 cubic inches up to 400-ci. Mass-production makes these engines very available and affordable, with the most common displacement being the 350-ci / 5.7L size. It was lighter and more compact than previous V8's of a similar displacement capability, due to improvements in metal casting techniques. | |
| GM "LS" V8 engine (1997–present) | The recipients of an "LS swap" are too numerous to list | In 1997, General Motors began producing a new family of engines that had been designed with a clean sheet of paper, based on their experience over the previous decades. The "L" family of engines (LS, LT, LY, etc) were compact and light. They were available in displacements from 4.8L to 7.4L, and typically use a cast iron block with aluminum heads (although variants have an all-aluminum construction). Mass-production has made the common versions very available and affordable. There are many minor improvements over the previous SBC, such as adding a coil-over-plug ignition, steam vents, and the cam location was raised slightly to allow a longer 4-inch stroke. One major improvement was that a deep skirt was added around the crankshaft (similar to the 426-Hemi race engine from 1964), using cross-pinned six-bolt main bearing caps, which are known to easily survive 800-HP in their stock form. Although the aluminum blocks and the displacements from 6.2L to 7.4L remain expensive, the two most notable versions for swaps are the 5.3L LM7 and the 6.0L LQ4/LY6, all of which can be found in salvaged trucks and SUV's. | |
| Ford Windsor V8 engine (1961—2002) | Commonly swapped into Hot Rods, Ford Mustangs, Ford Ranger and other pony cars, kit cars, Miatas, MGBs | The 351W has a higher deck-height (and thus a longer stroke potential) than the 302W, but both could swap heads. The fully assembled 351W was taller and wider, so the 302W was more compact, leading to the 302W version being popular for swaps into smaller cars, which could be much lighter than the common sedan or truck that it was found in. Early 1990s 302Ws had a high nickel content in the cast iron, and are considered desirable. | |
| Commonly swapped into Hot Rods, Ford Mustangs and other pony cars, kit cars | Quite a wide engine, being about the same width as the Ford FE engine. The previous Windsor family of Ford V8s used a single cam-in-block with pushrods. The Ford modular family of V8 and V10 engines shared many of the same components, and all used an overhead cam for better high-RPM breathing, making this engine wider and taller than previous Ford variants. The 4.6L V8 was the most common version. | ||
| Ford Coyote engine | Hot rods, kit cars, Ford Mustang | Ford produced millions of the 4.6L V8 Modular engines, and the 5.0L "Coyote" is an upgraded high-performance version of this DOHC engine family. | |
| Mitsubishi Sirius 4G63 engine | This 2.0L DOHC is commonly swapped into Mitsubishi Lancer early 5G, Eagle Summit 4G, Dodge Colt 3G and 4G, kit cars. | Fitted to many Mitsubishi variants, including the Eagle Talon 1G and 2G with the DOHC turbo model. A very strong engine developing ~200 hp in factory turbo form, and 300+ hp with relatively minor modifications (bigger turbo, intercooler, exhaust and improved engine management computer). Some drag racing builds have been claimed to develop 700-1000 hp. Installation into 4G and early 5G Lancer variants is relatively straightforward and can use mostly standard Mitsubishi parts,[2] as the Mitsubishi Lancer Evolution models used the essentially same engine. Later 5G Lancer models have the 2.0L 4B11T engine and simplified transmission that result in the intake and exhaust manifolds being on opposite sides compared to the 4G63. The early '90s six bolt engines are the most desirable because the connecting rods are much stronger and they do not suffer from crank walk and bearing failure seen in many of the later (mid '90s) seven bolt engines. | |
| Subaru EJ engine | VW Type 1, VW Type 2, VW Type 3 Light aircraft, kit cars, dune buggies, Trikes. | Adaptors available off the shelf for a wide variety of vehicle swaps. Note this is not applicable to automatic-transmission models which, at the time of writing, cannot be converted using an off the shelf adaptor. This liquid-cooled "flat-4" engine has a factory-turbocharged version that is quite desirable for certain applications. | |
| Fiat Twin Cam engine | Morris Minor (until the 1990s), Hot Rods, kit cars. | Now supplanted by the lighter Rover K-series in Morris Minors. | |
| Rover V8 engine | Hot Rods, kit cars, British Sports cars, light aircraft | This small aluminum-block V8 weighs less than some iron-block four-cylinder engines. Typically mated to a T5 gearbox as used in Ford Cosworth RWD cars – this requires the correct bellhousing similar to TVR's. These are usually available off the shelf. BL's LT77 (as used in the Sherpa van and Rover SD1) may also be used but wear can be a problem in units covering anything well over 70,000 miles. Later LDV Pilot vans used a two-wheel-drive version of the stronger Land-Rover R380 gearbox that was developed from the LT77. | |
| Land Rover 200TDI engine | Land Rover Series | Used in turbocharged form with or without inter-cooler. On older Land Rovers sometimes without the turbocharger. Mechanical Bosch VE pump, direct injection. | |
| Rover MDI / Perkins Prima | Land Rover Series | Used in turbocharged form on older Land Rovers. Donor vehicles had no inter-coolers. Mechanical Bosch VE pump, direct injection. | |
| Rover K-series engine | Hot Rods based on the Morris Minor, Sprite, MG Midget, Caterham 7's and other kit cars, Austin Mini (1959–2001) | Needs Ford Type 9 transmission for rear wheel drive conversions. It weighs less than the Austin A-series engine. | |
| Honda B engine | Honda Civic, Austin Mini (1959–2001), mid engined kit cars | Not suitable for inline RWD layouts, because engine turns counter clockwise (Chevy Corvair flat six turns the same way), though it could be placed in a mid engined sports car. The historically notable variant is the B18C found in the Acura Integra Type-R, which easily bolts up to the light-weight Honda Civic 2-door hatchback. | |
| Honda H engine | Honda Accord, (1990–2001), import tuner car, Austin Mini, mid engined kit cars | With original equipment F series motors capable of 130–150 HP, SOHC, some models with VTEC and lower rod ratios, the swap to a more potent H-Series motor (H22, or H23) with DOHC, VTEC, high revving friendly rod ratios, and 200+ HP is desirable. 1990–97 Accord engine swaps are straightforward drop-ins with minor modifications required for the wire harness, whereas the 1998–2002 Accords require swapping the driver side mounts to fit. This engine is also used in Formula 3 cars, and so it is able to be fitted into a RWD car. | |
| Honda/Acura J-series V6 engine | Honda Civic, Honda S2000, Mazda Miata, Hot rods, Kit cars | Can be used in both front and rear wheel drive layouts; the latter can be done with a GM TH-400 automatic transmission, a Mazda Miata, or Honda S2000 transmission. Popular in certain circles because it puts out more torque than a four cylinder. The most common displacement is 3.2L, and it can also be found as a 3.5L and 3.7L | |
| Honda F20C engine | Hot rods, kit cars | Becoming popular because it is designed for RWD applications. | |
| Honda K engine | Hot rods, kit cars, Mazda Miata, Austin Mini | Can be used in both front and rear wheel drive layouts, because it rotates in a clockwise direction. Adapter plates are available to bolt it up to a Mazda Miata transmission. The K24 is a 2.4L 4-cylinder engine that was mass-produced for a wide variety of common Honda vehicles. The stock block has been widely verified to perform well at 300-HP, so this affordable and available engine can be turbocharged and retro-fitted to many smaller and lighter Honda cars, such as the light 2-door Civic hatchback. | |
| Ford Zetec engine | Hot Rods including most older Fords, such as the Ford Cortina, Ford Escort, Ford Anglia and also Kit cars | Needs Ford type 9 transmission in RWD layout, which bolts straight up. | |
| Porsche flat-six engine | VW type 1, VW Type 2, VW Type 3, light aircraft, trikes | Needs sheet metal in engine bay removed to fit vintage air-cooled VW's, and can be tail heavy. | |
| Ford Cologne engine | Hot Rods, Saab 96, kit cars, other RWD Fords. | Makes Saab nose heavy and requires to move the radiator either to the side or to the rear. There is also a Cosworth designed 24-Valve version, but the Cologne is available in displacements of up to 4 litres. | |
| GM Duramax V8 diesel engine | Pick ups, Rolls-Royce Saloons (Often done for torque and economy) | Can use TH-400 automatic transmission. | |
| Suzuki G engine | MG Midget, Sprite, Austin Mini, Morris Minor, light aircraft | Needs Suzuki Swift transaxle in the Austin Mini, but bolts up to Suzuki truck/jeep five-speed for RWD cars (Transfer box is separate). | |
| Mazda rotary Wankel engine | VW Type 1, VW Type 3, MG Midget, Sprite, light aircraft, Lotus 7 style kit cars, hot rods, Morris Minor | Very light and compact, suiting a wide number of small RWD cars. It is also popular for home-built aircraft, due to its light weight and high power potential. | |
| Chevrolet Turbo-Air 6 engine | VW Type 1, VW Type 2, Karmann Ghia, light aircraft, dune buggies | Not suitable for inline RWD layouts, because engine turns counter clockwise; however it can be used in a mid engine configuration. | |
| Saab H engine | Saab 99, BMW | 16V turbo engines are easily tunable and highly available. May also fit in Triumph Herald and Triumph Dolomite, which as it is derived from the Triumph Slant-4 engine and it could bolt up to the Triumph 5-speed. | |
| GM/Opel Coscast C20XE engine | Austin Mini, hot rods, Lotus 7 style kit cars. | May be too powerful. Can also be fitted in RWD layouts with an Opel Manta/Vauxhall Omega or Ford Type 9 5 speed transmission. | |
| Toyota JZ engine | Celica Supra | The xA61 version of the Celica Supra have off-the-shelf adaptors for this car to swap out the 5M/1G engine with a 1JZ/2JZ engine (With the off-shelf adapters, this swap bolts in). | |
| Cadillac Northstar series | Hot rods, kit cars, sand rails, dune buggies, light aircraft, Pontiac Fiero and other GM late models. | Bellhousing is similar but slightly different than the GM metric engines pattern. | |
| Cummins B Series engine | Jeeps, rock crawlers, Dodge pickups, Ford pickups, Chevy pickups, Toyota pickups, off-road vehicles, and a wide variety of truck pulling vehicles | The 4BT is desirable for diesel-swaps due to the compact size and lower-weight of this 4cyl, vs the common larger inline 6cyl (known as the Cummins 5.9L). Using a stock GM transmission adaptor plate for a 4BT will yield a tilt to the engine while Ford and Dodge adapter plates will not. There are a wide variety of various adapter plates for the B series due to its wide use in agriculture and on road vehicles. Normally used for its reliability, low-end torque, and fuel economy. | |
| General Motors GM 3800 (Buick V6) series | Jeeps, Chevrolet S10s, Pontiac Grand Am, Pontiac Fiero, hot rods, kit cars. | The 3800 engine was offered in different configurations ranging from 165hp in the Pre-Series I to 260hp in supercharged Series III engines. Compression ratio was typically 9.4:1 in naturally aspirated versions and 8.5:1 in the L67 supercharged version. Conversions are popular due to a large supply—in GM midsize cars and minivans from the late 1980s through mid-2000s. Even though it is a 90° V6, the engine shares the GM 60° V6 bell housing bolt pattern and swaps between FWD and RWD transaxles and transmissions are straightforward. Can be adapted to more traditional Front-engine/rear-wheel-drive set ups and is a cousin of the Rover V8. The 1987 turbo-charged 3.8L in the Buick GNX is widely considered the best example of its power potential. | |
| Ford Pinto engine & Cosworth engines | Hot rods, kit cars, VW type 1 | A common swap for many small Fords, with the Cosworth version being capable being tuned of 500BHP. This is being replaced by the Zetec, Duratec and Ecoboost engines. | |
| Toyota 4A series | MR2s, Corollas, kit cars, Morris Minor. | The 4A engine was offered in different configurations ranging from 90hp to 170hp. The high performance variations included either a five-valve-per-cylinder configuration or an intake coupled with a roots-type supercharger. Conversions are popular due to a vast aftermarket and many compatible parts between engine versions. Some conversions are very easy; for instance, the supercharged 4A-GZE engine and electronic fuel injection (EFI) system are a direct plug-and-play conversion into a non-SC AW11 MR2. Even the SC-type wiring harness plugs directly into the non-SC-type chassis harness of the non-SC AW11 MR2. The non-SC flywheel, clutch, a C56-type transaxle, and axles can all be directly fitted to the SC engine with no modifications, making conversions less of a hassle. FWD variants are able to be converted into RWD configurations and is also one of the common swaps for the Morris Minor, coupled with a Toyota T50 5-speed manual gearbox. | |
| Toyota 3RZ-FE engine | Hiluxs, 4Runners, and other Toyota rock crawlers. | The 4-cylinder 2.7-liter 3RZ-FE engine came as standard equipment in 1994-2004 Toyota trucks. This engine develops 150hp and 177 ft-lbs torque. Older Toyota Hilux pickups were equipped with 4-cylinder engines ranging from 90hp and 122 ft-lbs torque (1979-80 carbureted versions) to 135hp and 173 ft-lbs torque (rare 1986-87 turbocharged versions). These older engines, like other engines of their time, had relatively low compression ratios ranging from 7.5:1 to 9:1, and when used in a daily driven rock crawler, an average of 12–16 miles per gallon fuel economy is expected. The much improved 3RZ-FE engine features a 9.5:1 compression ratio and uses newer technology such as a hot wire mass airflow sensor, knock sensor, and a narrow angle dual camshaft cylinder head. The result is a more powerful engine with much improved efficiency, achieving 17–21 miles per gallon[3] when used in a daily driven rock crawler. Additionally, the 3RZ-FE uses the same family of Toyota W-series transmissions as the fuel injected Hilux, so older Hilux W56 transmissions may be used with the new 3RZ-FE by using the W59 bellhousing. The 3RZ-FE flywheel and clutch components are fully compatible making this a great replacement engine for old Toyota Hilux engines. | |
| Volkswagen Turbocharged Direct Injection | Suzuki Samurai 4x4s, Chevrolet Tracker, Suzuki Sidekick/Vitara | Aftermarket kits make this a straightforward conversion, but it may also be possible to use the petrol engine with them too. Kit could be adapted to a small hot rod or kit car with the petrol engine. | |
| Toyota UZ engine | Older RWD Toyota cars and trucks including the Toyota Hilux and Toyota Supra, Hot rods, kit cars, light aircraft. | Commonly sourced from the Lexus LS, as well as other Lexus vehicles. | |
| General Motors 60° V6 engine | Hot rods, kit cars, Pontiac Fiero, MGBs, MG Midgets, other British sports cars, Chevy S-10 | Can be fitted in both front & rear wheel drive applications, sharing the bellhousing pattern as the Cadillac Northstar and Buick V6. That said, transverse & inline engines use different blocks. A notable example is the cast-iron Chevy 3.4L "L32" longitudinal version, designed for rear-drive applications. For high-airflow heads that are made from aluminum, The heads and intake from the "3400" Pontiac Grand Am GT "FWD" are a direct bolt-on. | |
| Dodge Viper V10 engine | hot rods, pick ups, kit cars | Displacement is the same as the Big Block Cadillac engine, at 500 cubic inches. | |
| Chrysler Hemi engine | hot rods, older Mopar vehicles, Kit cars, dragsters | The 426 Hemi was developed for NASCAR racing. The block is very similar to the 440 Chrysler truck engine, but the heads used a more hemispherical "bowl" shape to allow larger valves. The benefit was the improved high-RPM breathing. The requisite high-compression-ratio domed pistons inhibited the flame propagation, which was one of several reasons for its demise, due to poor emissions (newer versions use two spark plugs per cylinder). Homologation rules required a certain number of engines to be sold to the public for it to qualify as a "stock" engine option (500 units in 1969, 2000 units in 1970) and the Hemi was unable to pass the increasingly stringent emissions laws. High insurance rates and poor fuel economy also contributed to its lack of popularity in sales to the public. | |
| Chrysler LA engine | hot rods, kit cars, muscle cars | Comes in V6, V8 and V10 configurations. | |
| Big Block Cadillac engine | Hot rods, kit cars, pick ups, American GM Muscle cars from the 1950s-1970s. | One of the largest displacement car engines ever mass-produced, with the biggest ones being 500 cubic inches (8.2 litres). Very easy to get hold of in scrapyards and are very torquey. The early heads (late 1960s) had higher compression, resulting in more power, but the later blocks (early 1970s) had a better oiling system. | |
| Mazda B engine | Hot rods, kit cars | Can be used in both front and rear wheel drive applications, with the transmissions being used in many other applications. Adapter plates are available to fit other engines in front of it. | |
| GM High Feature V6 engine | Hot rods, Mazda Miata, Kit cars, late model GM cars, import cars | ||
| Oldsmobile Quad 4 engine | Hot rods, kit cars | This engine had a brief spurt of popularity among Hot Rodders because it bore an uncanny resemblance to the 1930s Offenhauser Twin-Cam. | |
| Ford EcoBoost engine | Hot rods, kit cars, Ford Mustang | Becoming more popular as a replacement for the Pinto and Cosworth engines, with the V6 being an alternative to the Modular and Coyote engines. | |
| Nissan/Infiniti VQ V6 engine | This is not yet a common swap, but this V6 is a narrow and light high-performance option. | This is a narrow 60-degree all-aluminum DOHC V6 that is well-regarded. The most common displacement is 3.5L. | |
| General Motors LFX V6 engine | This is not yet a common swap, but this V6 is a narrow and light high-performance option. | This is a narrow 60-degree all-aluminum DOHC V6 that is well-regarded. The most common displacement is 3.6L. The LFX has been succeeded by the LGX and the LFY. | |
| Ford Australia 'Falcon Six' I6 engine | Ford Falcon, Ford Cortina | This engine has a large iron block, with an alloy head and has a pushrod design. They have non-crossflow heads and inbuilt manifolds. These engines are a common swap given the ease of swapping, with mounts, sumps, transmissions etc. crossing over with the stock engine. The CF6 has been succeeded by the SOHC Intech and the DOHC Barra engines. | |
| Ford Australia Barra Turbo I6 engine | X-series Ford Falcons, Ford Cortinas, Ford Mustangs, Shelby GT350s | This engine has an iron block, and an alloy head. This engine has become somewhat of a cult-classic, as opposed to the 'Falcon Six' Crossflow, and has gained world wide recognition and support, competing with the Toyota JZ series and Nissan RB series, due to being able to withstand upwards of 600-800 hp (450-600 kW) on a stock engine block and bottom end (pistons, connecting rods, and crankshaft). They have been known to produce >1000 hp with extensive modification. | |
| Triumph Pre-Unit | Triton motorcycle | Popular with Ton-up Boys and rockers back in the fifties and sixties, this is a Triumph engine in a Norton Featherbed frame. The idea was to marry the best engine to the best frame to make something that has the best of both worlds. Namely, a high power to weight ratio. |