Toyota Twin-Cam History
Toyota is the largest producer of TwinCam engines. Toyota offers more TwinCam models than any manufacturer. Here is a brief historical outline to the milestone Toyota engines of the TwinCam variety and the race engines they are based on.
The earliest and rarest production Toyota TwinCam engines were the 3M and 9R. Both engines were produced during 1966 to 1968, and ironically did not carry a G engine designation. The 3M was a 2 valve twincam 6 cylinder engine with triple Mikunis used in the 2000 GT. The same block, modified through the years became the 5MG/6MG/7MG engines- with a totally different head. The 9R was a 2 valve twincam 4 cylinder with twin Mikunis used in the Corona 1600GT.
The 2TG was introduced in Japan 1970 for the Corolla, Sprinter series in Japan. It was available in various forms (through the years) until 1984. The 1600cc 2TG came with twin-side Mikunis in 2TG, 2TGR, and 2TGU models. Eventually it came with fuel injection as a 2TGEU. The last model in this series engine was the 3TGTE (although it was never available in the Corollas). In the US, these engines were popular in Corollas, Carinas, Dune buggies, and Lotus 7 replicas. The 1750cc and the 2000 cc conversion were extremely popular and more reliable than the later 2140 versions.
The 18RG was first introduced as an 8RG and as an interim 10RG (both 1900cc) in 1971 for the Celica GT models and the Mark II, respectively. The 2000cc 18RG came out in 1974 with twin-side Mikunis in 18RG, 18RGR, and 18RGU models. Eventually it came with fuel injection as an 18RGEU. In the US, these were popular in Celicas, Pick-ups, and Dune buggies. The 2200cc conversion was very popular and some were even setup as 2400cc.
In Toyota-speak, the G designation means TwinCam Sport type. For both 2TG and 18RG engines: the extra R designation denoted regular gas (lower compression); the U denoted emmission controlled. For all other TwinCam engines: The additional letter designations after the basic engine model mean: E for fuel injection, T for turbo, Z for Supercharger.
The 2TG and 18RG were the original production Toyota TwinCam engines. These were the most widely available and produced TwinCam engines for production cars in the whole world (in that era). Even Lotus (with their own Ford-based engines) tried to buy and use these engines. The use of these engines in competition saw many major victories for Toyota world-wide. The 2TG was more developed in terms of parts from TRD since it was widely used for both racing and rallying. The 18RG was used mainly for rallying, most notably by Toyota Team Europe, but similar race specification parts that the 2TG had were also available from other sources. Toyota also produced a limited number of twin-plug 18RG that never reached production.
The 3TGTE, a twin-plug version of the classic 2TG and 18RG cylinder head design- with a turbo was the last model utilizing the bullet-proof and trouble-free 8-valve heads. This model replaced the 18RGEU in the Celicas in 1983. In fact the latest models 2TGEU and 18RGEU shared the same valves and valve train components. The 3TGTE was the base for the 4TGTE homologation engine for Toyota's Group B Rally Car. This engine, in the highly competitive and eventually cancelled Group B SuperCar class in the FIA World Rally Cup series, took Championship honors. Group B was cancelled This was a fitting tribute to the outstanding technical design of the 2TG and 18RG heads and blocks, before the whole world used 4 valves for everything.
The ultimate versions of both the 2TG and 18RG were made by TRD- they were known as the 151E and 152E respectively and came with 16 valve heads, both were available in carburetor (50mm Mikunis) and fuel injection (mechanical Denso) models. There was also a 150E 16-valve version of the 3K / 4K engines. These 16 valve heads were the forerunners of today's 4AG, 3SG, 7MG, and 2JZG engines. These were race only non-production heads, with heavily modified blocks. The 152E race engine was used for US Toyota's early back-to-back victories in desert/stadium racing and IMSA GTU events. The 152E was used in Europe for the FIA World Rally Cup series.
The most famous and successful Toyota Race engine- the 503E was used in Toyota's Triumphant Championship seasons in IMSA GTO / GTP, Pikes Peak, Le Mans, and in the mid-90s Japan Touring Cup Championship. It is important to note that the 16 valve cylinder head layout from the 152E engine and the T block crankshaft saddle design were used as design base for this ultimate Toyota 4 cylinder Turbocharged race engine. The 503E represented the most powerful 4 cylinders in competition history developing over 1000HP in qualifying tune, 800HP for sprint races, and 600 for endurance events. IMPRESSIVE.
The 5MG and 6MG were both 6-cylinders introduced for the MA60 series Supra and high performance sedans in Japan. These TwinCams ushered in a new generation of TwinCam design and application. The innovation of self-adjusting hydraulic lifters, required no extra maintenance for the valve adjustment. This promised service simplicity to the average Toyota mechanic. The towering cam position was impressive and heralded the arrival of the 6 cylinder TwinCams.
The 4AG and 1GG engines introduced the new generation 4 valve TwinCams of the "G" engines. This represented the 4th production generation TwinCam heads. The 1600 4AG was the 4-cylinder version and the 2000 1GG was the 6-cylinder model, both were available with or without superchargers. The 3SG and 7MG soon followed with or without a turbocharger. All true high performance Toyota engines carry the G designation, including the new 1800 2ZZGE. The newest G series engines use up-graded features- variable timing, variable lift, 5-valves, independent throttle bodies, supercharger, turbo, and even twin-turbo!
Most current Toyota in-line 4 or 6 production engines have a G model version, except the Tercel, which makes do with a 4EFTE engine, a turbo variation. The "G" engine guaranteed the Toyota driver- performance above par. The "F" designated engines are also TwinCams but are not the performance models. The F engines are designed for normal low rpm, high torque, and quick response. Most of the current Toyota engines use an F type cylinder head, including all the V6 and V8 engines, enabling Toyota to continue claiming to be the world's leading supplier of the TwinCam engine design.
The Yamaha connection needs to be mentioned: Yamaha developed the Toyota 2000GT and was a partner of Toyota in the design of most successive G model heads. Most G engines/heads, including the 3SGE/3SGTE (now in it's 3rd generation), the Previa specific 2TZFE/Z (no relation to the old T engines), and the newest 2ZZGE engines were and are still designed and cast by Yamaha. The 4AGE and 2JZGE heads are proprietary Toyota designs and manufacture, although many components are still made and supplied by Yamaha.
Toyota's "G" production engines in Motorsport trim and competition tune is unmatched by any engine manufactuer. The 4AGE is the successor to the 2TG, as the 3SGE is to the 18RG, in the important 1600 and 2000 class of racing engines. Both engines in their respective classifications are used widely in Formula type competition. The TRD Formula Atlantic 1600ccc and TOM's Formula 3 2000cc engines showcase the design integrity and tuning capability of both production engines. They are all proven winners, they are all production based.
The Toyota TwinCam engine is Toyota's only claim to a technical heritage or legacy in the automotive industry. The classic TwinCam design has worked very well for Toyota and has powered all milestone Toyota models. The new 3rd generation 2JZGTE, 3SGTE, 2ZZGE engines, updated with Dual Variable cam timing and lift- showcase the ultimate Toyota performance engines. No other manufacturer can claim over-all superiority on production based TwinCam engines, although other manufacturers are currently able to exploit the benefits of TwinCam technology further. Toyota will have to reclaim this historic edge and actually raise their design parameters to match the other trend-setting TwinCam introduced by other manufacturers.
Toyota's high profile entry in Le Mans, WRC, CART, and soon Formula 1- is highly anticipated by Toyota enthusiasts and competitors. More important to diehard and prospective Toyota enthusiasts is to have the most sophisticated and advanced TwinCam engines under their hoods, and in their cars. The historic role of the Toyota TwinCam engines in Toyota's place in the automotive industry was very crucial and important. In focusing sharper into Motorsports, Toyota must protect and not forget the important formula- TwinCams in Toyotas.
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