Toyota Specialist

Specializing in Parts, Products and Accessories for Toyotas.


Information and Modification tips for
2T-G, 18R-G, and 3T-GTE Toyota Engines



Info about Toyota 2T-G/18R-G/3T-GTE

Toyota built their formidable Twin Cam reputation on these engines. Based on the popular T block and R block of the early 70's, these engines were the envy of all car manufacturers. These engines evolved- from the early stock ohv and sohc variety to the pure high performance G models, then the smog controlled models, and finally the fuel injected and turbo models. Originally the 2TG (1588cc) started at 115 HP, and the 18RG (1968cc) at 145 HP. Both engines had a twin- the 2TGR and 18RGR which had low compression pistons, but identical cylinder heads. In the mid 70's both the 2TGU and 18RGU saw a further drop in compression, emission controlled carburetors, and shorter duration camshafts. However, the heads were upgraded with bigger valves and hardened valve seats (for unleaded fuel). Horsepower figures typically dropped about 10/15 HP. By the late 70's, the fuel injected models arrived as the 2TGEU and 18RGEU, to regain all the lost horsepower. These models, despite still shorter duration cams and lower compression, had the best cylinder heads with still bigger valves.

The 3TGTE (1770cc) replaced both engines by 1983. The well-proven head design- now had 2 spark plugs per cylinder and a turbocharger to develop 160 HP. Despite claims of Toyota that the 503 race engine was based on the 3SG design- the bottom end was patterned after the 3T block (which had become wider in the lower block skirt to accommodate the longer stroke crankshaft. The crankshaft saddles are identical!

The competition models of the 2TG and 18RG, developed with parts from TRD saw many worldwide wins for Toyota- Corolla Levins, Sprinter Truenos, and Celica 1600 GTs with the 2TGs. In Asian and European Formula racing, the 2TG in the 1600cc category regularly beat all the other engine manufacturers. The Celica 2000 GTs saw many race and rally victories worldwide, including the European based WRC (World Rally Cup).

In the ultimate WRC Group B series, "the super class" in the World Rally Cup- the 4TGTE (homologation model of the 3TGTE) powered the Celicas of Toyota Team Europe to the Championship. The Group B class was soon cancelled after the general public and some rally entrants protested that the cars were unsafe because of the powerful engines.

The ultimate versions of the 2TG and 18RG were the 151E and 152E. These were not production engines. The heads and blocks were not interchangeable to the production units. (These heads were the design forerunners of the 503E heads.) Both engines had 4-valves per cylinder with either carburetors or mechanical fuel injection. These racing heads were fitted on heavily modified T and R blocks- basically to accommodate the new heads’ chain set-up (for the fuel injection and the dry sump oiling system). Originally they came in the same 1588cc and 1968cc configuration that were targeted to the specific 1600 and 2000 classifications for FIA (Federacion Internationale Automobile) regulations. For the U.S. IMSA (International Motorsport Association) the 152E was bored to 2200 to qualify in the "under 2.5 class"- normally aspirated at 330 HP.

The first race engine based on the 2TG was made by TMC (Toyota Motor Corporation) in 1970 and was known as the 100E. Toyota built about 25 engines with full racing specifications- specially casted head (11111-______) yes, blank numbers!, special intake manifolds, dry-sump oil system, 50mm Mikunis, ND igniter and instrumentation, ND fuel pump and some other trick stuff. Of the 25 engines- 8 went into Corollas (Levin and Trueno), 10 went into Celicas, and the rest were spares. Eventually TOSCO (Toyota Sports Corner) was organized and some parts from this project became available individually. TOSCO later became TRD.

The success of these engines has been greatest in the streets. The Celicas with built 18RG could outrun the 240Zs and Skylines, of that generation. The Levins and Truenos with prepared 2TGs outran all Japanese models and all European Twin Cam models- the Alfa-Romeos, Lancias, including the Lotus Cortinas and Escort Cosworths (of the 16-valve BDA variety. The Toyota Twin Cams was regarded highly by all competitors. It was the envy of the other manufacturer tuners. Some tuners in European formula racing made valve covers with their corporate names, to hide the Toyota origin.


MODIFIYING THE 2TG AND 18RG

The 2TG and 18RG, in all the different varieties- offer immense tuning combinations.

Block: The 2TG blocks were similar to the 2T and 3T blocks of the same year generation. For modification purposes the 3T block is preferred because it has the longer stroke crank, and with a bore-up to 89mm becomes a 2000cc. The later model 2TGEU block is the same as the 3T, and will take the 3T crank with no modifications. The 2TG stock block can be bored to 1750cc, with a similar bore-up to 89mm. To fit the 3T crank in an original 2TG block can be done with a lot of work- grinding the inside of the block skirts to clear the rods. The 2T and 3T cranks are forged. There is also available a 2150cc. using a modified Toyota 4Y crankshaft. The 4Y crank is not forged, but there is an aftermarket steel billet unit. In converting a single cam block to a twin cam, aside from switching over all the front valve train components, the original cam bearings have to be turned and repositioned. You must have a complete donor Twin Cam to do the conversion. Installing the 2TG into any T engined Corolla is a bolt-in deal with no modifications to the crossmember or brackets.

The 18RG block can be bored to 2200cc (92mm) or stroked to 2400cc (using a modified 20/22R crank). No the 18RG head will not bolt on a 20R/22R block! The stroker crank is not recommended. Aside from the very expensive to modify to fit the 18RG block, it seriously cuts into the revving characteristic of the Twin Cam. The 18R blocks did not change that much, but installing into the later model pick-up and Celica will need the newer block that have the extra engine support holes embossed on the sides of the block. Because of the wider variety of models the engines originally came in, there are 4 different oil pans, six different engine brackets. Fitting into specific applications will be a matter of matching the oil pan configuration to the original engine; and the engine brackets to the width of the crossmember. On the older Celicas with the 18R engine- it is a bolt on by using the pan and brackets off the original engine.

Cylinder Head: The early generation 2TG and 18RG heads had the best camshaft profiles and carburetors. They will respond extremely well to porting and big valves. If the block is bored out or the compression raised, longer duration cams will be needed. The mid-generation 2TGU and 18RGU heads had bigger valves, hardened seats, lower duration cams, and problematic carburetors. This is the head to use for turbocharged applications- since the head can be used with the original cams with the hardened valve seals and the (piston) compression is lower. The 2TGEU and 18RGEU had the reinforced heads, bigger valves, and the lowest compression (pistons). The EFI intake can be retrofitted back to carburetors.

The Twin Cam head must only be machined by experienced machine shops. Valve service and installation is very critical. If not properly machined there will be a problem adjusting the shims, valve spring tension, and camshaft timing adjustment. The head must not be surfaced more than 1 mm or .040 in. Please read notes under Recommended Set-ups / Race configuration!

Fuel System: The best performance can be achieved by using Fuel Injection over the carburetors. The standard Toyota ECUs are in short supply, but the most reliable set-up. For the EGU engines- the early 4AG Corolla GTS and MR2 computers can be used, since they operate within the same rpm range. Programmable Fuel Management systems will allow high compression, and radical cams- even turbo. Carburated motors will need Mikunis or Webers- if the stock Mikuni-Solex are not serviceable or to up-grade the GU carbs. For bored-out 18RGs the minimum carburetor size is at least a 44, and 40s will be sufficient for the 2TG up to 2000cc. The chokes must be changed to match the displacement. Turbocharging through carburetors is limited to about 10 psi using a fuel pressure-adjusting regulator. Do not rely on the Toyota mechanical or electric pump- use a low pressure, high volume pump.

Ignition System: The latest generation 2TGEU and 18RGEU use a breakerless distributor. Older units can be up-graded using original Toyota distributor components from later models. Ignition amplifiers and knock sensors must be used to avoid high RPM misfires and detonation. Wire sets that have the original configuration are the best to use- they keep dirt out of the deep sparkplug pockets that may enter the block when the plugs are serviced.


Some Recommended Set-ups:

For Stock configuration- the early model 2TG and 18RG will give the best performance. Update the heads for unleaded fuel. This is ideal for vintage restorations. The 2TGU and 18RGU are also good, but change the carburetors and remove the exhaust air recirculating system. The 2TGEU and 18RGEU can be run with the early Toyota 4AG computers and will be excellent low maintenance fuel injection systems. Since these are high performance engines- assembly specifications are different from the regular variety Toyota single cams. Do not attempt to overhaul without the correct 2TG or 18RG manual! There have been a lot of heads and complete engines destroyed- when an important Twin Cam detail was overlooked even by "expert" Toyota mechanic. Set-up properly these engines will last a long time- like any Toyota engine.

For Modified configuration- Prepare the head with big valves and a good port and polish job, this is the best modification that can be done. The blocks can be bored to 1750cc (2TG) and 2200cc (18RG) without changing crankshafts. The 3T crank can be used in the 2TG to give 2000cc. Avoid stroking both engines beyond these, the loss of RPM capability and inherent internal imbalance are not worth the power gain. Anytime high compression pistons are used- the cams must be replaced to avoid extremely high cylinder pressures- that will call for retarded ignition timing (and a loss of RPM and HP). The stock carburetors should be changed to at least Mikuni 44s or Weber 45s.

For Race configuration- Treat the head to a competition port and polish with the most aggressive cams usable. You may need a custom intake manifold because stock manifolds will be the limiting factor to the port job. The big valves and dual valve springs are mandatory (they are bigger than the largest stock valves). The crankshaft and rods must be prepped- stress reliefed, heat treated, line-bored. Optionally rods may be upgraded to Carillos. Piston clearance is critical since these are high revving engines, follow the piston manufacturers tolerances. Piston valve pockets must also match the camshaft and valves used. The oil pumps in the 2TG and 18RG are different from the single cam models, try to use the original Twin Cam pumps, specially when converting to the 3T block. If available the TRD oil pumps must be used for the 2000cc 2TG. The oil pan has to baffled, specially for race and rally use. For the Full Race set-up use 320 intake and 304 cams. For the Rally set-up use 304 /288 or 304/272 cams. For the Street racer, the 304/304 set-up is very streetable and have a nice mild lobe at idle. It is very discrete! These cams cannot be used with stock pistons!! (The 288/272 cam set-up maybe used with stock pistons, as long as the head has not been cut.) Naturally adjustable gears are needed for the cams.

The fastest 2TG set-up we have done used 330/310 cams with 1750cc pistons. The fastest 18RG used 320/304 cams with 2200cc pistons. If you need a 2-liter engine, use the 2TG (it is lighter and has slightly better Connecting Rod / Stroke geometry. The 18RG will ultimately produce more HP and torque. The Twin Cam engines will respond to tuning like real race engines. Cam timing, ignition, compression ratios, exhaust design, port profiles- all have their own advantages and disadvantages. The most popular set-ups are the 2000cc 2TG and 2200cc 18RG with all camshaft combinations. There are proprietary set-ups that may be used but try these recommendations first. Do not forget water treatment as these aluminum heads will corrode fast- and there are not enough of them left.

If you have a RWD Toyota- these are the ultimate engines to upgrade to. All the popular cars had them as factory options! The late model 16 valves- aside from the 4AG which at one point was available in RWD, are almost impossible to convert because of they were installed at an angle, although we have conversion kits!

Note: The 3TGTE will respond to tuning also. Since it is a turbo- all the turbo tricks will give more power than internal work- aside from the mandatory forged pistons.

The 3TG engine is an 1800 twin cam, twin spark, fuel injected turbo engine. The engine puts out 160hp standard, the standard turbo and injectors are limited to around 200hp. This is a great engine, but it lacks an intercooler and blow off valve in its standard form. If the turbo and injectors are upgraded, it is possible to get around 300hp from this engine using the standard computers.

ENGINE CROSS MEMBER

Once you have your old engine out you should make the following changes. The cross member needs to be modified to suit the 3TG engine. The drivers side can remain the same if you use a standard 2T or 2TG engine mount and bracket. You can fit the 3TG mount to the drivers side. To do this the 2T engine mount bracket which is bolted to the engine block, needs to be shortened by around 11mm. I did it this way because I think the 3TG mount is a bit more solid than the standard 2T mount.

The turbo side needs to be modified to clear the turbo oil return line. I used the standard 2T rubber mount for this side because there isn't much room to play with. The cross member bracket needs to be cut off and moved out by around 2 inches. I cut the bracket off completely and then sat the engine up to the cross member to make sure of the correct position before rewelding. You don't have to do it this way, but it is the neatest.

FUEL LINES

While the engine is out the fuel lines should be upgraded from 1/4 to 5/16. Also the original fuel filter needs to be thrown out and an EFI filter fitted. The standard paper filter will not cope with high fuel pressures so make sure of this if you don't want a fire.

GEARBOX

The standard T50 gearbox will bolt straight onto the 3TG engine. Depending on how you drive, this maybe ok. If you drive hard the T50 may fail. If the standard gearbox is used, simply bolt the original flywheel to the 3TG. It fits straight on and the standard gearbox and tailshaft will remain unchanged. The 3TG engine has the same block design as the 2T and 2TG.

If you want a better gearbox, a W55 from a Supra will bolt up to the 3TG. This is actually the gearbox that is used on the 3TG. The W55 does fit into a Celica without too much trouble. To do this, another gearbox cross member is needed. I used a cross member from an automatic early Celica as it only needs minor changes to fit properly.

The tailshaft also needs to be changed, the easy thing to do is find a tailshaft from an early automatic Celica. I found this out by mistake, but it's the way to go because it will bolt straight onto the W55 gearbox and the TA22 diff centre. It is even the right length, you gotta be lucky sometimes.

The W55 is a pretty neat fit under the Celica and it may be necessary to make a bit more room for the gearbox. In other words a bit of hammer work to widen the gearbox tunnel. It doesn't need much and will fit straight away, just will be very close to the body panels around the gearbox.

ACCELERATOR CABLE

The standard linkages can be removed. A cable needs to be fitted instead. Again, there are many ways of doing this depending on the quality of the job you want. I used a cable out of a Corona as it was the right length and had the same end as needed for the 3TG. The end that goes on the pedal needs to be modified as well. I just attached the end of the Corona pedal onto my original Celica pedal arm. Its no big deal.

FUEL SUPPLY

An electric fuel pump needs to be fitted. A surge tank should really be used to stop the engine from leaning out around corners when the tank is less the 1/4 full. An external or internal surge tank can be used. An internal surge tank is the best as you only need one pump and it is the neatest.

Otherwise an external surge tank will be ok, just need to find room for it. Two pumps are needed for this, one to supply the surge tank and one to supply the engine from the surge tank. The pump supplying the surge tank needs to have a flow rate at least equal to the pump supplying the engine, but it doesnt have to be high pressure.

The pump supplying the engine must be able to supply a pressure of around 4 bar. The standard fuel rail pressure for the 3TG is 255kPa. The excess fuel from the rail is sent back to the fuel tank. The fuel pump must be able to supply the 255kPa, plus your boost pressure.

COMPUTERS

Now this is the tricky bit. If you are not good with electrics then leave this to the experts. I have done this work myself. Once you break it all down, its not that bad. There are two computers, an EFI and a knock control with the standard system. It is possible to get good results from a standard computer. For the engine to function properly using the standard system you need to use the standard air flow meter. This is a flap type meter which feeds info back to the EFI computer regarding the required fuel mixture.

The standard system also has two coils and three pressure switches. Two of the pressure switches are used by the EFI computer. One is for fuel enrichment above boost pressures of 0.15 bar (connector PE), the other is for fuel cut off when the boost gets above 7.3 bar (connector PC).

The knock control computer uses the other pressure switch, this is because the knock control is not active at low boost pressures.

For more info on the ECU plugs, click here.

Here's the 3TG TEU wiring diagram, it's broken down into four pieces.

I fitted the computers under the drivers seat for easy access. There really isn't much room to fit them anywhere, unless you put them in the glove box.

You can use an after market computer, this will give the ability to reprogram. The standard computer cannot be changed much that I know of.

ALTERNATOR

The 3TG engine has an alternator with an internal regulator. The standard Celica used an external regulator. This old regulator needs to be removed, it has 6 wires going to the regulator. Only three of these are needed for the internal regulator, the other three can be cut off and covered over.

RADIATOR

The standard radiator needs to be modified to suit the 3TG. The current set up has the radiator to far back and it will hit against the 3TG fan. The top outlet pipe also needs to be changed to some sort of bend. The bottom outlet is ok as it is. The radiator needs to be moved forward around 1 inch to allow enough clearance.

Once moved forward the bracket that goes across the top of the radiator also needs to be modified, as it will now foul on the radiator as it has been moved forward. Another option is to use a radiator bracket from a GT model as it already had this offset as standard. Pretty hard to find if you don't already have one.

EXHAUST

The 3TG originally had a 2 inch system. But if you want more power a 2.5 inch system is needed, 3 inch is even if you can fit it under the car. Turbo engines are pretty quiet, a big pipe allows the exhaust gas to flow more freely, therefore the turbo can spool up quicker. A catalytic converter should be fitted to meet emission standards, get a free flowing cat for this.