The 3SG was introduced in 1986. This engine series was initially available in a FWD, AWD, or mid-ship configuration. Transverse. The block is based on the S series engines- a lightweight steel block that was earlier used with SOHC heads. Again this is an evolutionary engine. The 16-valve design is very similar to the 4AG and 7MG, in fact valves, springs, lifters- are very close dimensionally. The head is of the G type, meaning it was designed as the performance model as compared to the F types that are designed for torque and low-end response. Our concern here is performance so we will discuss only the G models.
There are 4 distinct generations. The 1st generation, most common in the US, is TVIS inducted (dual-runners with large ports) available in NA or Turbo editions. The 2nd generation was also available in both NA and Turbo forms, but had a different intake system (and smaller ports). The old TVIS system was replaced with a new short/long ram induction system on the NA models. This was achieved using a plenum that redirected air thru a shorter or longer passage- depending on throttle position and vacuum. On the turbo models the manifold just went straight to the head. This resulted in a much better throttle response, and with the added compression gained both HP and torque. The 3rd generation revised the valve adjustment set-up. The shim adjustment originally on top of the lifter, was moved under the bucket- like the old 2TG/18RG set-up. This was to correct a problem with shims falling out at very high RPM’s (on modified engines specially with aftermarket sports cams). This was a modification introduced earlier for higher lift and longer duration cams by sport tuners.
The 4th generation was upgraded to incorporate variable timing and lift, similar to the later model 2JZ Supra / Lexus engines. This engine finally found itself in RWD form in the Toyota Altezza / Lexus IS200! Maybe Toyota is starting to listen. Finally the 3SG in the important 2000cc class had power equivalent (or close enough) to other offerings from other manufacturers.
In international competition the 3SG has powered formula type cars that have been consistent international winners specially under the TOM’S Racing Banner. The 3SGTE engines in WRC won for TTE (Toyota Team Europe) several Championships for Toyota. It is also the engine used in the WRC Champion Toyota Corolla, set up to a limited 300HP.
The engine is very similar to the JTCC / IMSA Champion 503E engine- but none of the parts are interchangeable. In fact the development of the 503 was the basis of the 3SG, in effect the 3SG was based on a racing engine! A 503 was running even before the first 3SG.
This lightweight 2000cc block and 16 valve head with Toyota lineage- is a must have for the old school Toyota camp, needing (wanting?) a modern powerplant. We have available RWD conversion kits to retrofit these engines for RWD!
With Toyota’s introduction of aluminum blocks, this may be the last of the 4 cylinder iron blocks. This is important to note because current new generations of aluminum blocks will need major preparation to be able to reliably sustain HP outputs that this iron block will easily survive. For ultimate Toyota power in the 2000cc class the 3SG is the final answer.
MODIFYING THE 3SGE / 3SGTE
Block: There are two different blocks- turbo and non-turbo. The basic difference is that on the turbo block, the oil passages for the turbo unit is pre-plumbed and piston oil coolers are present. There is no strength difference. The later generation blocks have better connecting rods (rods were similar on NA and Turbo of the same generation). Early generation conrods are marginal if mega horsepower build up is anticipated. As a minimum upgrade 1st generation rod bolts to ARP units. Even in disassembly some rod bolts would snap! For any extended performance upgrades go to Carillo Rods. (See other notes for RWD conversion).
These blocks are lightweight but structurally stable. There is no perceived torsional weakness even under very high boost and RPM levels. The crankshaft is also very robust. Chamfering the oil holes will help reduce friction and guarantee good oil supply. Oil supply insufficiency has killed more engines than boost! There are casting provisions for installing piston oil coolers on the NA blocks. A competent machine shop should be able to tap into the oil galleys with no problems. The oil feed bolt and squirter is now available separately.
The latest generation blocks can be identified by an aluminum block / oil pan extension. The oil filter is relocated low in the front. The timing components are all different from the previous 2 generations. We support parts for these engines.
Stroking the engine to 5S specifications is a possibility. Although the 3SG bore / stroke is already optimized for performance, the additional 200cc of the 5S combined with a G head will provide a noticeable increase in torque. This will however require new pistons. Ultimate HP output will be limited by the weaker crank design. Definitely not for turbo applications.
Cylinder Head: Like all Toyota G type 16 valve heads, only minor porting is required. Except for early All Trac heads (ST165), all heads can use the aftermarket cams. On the older ST165 All Tracs, you will need to modify the lifter or valve because they will bottom up. Always check the cam manufacturers suggestion specially if the lift is more than 7.5mm and duration is over 288! Convert to- shim-under-the bucket, valve adjustment if the car will see serious competition use. There is no advantage going bigger valves, unless they have to be replaced anyway. If the heads need to be resurfaced because of warpage- do not exceed 1mm cut. If it needs to be heated to straighten out- replace the head. The head has to be surfaced to a mirror finish if a metal head gasket is being used.
The 2nd generation (small port) head is advisable on a ground-up engine preparation. This head will flow better than the old TVIS type head- for turbo applications or individual throttle body installations (and carbs too!). The 3rd generation head, when available, is very hard to get and expensive, but still cheaper than buying the shim adjustment conversion package. We have some available. The 4th generation is almost impossible to set-up because all the electronic functions are electrically related to the ECU- meaning drivetrain, suspension controls, and steering inputs are first processed. Short of a stand-alone fuel injection, it cannot be modified. If you have to ask how- please do not even begin.
Rear Wheel Drive: The 2000cc 3SG is a good choice for RWD conversion. We can supply the engine brackets, oil pick-up, oil pan, flywheel, clutch set, and other related pieces to install in a RWD vehicle. There is a choice of either T-type (Corolla) or W-type (Celica) transmissions. Unless necessary, use the W type transmission. The T-type transmission is marginal when engine output in excess of 180 hp is expected.
The non-turbo block has provisions for the L & R engine brackets. The turbo block will need further modification to use (there is no provision for the engine bracket on the turbo side). Whether the planned application is turbo or non turbo- the NA block offers more flexibility because of the present engine bracket bosses. Piston oil coolers can be retrofitted on the block. Another advantage is that the oil cooler can be relocated away from the area where the factory turbo normally hang. After-market turbos cannot use the original factory turbo plumbing anyway.
Depending on the install, the water pipe routing will also need to be reconfigured (similar to the 4AG transverse going into a RWD application). The distributor will also need to be configured, or the firewall modified to clear it. A stand-alone Fuel injection set-up, with ignition capability is the preferred way to go. This way the ignition timing can be derived from a crank trigger, bypassing the distributor problem.
As mentioned earlier, oil delivery is crucial. Although the original transverse oil pan can be used, the pick-up and baffling is completely wrong. You have to get the correct RWD pan and oil pick-up, or risk losing the engine due to oiling problems. The late model engines have a higher output oil pump.
Turbo Upgrade: The 3SGTE in both the All-Trac (GT4, overseas) and MR2 have numerous after-market turbo upgrades available. The factory turbo is able to run boosts up to 14 psi (1 bar). Trying to boost above this is ill-advised. In order of importance- the exhaust, intercooler, boost controller, ignition, fuel computer, turbo, vein pressure converter, injectors are the steps in upgrading. For anything over 12 psi sustained, a new block with forged pistons is necessary. Adjusting compression ratio for a non-turbo being upgraded to turbo, by the head gasket is not recommended. The availability of metal head gaskets in various thickness and composition is more to compensate for the milling of the head and block, and slight adjustments in compression.
The most usable turbo upgrade is based on the factory CT26 stock turbo. We were the first company to do this and maintain proprietary specifications. Some companies also perform factory turbo based upgrades, but ........... There are numerous other aftermarket single turbo set-ups, but they are not as streetable, and for daily drivers become truly intolerable.
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