3S-GTE Conversion


I have recently completed converting a 1996 Japanese Spec SW20 MR2 Turbo motor to ST205 spec.  I bought the SW20 motor a while back and was rebuilding it to go into my ST165.  Well,  plans changed and I decided to continue rebuilding the motor for my ST205.

Now these motors are of the same generation and the same model,  but obviously Toyota had to make changes for the different installs.  So what did Toyota change,  and what must be done to fit a MR2 motor to a GT-Four?

Differences (and similarities):

  Intercooler,  well duh!  The GT-Four of course uses a water-air intercooler,  while the MR2 uses air-air.  In terms of changes to the actual engine they are minimal.  If fitting a ST205 IC then you need the rubber connector to the throttlebody and the IC bracket,  which the IC bolts to.   Also the throttlebody to camshaft cover bracket is different.

  The lower cambelt cover is different to match the different curvature of the engine mount.  The black metal plate under the camshaft pulleys is different too to match the lower cover.

  The crank pulley is different to suit the different belt layout.

  There are very minor differences in the block fittings,  but not the casting.  The MR2 has studs fitted for the alternator bracket (the Celica power steering bracket in the same location uses bolts),   whereas the Celica inner engine-gearbox bracket uses a stud where the MR2 has unused holes.  All easily swapped.  The MR2 block has two dowel pins on the rear of the block for an unknown purpose,  to fit the Celica exhaust bracket one of these must be ground flush.  Otherwise the short block and sump are identical in everyway.

  The head and cams are identical on both cars,  as are the camshaft cover and top cambelt cover. 

  The water and oil pumps are the same,   although the radiator hose junction at the end of the head is significantly different.  The gearbox end radiator hose goes rearwards on the Celica,  and forwards on the MR2.  The casting is more complex on the MR2.  Incidentally the Celica 3S-GE casting is different to the GT-Four casting too (as I found following assembly!).

With those parts out of the way the main differences are the engine ancillaries.  The MR2 has the alternator mounted on the rear of the block,  the Celica on the front up top.  Obviously the brackets are different too.  The air conditioning pumps are of a different design,  although mounting in the same place.  The Celica has a power steering pump,  the MR2 pump is electric mounted up front of the car.

The wiring harness is totally different on the MR2 because of the different layout.  The Celica one includes half the fusebox and interfaces more with the car's main harness.

Additional parts needed for SW20 into Celica:
(note * means ST165 or ST185 parts can be used,  sometimes with modification)

A SW20 engine is easier to find,  but the following parts must be swapped over.

Celica alternator*
Celica alternator bracket (apparently ST202/205 part needed)
Celica air conditioning pump*
Celica power steering pump*
Celica power steering pump bracket*
Celica dipstick and tube
Celica crank pulley*
Celica lower cambelt cover (SW20 may work with mods)
Celica upper cambelt cover support plate - under camshaft pulleys (if SW20 lower cover used)
Celica 3S-GTE radiator hose junction
or    Celica 3S-GE radiator hose junction with wiring harness mods
or    SW20 radiator hose junction with modification
Inlet manifold support brackets
-    One at throttle body,  only required if using ST205 intercooler adapter
-    Two rear manifold supports - required to clear PS pump

There you go,  no excuses,  jump to it!!

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