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We recently visited a customer (Terry O'Beirne of Road and Track in North Ipswich) carrying out a 2GR conversion into a turbo SW20 MR2. The engine and related electronics from 2009 Australian Aurion sedan.

Below are the details on terrys project that we will be documenting from start to finish

Arrival
The engine package comprised engine as removed, air-box with intake piping, plastic incoming fuel line, security ECU with matching key & transponder, air-con compressor pipes, engine ECU & matching harness, special harness for the security system & the electronic throttle pedal.

Despite "assurances" about gearbox fitting, we quickly found only some E code boxes come close to fitting properly. The pre-93 MR2 boxes only have 3 holes that line up, and one of them requires the block to be helicoiled. A later E153 box had 7 bolts that lined up. Any MR2 turbo box post Oct 93 should be OK, except it will have ratios unsuited to the V6.

Gearbox & axles
A 3VZ V6 Camry flywheel with matching bolts, was found to fit perfectly.

After studying the gearbox situation, we concluded the existing early SW20 box will not suit. We selected a late model V6 gearbox due to a combination of better ratios and it bolts up much better. The V6 Camry gearbox however requires complete dismantling & the shifter mechanism reversed (we have made tooling to do this job) . The speedo gears in the V6 box wont suit the MR2 speedo, so these have to be changed. A TRD plate type LSD was fitted while we had it apart.



MR2 SW20 3sgte

3VZ wide-body camry V6

diff

60/14=4.285

58/16=3.625

1

42/13=3,231

43/12=3.583

2

44/23= 1.913

45/22=2.045

3

39/31=1.258

40/30=1.333

4

34/37=0.919

35/36=0.972

5

30/41= 0.732

30/41=0.732

A number of issues quickly became evident.

The MR2 clutch slave cylinder hits the block and grinding the block away will remove part of the factory engine number.Spacing it out away from the block will result in a poor shaft angle and likely a short cylinder life, so that idea was rejected. The entire SW20 clutch cylinder and bracket has been relocated with a specially made adaptor, and the untrained eye would never notice the change.
none of the various 3SG rear engine plates will suit the V6, so we will leave it out. as its mostly a seal plate, this wont be a problem on this conversion as the V6 box seals against the block OK.
the axle seal plate on the side of the box, hits the block. this can be fixed with minor grinding of the plate and block. This plate on the V6 box is not the same as MR2 as it is missing 1 bolt that is part of the engine mounting bracket. The MR2 plate will be refitted.
The support bearing on the long axle had to be moved 10mm to allow it all to align with block mountings
A 3VZ V6 flywheel was lightened ( down to 6.6kg) and we have made an uprated organic clutch based on a stock GT4 unit. By increasing the pressure plate clamp force, we should have a reliable clutch that is still nice to drive.

Wiring & electrics
A 2-volume wiring manual was obtained and we quickly sorted out where most of the wiring went. We also found out the Australian built Aurion has unique harness/ECU, so info from other conversions in the USA and UK is not 100% useful.

The engine loom has a few un-used plugs for radiator & air-con fans that we taped up securely, as removing them totally from the loom would take many hours. Various sections of the 3SGTE harness were removed and others merged with the 2GR harness to make connections into the fuse box etc, much easier. The Australian Aurion engine operates with a complex security system which must be retained and integrated into the MR2 to get the engine running. The only alternative to this is to use a non-standard computer, however this will preclude fitment of the Qld approved modification plate, so we did not go down that route.

For the engines first test run, the electronic throttle was temporarily connected down in the boot with the ECU. We later obtained some special 7 core cable and the electronic pedal was finally mounted where it should be, using a custom made alloy bracket.

The stock tacho was modified to suit the new ignition signal.

The wiring took 8 solid days of work to get it looking like a factory install, with everything working as expected. Another one would be much quicker, but merging the harnesses neatly will never be a few-hour job.

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