turbo mr2 gen3 3sgte conversion

[hunging]

I am posting this around different forums so I can get a wider range of opinions on this. I am trying to drop a gen3 3sgte into a gen2 turbo sw20 mr2. I hope someone on toymods has done this and give some insight.

I have recently picked up a gen3 turbo engine with no loom. Gen3 ecu is on its way. In the meantime I have been using every spare minute of my life doing research on putting the engine in.

As far as I know the engine should drop straight in without much difficulty. I think the difficult part would be the wiring. My plan is to re-pin the ecu according to the ecu diagrams on the net. Add a few wires for the additional for the extra sensors (MAT, IAT). Then for the I'll have to rewire the box fuse box as well.

Is that what I need to do?

[Joshstix]

It bolts straight in on the same mounts as the Gen2.

The only real difference in terms of interfacing with the rest of the car mechanically is you need a intake without the AFM and the dump pipe ends up about an inch closer to the centre of the car.

The wiring will definately be the hard part of the swap especially if you have no loom. Personally I'd be thinking very seriously about getting an aftermarket computer onto it. It would save a lot of headaches and give more potential for serious power in the future.

Do you have the stock Map sensor etc?

[Draven]

Agree with Josh... unless you're weird like Mos and Karl and actually like doing wiring (or are masochistic), either try and find a loom or go aftermarket.

[hunging]

I do have the stock gen2 map sensor and as far as I know the gen3 ecu will support it up to around 18psi. That's probably good enough for me for now. I'm not sure if my bank wants me to venture into the world of aftermarket computers yet.

LOL and no bdsm is not my cup of tea, whether that'd be morning noon or night. But maybe i could find a mechanic that would enjoy it . Also I have read using the gen3 harness (not sure if it's combination of gen2 body harness + gen3 engine loom or gen3 harnesses in gen2 body) will need still re-pinning. Is that going to be so much easier than just repinning the existing loom that it's worth me tracking down a gen3 harness from overseas?

[Joshstix]

The Gen2 MAP sensor will not work properly with the Gen3 computer. The Gen2 MAP is a 2 bar sensor and the Gen3 is calibrated for a 2.5 Bar sensor. The Gen2 map sensor is there for nothing more than to run the boost guage and boost cut.

People converting the Gen2 to run Gen3 management always have to replace the MAP and IAT sensors.

[hunging]

The Gen2 MAP sensor will not work properly with the Gen3 computer. The Gen2 MAP is a 2 bar sensor and the Gen3 is calibrated for a 2.5 Bar sensor. The Gen2 map sensor is there for nothing more than to run the boost guage and boost cut.

People converting the Gen2 to run Gen3 management always have to replace the MAP and IAT sensors.

I got that information from http://www.mr2oc.com/showthread.php?t=141075 [membership required].

For those without access to the American MR2 forums it's a comparison of the output of gen2 and gen3 map sensor. Basically they are saying the difference in the signal output is minimal and its effect will be negligible up to around 18psi. After 18psi the signal of the gen2 sensor peaks at 5volts. The same thing occurs with the gen3 around 30psi. Here is the image:

I hope what the guys in the States are saying is true.

[Joshstix]

That is not what that graph shows at all.

Lets look at the 4V output mark. With the Gen2 map sensor it will read 4V at ~10psi, with the Gen3 map sensor it will read 4V at ~16psi.

Now to me that is not negligable.

[Mos]

The difference might not be "much" in some people's view but in terms of engine control this difference is huge, where fractions of one PSI make a significant difference to the fueling requirements.
There is also a difference in the atmospheric pressure output which the ECU uses for the initial baseline calibration of the atmospheric pressure each time the engine is started.

As Josh said, it's far far from what anyone would consider negligible.

From memory there was a difference of only one wire on the engine to chassis loom plugs between an atmo SW20 and a gen 3 SW20, but this was many years ago so I could be wrong. Personally I wouldn't consider an aftermarket ECU given the availability of a PowerFc for the gen3, but you would still need to find a loom.

And fwiw, far too many people interpret ability as enjoyment.

Mos.

[Draven]

you know my tongue was planted firmly in cheek Mos