2005 Prius engine into 1986 MR2: mk1 1nzfxe Prius swap (gas only)

[Sean.Heihn]

Originally Posted by vskid3

One question, how do you figure that the Atkinson valve timing makes it 750cc and 6:1 compression? I've never seen any numbers for the effective compression ratio and I just didn't expect it to be so extreme.

Using the valve timing numbers:
http://www.mr2.com/files/mr2/techinf...ata/1nzfxe.pdf

I think he means effective intake draw volume, since the displacement is always 1497cc. The 1NZ-FXE varies intake draw from 898cc down to 539cc. And since you're compressing less volume, your effective compression ratio is lower than your physical. Something like 7.8-4.68:1 vs 13:1.

[mr220v]

Originally Posted by California98Civic

I have a very basic question about this project that will reveal my inexperience but that would be helpful with my own longterm mod planning. How do you learn which engines and transmissions will mount easily in the engine bay? Do you judge from factory service manuals or do you have to get your hands on the engines first to compare? Is it just gradual accretion of knowledge through experience? How would I learn how adaptable a given engine is with a transmission? A given engine/trans combo in an engine bay? I do not want to distract the thread. I'm just really impressed with your fluency with these swap possibilities. THANKS!!

I'd say an accretion of knowledge over time. I do custom Toyota engine swap wiring as my side occupation. I've been doing it for hire for almost 10 years now.

[MetroMPG]

Out of curiosity, I don't suppose you've posted any video of the car, have you?

[mr220v]

No, not yet.

[pgfpro]

The tune that your running now is it in open or closed loop?

[cRiPpLe_rOoStEr]

Originally Posted by vskid3

Awesome project! A pipe-dream of mine is to swap a Prius or Camry Hybrid drivetrain into something like an MR2, or regular engine w/ manual tranny into a Prius. The Prius is great for economy, but has much to be desired in the acceleration department.

I actually like the aerodynamics of the Prius. It would be great to get a Prius body with a dead driveline to fill it with that 1.4L D-4D from European versions of the Corolla and the Yaris.

[mr220v]

I currently have o2 correction/trim turned off. The idea is that you tune with your wideband, get the afr's where you want them, and then turn fuel trim back on. You can't have the o2 correcting while you tune.

[H-Man]

Originally Posted by Occasionally6

That was my though too but it might not be practical. There is at least one stand alone throttle controller but the one I am aware of is ~$800. A couple of the high end engine management computers will do it too.

I'd love to try it.

I wonder if a microcotroller could be used to control the electronic throttle body with a few sensor inputs so that it could switch over and have the right throttle opening. It wouldn't need to be super fast, all it would need to do is guess where to put the throttle when it switches over to avoid any jump in power.

Searching, it looks like the arduinos are fast enough to handle throttle body duty. You might need a good 100 datapoints to make a good map though, maybe some way to warn the ECU when it is going to go 13:1 also so that it doesn't go lean.
You may be able to rig up an electromechanical setup that shuts the throttle body somewhat when the engine switches to 13:1 and set up the throttle linkage to take it WOT at part throttle when in 6:1

[turbovr41991]

welcome to the forum MM220V! My 86 MR2 is still running on your harness with a black top 4age 20 valve engine. Great work!

[Occasionally6]

Originally Posted by H-Man

I wonder if a microcotroller could be used to control the electronic throttle body with a few sensor inputs so that it could switch over and have the right throttle opening. It wouldn't need to be super fast, all it would need to do is guess where to put the throttle when it switches over to avoid any jump in power.

Searching, it looks like the arduinos are fast enough to handle throttle body duty. You might need a good 100 datapoints to make a good map though, maybe some way to warn the ECU when it is going to go 13:1 also so that it doesn't go lean.
You may be able to rig up an electromechanical setup that shuts the throttle body somewhat when the engine switches to 13:1 and set up the throttle linkage to take it WOT at part throttle when in 6:1

I think it could be tricky. Just getting a throttle to follow the pedal position is a pretty complex exercise in control. You then get to add in another parameter in the form of the VVT position. The pedal position would be treated as a torque demand (same as all DBW) and the best combination of throttle position and VVT position figured out to provide it.

I did find (some time ago) a guy who had built his own DBW controller (for use in a Countach) and who was going to post up a how-to-do-it on his page (he hadn't done so last time I saw it).

The DBW do use two or more pedal position sensors and two microcontroller circuits to provide error checking. Might consider that if designing one from scratch.