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

[H-Man]

You could actually do the throttle adjustment mechanically now that I think about it. You would need the pully the throttle cable turns to be connected to the throttle body by a differential or another mechanism that would enable something as simple as an electric motor with limit switches (when at the right position, the switch cuts power to the motor) to turn the other part of the differential so that when switching to 13:1 mode, it would close the throttle the correct amount when the VVT solenoid is actuated. The VVT solenoid could be actuated by another switch or by the ECU.

[mr220v]

Originally Posted by 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!

Glad to hear yours is still going strong. I have put a lot of those in circulation over the years. Still a very popular swap, and easy to do in the mk1 mr2.

This is the 5th motor I've had in this car. I was tempted to jam a gen4 3sgte into it, but that would have been too conventional. Of course somebody brought me a gen4 3sgte swap to do, so I'll get to drive that around a bit once complete.

Ultimately there might be a market for 1/2nzfe tercels, or other older toyota's running one. Hard to say. I guess that would partially depend on whether we get $5+ gas at some point.

[rmay635703]

Originally Posted by mr220v

Glad to hear yours is still going strong. I have put a lot of those in circulation over the years.

Ultimately there might be a market for 1/2nzfe tercels, or other older toyota's running one. Hard to say. I guess that would partially depend on whether we get $5+ gas at some point.

Real question is what kind of FE does this motor get in a light car without the hybrid system?

I have a pair of vehicles that would make good gliders for something of this power level, would rather have the EV side intact though

[BobS]

Quote from page 4:

The 1nzfe ecu runs the vvti based on rpm. I want to run it based on throttle position. With the setup I have, the vvti actually needs to operate more like displacement on demand than normal vvti. That's the object. Cruise at 750cc's, and move to 1.5L when I need to. End Quote.

Response: The ecu receives an rpm signal that it uses to choose between the two operating modes. If you put an oscilloscope on that line, you can determine the trigger signal (there is always a nerd with an oscilloscope at any high school). It is probably a sine wave. Whatever the waveform, it is probably easily duplicable with a simple 555 timer circuit that can easily be triggered between modes by a switch, say one under the gas pedal. And cheap, too.
Sorry about the above quote mechanism. I'm a noobie and don't know how that is normally done.

[serialk11r]

Originally Posted by Sean.Heihn

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.

That's not how it works. All cars come with cams with well over 180 degrees advertised duration but they manage higher VE than you'd expect even at low speed because air doesn't flow through the valve so easily when there's not much lift. Compared to a normal car the Prius might be comparable to a 9:1 compression ratio. Race engines have way more duration than the 1NZ-FXE, it doesn't mean they have low volumetric efficiency. It just means they peak out their volumetric efficiency at a higher rpm. There's a reason why people spend lots of time on headers and intake tracts, it's not as simple as "the valve closes, that's when air stops flowing".

[mr220v]

As far as VE goes with this motor, I suspect that when you "reclaim" your full 1.5L, you also tend to overlap the exhaust cam more as well. This would lend itself well to a better VE at higher rpms.

You could possibly degree the intake cam to close earlier and overlap the exhaust cam even more on the high setting.

[Mrhiguy]

Great job! I always wanted to see more of the 1nz swapped into other cars.

[danwat1234]

Originally Posted by mr220v

Aside from the weight and fuel economy, this is an atkins cycle engine. Well, it has an atkins cycle mode depending on what position the vvti cam is in. I currently have it set for on/off. This gives me two settings. 13:1 compression using the full 1.5L and 6:1 at 750cc's.
........................
Just driving it around, it actually feels stronger than the original 4age. This is in the 13:1 1.5L mode of course. The low comp/displacement setting will leisurely pull away from a light flooring it.

Toggling modes manually, I was able to get 37mpg where the various 4age's I've had would get 30, and the beams 3sge would get sub 30. This is running an echo ecu and no o2. Really a tune just good enough to run and drive.

Wait wait, I have never heard of the Prius engine (whether the 2nd gen 1.5L or the 3rd gen 1.8L) having an OTTO cycle mode! That is why the 1.5L is only rated at a peak of 76HP and the 1.8L 3rd gen Prius engine only has a peak of 98HP. Maybe it's because it does OTTO sometimes at low RPMs for power, but always Atkinson at high RPM (see post #43), hence the low peak HP.
Are you saying that it has an OTTO cycle mode? I have never heard of this, I thought it was strictly Atkinson cycle, hence why it needs an electric motor for assistance, especially at low RPMs.
I thought some of the new Honda/Acura "Earth Dreams" engines that are 2L and smaller will have on demand Atkinson/OTTO cycle behavior so it'll work well in a car that doesn't have an electric motor to help out at lower speeds and could get hybrid like economy on the highway.

If the Prius engine does have an OTTO cycle mode, then why isn't/wasn't it made for some Toyota cars that weren't hybrid, such as a Yaris?

Great innovative project

[Lemmiwinks]

Hi Mr220v, I had considered for many months about what engine to swap into my 86 mr2 and the thought of a prius engine did cross my mind a few times. I wanted to get more performance than the 4AGE that was for sure.

I could have bought about any engine with the budget I had and sprung for the 2AR-FE. Thanks for posting up your 1NZ swap results and tech.

John

[Frank Lee]

Originally Posted by Sean.Heihn

Now what I'd do is buy a 1NZ-FXE (or a small diesel) and make a 'battery pack-less' series hybrid. Have the engine drive a generator to supply electricity for the traction motor/s, with start/stop, a small battery pack to supply power to start the engine/power the traction motor/s while the engine spins up, regenerative braking to charge the battery pack. You'd cut down on weight and cost without the huge battery packs in current hybrids, plus with hub traction motors you'd cut down on complexity, cost, and power transmission loss and the engine, since it only provides power to the generator, can spin at the peak efficiency rpm range. Basically this is how diesel/electric locomotives work.

Please tell me this is a joke or a test to see if everyone is awake.