From what I recall reading the Toyota papers the IM creates more tumble (notice the extra curvature) to increase flame speed and the extra 7% EGR slows it down. So they balance each other for the same horsepower and improved fuel economy. I believe the 4th Gen IM, EM, and EGR work together - I wouldn't mix the generations. Pixel XL ?
So IF everything inside the engine is the same, then the Gen 3 externals will have the Gen 4 run as a Gen 3(?) I hope.
A good resource that explains in pictures what has changed in Gen 4 vs. Gen 3: 4th-Generation Toyota Prius Teardown (Part 1) - MarkLines Automotive Industry Portal Pixel XL ?
I saw that. That’s part of what made me realize the swap was possible. Then the email from John Kelly told me that it was likely to work. Now after seeing the intake fit last night, I'm nearly certain it is going to work. Just a few issues to sort out. EGR and coolant hose routings.
I tried to undo the cat from on top last night. The heat shield showed me that it’s not the greatest of ideas. But that’s what tomorrow and jack stands are for. LoL
It’s going to have to wait until the transport shows up tomorrow morning. The engine will not start at all. I have ceased attempts to move the car under its own power until the engine is replaced. I need to have it towed to another location where the tools and equipment are to change the engine.
So the intake bolted directly on. And the exhaust was a direct bolt on. The EGR cooler interferes with the water outlet. The yard I bought the engine from will let me have the EGR cooler and manifold for 365 more dollars.
I found a different solution. Since I need the three fittings that are made into the head on the failed engine, I am going to rebuild the old head with the valves and cams from the engine I bought. It sets me back more labor time, but money outlay is significantly reduced.
Head is in good shape. I did a failure analysis and found this. Number 1 piston is broken. I’ve torn down a lot of engines, and this was a first for me. The rod is badly beaten up. You cannot take the rod cap bolts out of it.
My plan for tomorrow is clean up the lower half of the old head a bit. Install the valves from the newer head on my cleaned up head. Use the cams and cam bridge from the newer engine. Head bolts are coming from dealer. Reassemble head and block Friday evening, and put engine back in this weekend.
I did create a new post that details the issues that I ran into trying to put the engine in as purchased. I am still hoping that I can use the Gen 4 valve cover. I may get some black wrinkle paint for the valve cover just to dress things up.
I do think I spent too much time in the sun today. My wife took this picture. The engine mount bracket bolts were being stubborn on the failed engine, so this is how I broke them loose.
One thing I did not do, when pulling my engine. None of the high voltage cabling was disconnected. I pulled the ground off my 12v and the orange safety plug, but that’s it. The A/C compressor is still hooked up and plugged in. I just unplugged and hung over the fender all the sensor wires. Intake and exhaust removal took 20-25 minutes. All the bell housing bolts took about 15, and the front engine mount took about 10. Engine was out in a little over an hour. I did pull passenger splash shield loose for access to a water pump bolt, but that’s it that hasn’t been detailed in other posts.
As I’m reassembling my Frankenstein’s monster of an engine, I did an impromptu test. My blown engine, with a beam type torque wrench, cannot be persuaded to turn over. This is with it missing one piston, and the head removed. The Gen 4 short block, I can look at the torque wrench crosseyed and the engine will turn with the head removed. Literally the weight of the wrench will turn it. Did I want to have to do all of this extra labor? Nope. Would I do the same thing again? Nope. But we now know you cannot directly put a Gen 4 engine in a Gen 3.