JDM Engines the same as US Spec?

Just take your original engine apart, and rebuild it using the latest spec Toyota parts. Why mentally masturbate over JDM this and JDM that?

 

You CAN use a Gen4 engine. Just use the head from the Gen3 engine.
If you keep the Gen4 head, you'll have to do some bending and modifying of the exhaust for the egr cooler.
Not sure about then not knowing what year the engine came from. They should, buttttt....

 

I find it sorta hard to believe that the bottom end of a JDM XW30 engine would be different than a North American spec motor, but I cannot credibly discredit what the salesperson told you.

TL ; DR
They probably do not have the piston ring problems, but they probably have the same piston rings.
I would buy one unreservedly...AFTER a FULL visual inspection and WITH a verifiable warranty.

Longer version:

There are some interesting urban legends (myths) that surround JDM engines, and most of them are hooey.
They mainly result from cultural differences AND a system of inspections in the Japan called Shaken.
Motor-vehicle inspection (Japan) - Wikipedia

The "official" purpose of Shaken inspections is public safety....sorta like CARB in California.
The REAL purpose of this system of inspections is to encourage people to drive newer cars (because Japan's economy used to be based ON.......???) and to create government jobs and levy taxes disguised as "fees".....just like CARB in California.
Author/Historian Dan Carlin said in his podcast about Japan that “The Japanese are just like everyone else, only more so.” which sums it up fairly nicely.

So.....
Here's why JDM engines are "probably" > US-spec engines:

1. They're more anal about maintenance than lazy Americans.
2. If you've ever been to Japan then you know that driving is expensive, and built to STAY that way. Gas is expensive. Tolls are more widespread. Taxes are Insane.
3. Many Many Many more people in JA use public transit when and where they can for regular hops reserving their cars for irregular trips.


HERE is where they may NOT be > than US-spec engines:
1. The myth that JDM engines have never been flogged and dogged is just that....a.myth.
Ever been to California?
Yeah.
Me too.
Ever see a bunch of cars that made you wonder HOW the Eff they EVER passed CARB inspections when you can't even legally use an Oil Catch Can?
The reason is simple.....they either DIDN'T and don't give a crap....found a mod-friendly shop to gundeck the inspection....OR....they "made their car legal" just long enough to pass a REAL inspection.
Japan has tuners just like everybody else....only MORE so.

2. The myth that JDM engines are limited to xxxxx miles is balloon juice. They have high mileage cars....just like everybody else. Japan is just about the size of California. Bigger if you flatten it out. Some cars pull intercity duty. Some get used as taxis. Japan has Uber.

3. Ever driven in Japan? I have....and it's kinda exiting, and NOT just because they drive on the wrong side of the road!
Here's the thing....they actually have FEWER accidents than US drivers despite their rather interesting driving style. This due to very obvious factors...BUT.....they DO have them.....juuuust like everybody else.
Shaken regs make it harder to produce 'zipper' cars like we have in the US, and one of their capital crimes is probably title washing and odometer fraud...and yes....like most developed nations they they DO have the death penalty!
Fun Fact:
In JA you only get executed one way.
Hanging.
So....this means that your low mileage JDM motor "may" have a much better chance of originating from a "previously un-wrecked" car.

4. Traffic Patterns. Which engine would you rather buy? One that has been driven in ultra-dense city traffic or more of a highway warrior?
Remember.....a JDM engine MIGHT only have 40,000 miles on it but how many hours did it spend idling in log-jammed traffic with the owner whamming away furiously at the steering wheel? It MIGHT be like buying a police car here in the US (only without the damage from "peaceful" demonstrations.)

5. Efficiency.
Engines are heavy, and they have a life cycle of well over 100,000 miles.....even when they are owned by people whose idea of 'proper maintenance' is tossing the keyfob on a service manager's desk every 10,000 miles and asking how much it will be THIS time.

Why ship them HERE?

YMMV

 

I hate trick questions.

 

Wait.......what......you have a car that needs BOTH a new hybrid battery AND a new/rebuilt engine ???
And you are seriously considering going that ???
Something is wrong with this picture.

 

When you can get the Gen 4 engine for $700-800, why not save the few dollars and get the better engine? The JDM engine will at some point do exactly what the current engine is doing now. July 2018 I put the Gen 4 short block in mine. The local yard to me that listed a “running core” 2010 1.8 with 200k for $1400 still has that engine now. At the very least, be particular about the replacement engine, and get the newest, lowest mile engine that you can get.

 

And when you are done you will STILL have a car that is over 11 years old, with other parts likely to fail right along.
Not to mention the time and trouble you will have invested.
Not a wise decision in my book.......but to each his own.
Good Luck !!