Question: I know there are hundreds of threads on Subaru conversions. I’ve read a lot of them including the write up from Renegade Hybrids about the more popular Subaru conversions using the EJ motors. The one that makes a lot of sense is the conversion done by Bob (BIGKAT) back in 2016/17 on a blue 72 914 using a Subaru EZ30D flat six out of a 2003-09 Legacy or Outback. Putting out around 230/240 horsepower. Also used a Subaru 5-speed transaxle where he flipped it around and the rear output is blocked off. My question would there be a problem using a 6 speed Subaru trans that came originally matched to the EZ30D engine out of a Legacy instead of a 5 spread Subaru trans? Feedback on the EZ30D engine vs some of the EJ motors? Thanks

EZ30D is 2000-2004, easily identifiable by the cast aluminum intake manifold. Can use factory ECU but all were automatics that can cause some odd drivability issues.

EZ30R is 2005-09, plastic intake manifold. Cannot use factory ECU due to immobilizer and CAN bus issues

Only 6 cylinder Subarus with a 6 speed are EZ30R in Japan only.

6 speed will not fit in a 914 unless you cut out a section of truck floor.
Also the 6 speed is harder to convert to FWD due to a second set of support bearings in the center diff and the oil pump drive being part of the center diff.

The biggest difference between an EJ and EZ is reliability. The EZ engines rarely have any issues.

If you're talking non turbo, the EZ30 makes way more torque and HP

If you're talking potential, there are no real performance parts for the EZ engines, the turbo EJ is endless.

I really should sit down and write thread about this

Thanks for the insight on the 6 speed trans option and the insight on the EZ vs the EJ engines. That also explains why he used a Megasquirt system to connect things to the ECU. I would think staying with the non turbo EZ30R engine would be adequate. Along with either using a 5-speed Subaru trans or stick with the stock 901 trans with an adapter. It’s tempting when you can pick up a complete EZ30R engine for under $1,200.00 with less than 50K miles on it. Great horsepower/torque and reliability.

Do tell. What are the drivability issues?

PM sent to 76-914 about his 73-914 with Subaru 3.0 six

You should take a look at Kent's build as well:

76-914 EZ30

Very detailed. He used the stock ECU.

I drove BIGKAT's car before he sold it. Had plenty of power and very smooth.

Chris thanks, I will take a look at Kent’s build. Appreciate it.

The "Essentials" of 2001 EZ30D wiring (no AC, no post-cat O2 sensor, standalone fusebox + relays for the engine). Slight differences for MY 2000 (1 or 2 ECU pins different) Later ECU's (not sure when moved to a different fuel pump wiring convention). I wired my clutch interlock into a factory Subaru neutral safety switch so the car can't be started in gear.

Click to view attachment

Flipping the intake manifold can be a pain, I left mine in the stock orientation and run a homemade flipped throttle body with a minimum radius mandrel bend. This guy sells em and they look a lot prettier than mine does... His are for EJ's so they wont work directly on an EZ but I'd bet he would so some EZ series parts if others were interested...

https://www.busaru.com/busaruparts/tbr

I have an EZ30D, no maintenance or driveability issues that I know of.

The biggest downside of the conversion is where to run the coolant lines, but @Chi-town seems to have that whipped!

-Ross

Ross thanks for the information. Roy

Don't believe the JDM engine importers, those engines are actually closer to 100k miles. They've been lying about it since the 90's

@76-914 I've seen some low rpm ignition curve issues in closed loop due to it the ECU not being able to use gear calc correctly because the auto trans controller not being used. Some also have idle stall on hard braking after extended highway use due to the same thing. If you toss them on a dyno you usually see the slope start off kinda weak and then start to make good power around 3k-3500rpm in open loop (+75% throttle ~).

I don't have the low idle problem even when I run the AC. I did ground the PS pump wire and activated the AC wire to get an additional 100 RPM. There is a free program (freess) or something like that available that will allow you to set the idle speed (and other things) but is is PC based and I have a Mac. If you do run the stock ECU you'll need to connect the VSS or it will quit after about 10 min's on the hi way. It resumes to normal once you take your foot off the gas but it's an eye opener the first time it happens. Ask me how I know this. As far as get up and go from a standing start, it is insane. No bogging down. It pulls all the way up to 7K when the ECU gives it a stall.

It’s definately a journey......