The EZ30R in my opinion is one of those really slept on engine platforms. Its one of those engines that even the manufacturers overlooked, or perhaps they just only put it in unassuming cars. So, what is this engine, what good is it and what can we do to it.
Let's find out together, by modifying my otherwise reliable daily driver 2006 Liberty Spec B. Turning it into an AWD 350z killer that sounds like a Porsche!
Subaru's oddball engine(s), what is an EZ30
The EZ30 is an even stranger engine when you consider where it came from. Subaru, best known for there Flat 4 Cylinders actually has somewhat of a legacy with 6 Cylinder engines that has flown under the radar, but that's not because they are a bad engine. As we will go on to discuss here, the EZ30 is slept on big time.
The flat 6 engines all started in 1985 with the ER27. This engine powered what Subaru called the car of the near future, the "Alcyone". When the car released, the ER27 was the only water-cooled Flat 6 on the market, so it was certainly unique, but at this stage it was a once off for a concept car gone production that didn't move all too many units.
This concept car Flat 6 trend would happen again with Subaru's next flat 6 design, the EG33. This engine is slightly better known than the last, being one of the powerplants available in the better known Alcyone SVX, however this engine too only ever saw use in the SVX and once that car was gone, so was the engine.
Finally we arrive at the EZ30, this design would see much more use than its last two counterparts, appearing in many models and even being the exclusive powerplant of the come that cars release in 2005. Its initial version was certainly not much to write home about, using exhaust headers cast into the cylinder heads and lacking any VVL or VVT. The real focus of this post,
is the Gen 2 engine, dubbed the EZ30R.
So, what are we working with here
The EZ30R was a big upgrade from the first gen EZ30D. Featuring Exhaust ports per cylinder, VVT and VVL as well as Drive by Wire. The engine from the factory could muster up a fairly impressive 180kw (240hp) at the flywheel which was a great improvement from the first gen's 162kw (217hp) at the flywheel. Even more impressively, the first gen Barra Grey Top only musters up 182kw from the factory at the flywheel despite having a full Liter more displacement, that's only 2kw more than the much smaller EZ30.
Turning the EZ into the Poor-sh it was supposed to be
With all this potential on the table then, how can we turn the EZ into the poor mans Porsche. It all starts with an exhaust system, and not just to get the Flat 6 sound out. To unlock a massive power gain from the EZ, the first mod that should be undertaken is an exhaust with extractors. The extractors are especially important, as while the stock manifolds might look ok at first glance, they actually are hitting power output by as much as 30hp!
Next up for the EZ in terms of hardware would be a decent panel filter (We recommend the K&N washable panel as an upgrade to the stock one) as well as a custom intake pipe, which replaces the factory flex pipe with the anti-resonance component and the secondary airbox right before the Throttle Body. We like the stock airbox as the panel element is quite large and the cold air intake duct is also very effective, though that's not to say it cannot be improved. We would recommend doing your research if you are looking for another option, or even to go custom fab.
Lastly, if you haven't already and your engine is due for some, get some new spark plugs in the engine and if you have the funding coil packs too. These are frequently ignored in Boxer engines which can really start to have a hit on power as they age beyond there recommended 100,000km service interval. Don't cheap out on plugs either, especially so with the EJ and EZ engines, the poor man will pay twice and plugs are not a fun job to do on these engines. Platinum or Iridium are the way to go as well as a known good Aftermarket coil brand or genuine OEM part.
Now for the tuning
The last part of turning the EZ into the poor mans Porsche is a tune, this is where we can come in and truly unlock the engines potential. The factory tune has a major set of shortfalls which after addressing, provide another big uplift in power, to the tune of around 10-15kw at the peak, but more importantly 15-20kw at the lower end of the RPM band.
This is mostly achieved through tuning out some of these big issues:
Overfueling. The EZ from the factory runs really rich, down as low as the 11s from the factory, which kills off a lot of power, especially up top. Tuning this back to about 12.6-13 keeps the power on at High RPM, increasing peak power.
Camshaft Timing. For some reason, non JDM model cars containing the EZ30 over advance the intake cam badly. The cam advance at 2000rpm can be 50 Degrees at WOT, which is far too much, causing the engine to hesitate and stumble, not to mention kill off most bottom end power. The JDM models however don't have nearly as much excessive advance, keeping it in the 10-20 Degrees range at WOT. We have kept our settings similar to this to get maximum power from the engine, as well as improve throttle response.
DBW Tuning. In some models, the DBW is configured to limit low end and top end power, which can hurt the final output down low and up top. We tune this out to provide 100% throttle opening at WOT no matter the engine RPM.
Spark Advance. Although the EZ30 can be sensitive to timing, we found the factory setup to be really rough in the tables, with large timing dips in places and a large amount of advance being provided by the Ignition Advance Multiplier tables, causing the Ignition Advance Multiplier to run very low. Our tables are essentially a full rework, allowing the Base tables to provide most of the timing.
The results!
While we are sadly still lacking our Dyno due to our facility being under construction, this didn't stop us from going to test the car out on track and on the street against some other cars. The car which we have been using as a base for our 3.0r tuning is a '06 Liberty Spec B. A nice car none the less, but not something many would expect to be a competitor on track or on the street. But lets see if we have changed that.
Firstly, we picked on a friends Nissan 350z Soft Top with the infamous VQ35. The car itself only has very light physical mods at the moment, a K&N panel filter and some form of what we suspect is a stage one map on the ECU. We would estimate it isn't far above the stock power level, perhaps 5-10 flywheel KW. Off the line the Subaru can certainly launch. AWD helps in a big way, and it gave the 3.0r the initial leap it needed to build into its 5-7.5k RPM power band. Torque was still leaving some to be desired though. The Launch RPM has to be raised quite high to make up for this with launch RPM being in the range of 3.5-4.5k, which can be hard on the clutch. Despite this, once the Liberty had its lead it kept it, right up till the end of our drag one @ 130 ish KMH. Its worth noting both the liberty and the 350 were equipped with there respective 6 speed manuals. We are still experimenting with the 5EAT H6s.
Next up we decided to get a bit greedy and see how the liberty stacked up against a 2.0 Focus ST on 22 psi. This wasn't exactly a fair race for the liberty. The 22 psi ST had already been tuned by us in the past (Blog post coming soon) and was a serious car, keeping up with the likes of a tuned MK3 7M Supra on 16psi and several LS powered SS commodores. Safe to say we didn't win, but again the launch was very impressive, jumping over a car ahead and holding the gap till about 70kmh, where the ST was able to get some traction under it and catch it back up, though not as quickly as one might think.
Conclusion
All in all the result was impressive, we think the 3.0R is a really nice platform, and we haven't even gone into forced induction yet. Even N/A the engine does really well after the Exhaust has been taken care of. Tuning also got a fair amount more of the power potential unlocked, making for a very snappy and fun to drive Liberty, that was putting the pressure on even on cars that you would expect would be out of its class.
So, what are you waiting for, if you have a 3.0r and want to see what a tune can do for you, send us a message and we would be glad to help you.
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