Dissecting Supergramps

The Gramps and Supergramps builds have been an epic journey, one that now feels a bit more finished as the car is painted, looks mad, drives well and is an awesome all rounder daily.

For me this has definitely been a car that's used the best of what i've learned over the years about Subaru's. It seems to be a common theme that people, for whatever reason, find a make or model of car that suits what they do and who they are. For me, a wagon was the best compromise of a car I could live with but also drive. Years ago I thought about other cars that might achieve this. A rear wheel drive Falcon Wagon, it's big, parts are cheap and common... but the suspension and engine were fairly old tech. Holden? same thing. Then there's euro wagons, they are more advanced but also expensive for parts in Australia. That takes us to Japan. Toyota has wagons, Nissan have wagons although not many locally delivered. Toyotas were mostly front wheel drive and Hondas were.. well... Hondas.

So that left me with Subaru. It's got a flat engine, which in reality does limit achievable power - but it's also got all wheel drive, meaning that whatever power you do make, you can put that power to use. Rally wins proved it was a formidable car with good performance and reliability. 

I've owned a few Subaru wagons and know them back to front so it seemed like the logical choice. I'd picked up the first and original 'Gramps' from the guys at Ichiban. They'd put it together from a collection of spare parts from front cuts after they've come across the shell. It was clean, straight and perfect for a build.

Nothing I own stays stock for long, soon after I was talking to Al (Turbo Yoda) about creating the ultimate Grandpa wagon. We threw around the usual ideas that people who are into Subaru's do. "Build a 2.5l!" "Build a high revving 2L" "Throw a stock block in and boost it till it blows". Then Al said "EZ36.. complete the task". I had to look up what the engine was from. Subaru Tribeca, a strange looking large SUV that looked like it was made for the American market as it didn't fit the usual mould of what Aus delivered cars are. Turns out the EZ36 is one of Subaru's most advanced engines. It also manages to fit 3.6L of displacement into an block that isn't a great deal bigger than their 4cyls, meaning it would drop into most Subaru engine bays.

AM Auto have a reputation of doing all kinds of weird and wonderful engine conversions. There's an art to getting an engine to fit into a car it was never designed to accept. There are basics like engine mounts and positioning, but its all the little things like engine management, wiring, neatness and even air conditioning that turn it from a 'toy' into a proper usable car.

The story of the driveline going through two shells is well known, I covered it recently in this post.

So the car is painted, it has an interior, and can be driven around like a normal car again. So what's next? In short, a LOT.  

There are some challenges. Firstly, the EZ36 was never designed to be boosted. There was originally the option of using the 3l EZ30, which shares a similar design to the EZ36 but with less displacement and less torque. I've driven a Liberty with a turbocharged 3 litres and they are fast! You can also buy off the shelf forged aftermarket parts for this engine, which makes building a motor designed for more power easy. The EZ36? It hasn't received the same aftermarket support yet, and may never do so. 

So where does that leave me? Either i can remove the EZ36 and build a 3 litre, of forge ahead with completely custom parts. The 2nd option is expensive, probably out of the available budget for something like this. Being the first is always more expensive as you bear the cost of all the R&D.

That said, the 3.6 is an extremely torquey and tractable engine. It's a pleasure to drive with a manual and turbo and unlike anything i've experienced. It's exactly what you want from a fast, daily driven performance car. It comes on boost quickly, it's smooth, and agile.

So, now the mission begins to find parts that may fit the engine. I'd like to stay 3.6 if it's possible, but if the zero's keep adding on to the quote for parts, it may not be possible. With the compression ratio a very high 10.5:1, turing for performance becomes a knife edge exercise with one side being bulk power, and other - exploded parts, or more commonly with Subaru engines, cracked pistons and ring lands.

And the rest of the car? It's fairly well sorted as it is. It's got adjustable coil overs, 6 speed STI gearbox, 3RB diff and brakes in the rear end, braided brake lines and Bridgestone Potenza RE003 Tyres we've used throughout this series.

So in coming episodes you'll see Supergramps get a few small but tasteful mods that will improve it even more as a daily driven car. It won't be making any more serious amounts of power until the engine is strengthened and compression ratio dropped which will allow us to work the turbo harder.

That's it! Thanks to everyone who has come along for the ride on this series, it's been new for both Moog and myself, we've learned heaps and hopefully you have too.



  • Judah Krantz

    How did you manage to join a 6MT STI transmission to the EZ36 block? I’m thinking about doing the same thing to me EZ36, however I don’t know fit a manual transmission to it

  • Josh Stancil

    Should talk to Outfront Motorsports in California, I’m going to try and do this swap in my USDM 05 STi. The swap is slowly getting noise in the US. I know they have Billet cams that Outfront is making as well as everything else to build the heads. also have a way of de-stroking it to a 3.2L with rods and pistons. Obviously this gets rid of those weak OEM rods. Hope to see more on this build later on!

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