Impreza H6 Swap FAQ

Do you have any pictures of it? Yeah, right here Why didn't you use a turbo (WRX/JDM/2.5RS/EJ20/EJ22/STi) motor instead? That's a lot of work for not much horsepower. I had several reasons for going with the 3.0. The car was prepared for a particular rally racing class. If I had no restrictions on design and wanted a lot of power, I would likely chose a turbo. However, within the restraints of the class definitions, this was a better choice. The car started with a 1.8 four cylinder. Something needed to be swapped in, and starting from the 1.8 and going to either a turbo four or naturally aspirated six would be a lot of work. A broad, flat torque curve, no turbo lag. I have no interest in racing a 400+ (or whatever number you like) horsepower car, which I suppose could be obtained by a turbo four. I need to live to collect trophies. The simplicity of NA without any of the high heat and turbo failures. Reliability wins races. It's ridiculously cool to have the only car of it's kind on the whole planet. When did you do this? 8-18-2003 - I pulled out the old engine. 9-06-2003 - The 3.0 is in the car and connected to the tranny. 9-19-2003 - The engine fires and comes to life for the first time. 10-22-2003 - Drive the car for the first time with the new engine. Is that the engine that came in the SVX? No, the SVX had a 3.3 liter H6. There was also a H6 that went in the XT that was something like 2.6 liters I think. This engine is the H6 out of the new, 2001 and up Subaru Outback. Is there room for a turbo in there? The distance from the front of the transmission to the firewall hasn't changed. Since that's usually where the turbo goes in the 4 banger, it should fit. How much heavier is that engine than the (1.8/2.2/2.5/WRX/Sti) engine? I don't know. Doesn't that engine make the car very nose heavy and screw up the handling? By removing the ABS block completely, which is a pretty huge hunk of aluminum, and relocating the battery to the trunk, the front to rear weight distribution is within about 1% of where it started. I still need to get it back on the scales that I weighed it before the swap to get better resolution on that figure. What are the exact dimensions of the engine? I have measured these, and won't have any others for a very long time. (till the engine comes out... maybe next year) Across front: 32.25" Across body: 29.75" Across tranny attachment: 14.75 Between motor mounts: 14" Front to rear: 18" Height, sump to intake: 25.5" Why do you still have the AC in there? The air conditioning was kept for two reasons: I'm already very close to the allowed minimum weight for my class. It's hot down here!!!! The outside temperature reaches 40C in the summer, and the transmission tunnel can get up to 65C!!! I sometimes use the car for brisk TSD rallies, and also to create the route books for new rallies. This involves a lot of careful measuring and writing notes and stuff, so the car has to be livable. What computer is running it? I'm using the stock H6 computer. I started with a nearly complete engine harness, and a hacked up main harness. These two got spliced together with the existing 1995 wiring. Can you send me schematics? No. All the years are so different, it wouldn't be accurate. You will need to buy the factory manuals for both years you are swapping. How did you mate it up to the transmission? Subaru never shipped that engine with an manual transmission. Amazingly, the tranny "bolts right up". What are you using for a flywheel and clutch? I used the aluminum Fidanza 9.5 pound flywheel for a 2.5 RS, an ACT heavy duty pressure plate, and a semi-metalic clutch. Does the regular exhaust bolt on? If by "regular exhaust" you mean anything that ever came on an Impreza, no. Each side only has one exhaust outlet. I assume that the stock Outback exhaust would bolt up to the engine, but I can't imagine it mating up to the stock Impreza exhaust at any point. That's just a guess, I haven't researched it. So what kind of exhaust did you use? Custom from the exhaust flange back to midpoint, then a Scorpion exhaust. Mandrel and 2.25 inches. Does the regular power steering fit? No. The reseviour is too tall since it is attached to the pump. I used the Outback power steering pump, and the hoses will mate up to the Impreza steering rack. What did you do for engine mounts? The H6 drops onto the right spots with the stock H6 engine mounts. What tranny are you using? I'm using the stock transmission that came attached to the 1.8L engine originally in the car. Won't that stock tranny break in a heartbeat? If I raced on tarmac, probably. Since it's a rally car, I rely on the dirt to give way before the tranny does. I expect to have to switch to some dog cut gears in a year or two. What is the 0-60? What does it do in the quarter mile? I have no idea. Since I have no plans to race on pavement with this tranny, I don't have any interest in these numbers. Will you do one for me if I bring you the car and the engine? Um, no. Well, ok. $10,000, you supply car, engine, computer, wiring harnesses, radiator, and power steering. And you have to give up ABS. Oh, and working with the dash is a pain in the ass. Make it $12,500. Two month process. Where can I get a H6 3.0? Look on car-parts.com. Look under 2002 Subaru Legacy. Sometimes they have none, usually a couple, I've seen as many as nine. How much did it cost? It cost a lot. That's all you'll get out of me. How long did it take? From the day the old engine came out, to the first day the new engine ran, about six weeks. To the day it was actually ready to drive around, about another four weeks. Ten weeks altogether. Do the pistons from any of the H4s fit in the EZ30? No, the pitch, bore, and stroke are all different. H6 H4 Pitch 98.4 mm 113 mm Bore 89.2 mm 99.5mm Stroke 80 mm 79 mm What is the firing order? 1-6-3-2-5-4 Is that the same firing order as a Porsche 911 flat six? No, a Porsche does 1-6-2-4-3-5. However, several people have mentioned that it does sound like a Porsche. It certainly doesn't sound like the rest of the Subarus!!