Engine swap options

Max Orido style :)
Lexus IS-F V8

Droo-P Cosworth EJ swap:

Quote by Paul Hansen (involved in building Droo-P/AVO D1 86):

Technical tidbits - the standard transmission is built by Aisin for Subaru, labeled as a Subaru. It won't bolt up to a EJ series motor. The bellhousing is different, and the starter motor has been swapped to the other side. We'll be getting a custom Hollinger gearbox in for this build.

I wouldn't get too broken up about the transmission not swapping over to a EJ. Even if you did want to shoehorn a turbocharged EJ in, the turbo isn't going to fit. In the location where it is now on the WRX/STI, it won't work. We checked. Simply, no space.

So a turbocharged FRS/BRZ is going to happen with a turbo kit designed specifically for the cars, whether or not it's the standard FA or the EJ. It looks like what we are designing for the Droo-P car is going to be cutting edge enough that we may have picked up another D1 team car to build.

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Bah, I have to eat my words - I didn't hear it right when we were discussing the car's build. The race car *is* going to have a turbocharger up on the side, similar to an STI/WRX build. That's only because of the Hollinger gearbox that is going in. The *production* turbo kits that I'm not supposed to talk about are going to be front mounted.


I guess this is as good a place as any other to discuss why's and how's of turbo placement in regards to Subaru, and for people new to the Subaru motors.

Three major factors are in play for turbocharger placement on the FRS/BRZ - space in the engine bay (very important!), distance from exhaust ports on engine (also important!), and gravity.

The last part is a bit odd to bring up, I'm sure, but I'll explain. Turbochargers need oil through the bearings so they don't immediately overheat while spinning at eleventy billion rpm. Lots of oil. Oil is drawn in from the motor somewhere, and then drained down back into the engine, preferably straight to the oil pan where all that molten oil can cool down a bit and sip a coke. Now, most makers rely on simply gravity to drain the oil. The turbo being placed higher than the oil pan takes care of matters. Feed oil through top of turbo, gravity drains it down to the oil pan. It's a simple, effective system that doesn't fail all too often. Except here comes Subaru, which has it's exhaust ports on the bottom of the engines, not out to the sides. So instead of placing the turbocharger right off the exhaust ports a few inches, like the inline 4's, they had to move it off and up to the side. It's not ideal, but we go back to the keep it simple system for oil drain.

Subaru has finally moved away from that concept in 2010 with the new Legacy, placing the turbo underneath the engine at the front. They have dealt with oiling issue by having an oil pumping system to feed/drain the turbo. This is necessary since the turbo is actually lower than the oil pan, or at least parallel with it. Not as simple, possible reliability issues, but certainly better response and performance.

When it comes to the FRS/BRZ, any turbo kit that is going to work with the FA20 is going to have to do something like this, either at the front of the engine, or "remote" mounted at the rear. Remote mount would probably be easiest in terms of placement, but would perform horribly on a 2-liter. Expansion of hot exhaust gases is what drives a turbocharger, and if you put all this exhaust piping between the engine and the turbo, all that expansion action is over and one with by the time it reaches the turbo. Remote mounts only work with big v8's because of the sheer amount of exhaust gases available.

So we are back to a front mount turbocharger for the FRS/BRZ. Which means, amongst other things, that all of us aftermarket companies will be starting from scratch. Interesting times...

Now back to our regularly scheduled programming!

Regards,

Paul Hansen
www.avoturboworld.com
www.facebook.com/BRZSportsCarClub