Two main comments:
1) swapping in this motor makes no financial sense
2) despite that, the FA20T is much, much better designed for a turbo than the engine in the BRZ
Quote:
Originally Posted by industrial
Low revving, low displacement motors with tiny turbos. It's very efficient and great for emissions. Not what I want in a sports car at all. God why?
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People complain about transient response and low end torque. Then you make them an engine with transient response and low end torque and they complain it doesn't rev high enough or feel "turbo" enough.
Have you ever designed a direct injection turbo engine before? Do you have any idea how difficult it is to size the turbo? It's waaayyyyyy harder than picking something for a custom project or a kit sold in small volumes. I have seen guys who size turbos for a living get it wayyy wrong, surging at low speed and choking at high speed. That kind of mistake can cost a supplier huge contracts when they fail to meet targets. Have some appreciation for what's involved in making that kind of "truck" torque curve. Coincidentally, the new M5 and S8 have a similar curve, although high output spec DI engines do rev a bit higher. Also, BMW and Audi have 2 liter turbo gas engines in their sporty cars.
Quote:
Originally Posted by Turdinator
I wasn't disputing that the FA20DIT has different heads. I was questioning your proof of those heads being superior or even that our heads are junk...
On a related note, are there upgraded direct injectors available for the subaru system? Or would you be stuck with the power that the stock injectores maxed out at?
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The D-4S heads are designed for flow. The FA20T, like basically every other 2 liter turbo DI engine in production, are designed for knock resistance and combustion efficiency. They use high tumble ports matched to appropriate piston bowls. That's why they can make so much torque at low speed--low speed torque is difficult because that is a highly prone knock area.
Quote:
Originally Posted by wparsons
You're kidding right? You do know that both of those have exactly zero to do with the D4-S technology, right?
The torque dip is because of the header design and the stock tune, and the tip-in knock is the stock tune.
Change your header and flash a new tune and both issues are 100% gone, without touching the D4-S hardware.
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As I've pointed in previous threads, basically every n/a DI engine has a "torque dip" somewhere, including the GM 3.6 in the Camaro, the Lexus D-4S V6 and V8 engines, and the Infiniti DI V8 engine. It's the nature of scavenging, cam phasing, manifold design, etc. Yeah with the right hardware you can work towards flattening it out, but you're giving up something no matter what choice you make.
Quote:
Originally Posted by regal
It is different fuel injection, no port Fuel injectors, no D4-S. This engine is the reason Subaru agreed to build the twins, they wanted DIT bad and Toyota gave them the tools to develop it. It is a very good engine, what should be in our twins.
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You don't know who worked on what. Toyota has no turbo direct injection engines in production right now, although I'm sure they'll have one by 2017 model year. They've been working with Yamaha on D-4S for a long time. It's highly likely that they don't really know what they're doing, at least no more than anybody else. I can tell you that Subaru is a small company with a small staff. For 20 years they really only had two engine families.
Most likely Subaru hired a consulting company, most likely AVL in Austria, to do a significant amount of the work.