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Originally Posted by WRX06TR
I remember reading something from AMS that says they think the new motor is better than the 4G63 and they see no problem making the power they used to...doesn't sound plausible to me what, what do I know...
Thanks Kevin, I guess I was just referring to the high revving motor as able to spin the massive turbo's that evo owners run. Which is sort of irrelevant because Subies run big turbos, but I just figure it a GT35R spools at 4k then it should hold that power all the way to the 8k rev limiter vs the STi's 6.5k. But the subies flow more air with a 2.5l so i guess its a trade off.
I think I am going to leave this thread before I prove my incompetence...
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The only thing you're doing wrong is assuming the Evo is "high-revving" and the EJ is not. Physically, both motors have around the same rev limits for a given level of mechanical improvement, it's just that the Evo responds better as you slide your powerband to the right and go to larger turbos. A well thought out Evo motor that has a power band up near 8k RPM will generally speaking make more horsepower than a Subaru with the same basic powerband, but wouldn't necessarily be faster. You're on the right track about the displacement making up for a lower rev limit though. Airflow is airflow; think of the turbo as the sole determinant in how much air will flow through the engine. The larger the engine, the slower it needs to turn to generate that peak. So when you flow X air through an engine with 2.0 liters of displacement vs. one with 2.5L, you should make roughly the same peak torque. But since horsepower is a function of torque and engine speed, the smaller engine will make more horsepower because it's making that torque at higher revs. There's a TON of other stuff that goes in to tipping the power in favor of one engine or the other, but if all things were theoretically equal, Turbo X would make Y torque on any engine of any size, but horsepower would vary linearly with the change in size. More motor, less revs for a given turbo.
I'm meandering a bit but I think that covers the very basic idea of what we're talking about.