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Old 05-14-2021, 10:46 AM   #11 (permalink)
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spyder2 - '00 Toyota MR2 Spyder
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Originally Posted by BongoBennie View Post
It's an a3 head on an a2 block... A3 head will give any K20a2 piston an additional .5cr due to smaller CC.

It's only @5.5psi so the easiest way to drive no boost is by light throttle. The car can be driven fast as a civic without hitting boost.
Ah, I see, good to know.

It doesn't matter how little boost the turbo produces, if you have extra restriction in the exhaust at part throttle, it's wasted energy. If you lose 1psi of restriction you'll pick up on the order of 1mpg from pumping loss reduction alone. Additionally, if the turbo is reducing manifold vacuum, you're reducing the internal EGR effect at part throttle too.

That's what electronic wastegate control is basically for; you'll never see an OEM running a passive wastegate.

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