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boost drop off at high rpm's

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Old 04-09-10, 09:29 AM   #1
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boost drop off at high rpm's

88 RX-7 T-II
3" Turboback to dual 2" resonators
3" Intake
Flex-a-Lite 180
Ported wastegate
engine has 24K on rebuild

Got back into rotary's again back in october, used to work on rx-2's and 3's with my dad 25 years ago. anyway, boost picks up to 9-10Psi around 4K then maintains till around 5500 and drops off to around 6psi by 7K. Turbo is stock so if this is normal then I can accept this bt I was wondering if its possible that my secondaries arent opening thereby restricting my flow at high rpm's. Also, can i simly remove the butterflys without removing the shaft? any adverse effects to doing this?
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Old 04-09-10, 11:24 AM   #2
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It's just the stock turbo, we all deal with it.
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Old 04-09-10, 01:17 PM   #3
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Here’s a little more detail as to way, they stock internal wastegate is not efficient enough to keep boost at its preset levels; this tends to happen with 90% of stock turbocharged vehicles. As RPMs climb so does the amount of exhaust gas coming out of the engine and into the turbo/wastegate. The stock wastegate actuator is not strong enough, so the exhaust gas pushes the flapper open more than it should be, and in turn you get less boost. If you would like to solve this problem you will have to go with an aftermarket turbo manifold with an external wastegate flange, an external wastegate, and a decent electronic boost controller.

GL with whatever you decide to do.
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Old 04-10-10, 12:56 PM   #4
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Thanks for the info. Im happy where its at. plenty of power for my needs. I pulled the tbody last night to check on the secondaries anyway, they open at least 80% + so I'll just deal with where I am.
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