Single Turbo RX-7's Questions about all aspects of single turbo setups.

Boost falls off at high rpm.

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Old 03-16-18, 05:56 PM
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Boost falls off at high rpm.

So, setup is hybrid ht18s, stock ports, i/c, stiffer spring at wastegate and ported, Adaptronic ecu, MAC valve.
Pressure goal is around 14 psi.
1st and 2nd gear there is no possibility hit 14 psi. Boost is around 9.5-10 psi and as goes to redlines drops off..
3rd gear hit 14psi but again at high rpms falls off.
Old 03-16-18, 09:23 PM
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Simple Answer: the turbo is too small and choking.
Old 03-16-18, 11:05 PM
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Originally Posted by SirLaughsALot
Simple Answer: the turbo is too small and choking.
While very likely your turbine is too small, there is another possibility to explain your symptoms. What are your hot compression numbers?
Old 03-16-18, 11:53 PM
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If compression is good enough to make boost in the midrange it will only be better at "high" engine speed for a stock port.

Mainly you don't have enough turbo, the ported gate may be contributing a bit too as emp will be rising.
Old 03-17-18, 07:20 PM
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Originally Posted by Slides
If compression is good enough to make boost in the midrange it will only be better at "high" engine speed for a stock port.
Unless the engine is leaking compression, in which case your statement is completely false...

Last edited by cone_crushr; 03-17-18 at 07:23 PM.
Old 03-17-18, 08:30 PM
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if there is a failure mode you can clearly explain I'm not aware of I would love to learn about it.

please explain your reasoning so we can discuss it.

Last edited by Slides; 03-17-18 at 09:07 PM.
Old 03-19-18, 02:11 AM
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Originally Posted by cone_crushr
While very likely your turbine is too small, there is another possibility to explain your symptoms. What are your hot compression numbers?
7.0 kg/cm^2
7.3
7.1
Old 03-19-18, 05:58 AM
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Nothing wrong with that.
Old 03-19-18, 03:50 PM
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Originally Posted by mariosrotary
7.0 kg/cm^2
7.3
7.1
Are these values for the front or rear rotor?
Old 03-20-18, 06:51 AM
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Originally Posted by cone_crushr
Unless the engine is leaking compression, in which case your statement is completely false...
Please educate me.
Old 03-20-18, 08:04 AM
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I was thinking of doing something like this..
Old 03-20-18, 03:03 PM
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I sure hope not. That's not a very efficient way of running an EWG. Just put it on the turbine housing when it's still a Twin Scroll "snail" portion".
Old 03-21-18, 10:23 AM
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I know it's not the right way but i can't think something else instead of fabricate a new manifold.
Old 03-22-18, 12:58 AM
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I just told you something else.
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