Is there a better actuator solution for low boost applications?
#1
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I am in the process of my first turbo build, converting a 1.6 Spec Miata into a low boost 8-9psi, race car. I was surprised at the inefficient manner in which I had to dial down the boost and how much later the torque and HP came on. It would be nice to see the boost come on earlier and just not build as much instead of it getting all dumped out the wastegate after lengthening the actuating rod.
I was seeing tons of torque at 4200 RPM's with a max boost of 13psi but when I dropped the boost to 9psi it moved the boost (and the torque) way up the rpm band to overcome the open wastegate.
I am using a T28 turbo. Any suggestions would be much appreciated.
Jeff
I was seeing tons of torque at 4200 RPM's with a max boost of 13psi but when I dropped the boost to 9psi it moved the boost (and the torque) way up the rpm band to overcome the open wastegate.
I am using a T28 turbo. Any suggestions would be much appreciated.
Jeff
#4
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EWG = external wastegate
MBC = manual boost controller
EBC = electronic boost controller
What specific T28 are you using. Knowing it is a "T28" does not actually tell us anything overly useful about the turbo.
MBC = manual boost controller
EBC = electronic boost controller
What specific T28 are you using. Knowing it is a "T28" does not actually tell us anything overly useful about the turbo.
#7
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Run a huge exhaust with no backpressure:
![](https://www.miataturbo.net/attachments/diy-turbo-discussion-14/38247-there-better-actuator-solution-low-boost-applications-200_vs_225.jpg?dateline=1332953406)
2.25" v 3" on the same setup and boost level.
use a MBC or EBC even at the low boost pressure.
get a wastegate can with a huge diaphram.
Size the turbo to the task at hand:
![](https://www.miataturbo.net/attachments/diy-turbo-discussion-14/38248-there-better-actuator-solution-low-boost-applications-nov_13_2010_china_vs_nov_10_2008_garrett.jpg?dateline=1332953406)
my 50 trim T3 vs. a 60trim T3, same boost, same setup
![](https://www.miataturbo.net/attachments/diy-turbo-discussion-14/38247-there-better-actuator-solution-low-boost-applications-200_vs_225.jpg?dateline=1332953406)
2.25" v 3" on the same setup and boost level.
use a MBC or EBC even at the low boost pressure.
get a wastegate can with a huge diaphram.
Size the turbo to the task at hand:
![](https://www.miataturbo.net/attachments/diy-turbo-discussion-14/38248-there-better-actuator-solution-low-boost-applications-nov_13_2010_china_vs_nov_10_2008_garrett.jpg?dateline=1332953406)
my 50 trim T3 vs. a 60trim T3, same boost, same setup
#13
Boost Czar
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also, im a little confused by the OP's post. are you using a MBC or something to increase boost from 9 to 13psi? or are you just tightening/loosening the rod.
that's an issue right there.
the proper way would be with an MBC and you'd get result like my setup:
![](https://www.miataturbo.net/attachments/diy-turbo-discussion-14/38429-there-better-actuator-solution-low-boost-applications-nov_13_2010_chinacharger.jpg?dateline=1333032284)
The only change in low-end torque is where you start making more boost above that where the lower boost threshold is. The spooling characteristics should remain identical.
that's an issue right there.
the proper way would be with an MBC and you'd get result like my setup:
![](https://www.miataturbo.net/attachments/diy-turbo-discussion-14/38429-there-better-actuator-solution-low-boost-applications-nov_13_2010_chinacharger.jpg?dateline=1333032284)
The only change in low-end torque is where you start making more boost above that where the lower boost threshold is. The spooling characteristics should remain identical.
#14
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I'm pretty sure his actuator spring is factory set to 13psi or something, and he's extended the arm to lower the boost (Because you can't use a MBC or EBC to lower the boost beyond the actuator spring level). This has resulted in the wastegate flap being open partially, which would make the turbo totally inefficient because it would be bypassing most of the exhaust. What he really needs is a wastegate actuator that runs the PSI he wants or less then what he wants, and then use a MBC to reach the proper level.
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