Boost tapers off (16psi down to 14)
Under WOT in 3rd gear, my car will indicate just about 15.5 psi before the tial wg cracks open, and hold approximatly 15 psi until about 6krpm, at which point the boost begins to slowly taper off down to a 13.8-14.2 at redline as indicated by the haltech.
What can I do to solve this issue? I was thinking of replumbing the Tial wastegate in accordance to the following diagram; http://www.tialmedia.com/documents/w..._wginstall.pdf Currently i have a spring and ball style MBC (w/ pinhole vent) connected to the WG's side port. I want to move it to a T'ed off fitting on the top port as shown in the diagram and then vent the wastegate to atmosphere. I would set the MBC to about 7 psi relief to start, in attempt to match the 8 pound spring which should get it to about 15psi. I feel this will accomplish my goal of stabalizing 15-15.5 psi until 7500rpm. Any ideas? My second idea is to get a larger compressor but thats just too costly at the moment. |
Umm, I'm no expert on turbo systems, but is your turbo big enough to sustain that sort of boost to redline? It sounds like a normal high-rpm roll-off to me.
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Im starting to think it not big enough, however my wastegate doesnt even sound like its closing when the boost tapers off so I dont really know.
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Originally Posted by SaabGuy
(Post 7631788)
Under WOT in 3rd gear, my car will indicate just about 15.5 psi before the tial wg cracks open, and hold approximatly 15 psi until about 6krpm, at which point the boost begins to slowly taper off down to a 13.8-14.2 at redline as indicated by the haltech.
What can I do to solve this issue? I was thinking of replumbing the Tial wastegate in accordance to the following diagram; http://www.tialmedia.com/documents/w..._wginstall.pdf Currently i have a spring and ball style MBC (w/ pinhole vent) connected to the WG's side port. I want to move it to a T'ed off fitting on the top port as shown in the diagram and then vent the wastegate to atmosphere. I would set the MBC to about 7 psi relief to start, in attempt to match the 8 pound spring which should get it to about 15psi. I feel this will accomplish my goal of stabalizing 15-15.5 psi until 7500rpm. Any ideas? My second idea is to get a larger compressor but thats just too costly at the moment. |
https://www.rx7club.com/single-turbo-rx-7s-23/question-engineers-499149/
Some good dialog with respect to boost control |
I'm fairly sure this Tial 38mm WG is using an 8 pound spring with nothing holding it down; meaning the top WG nipple is open.
What would be a suggested configuration for setting this up more correctly for 15psi? Thankyou |
Originally Posted by SaabGuy
(Post 7646447)
I'm fairly sure this Tial 38mm WG is using an 8 pound spring with nothing holding it down; meaning the top WG nipple is open.
What would be a suggested configuration for setting this up more correctly for 15psi? Thankyou BTW if your TO4B can make 15 psi at only 7500 you got a broken turbo. That's plenty of turbo for that low of an rpm. |
I was also thinking about hooking a boost solenoid to my haltech e6k which is much less expensive than a true ebc. The haltech can control duty cycle vs engine rpm which I think could be alright...
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I've had some engine builders tell me that it is usually beneficial to taper boost off as you near redline. Neither of them gave a reason though.
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Originally Posted by cjernigan
(Post 7682901)
I've had some engine builders tell me that it is usually beneficial to taper boost off as you near redline. Neither of them gave a reason though.
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