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(Post Link) post #1 of 7 Old 02-06-12 Thread Starter
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Blow off valve for JTD

I start new thread just after some tests, which I made on the road. My GT equipped with GTB2056 makes me worry. It spools nice in constant gear, but when selecting gears, surge is too high and turbo spools worse, than original. Its delay is too long to reach 3 Bar. Once I brake turbo rotation it takes a long time to get full pull (about one second). I am thinking about blow off valve to leave turbo in high rotation. I found some kits for diesel. Its electronic controlled, not overboost controlled. Input is gas pedal positioner, output is solenoid, connected to blow off and vacuum. Nice tssssssssssss sound is fine, but I want it for shorter spool. Ill be glad for your point of view. Does anybody have some experience with diesel blow-off? Do you think, could it help a little? Id like to have immediate reaction after gear selection.

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Suppose you still have the throttle on place? Remove it.
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Quote:
Originally Posted by yan.ko View Post
Suppose you still have the throttle on place? Remove it.
Yes, still I have throttle fitted. Do you think removing throttle will help? Can you feel the difference?
Here is video, where you can see spool delay after gearing.
Alfa GT Q2 0-170km/h - YouTube
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What about the manifold tumble flaps?
When those shut during gear change I can imagine it will slow down the turbo. They should be always open, or better, completely removed.
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I dont think either of those things (throttle body or swirl flaps) will help.

Throttle body is only activated when you switch engine off, and swirl flaps are deactivated above 3000rpm.

IMO the most important thing during gearchange is VNT precontrol map.
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Buterfly throttle should be activated during gearshifting and DPF regen as well on JTDm, but I can't confirm that (anyone with latest JTDm would)
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But agree there are maps for VNT/boost control during gearshifting
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