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The Juke has a Diverter valve. It diverts the excess turbo pressure back into the intake. They are called recirculation valves as well.

A blow off valve can be both a diverter and blow off the pressure. Some are on or off. Some can be adjusted so the blow off is a percentage of the air and the rest goes in the intake

A Blow off of any type can be heard. Thats the PHSSSST you hear on say Fast and the Furious when they shift gears.

The Juke uses a diverter since the intake air system is metered by the MAF and it helps to maintain accurate intake numbers.
 
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Discussion Starter · #3 ·
The Juke has a Diverter valve. It diverts the excess turbo pressure back into the intake. They are called recirculation valves as well.

A blow off valve can be both a diverter and blow off the pressure. Some are on or off. Some can be adjusted so the blow off is a percentage of the air and the rest goes in the intake

A Blow off of any type can be heard. Thats the PHSSSST you hear on say Fast and the Furious when they shift gears.

The Juke uses a diverter since the intake air system is metered by the MAF and it helps to maintain accurate intake numbers.
So what is recommended or better? Would you say the one that is both? If so what's a good ratio?
 

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The recirculating (diverter) valve is what the ECU is expecting. fuel is proportional to the amount of air entering the system to keep the AFR (O2 sensor) close to stoichiometric range (14.7 parts air to 1 part fuel). If you let off the throttle in a turbo car, there is an excess of air being pushed into the engine with very little fuel for a period of time after letting off the throttle. The recirculating valve dumps the air back into the intake side of the turbo but after the MAF so the AFR doesnt go severely lean. If you were to dump this already metered air to atmosphere, you run the risk of making the AFR severely rich where there’s too much fuel and not enough air. The latter scenario is harder to achieve. The engine does not like very rich or very lean AFR and engine knock leading to damage can occur.

now that all being said, there are forum members here that run a 50-50 blow off and recirc valve with no observed ill affects. You can run a full blow off valve, but the engine may run like poo.
 
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Most get the Turbosmart Kompact. Its certainly better than OEM but as on most Juke mods. It wont gain you any more power.
 
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The turbosmart kompact (which I have) has a spring that isn't quite the correct strength. It's just a tad bit soft, providing a "lazy" action to it. It sounds like the valve is slightly open during periods of light throttle and only fully closes on heavier throttle.

My personal recommendation would be the GFB diverter (Go Fast Bits) T9106 for the full recirculating or for a bit more $$ the hybrid T9006 which allows for vent to atmosphere and/or recirculation and is fully adjustable.
 

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I am partial to the Synapse style diverter (full recirc or BOV) valves myself but they are pricey. Their design allows them to hold tightly while still releasing quickly. Most problems with aftermarket diverter/blow off valves is that you are constantly adjusting them with swapping springs or adjusting the preloads. The Synapse eliminates most of that. They hold tightly to keep part throttle response up, release quickly to avoid compressor surge, and hold boost up top to maintain power.

A leaking BOV/diverter can definitely cost you power in terms of boost leaks which is why we upgrade them. Anyway, a reliable diverter valve upgrade will improve response and it's worth the upgrade.
 
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The turbosmart kompact (which I have) has a spring that isn't quite the correct strength. It's just a tad bit soft, providing a "lazy" action to it. It sounds like the valve is slightly open during periods of light throttle and only fully closes on heavier throttle.
Not sure where people are getting the idea that the spring is soft. We install these all the time on both stock and tuned jukes and no one reports any issues. We have done over 400 horsepower and 28psi of boost on these. No strange partial throttle issues, no leaking, nothing. Turbo spool is better than stock. We have also installed them on WRX's/STI's (its the same exact valve) with no reported issues from them either.
 

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Not sure where people are getting the idea that the spring is soft. We install these all the time on both stock and tuned jukes and no one reports any issues. We have done over 400 horsepower and 28psi of boost on these. No strange partial throttle issues, no leaking, nothing. Turbo spool is better than stock. We have also installed them on WRX's/STI's (its the same exact valve) with no reported issues from them either.
I say it because it is my own personal experience. That experience has been reinforced by other users on this forum over the years as well.

Stock/pre-installed/default spring:

Edit: using the next spring up from there will prevent the flutter (and the lazy partial throttle behavior), but it also keeps the valve closed for too long when initially accelerating, causing boost to come on slightly late.
 

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