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I'm new to the tubo world and am loving by truck. I have a couple questions about turbo operation. I understand the more throttle the more boost. Is there a time when the turbos are not providing boost? What is the maximum boost stock? Do they always spin? I assume the higher the RPM's the faster they spin and therefore provide more boost? Is there a simple definition of "wastegate" and function? Thanks in advance for enlightening an old school guy...........John
 

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John- Most of the time when the engine is not under load (meaning not throwing down the power) the boost is at the lowest or no effective enough to feel. Max boost from what I have seen/read is between 12 to 13 (Could be wrong but the modified EcoBeast have been boosted up to 17 safely). Turbos are always spinning and the more RPMs the more exhaust flow thus the faster the turbos and more boost than the BOV (Blow off Value) steps in (if required) and relieves the turbo pressure (Boost) and recycles the air back into the intake tube. Thats kinda of why you don't hear the typical loud gosh of air blowing off when your letting off the throttle quickly.
 

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I'm a visual guy... Watch this video. It should answer most of your questions.


Pretty sure max boost on a stock motor is abt 12lbs.

Hope this helps.
 

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12-13 is correct for stock. I'm running 16-18 # of boost with an LMS tune (I think). Never been dyno'd. Going off dyno charts with my same mods
 

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Thanks AK and TT-F150, good information and I have a much better understanding of the magic made by the 3.5 ecoboost................John
 

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I'm new to the tubo world and am loving by truck. I have a couple questions about turbo operation. I understand the more throttle the more boost. Is there a time when the turbos are not providing boost? What is the maximum boost stock? Do they always spin? I assume the higher the RPM's the faster they spin and therefore provide more boost? Is there a simple definition of "wastegate" and function? Thanks in advance for enlightening an old school guy...........John
Yes turbos always spin when the engine is in run mode as the flow of the exhaust is always spinning the exhaust turbine which is shaft connected to the compressor wheel. Boost is only generated under load, this is best observed with a combination vacuum boost gauge. Not sure why our display options on the instrument panel don't have this option, my wife's 2.0 EB Edge does. Generally speaking boost is obtained in any acceleration, though one can finagle the pedal to 0Hg and accelerate without generating boost, but its very difficult to actually do.

A waste-gate regulates pressure on the exhaust housing side, a blow off valve (BOV) regulates pressure on the intake or compressor side of the turbo housing. I understand from conversation our EB's have a BOV. The purpose of either is to regulate the contribution of the turbo to the power of the engine by regulating what drives the turbo or the boost produced. Both accomplish the same goal by a different means.

Yes the faster a turbo spins the more boost it creates to a point. There is a point of diminishing returns as anytime you compress air the by-product is heat. Hotter air is less dense the colder air, thus hotter air will product less power. The compressed air from the turbo is cooled to provide a more dense air charge via the intercooler, or the charge air cooler as its called. Thus attempting to produce 20 lbs of boost from our small turbo's would be inefficient. As this amount of boost exceeds our turbo's efficiency range. Typically small turbos are good for producing boost as they spin up quick in lower RPM applications, larger turbos take time to spin up because they expect more air volume and are heaver, thus are more efficient in higher boost applications.
 
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