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Under what conditions does the 1.4L engine initiate and use turbocharger boost?

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Hello fellow Cruze owners

Under what conditions does the 1.4L engine initiate and use turbocharger boost? In a properly functioning engine, when is boost mode activated?

Thanks in advance.

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It's a tiny engine, so most of the time you're accelerating, you're in boost.
 

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Hello fellow Cruze owners

Under what conditions does the 1.4L engine initiate and use turbocharger boost? In a properly functioning engine, when is boost mode activated?

Thanks in advance.

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I had a boost gauge installed in my Cruze. You’re under about 3 - 5 psi of boost under normal acceleration. At WOT, it’ll get up to 15 psi.


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Basically any time you're accelerating at 1500 RPM and above.

Cruising down the highway at very light throttle applications, you're mostly relying on the engine's own tiny displacement, which is where the fuel efficiency gained by having such a small engine comes into play.
 

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Discussion Starter · #6 · (Edited)
Further to my earlier question, the waste-gate actuator is operated by inlet air pressure I think. The pic of my Honeywell Turbo after unboxing shows the actuator. The spring holding the actuator rod inward and thus waste-gate closed is pretty stiff, so there would have to be some pressure above which the actuator diaphragm pushes to rod outwards and opens the waste-gate to stop boosting at high (I guess near red-line) RPM, so I reason (probably incorrectly). At what RPM with WOT does that happen, if it happens at all?

(Note: I saw a video the other day where an engineer guy was saying that in a turbo equipped vehicle one should not put the hammer down and go wide open throttle until after the engine is at warm operating temperature. In a G1 LT with a 217° thermostat, that would be 217°F. )
https://www.cruzetalk.com/forum/mem...ell-turbocharger-picture266687-0909181207.jpg
 

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Further to my earlier question, the waste-gate actuator is operated by inlet air pressure I think. The pic of my Honeywell Turbo after unboxing shows the actuator. The spring holding the actuator rod inward and thus waste-gate closed is pretty stiff, so there would have to be some pressure above which the actuator diaphragm pushes to rod outwards and opens the waste-gate to stop boosting at high (I guess near red-line) RPM, so I reason (probably incorrectly). At what RPM with WOT does that happen, if it happens at all?

(Note: I saw a video the other day where an engineer guy was saying the one should not put the hammer down and go wide open throttle until after the engine is at warm operating temperature. In a G1 LT with a 217° thermostat, that would be 217°F. )
The wastegate/boost is controlled (through vacuum hoses) via a solenoid under the intake manifold. Boost pressure goes down as RPMs rise, but it doesn't stop producing it as you approach redline.

A closed throttle or knock/misfire event will send a signal to the solenoid to open the wastegate fully.
 
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