Cadillac’s Giant 4-Cylinder Engine Has A New Dual Volute Turbo

[Bruce Nunnally]

 

How Dual Volute Turbos Work In Chevy's Massive Four-Cylinder Engine (and in the Cadillac CT4-V)

[BodybyFisher]

Very interesting design, I am confused as to why the highway gas mileage is less than a 5.7L though in the Silverado.  I suppose however its due to the Silverado's weight vs a 4 cylinder that has to work harder.  

[Bruce Nunnally]

I added this comment to the video: For 2020 Chevrolet shows the 5.3L/8speed/2WD at 17/23 mpg (vs 5.3L/10speed/4wd 16/22), and the 2.7L T/8spd/2WD at 20/23 mpg. So the 2.7L is 17% better in city, same highway in the same configuration. An interesting factor on the 2.7L is the low-rpm torque, and what potential it has for tuning.

I don't have comparative hp/torque charts for each of those engines, but I suspect the 2.7L drives better

5.3L: hp 355 / 265 @ 5600 (SAE certified) Torque 383 / 519 @ 4100 (SAE certified)

2.7L: hp 310 / 231 @ 5600 (SAE certified) torque 348 / 473 @ 1500-4000 (SAE certified)

So the 5.3L makes more peak power, but the 2.7L probably feels more 'torquey' off the line.

On the other hand, if they had put the 5.3L in the CT4-V people would be singing praises as a small sedan with a V8.

Reference: https://media.chevrolet.com/media/us/en/chevrolet/vehicles/silverado/2020.tab1.html

[cdgrinci]

I'm guessing hwy mileage suffers in the Silverado because of the lack of aerodynamics as speed increases.  Turbos can be efficient but only when they aren't called on (too much) for that extra needed power (kind of like a four barrel carburetor of old; efficient when power isn't needed but the extra power is available when the back two barrels kick in; my analogy to the turbo is the boost not used unless needed).  At hwy speeds, I'm guessing that the 2.7 turbo is relying on boost to run at speed.  The CT4 cuts a much better air path so it works much better at hwy.  Well, that's my take on those numbers anyway.

[Bruce Nunnally]

Perhaps at highway speed both multi-displacement engines are operating on two cylinders, the 5.3L on two 0.6625L cylinders, the 2.7L on two 0.675L cylinders, and so are pretty similar in fuel consumption.