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

9K views 51 replies 30 participants last post by  unkillsam 
#1 ·
From

Engineering Explained
27 May 2020

 
#2 ·
Video should say GM truck engine that's tuned to run on premium gas (and is good enough to be better then the actual Caddy 4 engine).
 
#3 ·
That's pretty cool, I love videos like this that can explain the working in laymen's terms. I'm a layman and I like the terms! Very nice engine in the CT4, I drove it in the premium luxury and walked away impressed!

Has anyone seen any real world Silverado mpg's V8 vs. this 2.7T? Curious if reality gives the turbo better mpg's.
 
#4 ·
Has anyone seen any real world Silverado mpg's V8 vs. this 2.7T? Curious if reality gives the turbo better mpg's.
Car and Driver did a real world fuel economy test for 2019 Silverado 1500 RST 2.7T 4WD Double Cab. Here's what they found:

"The undersquare engine, as you’d expect, is a grunter. Its 348 pound-feet of torque persists between 1500 and 4000 rpm, enough latitude to accommodate all normal driving. The 310-hp peak comes at 5600 rpm, only 100 rpm before redline, but you’ll never need it. Chevy pairs the mill exclusively with its eight-speed auto, and it’s a predictive ’box, giving you immediate torque on demand. The EPA rates this version of the Silverado at 20 mpg combined, but we achieved only 16 in daily use, the same fuel economy we measured from an all-wheel-drive 5.3-liter V-8-powered Silverado crew cab. On our 200-mile highway loop, the four-cylinder made liberal use of its turbocharger and yielded 18 mpg, 3 mpg less than that same Silverado [V8].
 
#34 ·
I remember long ago CD or MT or someone did a comparo of an Olds something, maybe F-85, Big Mill Loafing vs. Small Mill Grunting. I forget how it turned out, but I believe they preferred the V8.
 
#9 ·
Ford sells a V8 F-150 so how does that make any sense? Very confused why you brought up Ford here.

But, to their credit, Ford has proven the real world durability and performance of turbo engines in trucks. Only in the 3.5 Ecoboost case, the turbos don't have to produce a ton of boost on the highway and therefore kill MPG.
 
#15 ·
I think almost 100% of the difference is that it's tuned to run on 91 octane vs 87 octane.

Just for comparison, the Ford 2.7TT V6 makes 325/400 on premium. GM did a fantastic job with this engine considering it's down 2 cylinders and a turbo, and makes slightly more horsepower and slightly less torque then the Ford.
 
#12 ·
You gain fuel economy from a small turbo engine with the smaller displacement, the turbocharger adds the torque back however you only get better fuel economy when the engine stays out of boost. These engines are designed to run rich in order to protect the engine from detonation, really this only works as long as the vehicle isn't too heavy for a given displacement (much like GMs DOD). At 2.7L without spooling up the turbo it has to be able to propel the heavy vehicle with a large frontal area with acceleration forces that people are us to with V-6 and V-8 truck engines. This means that you will have to get into the turbo in order to pull this off.

For this reason even for Ford and comparing the EB V-6 engines and the 5.0 coyote the V-8 often test better when it comes to fuel economy in the real world. In other words in these trucks you have to be light footed in order to benefit from the fuel economy benefits of the small displacement turbo motors. However with the EB engine the equation is different as they not only have a 2.7L turbo V-6 engine but also a 3.5L version that packs on the torque and horsepower. In the smaller and lighter Cadillac CT4 the equation is going to be different due to the lower weight and smaller frontal area, to be honest this tactic seems like a dead end however as long as fuel economy test loops favor this tactic then automakers will take it.
 
#14 · (Edited)
Barely a third of F150s sold these days are 5.0 V8s which is kind of sad as it gets better mileage when towing than the EBs.
Interesting that GM sells more 1500 trucks than Ford but it's refreshing to know that the 5.3 V8 is around 70% of those sales.
Clearly buyers like different things for different reasons and no one is right or wrong as long as you get the truck you want.
Which is leading me back to say that the 2.7T is a great engine and probably a good fit in the relatively light CT4.
 
#23 ·
Interesting that GM sells more 1500 trucks than Ford but it's refreshing to know that the 5.3 V8 is around 70% of those sales.
Clearly buyers like different things for different reasons and no one is right or wrong as long as you get the truck you want.
Silverado 1500 customers certainly love V8 engines. Based on dealership inventory at cars.com, the proportions are as follows:

  • 77% V8 gasoline (5.3L, 6.2L)
  • 9% V6 gasoline (4.3L)
  • 9% I6 diesel (3.0L turbo)
  • 5% I4 gasoline (2.7L turbo)
 
#16 ·
The only way a four-cylinder ICE gets better fuel economy than an eight-cylinder ICE with a bigger displacement is because the throttle has to be opened farther in the four-cylinder (ignoring the weight difference) thereby lessening the pumping losses. They still have to do the same amount of work (assuming an identically driven route).

I suspect the Car & Driver people drove a route in such a way that the V8/transmission combo was in a better efficiency regime than the I4/trans combo and may have not have controlled the various acceleration, speed, and time variables to get results that were truly comparable. Turbo or not, the I4 should do better due to the higher throttle openings alone.
 
#21 ·
Caddy should do a better job of educating its dealers. I have seen several times advertising saying the CT4-V has a twin turbo. That error doesn't mean anything to the average buyer, but wait until some greedy lawyers decide to try a class action suit.
 
#31 ·
I think y'all are missing the point on this engine. The relevant comparison is with the 3.6 L V6. The 4 cyl has only 1 exhaust manifold, only 2 cams, a much smaller timing chain, only 16 vlaves. I don't know about the cam phasers, but it must be at least 2 fewer. I am just guessing, but I think the plan is to get rid of the 3.6L V6.
 
#35 · (Edited)
Ease of performance is what so many buyers used to love about Detroit’s vehicles, an era when you just touched the throttle and things just happened smoothly.

While the big blocks were generally silky smooth, the small blocks were there with better gas mileage, something that wasn’t an issue in the low cost fuel era.
 
#38 ·
Next: Up the ante to an inline five, 3.5 litters (sic) or so.
 
#41 ·
and i somewhat disagree on the no replacement for displacement mantra. the 2.7 TT ford has more torque at 2500 rpms then the 5.3L has total. 400 vs 383. the 2.7TT has 400 from 2500-5500 rpms. my truck goes up the mountain on i26 into nc in 9 th gear our tahoe downshifts 2 at a minimum. the 5.3L needs revs the 2.7 just torques it up the mountain at low rpms.
 
#42 ·
After driving my 2018 ATS 2.0 for two years, I have to say not really impressed with turbo engines. Under right circumstances it can pull off very good fuel economy....which is then more than negated by the higher fuel cost. Power delivery is also an issue. You are constantly dealing with an all or nothing engine, one minute you have no power 4 cyl engine and then boost kicks in and here come the power. Every V6 engine i had prior to this engine was more enjoyable to drive.
 
#43 ·
True. My CTS 2.0T has plenty of grunt down low but there is some turbo lag and it just dies at highway speed especially over 80 IMO. I way prefer the 3.6 V6 in my new Camaro. Spins up rapidly, is way more linear, and just keeps pulling to the redline. Sounds a lot better too. The V6 is a more sporting engine, but the 2.0T is more than fine for most drivers. Now I don't know about the newer 2.0T since they chopped it's nuts off. Funny thing is they kept the higher power version in the Camaro but not in the Cadillac sport sedans which is ridiculous.
 
#44 ·
Four bangers lack the refined NVH necessary for a sport-luxury sedan or coupe.

Try test driving back to back a Cadillac 2.7T I4 and a BMW 3.0T I6 and there is just no comparison. The BMW is turbine smooth while the Cadillac feels like it's powered by a tractor engine. I have no idea why anyone would buy a Cadillac four banger for the same price as a BMW I6 unless they work for GM or have family members who do.

FFS, I can option out a CT4-V for well over $50K yet it has less powertrain refinement than Toyota econoboxes. What really sickens me is that GM has smoother engines they could have used, like a 3.0TT V6 or a smaller V8. They simply lack the will to make a competitive sport luxury sedan/coupe.
 
#46 ·
FFS, I can option out a CT4-V for well over $50K yet it has less powertrain refinement than Toyota econoboxes. What really sickens me is that GM has smoother engines they could have used, like a 3.0TT V6 or a smaller V8. They simply lack the will to make a competitive sport luxury sedan/coupe.
CT5-V includes GM's LGY 3.0L twin turbo V6, for a starting price under $50k.
 
#49 ·
Autoblog posted its review of CT4-V yesterday. Their only major complaint was that the 2.7L engine is somewhat unrefined in low load situations. Otherwise, they consider the car a "winner".

2020 Cadillac CT4-V First Drive: The Cadillac of compact Cadillacs - This may not be the V of old, but it’s still a winner

Autoblog said:
"The CT4-V feels very complete. But it’s not perfect. The 2.7-liter four-cylinder is fundamentally very similar to the engine under the hood of the new Chevrolet Silverado and GMC Sierra pickup trucks. As Caddy’s engineers tell it, the trucks are the true beneficiaries of this arrangement, as the rather large four-pot was destined for the CT4 all along. Cadillac went to great lengths to make sure it was refined enough for duty in a luxury sedan and while the result is mostly good, mostly good is slightly bad.

While the dual-volute turbocharger and large displacement deliver torque for days, the 2.7-liter feels a bit awkward when accelerating slowly from a stop. This is probably at least somewhat down to the gearing of the CT4-V’s 10-speed automatic. In Touring mode especially, the engine seems to generate a disproportionate amount of noise for the power it’s putting out at lower throttle openings. It sounds overworked, which is the exact opposite of what you’d expect from an engine being asked merely for mild acceleration, making it all the more noticeable.

Considering what Cadillac set out to achieve with the CT4 — and the V model specifically — the fact that this is the worst thing we can say about it speaks volumes for GM’s effort. At it’s $45,490 base price (including $995 for destination), it takes the fight directly to its competitors, and in many ways that matter to enthusiasts, it’s the better buy.

So many of Cadillac’s recent products have prompted us to say things like, “It’s pretty good, but…” The CT4-V needs no such qualifier. To put it succinctly, they nailed it."
 
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