GM's 2.7L - Deep Dive

[4WD]

Can it alternate the cylinders that get shut down? such a design would help distribute wear evenly. As a guy who makes “design choices” in my realm, I’d be all over that. And if so, 2 cylinder mode probably wouldn’t bother me too much, unless it started to voice the signature of a riding mower. if it did that, in a sedan I might still be ok with the idea psychologically. But like many here, the thought of my truck running on 2 cylinders might not be something I could handle.

I don’t like it either - but this and S/S are signs they are running out of choices because
A. EV will not be ready or won’t work out as advertised
B. Some will not buy EV until there is no other choice
Right now the consumer wants more power on less fuel - but the OEM is already spending millions on EV

 

[MParr]

I don’t like it either - but this and S/S are signs they are running out of choices because
A. EV will not be ready or won’t work out as advertised
B. Some will not buy EV until there is no other choice
Right now the consumer wants more power on less fuel - but the OEM is already spending millions on EV

The better solution would have been a hybrid system, without cylinder deactivation.

 

[supton]

The better solution would have been a hybrid system, without cylinder deactivation.

I dunno—in a lightly used truck, yes. In a truck used as, well, a truck, not so much. Each time you do an energy conversion, some portion gets lost. And an electric motor that can source 300hp (or whatever) isn’t going to be small or light. And the energy getting dumped into the battery on a long downhill… probably can’t be done for long, not to make up for the energy spent grinding up the hill.

It WOULD BE an interesting thing to see, something like Toyota’s hybrid setup, but in a truck application. I’m going off pure guesses here, that, when used as a truck, the mpg would match what a regular ICE setup do, maybe even slightly worse if anything. The proof is in the pudding, maybe I’m wrong, but I think a hybrid approach under continous load is going to do worse. And that then the truck community would roundly condemn it, just as it has done for the Ridgeline. [Has it done so for this 2.7? No “real” truck is allowed to have an I4, just like all “real trucks” have a ladder frame? IIRC the 3.5L ecoboost had to wait a long time before it got accepted, not sure what the consensus is on this 2.7 is just yet.]

Maybe I’m wrong here. Am waiting to see how the Maverick pans out over time, although that is a lighter duty truck.

 

[4WD]

I dunno—in a lightly used truck, yes. In a truck used as, well, a truck, not so much. Each time you do an energy conversion, some portion gets lost. And an electric motor that can source 300hp (or whatever) isn’t going to be small or light. And the energy getting dumped into the battery on a long downhill… probably can’t be done for long, not to make up for the energy spent grinding up the hill.

It WOULD BE an interesting thing to see, something like Toyota’s hybrid setup, but in a truck application. I’m going off pure guesses here, that, when used as a truck, the mpg would match what a regular ICE setup do, maybe even slightly worse if anything. The proof is in the pudding, maybe I’m wrong, but I think a hybrid approach under continous load is going to do worse. And that then the truck community would roundly condemn it, just as it has done for the Ridgeline. [Has it done so for this 2.7? No “real” truck is allowed to have an I4, just like all “real trucks” have a ladder frame? IIRC the 3.5L ecoboost had to wait a long time before it got accepted, not sure what the consensus is on this 2.7 is just yet.]

Maybe I’m wrong here. Am waiting to see how the Maverick pans out over time, although that is a lighter duty truck.

Hybrid in light duty FWD is one thing … but in HD RD or 4WD it’s a formidable challenge

 

[JTK]

Can it alternate the cylinders that get shut down? such a design would help distribute wear evenly. As a guy who makes “design choices” in my realm, I’d be all over that. And if so, 2 cylinder mode probably wouldn’t bother me too much, unless it started to voice the signature of a riding mower. if it did that, in a sedan I might still be ok with the idea psychologically. But like many here, the thought of my truck running on 2 cylinders might not be something I could handle.

It must be pretty well balanced in terms NVH in 2-cyl mode given the relative simplicity of the exhaust system on 2.7T powered trucks. I guess that's another plus for the drivetrain. Simple cat-back system.

 

[hemioiler]

Can it alternate the cylinders that get shut down? such a design would help distribute wear evenly. As a guy who makes “design choices” in my realm, I’d be all over that. And if so, 2 cylinder mode probably wouldn’t bother me too much, unless it started to voice the signature of a riding mower. if it did that, in a sedan I might still be ok with the idea psychologically. But like many here, the thought of my truck running on 2 cylinders might not be something I could handle.

The 2.7 does not alternate, neither does the old GM AFM system or the Ram MDS. The new GM DFM does turn off between 1 to 7 cylinders and it does so as needed, it's constantly adjusting which cylinders are running. It's all seemless to the driver for the most though they have pretty bad failures in this system right now.

 

[hemioiler]

The better solution would have been a hybrid system, without cylinder deactivation.

I'm not a fan of hybrids. Ram did it right, I don't worry about the implementation because they still give you the ability to turn it off. My truck has run its entire life so far as an old school push rod v8, just how I like it.

 

[nthach]

I dunno—in a lightly used truck, yes. In a truck used as, well, a truck, not so much. Each time you do an energy conversion, some portion gets lost. And an electric motor that can source 300hp (or whatever) isn’t going to be small or light. And the energy getting dumped into the battery on a long downhill… probably can’t be done for long, not to make up for the energy spent grinding up the hill.

It WOULD BE an interesting thing to see, something like Toyota’s hybrid setup, but in a truck application. I’m going off pure guesses here, that, when used as a truck, the mpg would match what a regular ICE setup do, maybe even slightly worse if anything. The proof is in the pudding, maybe I’m wrong, but I think a hybrid approach under continous load is going to do worse. And that then the truck community would roundly condemn it, just as it has done for the Ridgeline. [Has it done so for this 2.7? No “real” truck is allowed to have an I4, just like all “real trucks” have a ladder frame? IIRC the 3.5L ecoboost had to wait a long time before it got accepted, not sure what the consensus is on this 2.7 is just yet.]

Maybe I’m wrong here. Am waiting to see how the Maverick pans out over time, although that is a lighter duty truck.

Toyota didn’t want to use their two-motor system in the Tundra for some reason. But it works fine in the Lexus GS450h/LS600hL. But then again, when was the last time you saw someone drive a Lexus for reasons beyond going to the local Costco or soccer practice?

Ford did a clever thing with the F-150 Powerboost with the on-board 120V system. Toyota didn’t do that with the Tundra iForce Max. But on-grid charging is missing from the Ford, else they would have been able to market it as a plug-in hybrid and take advantage of tax credits and other incentives.

 

[Cujet]

That 4 cylinder makes 8 cylinder power at lower RPMs than the 8.

Maybe so, but the 0-60 and 1/4 mile numbers don't lie. The 4 cylinder truck is slower than nearly all other options. Slower in fact than all of the V8's and V6's, (save one) when compared by model and configuration. With 0-60 between 7.3 and 9 seconds, and trap speeds between 80 and 89MPH. Ford's smallest turbo engine, also 2.7L, is more than a second faster to 60.

I clearly understand that those numbers are OK by past standards. But today, you'd have to look long and hard to find a slower new vehicle.

Add in the fact that the 5.3V8 often returns better overall fuel economy, and I'm not at all sure GM got this right.

 

[hemioiler]

Maybe so, but the 0-60 and 1/4 mile numbers don't lie. The 4 cylinder truck is slower than nearly all other options. Slower in fact than all of the V8's and V6's, (save one) when compared by model and configuration. With 0-60 between 7.3 and 9 seconds, and trap speeds between 80 and 89MPH. Ford's smallest turbo engine, also 2.7L, is more than a second faster to 60.

I clearly understand that those numbers are OK by past standards. But today, you'd have to look long and hard to find a slower new vehicle.

Add in the fact that the 5.3V8 often returns better overall fuel economy, and I'm not at all sure GM got this right.

That's more than likely the old 2.7 at 348 lb/ft of torque. The upgraded 2.7 has about 430 lb/ft now and basically there is no reason/need to get the v8.

0-60 doesn't tell the story. It's one number. What matters most to people not drag racing their heavy truck, is torque under the curve. And the 2.7 is stronger than the 5.3 in daily driving and towing, climbing a hill, keeping up with city traffic etc, its stronger everywhere than the 5.3 except perhaps WOT where the extra HP from the 5.3 finally has a very slim advantage.

You also can't compare the 2.7 from GM vs Ford directly like that. They're completely different trucks, and the Ford weighs less for a start as its basically an aluminum tin can. It's better to compare engines in the same truck to get a true feel for whether it's capable or lacking etc.

And finally lets also keep in mind that the 2.7 wasn't actually intended (at first anyway) by GM to replace the v8. It was intended to replace the 4.3 v6 which it absolutely destroys in every metric. The fact that we're even discussing it against v8s shows how strong an offering it really is.

 

[Cujet]

The upgraded 2.7 has about 430 lb/ft now and basically there is no reason/need to get the v8.

You also can't compare the 2.7 from GM vs Ford directly like that. They're completely different trucks, and the Ford weighs less for a start as its basically an aluminum tin can.

Good to know that it makes more torque now, nice! Even so, it is slower and it does not seem to meet the V8's real world fuel economy numbers. So maybe the V8 is worth considering.

I absolutely love turbocharged engines, and find the mid range torque very pleasing.

C+D: "The thriftiest 5.3-liter V-8, all-wheel-drive powertrain is rated up to 16 mpg in the city and 22 mpg on the highway; our real-world testing revealed that it was actually more efficient than the Silverado's smallest engine, the turbocharged four-cylinder: in our testing the V-8 achieved 21 mpg whereas the turbo-four returned 18 mpg"

 

[MParr]

“You also can't compare the 2.7 from GM vs Ford directly like that. They're completely different trucks, and the Ford weighs less for a start as its basically an aluminum tin can. It's better to compare engines in the same truck to get a true feel for whether it's capable or lacking etc.”

That’s alright. I’m happy with my “aluminum tin can”. Plus, I like the 2 extra cylinders and it doesn’t drop half of them. I’m averaging 24 mpg on winter blend fuel and 26 mpg on summer blend fuel.

 

[MNgopher]

To me, while an impressive mill, that's where it falls short - it doesn't even get real fuel mileage the same or better than the V8. Ford did manage to accomplish that with the 2.7 Ecoboost.

And as another data point, the weight difference between an F150 and a Silverado is less than you might expect.

 

[hemioiler]

Good to know that it makes more torque now. Even so, it is slower and it does not seem to meet the V8's real world fuel economy numbers. So maybe the V8 is still a smart choice.

C+D: "The thriftiest 5.3-liter V-8, all-wheel-drive powertrain is rated up to 16 mpg in the city and 22 mpg on the highway; our real-world testing revealed that it was actually more efficient than the Silverado's smallest engine, the turbocharged four-cylinder: in our testing the V-8 achieved 21 mpg whereas the turbo-four returned 18 mpg"

Car and Driver's test seems to be an anomaly. Many other tests have the 2.7 out in front. TFL Truck got like 6 mpg higher than C/D test at 24 mpg highway. Fuelly.com stats show it out in front as well, 18 - 21 avg for the 2.7 vs 15 - 18 for the 5.3.

 

[hemioiler]

To me, while an impressive mill, that's where it falls short - it doesn't even get real fuel mileage the same or better than the V8. Ford did manage to accomplish that with the 2.7 Ecoboost.

And as another data point, the weight difference between an F150 and a Silverado is less than you might expect.

Let's not focus on the weight; the point is they're different trucks, different weight but also different aero profile, different transmissions (8 gears vs 10), different rear gear ratios, even tires matter and can make up to a 1mpg difference. So the best way to test the 2.7 is to compare it directly to other GM engines in otherwise identical trucks so that the only difference is the engine.

 

[hemioiler]

“You also can't compare the 2.7 from GM vs Ford directly like that. They're completely different trucks, and the Ford weighs less for a start as its basically an aluminum tin can. It's better to compare engines in the same truck to get a true feel for whether it's capable or lacking etc.”

That’s alright. I’m happy with my “aluminum tin can”. Plus, I like the 2 extra cylinders and it doesn’t drop half of them. I’m averaging 24 mpg on winter blend fuel and 26 mpg on summer blend fuel.

I wasn't trying to dump on the Ford, never owned one but I'm sure they have their strengths and weaknesses just like the other trucks.

I've gotten 28 mpg in my 5.7 hemi in the summer according to the computer. Probably a little optimistic, but I have absolutely no trouble hitting 24 on a regular basis when it's all highway. I like the extra 2 (4 vs the 2.7 GM) cylinders too and MDS is disabled. Most of highway MPG is how you drive.

 

[MNgopher]

Let's not focus on the weight; the point is they're different trucks, different weight but also different aero profile, different transmissions (8 gears vs 10), different rear gear ratios, even tires matter and can make up to a 1mpg difference. So the best way to test the 2.7 is to compare it directly to other GM engines in otherwise identical trucks so that the only difference is the engine.

You are the one who brought up the weight and claimed the Ford's weighed significantly less. All I pointed out was that is not correct. The comparable GM is generally within 100-200 lbs.

 

[hemioiler]

You are the one who brought up the weight and claimed the Ford's weighed significantly less. All I pointed out was that is not correct. The comparable GM is generally within 100-200 lbs.

I did bring up the weight, but only as an example of how the trucks differ, that's what "for a start" meant.

 

[MNgopher]

Except they don't differ...

Not a good place "for a start".

 

[dnewton3]

...

Ford apparently has the water pump buried inside the engine.

That is only true for the Cyclone series 3.5L/3.7L in transverse applications (Taurus, Flex, Explorer; all shared the same platform design and drivetrains).

The Cyclone 3.3L engine in the F150 is the same basic design, but it has an external water pump because it's a longitudinal design.

The EB and Coyote motors never had internal water pumps.