2019 Silverado Fuel Economy: 2.7L Turbo Engine Returns 21 MPG Combined
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The EPA has finally dished out official fuel economy figures for perhaps the most anticipated 2019 Chevrolet Silverado engine. The 2019 Silverado with the new 2.7-liter L3B turbocharged four-cylinder engine will return 21 mpg combined (20 city, 23 highway).
We’ll address the elephant in the room right away: the Ford F-150 and Ram 1500 both outdo the 2019 Silverado with their EPA fuel economy ratings. When looking at each truck’s volume engine—the 2.7-liter turbo-four replaces the Silverado’s former 4.3-liter V6 volume engine—the Silverado falls shorts. Ford’s 3.3-liter V6 engine will return 22 mpg combined, as will Ram’s 3.6-liter V6 with a standard e-Torque mild-hybrid system. And both of the trucks will return 25 mpg on the highway, too.
The fuel economy ratings do not include figures for 4×4 models, which will drop compared to the 20/21/23 mpg figures for two-wheel drive pickups. And for further comparison, the figures aren’t far off from 5.3-liter V8-powered 2019 Silverado models. A two-wheel-drive Silverado with the 5.3-liter V8 will return 17/18/23 mpg with its Dynamic Fuel Management technology.
However, the fuel economy figure for the turbo-four engine is also a milestone in one way as it pushes the truck’s combined fuel economy figure over 20 mpg.
The 2.7-liter turbo-four engine will be standard on volume Silverado models: the LT and RST trims. Pricing for the LT starts at $38,395, while RST models command $40,295. Buyers will have to fork over another $2,400 for a short bed/crew cab truck, which is the most popular configuration. The new four-cylinder engine will also tow 7,200 pounds and haul up to 2,280 pounds. The latter is up to 600 pounds greater than the Ford or Ram, but the Silverado will tow 200 pounds fewer.
Why didn’t the fuel economy figures move more dramatically? Drag coefficient of an area. While the 2019 Silverado boasts a drag coefficient that is 7 percent improved over the old truck, its surface area has increased. The truck’s face has increased, which means the pickup has to cut a larger hole through the air, and that requires more energy to move the Silverado and cut through a greater resistance.
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Sooooooo the stigma of a 4 cyl engine without the fuel economy. In a pickup truck.
This would be better in the Camaro, replacing the base 2.0T
Not much progress. You could realistically get almost that mileage with a 1999 Silverado and a V8. That was two decades ago and gas was a buck a gallon.
I guess my question is “why bother”? Why did they invest in this engine? Could they not have just put a turbo on the 4.3 V6 and the 8 or 10 speed transmission behind it and achieve the same or more?
That’ll keep the v8’s alive and well. I was hesitantly optimistic….and over 20 mpg is an accomplishment…but I guess I was expecting more.
1 MPG difference between the 2.7T and DFM 5.3 is the greatest disappointment.
It’s just not quite enough engine for the big crew cab Silverado.
The 2.7L is more appropriate for regular cab, two wheel drive Silverado work truck or as the uplevel gas engine in the smaller Colorado or future mid sized/compact truck-based SUV.
It’s a alternative for the 4.3L V6. Nothing more.
They keep bring up surface area when they give those not so great fuel readings. Is the surface area on the competition that much or any different? Seems to me they spent a lot of time, money and effort investing in new engines and technology for not much payoff. There is an old saying if you can’t beat them join them. They didn’t beat the competition so they should have just joined them with a small turbo V6. They already have small displacement V6 so it would have saved them a lot of money and maybe made them the leaders in the MPG race.
Don’t believe it one bit. Gm has always sucked at the spa test and proven good real milage just as Ford build their trucks for the spa test and sucks at real mileage. Motor trend got a z71 high country to get 24.7mpg highway. And they test them at 80mph and drive them like a rental! I bet you this thing returns 27mph real life cruising at 75mph.
The EPA changed their test procedures in 2016. Ever since then, the EPA estimates for GM and Ram trucks seem to be heavily underrated and Ford’s trucks overrated. Clearly Ford has found a way to take advantage of the the new test standards or they had a hand in influencing the new procedure. I don’t buy the idea that the small weight advantage of the total aluminum body is doing it. Both Ram and GM have 8-speed transmissions that are extremely similar in gear ratio spread to Ford’s 10-speed. Ram and GM cut hundreds of pounds from their trucks for 2019, improved their aero drag, added start/stop systems, etc, yet both trucks saw little or no improvement in fuel economy. Owners of both Ram and GM trucks report that their trucks easily beat the EPA estimates by 1-3 MPG.
if gm could prove that there trucks typically beat EPA numbers and Ford typically falls short could they not sue the EPA? The EPA numbers mean a lot to consumers
Sure hope so.
SMH! One disappointment after another with these trucks! What’s the point of this engine (which actually sounded promising with its respectable power figures) if the fuel economy is worse than the competition’s larger displacement engines? Should’ve simply given the 4.3 a 10-speed and call it a day!
The 8-speed has nearly the same gear ratio spread as the 10-speed. The lack of a 10-speed isn’t the reason for lower fuel economy ratings. There’s obviously something with the EPA testing procedures that Ford takes advantage of better than the rest. The 2019 Ram’s fuel economy is identical to a 2018 Ram despite losing over 200 lbs and having an even better drag coefficient. They have have an airdam on the front that drops down at highway speeds. The GM halftons lost up to 400 lbs and the aerodynamics were heavily improved. They even added DFM to drop down to just 2 cylinders yet the fuel economy is practically the same as the 2018 GM truck that weighed more, had a less sophisticated cylinder deactivation system, and came standard with the 6-speed.
The F-150 is rated 21 highway with the 3.5 Ecoboost V6 and 22 with the 2.7 V6 EB motor. And that is with 4X4. This all new engine in a lighter truck can only manage 21 with RWD and probably 19 or 20 with 4X4. I DONT BELIEVE IT! And the blocky F-150 also has a massive oversized front end that can’t possibly offer less “surface area” than this truck. I now take anything the EPA says about a GM as untruth and have outperformed every EPA highway and combined rating with my 2017 Impala, a rental 2017 Cruze and Malibu and various 2014-2018 Silverado owners with the 4.3 V6. Meanwhile Motor Trend just ran a review of the 2019 Ram with the base eTorque 3.6 engine and came up with considerably less MPG than the rating and stated it was barely any different than the Hemi V8.
I’ll agree with you about the gears; it depends on the mass of the vehicle. Two wheel drives with 17″ rims and standard duty trucks with double cabs; not very appointed probably get no help from two more gears; the monster versions that are heavy and with 20″ rims probably get some gain; but Ford is not taking more advantage on EPA tests. I’ve got a 2015 F150, 2WD, short-bed, XL trim. Estimate back then was 19/26/22. My lowest tank full in three years and 37,000 miles has been 21.7; my highest, 26.7; but most tanks fall between 23-25.5. I hand calculate and have even measured several times and account for the trip meter error. People want to claim that turbo charged gas engines do worse versus the estimate than NA engines, but I had a 1997 F150 small V8, super cab, 2WD with a rating of 15/20/17; and I could not do better than 15 unless I was on a long highway trip. I then owned a 1999 with the 4.2 V6 with a rating of 16/21/18; and it was the same thing. We’d leave the driveway; drive 13 miles at 60 mph and back with maybe one or two stops and light traffic and could not do better than the city rating, but nowadays, I run the same speeds, on the same routes in my Ecoboost F150 and get closer to highway than I get city; so that’s proof that those beliefs are not always true in every case; and it also proves that the 2.7L Ecoboost can in some circumstances and configurations meet or beat the EPA estimate.
I think the writer has it right. The extra size must be countering the improved drag, because GM is losing mpg with the same power train (5.3 with AFM and 6-speed in the “value class”; 16/23/19 before versus 15/22/17 now; MY 2018 versus MY 2019, respectively); and only barely adding or staying the same when adding tech that should improve mpg. The 6.2L gains in the city but loses on the highway, canceling each other out, and the only winner so far is the new 5.3L with DFM and 8-speed that actually gains one in the city, stays the same on the highway and for combined and now matches F150.
As for Ram, it seems as though they’re right where they were with truck efficiency from what we can tell so far. The 5.3L Hemi standard is exactly the same as before, which is third worst behind the two Tundra V8s; and the eTorque moves it up very close to F150 and Silverado V8s but falls just barely due to one less on the highway 17/22/19 versus 17/23/19 and 17/23/19, respectively. The 3.6 Penstar and 8-speed comes in at 20/25/22; versus the old power train without eTorque at 17/25/22, indicating that it must not slip any better or worse through the air than before.
But F150 has 20/26/22 for the max in the 2.7L Ecoboost; and although GM and the media is reporting that Ford’s base engine gets a max of 19/25/22, according to fueleconomy.gov, the flex fuel version of F150’s base engine comes in at 20/25/22.
GMs truck engines typically bet their EPA estimates. I highly doubt that this engine wont meet or even exceed what the competition gets in their base motors. And your literally talking about a 1 mpg difference in combined fuel economy. What a BIG difference!
What octane requirements for all engines?
OK, so a 17% improvement in around the town fuel economy doesn’t seem that stellar over the V8, but that does rival what Dads 2009 GMC Sierra dual mode hybrid achieved around town. I do admit I was expecting better than 23 highway for the I-4 turbo.
However, I wonder about real world results vs. competition. For example, my Dad currently drives an eco-boost F-150 and only manages 16 mpg when driving coast to coast in the fall. That falls far, far short of the low 20’s his window sticker predicted, and in his mid-70’s he is no lead foot. While his truck is pretty powerful, it get worse mileage than my Duramax dually crew cab.
Needless to say, I am nudging him to look at the new half ton Diesel…
This truck is disappointing in everything. The 4 years old F-Series looks techier.
Until you notice the wavy misaligned aluminum body panels, misaligned doors, flimsy extended cab doors, terrible paint, and the warped dash. 4 years later and Ford style hasn’t done anything about the dash warp issue or the glovebox warp issue.
The interior is something most reviewers DO NOT understand. GM gets poor reviews on interior quality, but they don’t look at all the factors. GM interiors may not be a plush, but they last far longer and don’t end up warping and looking bad a few years down the road. THAT is much better quality in my opinion. Especially for a truck.
Another swing and another miss on this generation of trucks from GM. Truly disappointing. GM said 10,000 people worked on this platform. (https://www.bizjournals.com/atlanta/news/2018/08/27/automotive-minute-2019-gmc-sierra-stands-strong.html) WTF did they do all this time to come up with something so utterly unremarkable? The chief engineer should get fired for this crap.
Unremarkable. It offers better powertrain options than Ram, a significantly tougher bed than Ford, the most useful and largest bed across the board, a totally redesign IFS that gives a better ride and crisper handling, they finally got rid of the 3.08 axles ratio and the “tallest” gearing now used is the equivalent of the 6-speed and 3.73’s, the steering wheel is finally centered, the headroom is finally improved, rear space in the crew cab was finally improved, etc. I find it hilarious that so many people are in awe of the 2019 Ram’s interior. Lots of glitter sprinkled on the interior but built with that famous bottom-of-the-barrel FCA build quality. The F-150 has an advantage in a street race but that doesn’t make up for the extremely weak bed design, terrible engine reliability, or the cheap interior plastics that warp just sitting in the sun on the dealer lot.
I think they should make hybrids back if they want to push fuel economy and power , On Colorado and Traverse … as they share the 3.6, a 3.6 replacement hybrid with 2.7 Ltr 4 cylinder and hybrid transmission would bring very different numbers.
The same company that owns the technology for GM’s DFM also owns the technology that Ram calls E-Torque. GM could easily roll out a 2.7T with an E-Torque style hybrid system.
Given that the EPA ratings between these base model offerings are so close. How about a little contrast.
310 hp @ 5,600 rpm and 348 lb-ft @ 1,500-4,000 – 2.7L 4cyl. turbo Silverado
290 hp @ 5,600 rpm and 265 lb-ft @ 4,000…………..3.3L Ti-VCT V6 F-150
305 hp @ (N/A) rpm and 269 lb-ft @ (N/A)……………3.6L V6 eTorque Ram
Silverado 2.7L 4cyl. turbo tripower valvetrain with continuously variable valve timing, variable valve lift and Active Fuel Management. Dual-volute turbocharger throttle response quick enough to provide 90% of peak torque in less than two seconds.
F-150 3.3L Ti-VCT V6 port fuel and direct-injection system (PFDI)
Ram 3.6L Pentastar V6
90% of torque is available from 1,800 to 6,350 rpm.
eTorque accessory belt is good for the life of the vehicle. eTorque motor/generator can’t be used to start the engine initially if the 12-volt battery or starter motor fails.
If I were to consider a base model full size truck with one of these engines (which I would not) I would take the 5 – 20 hp and 79 – 83 lb-ft over 1 – 2 mpg every day of the week.
When it comes to mpg while hauling a load or towing. The eTorque will help the Ram around town but not on the hi-way. Where the low rpm nature (long stroke) of the Silverado’s turbo 4cyl. will more then likely help in both city and hi-way conditions.
What about the ford? My guess, it’s a fleet sale truck for market share (price) with no fleet manager fear of turbos or e-assist to scare them away. In reality, while loaded down, it will get the worst mileage translating to higher operating costs.
Does the 3.3 Duratec use the same water pump setup as the FWD Duratec V6’s? The ones with the nightmare water pump that’s inside the V of the engine and driven by the timing chain. When they start to fail it’s difficult to tell until you find milkshake instead engine oil or the engine locks up or the car starts throwing codes because the timing chain has slack.
No, this one is external water pump. Only FWD Ford vehicles and mounted in transverse applications use internal water pump.
Looks to be a possible good match for the Colorado and Canyon.
Would like to see the zip when stepping on the gas. Hope it is impressive. That is what I am anxious to see. Will test drive it.
Seeing the highway mpg for the 2.7 turbo I now find the rumored 28 mpg highway for the Duramax much more believable. Never underestimate the affects that surface area has on mpg. I guess thats the trade off for having such a ridiculously oversized front end. And the weight decrease is nice, but the reality is it has very little effect on fuel mileage, especially on the highway. We saw this when Ford went to all aluminum on the F-150 and we’re seeing it again with the Silverado. Don’t believe me? load 500 pounds into the bed of your truck and watch your instant mpg as you’re going down the highway. I bet you won’t see much difference if any.
All the money spent for this update and you get similar mileage with less weight and more tech. How the new trucks could be styled to breaking the air with a snow plow front is beyond me! Would assume computer simulations would be available to decipher the impact Of a big a.. front end on gas mileage.
If I were top management or the board, an explanation would be required. Heads need to roll at all levels!
Does anyone know the fuel recommendations/requirements for the 2.7?
Aerodynamics explanation from an engineer. Lower airdam guides air to the left and right side, creating a lower vacuum that sucks air through the front grill, increasing cooling and meaning there is almost no air resistance against the “plow” and calling it a plow is not really accurate as a plow isn’t really full of holes. The edges are microballyy designed to eliminate all traps that would create high pressure. Finnally, if you think about physics, if I apply equal air pressure on the back of the truck as on the front, then the back air pressure will push the vehicle through the wind as much as the front pressure will slow it down. In practice this is an impossible scenerio, but the back mounted spoiler on the new Silverado aids to direct air on the tailgate to increase rear air efficiency.
87 octane.
There is an old saying, probably older than most of the people who frequent this website and it holds as true today as it did when it was first spoken into existence. The saying goes “There is no REPLACEMENT for DISPLACEMENT!” The greatest engine ever made was the Chevrolet 350ci small block. Chevy needs five V8 engines. a 5.4, a 5.7, a 6.4L a 7.0L and a 7.5L along with a good twin turbo 3.8 Inline-6 and a N/A 4.8L inline-6. For the trucks, the 4.8L, the 5.4L V8, 5.7L v8, 6.4L V8 and the 7.5L need to be the options for the 1500 series
Horsepower
3.8L twin turbo I-6 380hp/405tq
4.8L N/A I-6 325/350
5.0L DOHC supercharged V8 580hp Z/28
5.4L 395hp/385tq
5.7L 425hp/450tq
6.4L 495hp/485tq
7.0L 530hp/500tq (supercharged 730hp/710tq)
7.5L 600hp/580tq
The Camaro would benefit from this also with the 380hp/405tq 3.8L twin turbo I-6 under the hood of an AWD performance 1RS Camaro with Magnetic ride, Brembo brakes and a host of other things making this car the hottest of the entry-level muscle cars. slotting above that would be the 5.4L 2RS package with the 5.4L 395hp/385tq V8 with optional AWD. Next should be the SS Camaro lineup with the 1SS 5.7L 425hp/450tq V8 and the 2SS 495hp/485tq 6.4L V8 being the pinnacle of the SS lineup. The 1LE package would drop for the Z/28 which would re-enter the world properly with a supercharged 5.0L DOHC V8 engine producing 580hp and be a stripped down, street-legal track car. The top of the line cars would be the 530hp 7.0L ZL1 and the 730hp supercharged 7.0L ZL1 COPO. For those of you who didn’t realize what i just did I’ll make it plain.
67-69 Camaro came with a base 230ci inline-6 (3.8L I-6) while the RS Camaro came with a 327ci (5.4L) V8
67-69 Camaro SS came with either the 350ci (5.7L) v8 or the 396ci (6.4L) V8
67-69 Camaro Z/28 came with a 302ci (5.0L Trans Am prepped V8)
’69 Camaro ZL1 used a 427ci (7.0L) v8
As for the Silverado, the base 4.8L I-6 would come in at 325hp/350tq. Right above that would be the 5.7L V8 pushing out 425hp and 450tq which beats out the 5.0L V8 from ford and the 5.7L Hemi with modern technology and better fuel economy thanks to the 10-speed automatic. The 5.7L powered pickup would offer an Classic-10 package with the two tone color scheme, an RST-350 pkg and a Trail Boss-350 package along with the High Country Z71 package. Next in line would be the 6.4L pickup offering packages such as the RST-396, ZR2 off road and the Z71 High Country package. At the top of all of this, Chevy would offer the return of the 454-SS and the Cheyenne-427 ultimate high performance pickup trucks. Where the 454-SS would be a two seater rear wheel drive short bed pickup, the Cheyenne-427 would be true 2+2 high performance muscle truck with selectable 2 & 4 wheel drive, 10-speed auto, lowered suspension, cowl induction hood, hard bed cover with an integrated spoiler, 22″ wheels, huge BRembo brakes, magnetic ride, stripes and colors that hearken back to the Chevelle SS-427 and Chevelle SS-454.
At that point you have not only given your customers two vehicles that they love but you’ve got your economy numbers and everything else to boot. Drop Buick/Opel all together. Revise Pontiac under the GMC umbrella, move the Corvette to Cadillac. Rename the Cruze to Nova and make it a RWD chassis hatchback with AWD options and drop in the 3.8L twin turbo and the 4.8L inline six give us a RWD based sedan and call that the Malibu so we can get a new Chevelle SS 350, SS-427& SS-454 along with a 3.8L Twin turbo Malibu and a 4.8L base Malibu. Chevy also needs a true 2-door Tahoe 5.7L Z71 Blazer package along with the Tahoe RST, Tahoe High Country, and lastly a regular Tahoe with a 3.8L twin turbo inline. Move the Blazer over to the Colorado Chassis and give it a three door option and now you have a lineup of
Nova/ Camaro/ Malibu = VSS-R
Blazer/ Colorado/ Tahoe/ Suburban/ Silverado/ Silverado HD = VSS-T
This cuts down on major cost across the board for GM and allows for much better vehicles to be built. Doing this also allows for vehicles to be sold at less expensive prices which would bring a larger profit for Gm since more people would want to buy their vehicles. Then GM could really focus on Cadillac to compete with AMG/ M/ Audi S/ Lexus F, Lamborghini, Ferrari and the like. It would also allow for GMC/Buick to perfect a perfect lineup for the customers who want premium (practical luxury) but aren’t ready to step fully into all out full blow luxury along with still allowing for major injections of excitement into their lineup but in a slightly more mature package.
The 350 is not coming back. Nor is the 427 or 454… Those were genuine Chevrolet Motor Division engines and that division has been closed since the early 80’s. These new engines, V8’s included are not Chevrolet engines. They are GM corporate engines that happen to be used in Chevrolet’s along with everything else. And as great flowing as the V8 LS heads are, I wouldn’t expect to see large cubic inch engines ever again.
And I completely agree with you, the 350 was great. So were all of it’s bore/stroke small block variants. And the 18436572 firing order sounded fantastic. Far better than the Ford firing order we have now… I also agree there’s no replacement for displacement. Manufacturer’s just use forced air to accomplish that now. I’d love nothing more than to see a simple fuel injected 454 under the hood of a new Silverado. The thing would barely even work to move that truck right down the road and with 8-10 speed transmissions, I’d wager the fuel economy would be better than most. That said, those Chevy engine glory days are sadly over. However, the Corvette will always be a Chevrolet.
Just a heads up, GM still makes the 427 and 454 along with a 350ci V8, their COPO engines come in all of those sizes along with a 396. Just a few short years ago the almighty Z/28 and the Corvette had LS7 7.0L V8 engines (also known as the 427ci V8). It would take absolutely nothing for them to make a production version of any of those engines. It would also cut the cost of them down because GM would be mass producing them. just a thought
Well considering the old 5.3 with added DSF makes the same as an advanced 2.7 turbo, make the 7.0 DSF and tune it to 650hp. It will get better gas mileage as the 6.2 supercharged and would be lighter and more reliable with less parts.
And what’s the CAFE # at vbondjr motors?
If you want big displacement your going to need more cylinders or you will have a hard time getting them to run clean.
All that without ev’s or hybrids and you think you can leap those two hurtles the rest of the industry is loosing sleep over?
You know what’s funny about that? They said the same thing about diesel engines awhile back. I’m not talking about the little car diesel engines, I’m talking about V8 truck diesels and things like that. Now most of them run clean enough that they barely produce more than water vapor out their tailpipes and these are stock engines that run over 500lb-ft of torque. We get told this BS about smaller engine efficiency and all that other stuff but honestly larger naturally aspirated engines constantly run cleaner and more efficient than small engines. If a Corvette can get nearly mpg with 460hp and 376ci of high performance v8 under its hood i don’t want to hear about v8 engines being inefficient or these over stringent CAFE regulations. The thing about it is this. V8 engines are cheaper to build and much more reliable than a turbo 4 or 6 cylinder and way more efficient. The problem with that is with less things to break, you spend your money less on repairs. Dealerships make more money on people getting their car repaired than they’ll ever spend on the car. Turbocharged engines usually have things such as forged internals, blocks and internals are reinforced to handle more power in a smaller package (not efficient because it wears faster) you have to have more sensors to monitor fuel mapping under different atmospheric pressure, different adjustments and sensors for timing, specialize oiling systems, more cooling, more piping for cooling, intercoolers, different valving for releasing and recirculating pressure at different times, sensors to monitor boost etc. On a simple pushrod V8 engine, you don’t have all of that stuff and your internals are under less pressure (even under hard acceleration). Even with engines that have cylinder deactivation and intake runner valves and things like that. Those vehicles had their inherent issues at first because they were new and the technology wasn’t what it needed to be but now those things work (for the most part) seamlessly. Like the guy above commented to my first post, you put a 7.5L V8 in a truck with a 10-speed auto the engine would barely put out any effort to pull it. And Dodge is the king of putting big engines in cars and they’re coming out with a 7.0L (426ci for those of you who are old school like myself). Not to mention Dodge currently has a 392ci (6.4L V8) so it’s not an impossible or improbable thing for GM to do. (mind you dodge is very successful in selling insanity for the streets and GM builds more reliable engines (in my opinion) so what’s stopping GM from taking the current 376ci 6.2L and bumping it up a mere 20 cubic inches to 396ci? That same block they make the 5.3L 325ci V8 can easily be bumped up 2ci to a 327 or 50ci to a 350ci V8 or even the LS1 spec’d 346ci. It would be easy for GM to do this and be cafe compliant
The new 2.7L I4 turbo is more fuel-efficient than what you think it is. You just need to keep driving speed at 55 mph and below on highway, that’s all. 4-cylinder engine works terribly hard at higher speeds, so it may end up consume more fuel than a V6 or V8 in the first place. Plus, this new engine is now a DOHC valvetrain instead of OHV, so it no longer have this “direct-driven” instant-feel anymore (which does help MPG while lowering RPM) due to a longer-sized timing chain used now (it may use two timing chains, actually).
Actually, the only reason 4-cyl. engines worked harder then 6 or 8-cyl. engines in the past. They where useing a higher percentage of their power if not all of it to reach those higher speeds, which is inefficient!
A 4-cyl. That puts out 310 hp and 348 lb-ft regardless of how will be more efficient then a 6 or 8-cyl. that produces less.
The difference between N/A and forced induction is the throttle on a N/A engine controls vacume. The throttle on a forced induction engine controls boost pressure.
We all know what Happy feet are. Inefficient with boost!
As far as a longer cam chains increased drag, the increased number of valves, springs, bearings and their reciprocating mass are much greater then chain length it’s self.
“Inefficient with boost…”
Could it be the turbo that is using more fuel than naturally-aspirated?
Guess I should have said happy feet are careless, or wayward with boost.
The more air in, the more fuel in. Stab the throttle at speed on the highway with a boosted engine and you burn probably three times the fuel as a N/A engine with not much to show for it
Gentleman,
Generally speaking a smaller boosted engine should be able to make power more efficiently than a larger naturally aspirated motor. In the case of an I-4 vs. a V-8 twice it’s size, the I-4 has half the rotating pistons and rods, but that might be offset by higher camshaft and valve per cylinder count.
The challenge is the GM has done an excellent job wringing mileage and efficiency out it’s V8’s and has had years to refine them. Plus, it takes a given amount of power to haul a truck down the highway, independent of what is under the hood.
Highway load is actually pretty low until you get high enough in speed for aero to matter, say 65 or so, but it seems that the little Turbo 4 can’t make low number any better than the V-8 for whatever reason. But the turbo has nothing to do it.
Turbo has everything to do about it. Efficiency is all about minimizing heat and friction losses. Turbos have extra bearings, intercooler losses, Turbo scroll heat losses and additional expelled gas losses. The biggest advantage is less ring friction surface area under low throttle condition
Respectfully, a turbo does not have a significant impact on a motor’s efficiency at cruise. The added air ducting is sized for WOT and full boost, so pressure drop (pumping losses)at low power conditions are minimal.
The additional oil flow to the turbo is a small parasitic compared to the flow required to rest of the motor. There is a bypass valve waste gate to let exhaust bypass the turbo under partial load conditions. The turbo system may have an impact under cruise vs. the same engine NA, but its a pretty small one.
Major factors affecting an IC engines efficiency are typically compression ratio, ignition curve, rotating friction and mass, etc.
That said, aside from small weight differences, it takes about the same amount of power to the rear wheels to drive a truck down the highway no matter the engine. Diesels have higher compression ratios, keep injecting fuel during the power stroke for a more isobaric power stroke and the fuel has around 10% more energy. Both my Duramax’s have Turbo’s but the manual tranny 2500 pulls down 19/23 while my automatic dually gets 14/18. The efficiency of the manual, plus the inefficiency of the automatic, plus the two extra tires and added wind resistance of the dual wheels separates the mileage, as the trucks only scale 500 pounds apart.
I doubt removing the turbo would change the economy, but would definitely kill the power.
I hope this makes sense.