GM’s New 6.2 Liter V8 L86 vs. 3.6 Liter Twin Turbo V6 LF3: By The Numbers
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In the red corner, weighing in at 6.2 liters of displacement, we have GM’s new 6.2 liter V8 (L86). The naturally-breathing engine makes 420 horsepower and 450 lb-ft of torque in the all-new 2014 Silverado and 2014 Sierra, using the trusted small-block push-rod setup, but with a few modern technologies, including Variable Valve Timing, Cylinder Deactivation (or Active Fuel Management/AFM), and Direct Injection.
In the blue corner, weighing in at 3.6 liters of displacement, we have another new GM engine: a twin-turbocharged 3.6 liter V6 (LF3). The boosted six-banger also makes 420 horsepower, but 430 lb-ft of torque in the all-new 2014 Cadillac CTS. The engine is as power-dense as they get (116 horsepower per liter), representing the state-of-the art in powerplant engineering and design, through and through.
As you may have expected, both engines take entirely different approaches to optimizing the modern internal combustion engine, but put out the same amount of power and sport similar torque figures. As it stands, The General can pick and choose the best engine for the appropriate application — using the big and burly V8 for trucks, and the smaller, boosted six-pot for sports cars.
Feast your eyes on the similarities, and on the differences:
| METRIC | 6.2L V8 L86 | 3.6L V6 TT LF3 |
|---|---|---|
| TYPE | 6.2L V8 | 3.6L V6 TWIN TURBO |
| DISPLACEMENT | 6.2L | 3.6L |
| VALVETRAIN | OVERHEAD VALVE, TWO VALVES PER CYLINDER, VARIABLE VALVE TIMING | DUAL OVERHEAD CAM, FOUR VALVES PER CYLINDER, VARIABLE VALVE TIMING |
| FUEL DELIVERY | DIRECT HIGH-PRESSURE FUEL INJECTION | DIRECT HIGH-PRESSURE FUEL INJECTION |
| COMPRESSION RATIO | 11.5:1 | 9.5:1 |
| RECOMMENDED FUEL | REGULAR UNLEADED OR E85 | PREMIUM REQUIRED |
| MAXIMUM ENGINE SPEED | 6000 | 6500 |
| POWER HP / kW @ RPM | 420 / 313 @ 5600 | 420 / 313 @ 5750 |
| TORQUE LB-FT / Nm @ RPM | 450 / 610 @ 4100 | 430 / 583 @ 3500 – 4500 |
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also the entire concept of engine torque being better is 100% useless, engine torque is a useless figure because it dosnt factor in gearing, which can easily make torque the same. 200 btq with a 4:1 gearing makes 800 wtq the same as 400 btq with 2:1 gearing. not only that torque is literally nothing more then a instant power figure for potential work. horsepower is what actually matters because that is work being done. despite the HORRIBLY incorrect myth that horsepower is just calculated it is in fact not. it is a measurement on work being done, the formula is 1 hp is the force needed to move 550 lbs 1 foot in 1 second.(in fact ALL inertial dynos measure horsepower and actually calculate torque the opposite of what people think.)
I note that most small engine makers–Briggs&Stratton, Kohler, etc. have now gone to primary reliance on torque data in their engine advertisements. You are correct that perceived engine power reflects multiple considerations. Top-gear ratios in particular have been trending numerically lower. My present car runs at less than 1500 RPM at 60 miles per hour. I consider torque and horsepower to have a determinate and fixed relationship at any given RPM.
most small engines also have a fixed gear ratio unlike cars, so it can be used without the information being misleading. if you have a car doing 1500 at 60 mph you likely have a CVT transmission since most traditional do not, i have not been in a new car in the past 5 years that did other then those with CVT.
torque and horsepower do have a relationship at a given rpm however the torque will change depending on gear selected horsepower however does not since the gear ratio which multiplies torque drops rpm to maintain the same horsepower. which is why for a automobile considering torque without knowing vehicle weight or gear ratio is futile and worthless. horsepower however eliminates the need to know the gear ratio to get an accurate representation of what the vehicle is capable of.
The car does not have a CVT, it does have a seven speed automatic and a V8 engine.
If the torque of an engine changes due to an RPM difference caused by the RPM it is operating at for a given road speed, then the horsepower will also, and always in a fixed mathematical relationship. Horsepower to torque conversion can be computed from the Horsepower to Torque Formula wherein Torque in Foot-Pounds equals Horsepower times 33,000 divided by two pi times RPM. Equivalent formulas exist for metric figures, and for converting from a known torque figure to horsepower.
As you indicate, if one changes gear ratios, then at a given road speed the maximum potential developed engine torque will also change, along with the corresponding horsepower because the engine will be operating at a different point on its power curve. I refer to potential power here. The actual throttle opening and hence developed horsepower and torque will vary according to such operating conditions as wind resistance, road slope, etc.
sorry bro your absolutely fucking wrong, no idea where you are getting your information from but you need to punch them in the face that isnt the formula and you should go to school for it(like i did) and build some cars before you try arguing with someone who has 12 years experience in the field. the proper formula for determining torque from hp and rpm is tq=(hp*5252)/rpm and the formula for horsepower is hp=(tq*rpm)/5252 you attempting to make some long winded crap so you appear knowledgeable. learn how gears work, torque is multiplied by gear ratio, that same multiplication of torque causes a reduction in rpm. result is horsepower remains largely unchanged minus a small % from parasitic losses that has nothing to do with changing the gear or rpm. the funny thing is your own formula also supports what i say.
as for your second point please do tell how a engine running at 5000 rpm with a 4:1 gear ratio is running at a different point in its power band then one running 5000 rpm with a 2:1 gear ratio. go ahead ill wait because i know for a fact they are operating in the EXACT same point in their power band both at 5000 rpm, and considering dynos are done at WOT you have made yourself look like a idiot because throttle wont change either. good job looking like a ignorant tool though despite attempting to over complicate shit you dont understand.
good effort at trying to cloud the subject though by over complicating things by bringing things into the conversation that have nothing to do with it such as throttle angle, gear changes causing drops in rpm, road conditions………….. because that has absolutely zero to do with the conversation since the topic was HORSEPOWER dosnt change based on gear ratios, which it dosnt, gear change dropping rpm? its dropping because of the engine rpm dropping dyno that same rpm in a different gear and it will still be the same horsepower, thats how gears work basic physics here. throttle change? ummmm no shit the horsepower isnt dropping from gearing its dropping from a restriction in the intake, torque is dropping also. again dyno with the same throttle percentage in a different gear and again horsepower will still remain the same. i could literally do that with every point you bring up because what you are doing is called a red herring fallacy, you attempt to distract from the main topic by bringing other topics into the subject. obviously you have never had a car on the dyno before vs the hundreds i have.
its also very amusing you mention where your vehicle operates yet then simply state its a “v8 with 7 speed automatic” with no mention of what vehicle it is. probably best you dont though because i know theres only a couple vehicles with 7 speed automatics and v8’s more then likely you dont have either and it would hurt your credibility if you mentioned what you have.
Your formula works just fine and if you like it, you should stay with it. It is only one of several mathematical expressions in which the torque and horsepower relationship can be expressed to arrive at the same results.
The car in question is a 2014 Mercedes-Benz E550 4Matic four door sedan in Diamond White. It has a 4.6 liter (4663 cc to be exact) V8 with twin turbochargers. I purchased the car in large part because of the excellent torque curve of this engine. Other cars with comparably strong engines include the V8 BMW 550, the Jaguars with supercharged V8’s, the Porsche Panamera with V8, the Audi turbocharged V8s, etc. Quite a few, actually.
You are right: I may have overcomplicated the issue. It is a hazard of discussing technical matters where many things interrelate. I don’t operate dynos, and am undoubtedly not conversant with the customary language of the dyno operator.
sorry but thats exactly what i thought, out of the cars you listed not a single one is a automatic transmission, in fact porsche dosnt even produce a automatic transmission of any gear. every one of them use a DCT or dual clutch transmission. it is in fact two manual transmissions in one using independent clutchs for two input shafts that run one inside the other. they do not share a single part with a automatic nor function in anyway shape or form even close to how an automatic functions.
Wow. You are a dick. Not only have you been wrong in some of your other posts, but you were wrong here with your attack on the parent poster. He was right. Period. You clearly a.) have zero knowledge of the genesis of the “horsepower” and b.) you are obviously terrible at math which leads me to the conclusion c.) that you are full of shit and do not have 12 years of experience “in the field” (unless you are a janitor at a car manufacturing facility and are thus embellishing “your experience”).
Go ahead and and do the math. What is 33k/2pi? Exactly. Also he pointed out that if you change gearing that the power produced by the engine for a given road speed would be different BECAUSE the engine is operating at a different point in its power band. You then somehow attempted to make a convoluted argument about the same engine running at 5k rpms? What? The parent is not the ass attempting to make himself sound more knowledgeable. You are. As to your advice about the parent punching someone in the face. I would offer the same advice to you, but would suggest shooting instead of punching, and the person you should direct that at is yourself.
You are a joke. Go away.
holy fallacys batman! actually he was wrong period and you should learn how a car works, mayby some time after you finish high school. 1) my definition of a horsepower is exactly correct next time you want to disagree with someone might wanna check facts first from http://www.thefreedictionary.com/horsepower
horsepower (ˈhɔːsˌpaʊə)
n
1. (Units) an fps unit of power, equal to 550 foot-pounds per second (equivalent to 745.7 watts)
2. (Units) a US standard unit of power, equal to 746 watts
Abbreviation: HP or h.p
oh look i was right the force needed to move 550 lbs 1 foot in one second imagine that.
2) for complaining that I dont know math you seem to lack the ability to understand how gears work or how speed is even achieved. road speed is 100% a function of tire diameter and rotations. of course you dont even understand what the arguement even was which was that horsepower is not affected by gearing. which its not the only one who is a joke is you. your argument is for x road speed power will be different because its at a different rpm point. hey news flash your comparing apples to oranges try comparing the same thing which is what makes my point 100% accurate and you look like a 12 year old angry at the keyboard. your saying that because the engine drops x rpm(lets say 1500 rpm thats a normal 1-2 shift) the power is different because you changed gears and the road speed is different(news flash its not you have to accelerate again first) well guess what not changing gears and just letting the rpm drop without it does the same thing, the engine will make the same horsepower regardless of gearing at x rpm. essentially your entire argument agrees with me in a fucked up convoluted way because that engine in that different gear will make the same power as that engine at that rpm in a different gear which is 100% the conversation.
come back when you can, you know drive, or have ever even been to a dyno since its obvious you havnt been to one, or fuck graduated high school even.
Jerry you imbecile re-read what I wrote. You do not understand math and you do not understand what the parent poster wrote. He was write on EVERY SINGLE point I brought to your attention. You said he was wrong. You were wrong. Give it up. You are not an authority. You are VERY far from an authority. You can resort to ad hominem argumentation when you are proven wrong (which I did) but it just makes you look like more of an imbecile than you already are. Leave this website. Do not come back. Nobody wants people like you here.
You are still a joke.
I don’t want to discuss power curves, gear ratios, and developed power any more. The topics are well presented in several auto technology textbooks. I do want to point out that the car brands I named, in total, offer variety of transmission choices. Automatic transmissions are among the them.
your back? sorry but no i already presented you that information, hell porsche hasnt made a automatic transmission in years. a dual clutch manual isnt a automatic just because it dosnt have a clutch pedal its nothing like a automatic, they dont share a single part in common, the only people who try to argue that are those who dont actually even know what a dual clutch manual is which is what the vehicles you presented use.
Jerryd87, I will quote accurately rather than paraphrase. I had said that “My present car runs at less than 1500 RPM at 60 miles per hour.” I thought it would be an inoffensive and uncontroversial statement of fact,
You replied by this: “if you have a car doing 1500 at 60 mph you likely have a CVT transmission since most traditional do not, i have not been in a new car in the past 5 years that did other then those with CVT.”
I responded that “The car does not have a CVT, it does have a seven speed automatic and a V8 engine.”
Your reply, in pertinent part was that “i know theres only a couple vehicles with 7 speed automatics and v8′s more then likely you dont have either and it would hurt your credibility if you mentioned what you have.”
I then provided you identifying information on my car so that you could access relevant technical information online to verify, or refute, my statement that the car had a V8 and automatic transmission, and said that “Other cars with comparably strong engines include the V8 BMW 550, the Jaguars with supercharged V8′s, the Porsche Panamera with V8, the Audi turbocharged V8s, etc.”
You then stated “out of the cars you listed not a single one is a automatic transmission, in fact porsche dosnt even produce a automatic transmission of any gear. every one of them use a DCT or dual clutch transmission.”
I now provide additional information to support my statements, with links to online documentation that you can read directly.
Reference my claim that BMW has an available 8 speed automatic transmission behind a turbocharged V8 engine: 8-speed automatic transmission, I provide this BMW quote:
“The 8-speed automatic transmission makes changing gears and driving significantly more convenient, thanks to fast engine speed transitions and shorter shift times. It unites outstanding comfort with palpable dynamics and increased fuel-efficiency. Gears can also be changed manually using the selector lever.” The 550i has BMW’s turbocharged V8 engine. “http://www.bmw.com/com/en/newvehicles/5series/touring/2013/showroom/driving_dynamic/8_speed_automatic_transmission.html
Also, here: http://www.bmwusa.com/Standard/Content/Vehicles/2014/5/550iSedan/Features_and_Specs/Default.aspx?from=/Standard/Content/Vehicles/2014/5/550iSedan/Features_and_Specs.aspx&return=/Standard/Content/Vehicles/2014/5/550iSedan/Features_and_Specs.aspx
Reference my claim that Jaguar has a supercharged V8 engine with an eight speed automatic transmission: “US model includes V8 supercharged 510 PS, eight-speed automatic transmission, and went on sale in late 2012 as 2013 model year vehicle.” http://en.wikipedia.org/wiki/Jaguar_XJ_%28X351%29
With regard to my claim that Porsche has a V8 engine with an eight speed automatic transmission: “The Cayenne Turbo is powered by a 4.8-liter twin-turbo V8 engine featuring direct fuel injection (DFI), VarioCam Plus and charge-air cooling. It generates 500 hp at 6,000 rpm. Maximum torque of 516 lb.-ft. is available between 2,250 and 4,500 rpm. Maximum speed is 172 mph, while the sprint from 0 to 60 mph takes as little as 4.2 seconds. By introducing a range of measures, e.g. standard fitment of the eight-speed Tiptronic S, we have been able to make the car 23% more fuel efficient.” http://www.porsche.com/usa/models/cayenne/ The Panamera, contrary to my statement, does have the PDK transmission. It is the Porsche Cayenne that has the available Turbo V8 and eight speed automatic transmission.
With regard to my claim that Audi has a turbocharged V8 engine with an eight speed automatic transmission: From AudiUSA.com website: (A8 model) “Trim & Engine 4.0 TFSI® .… Eight-speed Tiptronic® transmission Audi quattro® all-wheel drive.” http://www.audiusa.com/models/audi-a8/configurator#50710-4H25CA_U_1-2013/H4sIAAAAAAAAAPN1CtN1tNA1MjA0rjE1MDc00DXxMDJ1dowPjTeEiLqZmimAgFuUsrmHo65blK6fqatuoJGXspuhiUKAaYBpTU0NAPGjdFpHAAAA (sorry for the long identifier, it is on the Audi website).
I can provide additional supporting references on each of these cars, but many additional references are easily available on the internet in a variety of locations.
I personally would prefer the 6.2L V8, even in the CTS Vsport and ATS-V
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