Trucks need truck motors - How GM picked the wrong motor

"HammerheadFistpunch" (hammerheadfistpunch) 10/21/2014 at 16:46 • Filed to: Truck Yeah, Nerd Moment, Canyorado

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So like many of you, I was bummed that GM picked the Camaro/crossover suited LFX high feature 3.6 L engine for the new canyorado, instead of the orphaned but excellently suited to truck use 4.3 L ecotec III. After all, why go to the trouble of created a unique V6 meant for truck use to only use it on one truck, and a truck where it will be lowly base engine at that?

(photo credit GM inside news)

(photo credit GM authority)

I hear you say that the 3.6 is smaller, therefor lighter and easier to fit? No, the LFX weighs ~370 lbs, the 4.3 weights ~ 375 lbs from the best sources I can find. Dimensionally the LFX is bigger too, due to its DOHC vs pushrod arrangement.

Well the 3.6 has more HP! I mean look at that graph, its crazy!

Well, yes, its a very impressive looking graph with big (though jagged) peaks. Compare that to 4.3 and it looks even better.

Riiiight up until the point you notice the scale on the graphs for HP and Torque. If it looks wonky its because it is. I couldn't find detailed numbers so I did my best at trying to read the graphs to come up with my own that more accurately reflects a uniform scale

(Sorry for the graph, I don't normally into excel)

RED is the 3.6 torque curve, Purple is the 4.3 torque curve

Blue is the 3.6 HP curve, Green is the 4.3 HP curve.

As you can see the 4.3 has more torque everywhere, though the curve is a little more peaky. The 4.3 also has more power in more places, its only in the last reaches of the rev band (where the 4.3 redlines out) that the 3.6 has an advantage.

Other 4.3 advantages (that I know about)

Higher alternator (for less water damage risk)

As good as timing chains are you don't need to worry with cam in block

the 4.3 will run 297 hp and 330 ft-lbs on e85, the 3.6 doesn't change

the 4.3 has lower compression for longer life

The 4.3 is based on small block architecture for modularity for the OEM parts and aftermarket.

So, smaller, same weight, more power in more places and available. Why isn't this the engine in the Canyon/Colorado and what else are you going to use it for GM?

Grindintosecond > HammerheadFistpunch 10/21/2014 at 16:50

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If they have the 4.3 with meat everywhere usable, more would go for it over the more expensive 2.8 Duramax diesel thats coming, that's all i can think of anyway....put a 4.3 graph against that...whenever they release the data on it.

PS9 > HammerheadFistpunch 10/21/2014 at 16:50

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Probably because they'll phase out the 4.3 at some point.

HammerheadFistpunch > PS9 10/21/2014 at 16:56

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based on what? Why go to the trouble of making a new 4.3 (it really is a brand new engine) when the 3.6 was there all along?

MontegoMan562 is a Capri RS Owner > HammerheadFistpunch 10/21/2014 at 16:58

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I wonder if it'll be "swappable"

HammerheadFistpunch > Grindintosecond 10/21/2014 at 17:02

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This is the best I could find. Adjust for the peaks being 200 hp and 370 ft-lbs

HammerheadFistpunch > MontegoMan562 is a Capri RS Owner 10/21/2014 at 17:04

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everything is, with enough determination. Still, it kills me that this engine only serves as the engine no one wants in the full size truck, while it is simultaneously the engine everyone wants in the midsize truck. What were you thinking GM? I wish i could see the rationale.

RamblinRover Luxury-Yacht > HammerheadFistpunch 10/21/2014 at 17:04

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I'm guessing the 3.6 is more abusable via clever ECM for those oh-so-coveted EPA MPG figures. There is a distinct sense in which they can favor *worse* engines.

PS9 > HammerheadFistpunch 10/21/2014 at 17:08

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Production oddities like this happen all the time. The lead time on an engine can be a year or more, which means reaction time to new data is about as long. They have as much reason to pick the 3.6 over the 4.3 now as they did to outsource V6s from the first gen Vue to Honda and not use any of their own already-good-enough V6s at all (remember that?)

Maybe the 3.6 for reasons known only to GM didn't look good enough to be a truck motor even in the base, but then Ford and it's ecoboost happened, and now it does. Maybe a V8 minus two cylinders sounded like a much better idea, but then improvements to the 3.6 made it obsolete. I don't really know. I do know that there's no real reason to pick the 3.6 over the 4.3 right now with the limited information you and I have as outsiders for a brand new truck beyond phasing out the motor at some point. It doesn't make much sense to have a bespoke motor for a base model truck (even one that sells as much as they do here in 'murica), as you already pointed out.

HammerheadFistpunch > RamblinRover Luxury-Yacht 10/21/2014 at 17:08

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The only reason in my mind keeps coming back to those MPG. But the 4.3 is so good in the silverado, how could it be that much worse here? I mean, 17/24 with the 3.6/6 speed vs 17/22 with the 4.3/6 speed in the much bigger, much heavier silverado. At worst it would have cost them 1 mpg on the highway cycle.

Grindintosecond > HammerheadFistpunch 10/21/2014 at 17:08

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huh. I'm wondering if thats the accurate duramax turbo diesel figures....120hp? I would expect slightly fatter VW TDI ish numbers, oh wait. is that hchart in KW and nM? id have to convert

RamblinRover Luxury-Yacht > HammerheadFistpunch 10/21/2014 at 17:11

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It's probably not more than a couple percent, but that's probably enough for them to try dumping the architecture. They've got the 4.3 solid, true, but they may foresee slightly cheaper production of the 3.6 than rebuilding the tooling for the 4.3 - which is something surely on the horizon.

HammerheadFistpunch > Grindintosecond 10/21/2014 at 17:12

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yeah, the VM 428 is the same 2.8 liter VM engine that been available in many things for quite some time now. The new figures are 200 hp and 500 nm for the trailblazer (suv cousin)

HammerheadFistpunch > RamblinRover Luxury-Yacht 10/21/2014 at 17:15

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but the 4.3 is brand new, and based on an architecture that just wont die. If anything, the 4.3 is the safe bet. I mean, if they 3.6 was the smarter bet for the canyorado...why wasn't it the smart bet for the silverado?

HammerheadFistpunch > PS9 10/21/2014 at 17:17

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I just have a hard time seeing past the logic in building a motor like the 4.3 that is thoroughly modern (yes, pushrods but the rest of the engine is) and not use it for anything but one truck no one wants to buy. its like the 4.3 was the project of someone that the program director for the canyorado didn't like.

RamblinRover Luxury-Yacht > HammerheadFistpunch 10/21/2014 at 17:18

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Might be something as simple as supply chain - where it is or isn't convenient to get the motors built and shipped. Volume production shifting the balance toward the 3.6, any number of things. Could even be internal feud - 3.6 architecture favored because it came from *this* design team and not *that* one. There can be some surprisingly pointless reasons behind things like this.

HammerheadFistpunch > RamblinRover Luxury-Yacht 10/21/2014 at 17:19

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"Surprisingly pointless" as a motto must have been one of the leftover items that they brought over from old GM.

You can tell a Finn but you can't tell him much > PS9 10/21/2014 at 17:21

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Lead time on an engine is more like 3+ years. If you're simply changing displacement by reducing the bore and reusing everything except the pistons lead time is around a year. Source: I worked on a project that was exactly that.

DoYouEvenShift > HammerheadFistpunch 10/21/2014 at 17:23

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Ive been trying to make all these same points since the new 4.3 came out. Use the 4.3 for all trucks and SUVs. And keep the 3.6 in cars. I would even go as far as to say that a more performance tuned 4.3 would be better suited in the base Camaro.

PS9 > HammerheadFistpunch 10/21/2014 at 17:25

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Haven't you ever done something, and then realized something else was better right in the middle of it? Large corporations are the same way, minus the split-second reaction time and change of direction that a person can pull of in this scenario. It might be the case that they 4.3 looked like the perfect low-end truck motor until now. Clearly something's changed inside of GM with regards to this motor, and that something is likely not going to lead to it being put in more vehicles in the future, if they aren't willing to put it in their latest truck.

PS9 > You can tell a Finn but you can't tell him much 10/21/2014 at 17:26

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Wow, a 3+ year lead time would make everything so much worse. It's even easier to see how motors can appear and disappear from the market, given that.

Bytemite > HammerheadFistpunch 10/21/2014 at 17:30

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It is down to emissions and MPG. The 3.6 has more power, while being more easy on the gas and environment. Pushrods are nice for being cheap and compact, it is however the worst for mpg and emissions. It is a win-win situation. As for the increased RPM decreasing engine life, I wouldn't bet on it, the valvetrain is not stone-aged pushrod so the engine block itself was probably built to handle more revs.

HammerheadFistpunch > PS9 10/21/2014 at 17:31

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I think the 4.3 is actually the superior motor and I haven't seen any evidence to convince me otherwise, but I do understand that the production for the 3.6 is there and ready to go. I would just hope that its not a matter of convenience only that the made their choice (obviously each convenience choice also has a cost associated with it)

JBurd67 > HammerheadFistpunch 10/21/2014 at 17:32

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This is a very interesting right up. Nice data presentation!

Logansteno: Bought a VW? > HammerheadFistpunch 10/21/2014 at 17:32

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I for one give no shits which motor goes where, because they're both great engines.

The 3.6 is more refined than the 4.3 though, making the Canyonrado more livable from day to day. I know the old 4.3 is a little rough and sends a lot of vibrations into the cabin, and the 3.6 doesn't nearly as much.

And hey, the 3.6 smokes both the Taco and Frontier's 10-year-old engines.

uofime > HammerheadFistpunch 10/21/2014 at 17:37

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2valve pushrod motors are dinosaurs

HammerheadFistpunch > Bytemite 10/21/2014 at 17:37

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im going to disagree with you on almost all points.

1. more PEAK power. The graphs clearly show the 4.3 is the more powerful engine if you took an average.

2. mpg on the 4.3 is very good. in the much much heavier and worse .cd silverado this engine gets 17/22 in 4x4 form. compared to 17/24 for the 3.6. I would argue that the 4.3 in the colorado would probably get BETTER mileage than the 3.6, especially under load.

3. Emissions are complicated, and I don't pretend to understand them but they should be at least on par. The 3.6 has higher compression which is better for c02 but worse for nox.

4. I didn't say more revs = more life (though generally true) I said higher compression = less life. Generally speaking though, lower revs is better for the motors lifespan, and not just because of the valve train.

HammerheadFistpunch > uofime 10/21/2014 at 17:39

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so are rocket motors.

HammerheadFistpunch > Logansteno: Bought a VW? 10/21/2014 at 17:42

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I hear ya, I really do, though ill take your affiliation with the old 4.3 into consideration as a pinch of salt. The trouble is...the 2.6 only smokes those older engines in peak power. The Toyota engine makes something like 5 less ft-lbs of torque at lower revs too, if you look at the dual vvti 2gr-fe, its actually a much more powerful engine overall than the 3.6. If Toyota put that super old but refreshed engine in the taco, it would already be a winner over the relatively fresh 3.6

uofime > HammerheadFistpunch 10/21/2014 at 17:42

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and GM is going to drag them out until they are replaced by electric motors, hydrogen or unicorn fart powered turbo encabulators

mcseanerson > HammerheadFistpunch 10/21/2014 at 17:43

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CAFE. Also my opinion is the real truck guys Colorado/Canyon motor is going to be the diesel. Plus you're saying that the 4.3 is only going to be in one vehicle but it's one vehicle they sell a crap ton of.

HammerheadFistpunch > uofime 10/21/2014 at 17:44

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you are missing the point. rocket motors are old, steel is old, pushrods are old.

None are outdated. High tech doesn't have to mean more parts/features.

HammerheadFistpunch > mcseanerson 10/21/2014 at 17:47

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you need to expand on CAFE, because I firmly believe the 4.3 could outperform the 3.6 in EPA and real world mileage in this truck. 17/22 in a 4x4 5500 lbs 4 door silverado, how could it do worse than that in a 3900 lbs 4x4 4 door canyorado?

As for the volumes, yeah they will sell plenty of 4.3's to fleets, but wouldn't it make more sense to get an even better volume equation?

Bytemite > HammerheadFistpunch 10/21/2014 at 17:51

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Yes it has more peak power..so it is the more powerful engine. That power curve is not even peaky by any standards. It seems to make about 280-300 hp for the last 1,000 rpm. The 4.3 is making less, at 270-285 for the last 1,000 rpm.

Lower compression, higher displacement = tighter throttle positioning during idle and lower revs = more pumping losses. You can bet your ass even if it is marginal, the 4.3 will have less fuel economy.

And as for your coveted "available power", the 4.3 is making 60-150 hp from idle to 2,500 RPM, usually the range that Americans use to drive.

The 3.6 is making 110-220 hp from idle to 2,500 RPM. So no, there is no way the 4.3 is the more powerful engine, and no way is it making more "available power".

HammerheadFistpunch > Bytemite 10/21/2014 at 17:54

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Did you even look at the graph? the 4.3 makes more hp from 1000-5500, only there does it loose because the 3.6 revs past that were the 4.3 doesn't. Did you get the colors mixed up?

Bytemite > HammerheadFistpunch 10/21/2014 at 17:57

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Sorry, you are right, those graphs are really confusing and scaled weirdly. The 4.3 does make 60-130 hp from idle to 2,500, and the 3.6 makes 60-120 hp. So yeah, I guess for people who don't like to use their right foot, it would have more power.

uofime > HammerheadFistpunch 10/21/2014 at 17:58

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have they perfected variable valve timing for pushrod engines in a production vehicle? That's one of the more useful technologies for improving efficiency.

you were predicting a 1 mpg improvement by using the 3.6 given the crap mileage these get an the tightening emission standards that is a non-trivial % improvement

mcseanerson > HammerheadFistpunch 10/21/2014 at 17:59

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Best case scenario the Colorado gets 18/26 where best case Silverado gets 18/24. I don't think the 4.3 would gain 2 mpg highway. My main argument though is the diesel will be the real truck motor. Hold on to that, it is something precious to be appreciated.

HammerheadFistpunch > Bytemite 10/21/2014 at 18:01

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There is only one place on the graph the 3.6 is even marginally more powerful (16 hp) and its from 5500-6500. I think the answer is that for people who aren't contently flirting with the redline its faster. Which brings me back to usable power; faster from 1000-5500 is going to be a lot faster in all situations than more powerful from 5500-6500. if you feel like knocking that spread down a little you can fill up with E85 and get 297 hp and 330 ft-lbs too, so there is that.

HammerheadFistpunch > mcseanerson 10/21/2014 at 18:04

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I think the 2.8 is going to be great, and yeah, I think 2 highway mpg might be a stretch. I bet you would get 1 better city and 1 better highway though. more torque, lower down, less weight; yeah I think its possible. lets not forget that the 4.3 can run as a 3 cylinder under light loads too, which would be a lot easier in a midsized truck than a full size truck.

HammerheadFistpunch > uofime 10/21/2014 at 18:06

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um, the 4.3 has continuously variable valve timing....

HammerheadFistpunch > HammerheadFistpunch 10/21/2014 at 18:22

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to correct myself. 3.6 and 1gr-fe

uofime > HammerheadFistpunch 10/21/2014 at 22:25

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well, shit you are correct, my knowledge is not up to date. From what I've just read they still only have the one cam so I'm guessing they still can't independently vary intake and exhaust timing.

the heart of the matter is that the engine isn't as efficient still though, so there's that.

HammerheadFistpunch > uofime 10/21/2014 at 22:36

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if they are less thermally efficicent (im not sure they are) they make up for it in packaging and mechanical efficiency. I mean, take a look at any any gm engine compared to a dohc of similar output. The gm engine may be bigger displacement wise but they are smaller phyically and lighter and tend to be on par or better than he dohc motors.

You can tell a Finn but you can't tell him much > PS9 10/21/2014 at 22:54

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Yeah, the amount of development required to do something as simple as changing piston size is mind boggling. The project I worked on was decreasing a V6 by 300cc by decreasing piston diameter. The "new" engine was identical except for bore size and pistons. The conrods, wrist pins, crank were all identical. The cam profile may have had to change but I'm not sure. It takes a ton of planning to make even a simple change to an engine design. Even changing the process used to make a piston could take months to get approved.

samssun > Bytemite 10/21/2014 at 22:55

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How are pushrods worse for mpg? I don't know of a non-small-block engine that does 430+ hp and can hit 30mp

When it comes to "stone-aged", I've seen 1920s overhead cam engines in person (Museum of Speed in Lincoln, NE), so you're really arguing (a highly evolved version of) a 90 year old design vs. 120 year old design...

samssun > uofime 10/21/2014 at 22:56

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Having stood among numerous 1920s-era OHC engines, I'd like to hear what engine in common use you wouldn't call a "dinosaur".

uofime > HammerheadFistpunch 10/21/2014 at 23:02

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the real problem with this pickup is an autotragic transmission that shifts into the highest gear ASAP and a torque converter that locks up too soon. The DOHC engine has less displacement so less torque and it needs RPM or it can"t make equal power.

uofime > samssun 10/21/2014 at 23:10

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that was really just an inflammatory troll comment, but started an interesting discussion.

I would say modern engines should have VVT, DI, variable intake geometry (the 4.3 actually has all those) the one thing it doesn't have is 4 valves per cylinder .

MontegoMan562 is a Capri RS Owner > HammerheadFistpunch 10/22/2014 at 09:02

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oh I agree 100%. And yeah I know, technically I could drop a 5.3L V8 in a Canyon

I'm just curious if it'll be a nice easy swap. Will the trans match up or do you need a bigger one, how it will do with motor mounts, electronics etc.

HammerheadFistpunch > MontegoMan562 is a Capri RS Owner 10/22/2014 at 11:32

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I guess the easy place to start looking would be to see how easy V8 swaps are into v6 camaro's

MontegoMan562 is a Capri RS Owner > HammerheadFistpunch 10/22/2014 at 11:42

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hmm.

Luc - The Acadian Oppo > HammerheadFistpunch 11/11/2014 at 12:20

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Now that I fully understand what you are talking about (I'm a visual learner, the graphs helped a lot) it makes perfect sense. The 4.3 would of been WAY better suited for this application.

HammerheadFistpunch > Luc - The Acadian Oppo 11/11/2014 at 12:24

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sadly, the marketers of the world (hi there, I'm one of them!) would have you believe only in peak hp....its such a small part of the story and even veteran truck guys are starting to fall victim.