2014 Chevy/GMC specs

[Peacock]

I've never owned a Ford but I know my two GM's never got their rated mileage. I guess because I wasn't driving a 2wd truck with 3.08 gearing which would have been next to useless to me.

That's fine, but my point is that the GM and Ford engines get tested the same.

The new Gen V 5.3 is superior to the 5.0 Ford in nearly every measurable way.

 

[timswi]

I've never owned a Ford but I know my two GM's never got their rated mileage. I guess because I wasn't driving a 2wd truck with 3.08 gearing which would have been next to useless to me.

My GMC 6.2 is rated at 13-19MPG...I get an average of 16...On the highway it's 19-20...Where's the problem?..400HP in a 4x4 pickup, I ain't complaining...I knew what I was buying when I bought it.

 

[RollingsFarms]

My GMC 6.2 is rated at 13-19MPG...I get an average of 16...On the highway it's 19-20...Where's the problem?..400HP in a 4x4 pickup, I ain't complaining...I knew what I was buying when I bought it.

The problem was never the engine or fuel consumption for what it was. The problem was the quality of my 2011 was way below my expectations in a $48,000 truck and what it should be. That's hovering on BMW sedan territory and trust me, the quality between the two ain't even in the same stratosphere. My 2004 Z71 was a great truck, if it had the 6.2 and 6 speed it would have been my favorite truck. I'll never even look at a GMT-900 again for as long as I live and consider buying it or recommending it to others who ask me.

 

[crazyal]

I stand by my statement about (IN THE PAST) ohv engines vs. ohc.

In many cases ohv are lower revving they also in many cases produce more total torque than total horsepower. I know of very few normally aspirated ohc engines that can make that claim...

Ohc engines generally will rev higher producing more peak horsepower, but do not generally produce as much torque at low rpms.

A good example of these normally aspirated ohv engines are my favorite Pontiacs.

Like some of the versions Butler performance builds- the basic 455 cu producing 580 hp 625 ft. lbs. also average torque far exceeds average horsepower.

Many ohv engines produced more average torque than horsepower.


If ohc head designs produce as much or more low end torque, you would think they would be in use on more than half the diesel tractor engines and over the road diesels.. I believe its all about low end torque...

I maintain that in general - in the past normally aspirated ohv engines produce more low end torque than ohc engines

Here's a chart for HP and Torque for both the new 5.3 GM and the 07 Toyota 5.7. Yes the 5.7 is slightly larger and should make more power but Toyota's engine is a 7 year old design. These are real world numbers for two competing trucks you can buy today.


Both of these charts look like they have a very similar (flat) torque curve. How much of a boost did the GM 5.3 get over last years model?

The advantages of an overhead cam set up is there's less parts and weight that the valve spring needs to move when the valve is closing. That allows the OHC motor to rev higher without the valves floating. Since it can rev higher mfgs tend to make them do just that, but it's designed to take advantage of that feature. The 4 valve set up allows much better flow through the head. The OHV engine is easier to design variable valve cam timing.

The downside is that they require a lot more work to build. The heads are a lot more complicated. There's 4 cams vs a single cam. There's a complicated timing belt/ chain that has to go to both heads. There has to be a gear set up in each head to drive the second cam. Simply put there are a lot more engineering design work needed to get the most out of a OHC set up. The OHV design is simple. It's easy to work on, it's a tried and true design, it requires less machine work to build, it's lighter in weight, the head height is smaller so it doesn't fill up the engine bay, it's a solid engine. Personally I think that GM will switch over in the future. I just think that they would of needed to start working on the design back when they had a cash crunch.

 

[94BULLITT]

I still wonder how much they really changed in the new motor.

 

[deerefan]

I still wonder how much they really changed in the new motor.

From having messed with some LS series motors, a cam change makes significant improvements, in some cases 30-50hp. It would not surprise me if they changed cams, added direct injection and adjusted timing to get these gains. We installed a 5.3 in a 69 Nova, stock bottom end, cam upgrade, headers and a FAST intake. With a 4L60 trans and 4.10 gears, full interior, all steel car, runs 12.15 all day long.

 

[94BULLITT]

From having messed with some LS series motors, a cam change makes significant improvements, in some cases 30-50hp. It would not surprise me if they changed cams, added direct injection and adjusted timing to get these gains. We installed a 5.3 in a 69 Nova, stock bottom end, cam upgrade, headers and a FAST intake. With a 4L60 trans and 4.10 gears, full interior, all steel car, runs 12.15 all day long.

Doesn't a 5.3 have LS1 heads?

The new engine looks very similar to the old ones from the picture I have seen.

 

[Peacock]

None of the parts interchange.

 

[94BULLITT]

None of the parts interchange.

How do you know?

 

[Peacock]

Because they say. I guess that is reliable. Plus it looks different to my eyes.