5.3 has more power than GM advertises?

LongrangeLauber · October 12, 2016

My stock 14 using E85 will also outrun my buds 5.7 Hemi, when warm in the summer, it flat out annihilates it!

I only have one gas station down the street from my work, about 25 miles from my house, 15 from work, that has E85. The two times I have stopped by there the pump has been down. I'm scared I'm going to fill up with it one day and like the performance too much to want to switch back and end up going out of my way for it lol

markreed · October 12, 2016

I agree that, GM wouldn't post lower than actual numbers on the 5.3 to help 6.2 sales. The 5.3 is their best seller and they want those numbers looking as good as possible vs the competition.

I would say if anything, GM 6.2 numbers seem a tad low based on how those beasts run and dyno.

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Agreed.

Also, peak power is only one aspect of the conversation. I promise when you compare the hp/tq curves you will quickly see why the 6.2 pulls the 5.3 (no disrespect to the 5.3!!!)

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TJay74 · October 12, 2016

The years of 4wd trucks being at a loss on HP due to the 4wd system are gone. The front transfer case is open when not in use, it uses a clutch system to engage the front wheels. So I doubt there is much difference in a 2wd versus a 4wd truck on the dyno provided they are on the same transmission and rear gear setup.

Croak · October 13, 2016

The years of 4wd trucks being at a loss on HP due to the 4wd system are gone. The front transfer case is open when not in use, it uses a clutch system to engage the front wheels. So I doubt there is much difference in a 2wd versus a 4wd truck on the dyno provided they are on the same transmission and rear gear setup.

I'm gonna have to disagree. You may not be spinning the front diff because of a released clutch, but you're still spinning the transfer case. I notice a substantial mileage difference between when I have the transfer case set to Auto vs 2WD (and driving it easy enough that there's no reason it should be engaging the front diff).

TJay74 · October 13, 2016

I'm gonna have to disagree. You may not be spinning the front diff because of a released clutch, but you're still spinning the transfer case. I notice a substantial mileage difference between when I have the transfer case set to Auto vs 2WD (and driving it easy enough that there's no reason it should be engaging the front diff).

There will be when you use Auto, when in Auto mode the clutches in the front transfer case are loaded at 10% of their normal capacity. Once the system sees any wheel slip at all it fully engages the clutch pack in milliseconds and goes into 4Hi. It stays in that mode until a certain amount of decay time has elapsed and then drops back down into Auto at 10% loading.

While the chain inside of the transfer case is spinning, the output shaft that drives the front wheels is not moving. Granted the front axles are still spinning, I bet the difference from 4wd truck to a 2wd truck is less than 5% if everything else is the same.

bassJAM · October 13, 2016

There will be when you use Auto, when in Auto mode the clutches in the front transfer case are loaded at 10% of their normal capacity. Once the system sees any wheel slip at all it fully engages the clutch pack in milliseconds and goes into 4Hi. It stays in that mode until a certain amount of decay time has elapsed and then drops back down into Auto at 10% loading.

While the chain inside of the transfer case is spinning, the output shaft that drives the front wheels is not moving. Granted the front axles are still spinning, I bet the difference from 4wd truck to a 2wd truck is less than 5% if everything else is the same.

5% is probably about right. Most EPA MPG ratings have about 5% (21 vs 20) between 2wd and 4wd trucks.

I doubt the hp to the wheels difference is as high as 5%, but I'm sure it's still measurable.

Rawyzf · October 13, 2016

I agree, 5% is about what I would expect.

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MSPT · October 13, 2016

Interesting, I didn't know that auto kept the clutch's at 10% load. To be honest I haven't used 4wd on pavement ever. I'm in Canada where it snows most of the year so 4wd was always a winter thing. I was told lots of times that engaging 4wd on dry pavement would cause damage. Apparently I was wrong, I'll have a little advantage at the strip this year I guess

Next time I'm at the shop I'm going to ask him what other cars are dynoing. Maybe his system reads a little high. Also all you guys got me jealous that we don't have E85 here, we don't even have 93 lol

glcbn · October 13, 2016

Also all you guys got me jealous that we don't have E85 here, we don't even have 93 lol

Why is that?

BigBadSierra · October 13, 2016

Interesting, I didn't know that auto kept the clutch's at 10% load. To be honest I haven't used 4wd on pavement ever. I'm in Canada where it snows most of the year so 4wd was always a winter thing. I was told lots of times that engaging 4wd on dry pavement would cause damage. Apparently I was wrong, I'll have a little advantage at the strip this year I guess

Next time I'm at the shop I'm going to ask him what other cars are dynoing. Maybe his system reads a little high. Also all you guys got me jealous that we don't have E85 here, we don't even have 93 lol

You can run it in Auto all the time if your chose to. On my truck it doesn't even change the millage that much.

I do tend to leave it off most times though but keep it on in the rain.

Plus you get a could dead stop take off with it on ha ha.

BigBadSierra · October 13, 2016

I'm gonna have to disagree. You may not be spinning the front diff because of a released clutch, but you're still spinning the transfer case. I notice a substantial mileage difference between when I have the transfer case set to Auto vs 2WD (and driving it easy enough that there's no reason it should be engaging the front diff).

Funny you see this mine only changes by about 1 mgp if I leave it in Auto.

Rawyzf · October 13, 2016

Funny you see this mine only changes by about 1 mgp if I leave it in Auto.

I've never run it in Auto more than a drive to work and back when it was snowing, so I have no full tank calculations to compare.

1mpg isn't all that bad though.

MSPT · October 13, 2016

Why is that?

I'm in Eastern Canada, we get 91 and that's it. I've been told it's because of the cold climate and small market size it's not worth shipping it here.