342 vs 373 Real world experience

nards444 · September 21, 2022

12 hours ago, Stand By said:

I have a different experience. I tow similar to you. 5000lb boat, dru weight+trailer,fuel and gear pushing towards 10,000. Night and day from my previous 5.3 4 door. Empty, the 5.3 gets better around town. On the freeway, they're comparable, except the 6.6 HD is way more stable and accelerating to pass at speed limit+ is much quicker in the 6.6. It is doggish getting out of the hole, due to being torque sensing and not giving full torque without a load behind it.

Yeah I was never a fan of the 5.3 had an 07 and 14, moved onto Ford and Ram after those and which had better motors. While there is some lag I feel, the 6.6 seems strong out the whole, really just mid range sucks bad on the truck. I expected sub par towing experience when towing compared to the duramax, but sort of disappointed in all around performance while not towing. Definitely not as quick and nimble without a load as half ton unloaded.

sheath · September 22, 2022

It would be great to see an actual dyno chart on power at the wheels. What GM shows for the engine power output and how the truck feels in the real world, are two different things. Maybe its a drive-train package/programming situation. If I give the truck a good swift kick in the gas... pedal, it will perform. Kind of reminds me of a lazy horse.

On the other hand, if that is what it takes to get good fuel mileage, I won't complain. Gas prices are killing us.

vucelick · September 22, 2022

9 minutes ago, sheath said:

It would be great to see an actual dyno chart on power at the wheels. What GM shows for the engine power output and how the truck feels in the real world, are two different things. Maybe its a drive-train package/programming situation. If I give the truck a good swift kick in the gas... pedal, it will perform. Kind of reminds me of a lazy horse.

On the other hand, if that is what it takes to get good fuel mileage, I won't complain. Gas prices are killing us.

Here you go

https://www.gm-trucks.com/forums/topic/228184-2020-66l-gasser-dyno-pull/

Edited September 22, 2022 by vucelick
Accuracy

nards444 · September 22, 2022

1 hour ago, sheath said:

It would be great to see an actual dyno chart on power at the wheels. What GM shows for the engine power output and how the truck feels in the real world, are two different things. Maybe its a drive-train package/programming situation. If I give the truck a good swift kick in the gas... pedal, it will perform. Kind of reminds me of a lazy horse.

On the other hand, if that is what it takes to get good fuel mileage, I won't complain. Gas prices are killing us.

What gets me is the 6.6 is has a minimal advantage over the 5.3 in hp and torque numbers. I get the 6.6 is more HD with the iron block and all but that motor shoud be pushing 450 plus along with the torque.

Stand By · September 23, 2022

6 hours ago, nards444 said:

What gets me is the 6.6 is has a minimal advantage over the 5.3 in hp and torque numbers. I get the 6.6 is more HD with the iron block and all but that motor shoud be pushing 450 plus along with the torque.

The motor is suppose to be torque sensing, so hopefully when you truly need the power, it will compensate. Either way, the components are heavy duty, as well as the overall truck. Pulling my boat with the 5.3, I was reminded frequently it was back there. With the HD, it was more of an obtw.

nards444 · September 23, 2022

7 hours ago, Stand By said:

The motor is suppose to be torque sensing, so hopefully when you truly need the power, it will compensate. Either way, the components are heavy duty, as well as the overall truck. Pulling my boat with the 5.3, I was reminded frequently it was back there. With the HD, it was more of an obtw.

No i get it. But the stability portion has more to do with 3/4 1 ton frame rather than the motor. Put the 5.3 in the HD truck short of longevity you probably wouldnt notice a large difference motor wise.

These engines probably have the capability and should be pushing 450-500hp with 500-550 torque

Pryme · September 23, 2022

16 hours ago, nards444 said:

What gets me is the 6.6 is has a minimal advantage over the 5.3 in hp and torque numbers. I get the 6.6 is more HD with the iron block and all but that motor shoud be pushing 450 plus along with the torque.

There is a pretty significant difference between those two engines imo

sheath · September 23, 2022

21 hours ago, vucelick said:

Here you go

https://www.gm-trucks.com/forums/topic/228184-2020-66l-gasser-dyno-pull/

Thanks for posting this! I'm pleasantly surprised by that graph.

The truck doesn't feel like the chart shows (very similar curve to the GM chart). Which lends to what @Stand By mentioned regarding "torque sensing".

It is also very probable that I'm gauging this engines power against my last truck which was a diesel (5.9L Dodge). That is not in anyway a fair thing to do on my part.

I really do like this truck.

nards444 · September 23, 2022

4 hours ago, Pryme said:

There is a pretty significant difference between those two engines imo

No I get that. But doubt you notice the difference on the average given the performance specs for both. 50hp more isnt doing much

Pryme · September 23, 2022

5 hours ago, nards444 said:

No I get that. But doubt you notice the difference on the average given the performance specs for both. 50hp more isnt doing much

Hp doesn’t mean as much as torque and there is way more torque with a better curve and better gearing to utilize that power better.

nards444 · September 28, 2022

On 9/23/2022 at 5:16 PM, Pryme said:

Hp doesn’t mean as much as torque and there is way more torque with a better curve and better gearing to utilize that power better.

For sure, but your talking minimal numbers here. And if you look at the dyno numbers of the 5.3 vs 6.6 they are very close. At 2500 the numbers are identical and at 4k-4500rpm the 6.6 is minimally better by 30-40 ft lbs.

Again not going to argue longevity between the two, but I can promise you will not notice the difference between the two in practical applications.

Only GM puts a motor in a truck that has less juice then the dodge 6.4 that has been out for 7-8 years and the ford 7.3 tremor. Then again GM is usually playing catch up

Only hope in the 24 model, GM mates the 6.6 with the ten speed and programs the motor to put out more power, which would probably make the power pack satisfactory or better in class, which as of now its not.

Pryme · September 28, 2022

2 hours ago, nards444 said:

For sure, but your talking minimal numbers here. And if you look at the dyno numbers of the 5.3 vs 6.6 they are very close. At 2500 the numbers are identical and at 4k-4500rpm the 6.6 is minimally better by 30-40 ft lbs.

Again not going to argue longevity between the two, but I can promise you will not notice the difference between the two in practical applications.

Only GM puts a motor in a truck that has less juice then the dodge 6.4 that has been out for 7-8 years and the ford 7.3 tremor. Then again GM is usually playing catch up

Only hope in the 24 model, GM mates the 6.6 with the ten speed and programs the motor to put out more power, which would probably make the power pack satisfactory or better in class, which as of now its not.

They already announced it will have the 10spd

Stand By · September 29, 2022

The 6.6 is essentially a beefed up, but detuned version of the 6.2. 6.2 being one of the best recent engines introduced. But if you want better numbers than the other guys, you could go this route. https://www.enginebuildermag.com/2021/01/gms-6-6l-lt-iron-block/

Without researching the 6.4 or 7.3 for longevity myself, I'm inclined against the 6.4 at least. The 6.6 suits my needs, and has a lot o new features to preserve it long term, hopefully.

nards444 · September 30, 2022

On 9/28/2022 at 11:02 PM, Stand By said:

The 6.6 is essentially a beefed up, but detuned version of the 6.2. 6.2 being one of the best recent engines introduced. But if you want better numbers than the other guys, you could go this route. https://www.enginebuildermag.com/2021/01/gms-6-6l-lt-iron-block/

Without researching the 6.4 or 7.3 for longevity myself, I'm inclined against the 6.4 at least. The 6.6 suits my needs, and has a lot o new features to preserve it long term, hopefully.

6.4 is a really good motor, been out for 8 years now. But has aluminum parts and coated rods and such.