2020 Freightliner vs 3500 GMC Dually at the Ike

ShinerBock wrote:
The reason why they rise is because you do not have enough air for the amount of fuel you are burning so the best thing is to get as much dense air into and out of your engine as possible with the least amount of restriction of reduce fuel. If your EGT's are high when towing, downshift to increase rpms and back off the throttle. Increasing rpms moves more air in and out of the cylinders. Backing off the throttle reduces the amount of fuel being injected. Most if not all modern diesels will automatically do this if EGT's get too hot.

Mods like an intake, better intercooler, larger/more efficient turbo, and less restrictive exhaust are all things that lower EGT's.

The hood mounted air scoop was supposed to help with sustained power.

ShinerBock wrote:
The 2019 GMC 3500 C&C Dmax is rated at 445 hp/910 lb-ft just like the pick up version. Not sure how they were able to do this with the different emissions certifications, but they are the same output.

Its simple... Advertised hp and torque is understated in the pick up version.

Also I don't think the GM was defueling either since during initial take off the truck seamed a bit lethargic from what I could tell, but one could say the same about the Freightliner.

4x4ord wrote:

Me Again wrote:

4x4ord wrote:
They praise the performance of the engine brake on the Freightliner over the performance of the exhaust brake on the GMC, however, if more weight had been loaded into the trailer the Duramax would have held 50 mph yet the Freightliner would have required additional brake applications. Comparing two trucks on one hill with only one weight in tow doesn't really offer an honest comparison. I'm having trouble understanding why the GM slowed down as much as it did going up the hill ..... something doesn't add up. Even back in 2015 (with 396 HP and 765 lb ft) the Duramax towed 19000 lbs up the Ike in just under 10 minutes. link

I don't think your statement on the Freightliner is correct. The cruise control was holding it at 50 MPH, most likely had a lot more anchor chain in the chain locker. RAM has this feature also when the EB is in auto. I do not use it because it does not brake until about 3-4 MPH above the CC speed.

I think the new GMs likely adjust the exhaust brake in auto as does the Ram and Ford. I believe in the test they had the GM exhaust brake turned to "on" which makes me think auto wasn't available in 2017. With the Freightliner Mr Truck said he didn"t have the cruise set. He said the engine brake could be set at 3 or 6 and he had it set at 6. So the Cummins was braking all it could without downshifting.

I thought I read a few years ago that in order for the GM to maintain speed while using the exhaust and transmission grade braking system is to have the cruise control on.

Me Again wrote:

4x4ord wrote:
They praise the performance of the engine brake on the Freightliner over the performance of the exhaust brake on the GMC, however, if more weight had been loaded into the trailer the Duramax would have held 50 mph yet the Freightliner would have required additional brake applications. Comparing two trucks on one hill with only one weight in tow doesn't really offer an honest comparison. I'm having trouble understanding why the GM slowed down as much as it did going up the hill ..... something doesn't add up. Even back in 2015 (with 396 HP and 765 lb ft) the Duramax towed 19000 lbs up the Ike in just under 10 minutes. link

I don't think your statement on the Freightliner is correct. The cruise control was holding it at 50 MPH, most likely had a lot more anchor chain in the chain locker. RAM has this feature also when the EB is in auto. I do not use it because it does not brake until about 3-4 MPH above the CC speed.

I think the new GMs likely adjust the exhaust brake in auto as does the Ram and Ford. I believe in the test they had the GM exhaust brake turned to "on" which makes me think auto wasn't available in 2017. With the Freightliner Mr Truck said he didn"t have the cruise set. He said the engine brake could be set at 3 or 6 and he had it set at 6. So the Cummins was braking all it could without downshifting.

The reason why they rise is because you do not have enough air for the amount of fuel you are burning so the best thing is to get as much dense air into and out of your engine as possible with the least amount of restriction of reduce fuel. If your EGT's are high when towing, downshift to increase rpms and back off the throttle. Increasing rpms moves more air in and out of the cylinders. Backing off the throttle reduces the amount of fuel being injected. Most if not all modern diesels will automatically do this if EGT's get too hot.

Mods like an intake, better intercooler, larger/more efficient turbo, and less restrictive exhaust are all things that lower EGT's.

So, what is the best way to lower EGTs?

larry barnhart wrote:
This truck was a 2017 duramax.

chevman

The 2017-2019 3500 chassis cab diesels had the same 445hp/910lb-ft ratings.

This truck was a 2017 duramax.

chevman

larry barnhart wrote:
Didn't the freightliner manufacture own both trucks and the MD is their own build so was it fixed or not.

That is border line tin foil hat conspiracy stuff right there.

noteven wrote:

C&C 350/450/550 or 00’s are “detuned” so their small cooling packages can maintain engine and trans and air con cooling under work conditions.

The 2019 GMC 3500 C&C Dmax is rated at 445 hp/910 lb-ft just like the pick up version. Not sure how they were able to do this with the different emissions certifications, but they are the same output.

ib516 wrote:
A few other items to consider.
- The Freightliner is a 500k mile rig, even when hauling heavy weights, and is significantly more money to buy and maintain than the Dmax.
- Also, the M2 would weigh a lot more than the Dmax truck, so the GCW was much lighter for the Dmax.

Interesting outcome though.

Yes a M2 or similar truck has a commercial truck duty cycle design - it would happily haul all day every day at 90-100% fuel rate.

A pickup truck not so much.

C&C 350/450/550 or 00’s are “detuned” so their small cooling packages can maintain engine and trans and air con cooling under work conditions.

Oh and pickups ride like chit twining trailers compared to class 7 and 8 trucks...