HA...i remember seeing that video myself. if i remember correctly, i don't think they discuss the challenges of payload capacity at all. and he goes right through my neck of the woods too! thanks for your input and that link. when i get a little time later tonight, i'll have a better response for you.
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Hey, First Time Truck Buyer Here! could use some advice....
- Thread starter Ogamiitto
- Start date
HA...i remember seeing that video myself. if i remember correctly, i don't think they discuss the challenges of payload capacity at all. and he goes right through my neck of the woods too! thanks for your input and that link. when i get a little time later tonight, i'll have a better response for you.
Here is a real world comparison:
I had a 2017, CCLB, SRW, Cummins, 68RFE, that I kept every drop of fuel used over17,500 miles. This was a combination of 5000 miles towing about 14,000# and 12,500 miles empty. I averaged 14.1 mpg over that 17,500 miles.
My new truck is in my signature, but it has averaged 15.6 mpg over 12,000 miles with no towing.
I had a 2017, CCLB, SRW, Cummins, 68RFE, that I kept every drop of fuel used over17,500 miles. This was a combination of 5000 miles towing about 14,000# and 12,500 miles empty. I averaged 14.1 mpg over that 17,500 miles.
My new truck is in my signature, but it has averaged 15.6 mpg over 12,000 miles with no towing.
thanks! it's with that i'm pretty close to making my decision. looks like i'm leaning towards a 3500 Hemi. i figure even if i decide to get a larger airstream in the near future, i don't think those are over 10k lbs....this should be able to handle it. saving on the weight of the diesel engine should keep my payload capacity towards the upper end of the spectrum to what a 3500 is capable of.
i also store gas at home, in case of an emergency, like an earthquake. something we have to consider here in CA. sticking to gas will mean not having to store two different types of fuel and having to purchase diesel fuel containers.
so my last few questions are.... how would the Hemi do through the Grapevine going up an downgrades, towing nothing more that 7500lbs....a fraction of it's tow capacity? and at a fraction of it's payload capacity? i'm sure it won't act like a diesel, but it should have enough power to accelerate out of a jam right?
this will be a fully loaded Longhorn. sunroof and all. and a megacab.....how much do you think that will eat into it's payload?
D
Deleted member 80
Guest
It will do OK. I have been pulling at 23,160 GCW with a 6.4. I have driven trucks all my life, so it is second nature to me, but you have to plan ahead, and look ahead. It will get up to speed, but you are going to have to "wring its neck" to merge onto a freeway. It needs to really wind to get the job done. For steep declines, use common sense and start at the top at a reasonable speed, as it picks up speed you can manually downshift, and use the service brakes periodically to scrub the spped back to your desired speed, letting them cool in between. Plan ahead, scan ahead. This all becomes second nature.
thanks ! regarding what you said above, again, i'm only towing 7500 ibs, tops. do you think i'm really going to have to "wring its neck", to get this truck going? it's got to do better that OK, right?
completely understand your advice on going downhill. i'm sure it'll become second nature with some practice.
D
Deleted member 80
Guest
It's a small-block V-8, and if you are trying to merge briskly with traffic you are going to have to rev it out to get up to speed. It's just the nature of the beast. The Hemi is happy to rev out
To answer the question about how it will pull The Grapevine, requires a bit of thought.
Physics says that power is the measure of RATE of doinf work. If you move a mass over a distance, work is done. It doesn't matter how fast you move it whether it's over a period of seconds kr minutes....the same amount of work is done. If you measure the work done over a given time, you have measyred power. Work over time is power. So to go up a hill more quickly, tames a change in power.
In our trucks we can increase power by either increasing engine rpm, or for a given rpm, increase torque. And that is the gjst of tne difference in gas versus diesel. Due to design, diesels make more torque at a low rpm which gives you the user, more power at lower engine speeds. Gas engines make torque at higher engine speeds and need to be reved some to attain the same power.
We don't need to turn this into a math problem so let's make some assumptions. The Cummins makes it's peak tkrque at about 1650 rpm. The 392 makes it's peak torque at 4000 rpm. Let's assume they each make 250 hp at peak torque and it takes 250 hp to climb the hill at 60 mph.
The Cummins will chug along at 1650 and climb the hill nicely. The 392 will be in a lower gear, but at 4000 rpm, and also climbing the hill at 60 mph. That is the real difference....the gas engine produces the same amount of power as the diesel but at a higher rpm.
To climb your hill at the same speed, rate of doing work, you have to make the same power. To make the same power with the 392, you have to rev it higher. And that's why some do not like gas engines as they give the impression of working harder to pull a load. But it's just the nature of the beast.
Going downhill is something a lot of people do not understand. Gas engines have natural engine braking. This comes from having a throttle butterfly valve. When the throttle is closed, your foot off the gas pedal, the piston on the intake stroke pulls a high vacuum on the intake manifold. This pulling vacuum on the intake, tends to slow the piston and results in natural engine braking. Diesels have no throttle valve and have no natural engine braking without some added device.
Diesels have some device, either on the exhaust or in the valve train that turns the piston into a comptressor on the exhaust stroke. This compression on the exhaust stroke provives resistance to the piston and results in a slowing force on the piston. The modern light truck diesls all come with exhaust brakes tk provide "engine" braking when slowing. The older diesels, usually before 2007 did not have this feature and had little to no engine braking.
So going downhill should be a similar experience with a new truck. Slow down, select a lower gear, and descend the hill with minimal use of the truck brakes.
Physics says that power is the measure of RATE of doinf work. If you move a mass over a distance, work is done. It doesn't matter how fast you move it whether it's over a period of seconds kr minutes....the same amount of work is done. If you measure the work done over a given time, you have measyred power. Work over time is power. So to go up a hill more quickly, tames a change in power.
In our trucks we can increase power by either increasing engine rpm, or for a given rpm, increase torque. And that is the gjst of tne difference in gas versus diesel. Due to design, diesels make more torque at a low rpm which gives you the user, more power at lower engine speeds. Gas engines make torque at higher engine speeds and need to be reved some to attain the same power.
We don't need to turn this into a math problem so let's make some assumptions. The Cummins makes it's peak tkrque at about 1650 rpm. The 392 makes it's peak torque at 4000 rpm. Let's assume they each make 250 hp at peak torque and it takes 250 hp to climb the hill at 60 mph.
The Cummins will chug along at 1650 and climb the hill nicely. The 392 will be in a lower gear, but at 4000 rpm, and also climbing the hill at 60 mph. That is the real difference....the gas engine produces the same amount of power as the diesel but at a higher rpm.
To climb your hill at the same speed, rate of doing work, you have to make the same power. To make the same power with the 392, you have to rev it higher. And that's why some do not like gas engines as they give the impression of working harder to pull a load. But it's just the nature of the beast.
Going downhill is something a lot of people do not understand. Gas engines have natural engine braking. This comes from having a throttle butterfly valve. When the throttle is closed, your foot off the gas pedal, the piston on the intake stroke pulls a high vacuum on the intake manifold. This pulling vacuum on the intake, tends to slow the piston and results in natural engine braking. Diesels have no throttle valve and have no natural engine braking without some added device.
Diesels have some device, either on the exhaust or in the valve train that turns the piston into a comptressor on the exhaust stroke. This compression on the exhaust stroke provives resistance to the piston and results in a slowing force on the piston. The modern light truck diesls all come with exhaust brakes tk provide "engine" braking when slowing. The older diesels, usually before 2007 did not have this feature and had little to no engine braking.
So going downhill should be a similar experience with a new truck. Slow down, select a lower gear, and descend the hill with minimal use of the truck brakes.
I enjoyed the exhaust brake on my 2013 Cummins. Really the only thing I miss about it.
When going downhill, use a gear one lower than the gear you would use going up. That is straight from the CDL handbook.
I have a very steep grade about 5 miles long from my house to my camp. There is a 30 mph curve on the road half way down.
With the Cummins the exhaust brake kept it at 45 mph. With the HEMI, I select 3rd gear and guess what, 45 mph down the hill.
Like @hutchman said, the Cummins has to have something added to engine brake...the HEMI jusf has to get a bit higher into the RPMS.
TOWING under 15000 GCWR, I don't miss the Cummins at all, over 15000 ccombined the Cummins becomes worth ththe money.
When going downhill, use a gear one lower than the gear you would use going up. That is straight from the CDL handbook.
I have a very steep grade about 5 miles long from my house to my camp. There is a 30 mph curve on the road half way down.
With the Cummins the exhaust brake kept it at 45 mph. With the HEMI, I select 3rd gear and guess what, 45 mph down the hill.
Like @hutchman said, the Cummins has to have something added to engine brake...the HEMI jusf has to get a bit higher into the RPMS.
TOWING under 15000 GCWR, I don't miss the Cummins at all, over 15000 ccombined the Cummins becomes worth ththe money.
archer75
Member
The exhaust brake is pretty much automatic. It uses the turbo to great some back pressure to slow you down. It's an engine brake. When I reach the top of the hill and start coming downhill I tap the brake to set the speed I want to hold. And then you can come down a mountain, never touch your brakes, and it will hold that speed the whole way. You don't heat up brakes or wear them out quickly. If you don't tow over mountains then it probably doesn't matter as much.
I honestly don't get the diesel vs gas debate. The diesel is just a better towing experience. Routine maintenance is pretty much a wash. It's a daily driver without issue. Diesel here is cheaper than gas though in other areas it's more. MPG is better. I've never once wished I went with the gas engine.
Gondul
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Diesel has it's place and it works great for some people... each person has to run their own numbers to come to a conclusion.
As @DevilDodge stated, you still get engine braking with the 6.4, albeit at a higher rpm but that's the offset between the two.
For me in my area, the additional mpgs is not covered by the additional cost of diesel+def, gas is cheaper for me to run.
FWIW, TFL has a video (damned if I can find it now) where they compared the towing between a gas a diesel truck and the MPGs were are wash... less than 1 mpg difference.
For me the 6.7 makes no sense the 2500 due to the reduced payload... my 6.4 has a payload of just over 2900#, most of the 2500 with the 6.7 have right around 1800 or so... to me it really makes more sense in the 3500... but again, these this is based on my numbers and my needs.
archer75
Member
It’s not the mpg and fuel cost savings I care about. It’s the range that efficiency gives you. Based on the numbers people are posting I’d say the difference is pretty good.
Really on the 6.4 you’re just grade shifting. With the 6.7 you get that in addition to the exhaust brake and don’t have to work the engine as hard or manage that as it’s automatic.
My payload is 2100. But yeah it can be lower. Just get the 3500. Cost difference is minor.
Diesels have no throttle. Because of this they have no engine braking without an engine, Jake brake, or an exhaust brake. Without the exhaust brake on your Cummins you have no engine braking. The only way to safely descend a hill with no exhaust or engine brake on a diesel, is to slow down before starting down the hill and use your vehicle service brakes.
Period.
Many years ago, I bought an F350 CC DRW with a V10 and I still have it. It's the truck in my sig. Back then, I didn't want to buy the Ford diesel because it was junk. Even if it was junk, it was too expensive and I couldn't afford it. When I ran the numbers back then, I couldn't financially justify an additional $7k for getting to the top of the hill a little faster, and descending the hill a little easier. The savings would easily pay for the gas.
The V10 with 4:30 gears (stock) has towed our 5th wheel fine. Last year, we towed it over all the steep passes in Colorado during the heat wave (and fires). Other than the big brakes I added, it's completely stock and has never had a problem. Although I'm getting a new 2019 3500 HO Aisin DRW, I'm not getting rid of the F350 because it's in great shape and I'll use it for hauling heavy payloads. BTW, we live in California and have been up and down the Grapevine many times. The gas engine works fine.
With that said, if you get the Hemi, pay the added $145 and get the 4:10 gears and don't put on large tires. Tall tires (and heavy wheels) kill braking power. The Hemi has a little more HP than the V10 but a little less torque (there is no substitute for cubic inches). Plus, a 15 year newer engine is probably a better engine because it's 15 years newer. You'll go up the Grapevine a little slower than the cars but faster than the big rigs, as long as you maintain speed. Going down, it's true what others have already said: just take it a little slower.
All that's easy when you're saving around $10,000 for the cost of the diesel. If you want to save a little more, shop for a low mileage certified 3500 Hemi and pay a little extra for an extended warranty.
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archer75
Member
Huh? I can also downshift to slow the truck without the exhaust brake. Perhaps there is a miscommunication here.
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Diesels do not have engine braking like gas engines do. Here is a link that explains the difference.
en.wikipedia.org
Engine braking - Wikipedia
archer75
Member
Sure, but you can still downshift to slow the vehicle.Diesels do not have engine braking like gas engines do. Here is a link that explains the difference.
Engine braking - Wikipedia
Diesel engines do not have engine braking like gas engines. I don't know how to state it any more clear. Try watching this video.
If you choose to believe they do, that's up to you.
I know this from driving semis at 105,000# and towing 20,000# revs with pickups. If you start down a long 6% grade at 70mph in a diesel without an exhaust brake and start to speed up, you can down shift. The only effect the downshift will have is to increase engine speed. You will continue to speed up until you apply the service brakes, the engine blows up, or you wreck. The only way to descend the hill safely is to slow down to BEFORE you start down the hill. You have to be going slow enough at the top of the hill, so that your service brakes can dissipate the energy of the descent.
Turn on your engine or exhaust brake and it helps dissipate some of the energy of the descent....it supplements the effect of your service brakes.
What I am telling you is fact. But I will not argue the point. It is up you to research the question for your benefit.
If you choose to believe they do, that's up to you.
I know this from driving semis at 105,000# and towing 20,000# revs with pickups. If you start down a long 6% grade at 70mph in a diesel without an exhaust brake and start to speed up, you can down shift. The only effect the downshift will have is to increase engine speed. You will continue to speed up until you apply the service brakes, the engine blows up, or you wreck. The only way to descend the hill safely is to slow down to BEFORE you start down the hill. You have to be going slow enough at the top of the hill, so that your service brakes can dissipate the energy of the descent.
Turn on your engine or exhaust brake and it helps dissipate some of the energy of the descent....it supplements the effect of your service brakes.
What I am telling you is fact. But I will not argue the point. It is up you to research the question for your benefit.
D
Deleted member 80
Guest
Even with my 6.4 gasser, with a heavy trailer behind me on a steep down grade 6-7%, you can downshift until the engine is at redline and the trailer is accelerating you down the hill, and you will be on the service brakes A LOT. You have to slow down at the top, and preserve your service brakes, especially trailer brakes, as drums don't cool very well. The exhaust brake on the Cummins is worth its weight in gold.
archer75
Member
I didn't say otherwise.
I said you can downshift to slow a diesel truck. A simple google search will show that as well.
I do it, it works. Yes, the RPMs go up. Same as a gas engine. But downshifting will indeed slow the vehicle. I have to at much lower speeds where the exhaust brake no longer slows the truck and i'm behind people going super slow. Generally in construction coming down the mountain. No, i'm not going to manually downshift at 70.
The truck will also automatically manage the exhaust brake as well as downshifting together to keep the vehicle at a given speed.
A diesel exhaust brake also works much better than simply taking your foot off the gas on a gas engine. And you can downshift to manage speeds on both.
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i've really enjoyed reading this last page of posts. incredibly informative to a newcomer. i do have questions and comments, but work has kept me away from responding to the discussion. know that i am reading and paying attention and will respond sometime today. also with what build i finally went with.