Gas vs PSD
Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 742
From: Isanti, MN
I believe the standard figure is a 3% power loss for every thousand feet you go up.
So, at a 11,000 foot pass, such as the Eisenhower tunnel in Colorado, you'd lose 33% of your power.
Been over that pass in my work truck a few times. Believe me, until the turbos spin up, there's almost no power to be had!
So, at a 11,000 foot pass, such as the Eisenhower tunnel in Colorado, you'd lose 33% of your power.
Been over that pass in my work truck a few times. Believe me, until the turbos spin up, there's almost no power to be had!
Cargo Master
Joined: Apr 2007
Posts: 2,659
Likes: 2
Driving a vehicle is dynamic. An engine isn't an on/off switch that goes from idle to peak torque and/or horsepower. You have to drive up through gears and run at all engine speeds. The engine that makes the most average power during the race wins. There is no way in hell that a 300 Hp 5.4L can out tow a stock 7.3L. Hook up a load and the 7.3L makes greater power most of the time, while the 5.4L makes greater power a little bit of the time. The heavier the load the greater the disparity. And don't give me some wild idea that you're going to put 8.xx gears in the rear axle. You want a tow rig not a rock crawler.
Now, if you don't believe me then please explain why a 400 Hp Honda Civic engine isn't a good choice for a heavy truck. We all know it is true... but WHY???
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
The V10 does the same job in stock form as the diesel does. It does not use a turbocharger or any other power adder to do so.
JL
Cargo Master
Joined: Apr 2007
Posts: 2,659
Likes: 2
Wrong. 100 Hp is gained by adding more fuel. It really is a "magical diesel thing".
With a diesel you can make more power by just dumping more and more fuel to it. Any turbo upgrades are so that you can pack in higher density air to burn that fuel and make even more power. Try that on your V10, gassy.
With a diesel you can make more power by just dumping more and more fuel to it. Any turbo upgrades are so that you can pack in higher density air to burn that fuel and make even more power. Try that on your V10, gassy.
Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 742
From: Isanti, MN
Driving a vehicle is dynamic. An engine isn't an on/off switch that goes from idle to peak torque and/or horsepower. You have to drive up through gears and run at all engine speeds. The engine that makes the most average power during the race wins. There is no way in hell that a 300 Hp 5.4L can out tow a stock 7.3L. Hook up a load and the 7.3L makes greater power most of the time, while the 5.4L makes greater power a little bit of the time. The heavier the load the greater the disparity. And don't give me some wild idea that you're going to put 8.xx gears in the rear axle. You want a tow rig not a rock crawler.
It has so much more to do with how much time can be spent near peak HP for the gasser here. There's nothing to say that the gas motor can't spend the duration of the pull at 5,000 RPMs in 2nd gear, pulling at over 60 mph! In that case, there is NOTHING the 7.3 can do that would come close to it.
All it takes is for the tranny to be able to keep the engine near peak HP. And the 5R110 used in the last few years is remarkably good at doing just that.
"Mifflin Clay"
Joined: Jul 2005
Posts: 3,177
Likes: 4
From: Mifflin, PA
590 horsepower at 6,500 rpm and 509 foot-pounds of torque at 5500 rpm
Heres the link, good reading:
http://www.drivingenthusiast.net/sec...m58d/index.htm
Cargo Master
Joined: Apr 2007
Posts: 2,659
Likes: 2
It has so much more to do with how much time can be spent near peak HP for the gasser here. There's nothing to say that the gas motor can't spend the duration of the pull at 5,000 RPMs in 2nd gear, pulling at over 60 mph! In that case, there is NOTHING the 7.3 can do that would come close to it.
Seriously, think about what you're saying. You're going to load up a 5.4L to the point where it can't get past 60 mph. What do you think a 7.3L would do with that same load? Remember that both trucks have to begin from a stop in 1st gear. You know the truth... speak forth the truth!
Senior User
Joined: Dec 2007
Posts: 287
Likes: 0
From: Calgary Alberta Canada
If the combination of axle gears and transmission gears allows the 5.4 to be at peak rpms In theory it will be faster up a hill.
It's not rocket science.
The diesel is a nicer tow vehicle, because it does the job without as much drama. (5000rpm)
It's not rocket science.
The diesel is a nicer tow vehicle, because it does the job without as much drama. (5000rpm)
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Senior User
Joined: May 2004
Posts: 407
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From: Humble, Texas
I, for one, don't ignore that my diesel has a turbo. The turbo is the REASON I have a diesel. Sometimes I even roll the windows down just to listen to it in all of its glory.
Posting Guru
Joined: Dec 2006
Posts: 2,498
Likes: 3
From: Windsor, Colorado
I believe the standard figure is a 3% power loss for every thousand feet you go up.
So, at a 11,000 foot pass, such as the Eisenhower tunnel in Colorado, you'd lose 33% of your power.
Been over that pass in my work truck a few times. Believe me, until the turbos spin up, there's almost no power to be had!
So, at a 11,000 foot pass, such as the Eisenhower tunnel in Colorado, you'd lose 33% of your power.
Been over that pass in my work truck a few times. Believe me, until the turbos spin up, there's almost no power to be had!
(all on paper of course as we have yet to see a dyno sheet on a V10
)
Cargo Master
Joined: Apr 2007
Posts: 2,659
Likes: 2
If you want to maintain a constant speed up a constant slope then we have a steady state scenario. You will have to apply a constant pushing force equal to the weight of the rig pulling you back down the hill plus the rolling & wind resistance. Correct?
And the pushing force comes from the force created by the wheel torque applied at the road. Correct?
So, the engine that produces the greatest torque wins, right? We all know that is the 7.3L. Did I make a mistake? You're probably going to pull out the 4-speed vs. 5-speed tranny wild card. But I have a 6-speed. Never found a gear that wasn't perfect for any situation.
Fleet Mechanic
Joined: Feb 2007
Posts: 1,852
Likes: 39
Sorry, no. The engine that is producing the most power wins (if the gearing is right). Power is basically torque times RPM. As the gears reduce the engine speed, they increase the torque, but the power remains the same. A gas engine doesn't have to be producing more torque than a diesel motor, if the gasser is spinning much faster. After the more significant gear reduction for the gasser, the rear-wheel torque can end up being more.
Again, this is the beauty of using horsepower to compare trucks, because it takes into account both torque and speed. The horsepower at the rear wheels at any given moment is basically the same as the engine horsepower at that moment, minus drivetrain losses.
Senior User
Joined: Dec 2007
Posts: 287
Likes: 0
From: Calgary Alberta Canada
It has been a very long time since I did any kind of motion problems so I need your help.
If you want to maintain a constant speed up a constant slope then we have a steady state scenario. You will have to apply a constant pushing force equal to the weight of the rig pulling you back down the hill plus the rolling & wind resistance. Correct?
And the pushing force comes from the force created by the wheel torque applied at the road. Correct?
So, the engine that produces the greatest torque wins, right? We all know that is the 7.3L. Did I make a mistake? You're probably going to pull out the 4-speed vs. 5-speed tranny wild card. But I have a 6-speed. Never found a gear that wasn't perfect for any situation.
If you want to maintain a constant speed up a constant slope then we have a steady state scenario. You will have to apply a constant pushing force equal to the weight of the rig pulling you back down the hill plus the rolling & wind resistance. Correct?
And the pushing force comes from the force created by the wheel torque applied at the road. Correct?
So, the engine that produces the greatest torque wins, right? We all know that is the 7.3L. Did I make a mistake? You're probably going to pull out the 4-speed vs. 5-speed tranny wild card. But I have a 6-speed. Never found a gear that wasn't perfect for any situation.
I have a 6 speed too. (5.4) That was my point though, within a second or 2 I am at my peak hp. 4500 rpm+/-. then I shift from low to first, etc. The Idea of a transmission is to keep the truck at the rpm that works best.
For me it's high.
for diesels it's low.
the tires don't know or care if it's gas or diesel turning the drive train.
or if the engine is revving at 5g, or 2200. The truck accelerates based on the power being applied to the wheels.
hp is hp.
I also did say in theory. Although for the amount of heavy pulling I do, the 5.4 works great for me.
I have owned a few psd's and a 97 12v cummins.
The cummins kicks the crap out of the psd, and the v10 in real world everyday use.
I think for the most part, most will agree the diesel makes the most comfortable beast of burden.
but for some, they don't pull often. and if they do pull heavy, the v10 is more than capable.