Gas vs PSD
Post Fiend
Joined: Mar 2006
Posts: 7,841
Likes: 0
From: Vacaville, Ca
Ford does not have a 6.4/6.7 competion with the 6.8.
Ford is competing with the Duramax and the Cummins. That is the primary reason for the 3.73 gears, MPG. That darn Duramax get over 20mpg and Ford is chasing that.
Ford is competing with the Duramax and the Cummins. That is the primary reason for the 3.73 gears, MPG. That darn Duramax get over 20mpg and Ford is chasing that.
Fleet Mechanic
Joined: Feb 2007
Posts: 1,852
Likes: 39
How about we step back for a moment, and look at horsepower not as a measure of what an engine is capable of, but rather a measure of what is happening at a given moment.
For instance, a pickup truck driving up a 6% grade, pulling a 14,000 pound fifth-wheel, at 40 mph. If you take the speed of the rear wheels, and the torque present at the rear wheels, those two numbers will give you a horsepower number. That is the actual horsepower present at the rear wheels. That is the actual horsepower necessary to perform the task.
Let's say for speaking purposes that number is 250 HP. I don't know how accurate that is, but for the sake of argument, let's just say that's the number.
If we ignore drivetrain losses, then the engine in that vehicle is also producing 250 HP. You can NEVER get more HP at the rear wheels than the engine is capable of generating. It does not matter how fast you turn the engine, or how much torque it produces.
So if your engine is only capable of producing 250 HP, you are maxxed out. If you had 300 HP available, you'd still be able to accelerate. But the point is, the load doesn't care whether that 250 HP is coming from a chugging 7.3 at 1750 RPM, or from a screaming V10 at 5,000 RPM. The driver might care, but the load won't know the difference.
Starting the load, fuel mileage, noise, comfort, longevity, those are all variables that can be discussed in the gas vs. diesel war. But with a load that's already moving, in vehicles that are geared to run at their max power, then horsepower wins, regardless of how it's generated. Horsepower at the rear wheels determines load capability, and you can NEVER have more horsepower at the wheels than you do at the motor.
For instance, a pickup truck driving up a 6% grade, pulling a 14,000 pound fifth-wheel, at 40 mph. If you take the speed of the rear wheels, and the torque present at the rear wheels, those two numbers will give you a horsepower number. That is the actual horsepower present at the rear wheels. That is the actual horsepower necessary to perform the task.
Let's say for speaking purposes that number is 250 HP. I don't know how accurate that is, but for the sake of argument, let's just say that's the number.
If we ignore drivetrain losses, then the engine in that vehicle is also producing 250 HP. You can NEVER get more HP at the rear wheels than the engine is capable of generating. It does not matter how fast you turn the engine, or how much torque it produces.
So if your engine is only capable of producing 250 HP, you are maxxed out. If you had 300 HP available, you'd still be able to accelerate. But the point is, the load doesn't care whether that 250 HP is coming from a chugging 7.3 at 1750 RPM, or from a screaming V10 at 5,000 RPM. The driver might care, but the load won't know the difference.
Starting the load, fuel mileage, noise, comfort, longevity, those are all variables that can be discussed in the gas vs. diesel war. But with a load that's already moving, in vehicles that are geared to run at their max power, then horsepower wins, regardless of how it's generated. Horsepower at the rear wheels determines load capability, and you can NEVER have more horsepower at the wheels than you do at the motor.
Thread Starter
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Modular motor junkie
Joined: May 2009
Posts: 6,190
Likes: 8
From: Texas
Actually I believe that ford is using 3.73 in the diesel for milage. The 4.10 will always provide more torque. That is why every V10 owner doesn't think it would be fair to compare a 4.30 diesel to a 4.30 gas. The 4.30 will make even more torque than the 4.10. All of this is at the rear wheels. Torque at the flywheel will not change.
You can get 4,88s in either one, but that is no good in real life on the PSD.
The thing hits red line in OD at 85 with them.
Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 742
From: Isanti, MN
in 99 were the v10s a 2v or 3v? Cuase in my post I was talking about a 99, like I clearly stated.
The more torque you have, the more towing power you have. The more torque you have the more work ya get done (more load you can pull) More horsepower you have, the more speed you have.
Second of all, I drive rigs for a living, I tow stuff, heavy stuff. Ive drive lots of trucks, and lots of trucks with 350 horse engines (those same engines also had over 1000 ft lbs of torque.)
Now by what your telling me, a v10 truck would be able to outpull that ol kenworth with a 350 cummins in there (had a 13 speed and 4.11 gears) as long as the v10 was a 3v, and had 4:30 gears right? I mean the psd has more advantage cause its lighter, etc. (maybe not a traction advantage)
Now in the same breath, my 87 western star with the 444 cummins should be able to out tow and out speed a 3v v10 cause it has more horspower (8 speed and 4.11 gears also)
Now who do you think would win in a tow between a K/w with a 350 cummins vs a v10, and who do you think would win in a W/S with a 444 cummins vs a 3v v10 in a drag race? We both know the answer. ( yes there are more variables, but with the added weight of a big rig. that should drastically reduce the power of the engine, and give even more of an advantage to the v10)
Also does that mean a 500 horse civic with 300 ft lbs of torque could out pull a v10 truck as long as it had 4:10 or better gears in it?
As a guy that has a lots of experience towing, and what I have experienced, you guys are killing me! I may not know all the math to it, but ive sat in enough seats to tell you that hp dont mean diddly compared to torque while towing.
The 7.3 can, has, and will keep outpulling the v10.
The more torque you have, the more towing power you have. The more torque you have the more work ya get done (more load you can pull) More horsepower you have, the more speed you have.
Second of all, I drive rigs for a living, I tow stuff, heavy stuff. Ive drive lots of trucks, and lots of trucks with 350 horse engines (those same engines also had over 1000 ft lbs of torque.)
Now by what your telling me, a v10 truck would be able to outpull that ol kenworth with a 350 cummins in there (had a 13 speed and 4.11 gears) as long as the v10 was a 3v, and had 4:30 gears right? I mean the psd has more advantage cause its lighter, etc. (maybe not a traction advantage)
Now in the same breath, my 87 western star with the 444 cummins should be able to out tow and out speed a 3v v10 cause it has more horspower (8 speed and 4.11 gears also)
Now who do you think would win in a tow between a K/w with a 350 cummins vs a v10, and who do you think would win in a W/S with a 444 cummins vs a 3v v10 in a drag race? We both know the answer. ( yes there are more variables, but with the added weight of a big rig. that should drastically reduce the power of the engine, and give even more of an advantage to the v10)
Also does that mean a 500 horse civic with 300 ft lbs of torque could out pull a v10 truck as long as it had 4:10 or better gears in it?
As a guy that has a lots of experience towing, and what I have experienced, you guys are killing me! I may not know all the math to it, but ive sat in enough seats to tell you that hp dont mean diddly compared to torque while towing.
The 7.3 can, has, and will keep outpulling the v10.
First of all, I respect your experience, but you ARE NOT the only one here who tows for a living. I'm currently in Cleveland, TX and I just weighed my work truck at 76,500 lbs. It does NOT have a PSD in it!
It's a 2006 KW T-600, with a 435 HP Caterpillar C15 engine. 1750 lb-ft of torque. This truck at 1500 RPMs(peak HP) does NOT pull as hard as many here's PSD trucks will with tuners. The difference is efficiency and longevity. The C15 engine I'm referring to has 544,754 miles on it at this very moment, and only sees fresh oil every 40,000 miles. And it'll pull at peak HP all day, every day without reliability problems. A tuned PSD would blow up in short order maintaining that power output for any length of time. This is why a 15-liter, 1,750 lb-ft engine is necessary for this application. The engine alone weighs over 3,000 lbs.
Some big trucks have less power than that! I'm sure you're familiar with Schneider National up there? Their pumpkin colored trucks are motivated by 370 HP DD Series 60 engines. And a Toyota Tundra 5.7 can pull harder.
Remember this post I made?
Okay, Bill, I have time to figure this out now.
My 265/70/17 tires are 31.7" tall, which makes for a circumference of 8.29 feet. At 70 MPH they would be turning 743 RPMs.
4th gear on my TorqShift is direct drive, 1.00:1 ratio, which leaves the only gear reduction present at this gear would be my 3.73:1 rear end. Meaning the engine would be turning 2,771 RPMs at this speed and gear. Assuming 625 lb-ft at that RPM, would leave:
625 x 3.73 = 2331 lb-ft applied to the wheels. Adjust that for the 15.85" radius wheels, you'd have 1765 lbs of force pulling the truck and trailer up the hill.
Also, 625 lb-ft @2771 RPMs would equal 330 HP.
Now we do yours. For the sake of simplicity, I'm gonna use the same tire size for your van. Also, because I can't get specs as far back as 1999 on FTE, I'm gonna use the 2000 PI-head V10 for HP and torque specs.
So, 743 RPMs at 70 mph. With your 1.55 2nd gear and 3.73 rear end, that would put you at 4294 RPMs at 70 MPH. Which is just perfect for your engine, as your peak HP is supposed to be at 4250 RPMs. Also makes it easy to calculate torque.
305 HP @ 4250
HP = (TQ x RPM)/5252
Therefore, at that RPM you're making 377 lb-ft of torque. Remember that this is revving well past your torque peak, so this WILL be less than peak torque...but it's still pulling harder 'cuz of RPMs.
So, 377 lb-ft x 1.55 x 3.73 = 2180 lb-ft at the wheels.
Adjust that for tire diameter and you have 1651 lbs of force pushing the van and trailer up the hill.
In summary:
(disclaimer:All values here are ignoring driveline loss, which we can assume is reasonably close between transmissions, therefore they wouldn't change the outcome here. Also, I did A LOT of math on the side here not mentioned in this thread, as it would take lots more room.)
1765 lbs trumps 1651 lbs. Every time. This is because, regardless of gearing, I am pushing 330 HP at that RPM to your 305(IF you had a 2000 MY!).
See?
My 265/70/17 tires are 31.7" tall, which makes for a circumference of 8.29 feet. At 70 MPH they would be turning 743 RPMs.
4th gear on my TorqShift is direct drive, 1.00:1 ratio, which leaves the only gear reduction present at this gear would be my 3.73:1 rear end. Meaning the engine would be turning 2,771 RPMs at this speed and gear. Assuming 625 lb-ft at that RPM, would leave:
625 x 3.73 = 2331 lb-ft applied to the wheels. Adjust that for the 15.85" radius wheels, you'd have 1765 lbs of force pulling the truck and trailer up the hill.
Also, 625 lb-ft @2771 RPMs would equal 330 HP.
Now we do yours. For the sake of simplicity, I'm gonna use the same tire size for your van. Also, because I can't get specs as far back as 1999 on FTE, I'm gonna use the 2000 PI-head V10 for HP and torque specs.
So, 743 RPMs at 70 mph. With your 1.55 2nd gear and 3.73 rear end, that would put you at 4294 RPMs at 70 MPH. Which is just perfect for your engine, as your peak HP is supposed to be at 4250 RPMs. Also makes it easy to calculate torque.
305 HP @ 4250
HP = (TQ x RPM)/5252
Therefore, at that RPM you're making 377 lb-ft of torque. Remember that this is revving well past your torque peak, so this WILL be less than peak torque...but it's still pulling harder 'cuz of RPMs.
So, 377 lb-ft x 1.55 x 3.73 = 2180 lb-ft at the wheels.
Adjust that for tire diameter and you have 1651 lbs of force pushing the van and trailer up the hill.
In summary:
(disclaimer:All values here are ignoring driveline loss, which we can assume is reasonably close between transmissions, therefore they wouldn't change the outcome here. Also, I did A LOT of math on the side here not mentioned in this thread, as it would take lots more room.)
1765 lbs trumps 1651 lbs. Every time. This is because, regardless of gearing, I am pushing 330 HP at that RPM to your 305(IF you had a 2000 MY!).
See?
Torque and HP go hand in hand. You can have torque without horsepower, but only at 0 RPMs. Torque is MEANINGLESS without RPMs!!!
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
For instance, a pickup truck driving up a 6% grade, pulling a 14,000 pound fifth-wheel, at 40 mph. If you take the speed of the rear wheels, and the torque present at the rear wheels, those two numbers will give you a horsepower number. That is the actual horsepower present at the rear wheels. That is the actual horsepower necessary to perform the task.
I was down into first gear, 25mph. Truck was a '95 460 4x4 with Banks headers, cat delete.
Following year, same trailer, diesel truck this time, I only shifted down once and maintained 45-50 mph. Truck was completely stock at the time, no modifications.
Same trailer, same hill.
Only thing different was the truck pulling the trailer.
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
I can tell you from real world experience that a gas engine truck will not be going that fast pulling a load like that on a 6% grade.
I was down into first gear, 25mph. Truck was a '95 460 4x4 with Banks headers, cat delete.
Following year, same trailer, diesel truck this time, I only shifted down once and maintained 45-50 mph. Truck was completely stock at the time, no modifications.
Same trailer, same hill.
Only thing different was the truck pulling the trailer.
I was down into first gear, 25mph. Truck was a '95 460 4x4 with Banks headers, cat delete.
Following year, same trailer, diesel truck this time, I only shifted down once and maintained 45-50 mph. Truck was completely stock at the time, no modifications.
Same trailer, same hill.
Only thing different was the truck pulling the trailer.
JL
Senior User
Joined: May 2004
Posts: 407
Likes: 0
From: Humble, Texas
Axle torque, or by extension, tractive force, is only a part of the equation when choosing gears. One thing this thread has shown repeatedly is that the steeper the gear, the more axle torque. So 4.30's for a V10 and 3.73's for a psd are NOT the gears that will put down the most torque. They are the best gears to balance torque, reliability and fuel economy. If you do the math for each gear option, axle torque will increase as the gears get steeper but the penalty you'll pay in other areas will make those gear choices undesirable.
Maybe it's due to your age but it seems that everything is a race to you. If what you say about the 85 is true (and I'm not going to do the math to determine this) and I were about to re-gear a 7.3 with 4.88's, it wouldn't even be a consideration for me if it could only go 85. My F350 has NEVER been that fast, pulling or otherwise. There are a lot of other reasons not to put 4.88's in a 7.3, but limiting myself to 85 mph is not one of them.
Senior User
Joined: Oct 2005
Posts: 432
Likes: 0
as for examples, let's see: navi and ford fighting over who will cover all the warranty expenses, ford kicking navi to the curb and building in house, there thousands of examples covered there!
personal experience: cousins 03, warranty on turbo, head gasket, egr (this is a stock 2wd), friends 03 (never been back to dealer), cousins 05, head gasket and turbo, died on the streets, not even hauling a load, bone stock 4x4, cousins 07, you name it, it went back so much he traded it in, he could not deal with the lack of reliability (and he LOVED this truck, it was hard for him) my 01 V10, never for my engine, pinion seal and tach recal.
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Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
But I still don't think a V10 can keep up with a diesel pulling a big load like that.
Especially if the rear axle ratio is the same.
Thread Starter
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Modular motor junkie
Joined: May 2009
Posts: 6,190
Likes: 8
From: Texas
I towed a truck one day with the 460, towed it on the same road with the V10 the next.
The V10 is running 55 up hill, and stayed in OD on all but 2.
With the 460, forget OD, and on 3 hills, in had it down another gear, at red line.
The V10 E350 got 10 mpg and was 13,400 on the scales.
The 460 F350 got 4.5 mpg and was 11,200.
Lead Driver
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
Actually. the shear size of a locomotive's engine makes it totally unfeasible as a gasoline burner.
You can't have a huge displacement engine like that burn gasoline. It won't run efficiently, no way no how. You'd need a whole slew of much smaller cylinders, and the number of moving parts goes through the roof.
Diesel, on the other hand, burns slower. For a huge displacement cylinder, it can still be quite efficient.
On the other end of the spectrum, smaller displacement, gas burners make sense.
And has already been talked about, the Ford modulars are known to go 300K miles without major issues.
You can't have a huge displacement engine like that burn gasoline. It won't run efficiently, no way no how. You'd need a whole slew of much smaller cylinders, and the number of moving parts goes through the roof.
Diesel, on the other hand, burns slower. For a huge displacement cylinder, it can still be quite efficient.
On the other end of the spectrum, smaller displacement, gas burners make sense.
And has already been talked about, the Ford modulars are known to go 300K miles without major issues.
That is also why gasoline engines typically run more ignition advance then diesels, because it takes longer for gas to build maximum cylinder pressure.
Thread Starter
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Modular motor junkie
Joined: May 2009
Posts: 6,190
Likes: 8
From: Texas
So you would be ok running 75 with the red line being 85?
The thing about gearing is not rear end gear, it is ALL the gearing put together for what works best for the truck. With 3.73s, I can run second gear at 68 MPH.
With 4.10s, I would have to run third gear and I would put down LESS HP to the ground.
The thing about gearing is not rear end gear, it is ALL the gearing put together for what works best for the truck. With 3.73s, I can run second gear at 68 MPH.
With 4.10s, I would have to run third gear and I would put down LESS HP to the ground.
Postmaster
Joined: Jun 2006
Posts: 3,135
Likes: 0
From: Brinklow Md
you failed to mention that the T444E was de-tuned for that application, HP ranged from 184 to 238, less than the 275 offered in the PS. so, in order for the 7.3 to hold up, they had to reduce the HP output accordingly, so i get your point, turn down the HP to put it in a heavier truck, your right, the 7.3 is better????
1. You ALWAYS have to change filters every 10-15k that cost more than all 10 of my plugs combined that I have to change every 100k.
So you dont have to change any filters every 10-15k?
2. Yes, lets talk about the "ejecting" of parts. Or even the "blowing" or "leaking" or how about even the "complete catastrophic failure" of some parts....(that last one should be a Registered Trademark of the Ford Motor Company when used in reference to the "powerstroke diesel") Don't go there, you diesel guys have much more to keep up on than us gassers do, such as EGR coolers, head gaskets and variable vane turbo failures. Two of those little examples cost more to repair on your diesels than the replacement of a complete 2v v10 engine.
Your talking about the 6.0 motors, not all ford powerstokes. The 7.3 is one of the most reliable engines ever built. There are still over 2 million still on the road today.
If you would take a moment to go over to www.pickuptrucks.com and read the HD shootout test you'll see that yes, the diesel did start with a higher starting speed up a 15% grade with 10k behind it, But after a bit the diesel planed off and was stuck at one speed, the v10 was gaining spped at that point.
I cant get the link to work for me so I cant comment at this time fully
And I quote;
"Ford's F-250 and F-350 finally developed some unique performance patterns, even though they are using the same 5-speed TorqueShift transmission. But look at how well the V10 was running at the 250-meter finish line versus the V8 Power Stroke. Again the gasser was traveling faster than the compression ignition motor. The F-350's speedo barely inched up from 100-m to 250-m, while the F-250 gained over 6-mph."
Im assuming they are talking about the 6.0 or the 6.4 since the mention of the torqueshift trans,
This was going up a 15% grade with a 10k load.
I see PSD trucks on flatbed trailers DAILY. My v10 truck has never seen so much as a repair facility ever. Heck, I've only seen like 8 other V10 trucks period. PSDs are like a**holes, everyone has one.
How many miles on your truck? What do you use it for mostly?(just wondering, not for the sake of the argument.)
You said so yourself, there arnt as many v-10s on the road. You cant just go by the fact that you have seen more on flatbed trailers then v-10s.
there has to be a reason there are more PSD on the road hmmm....
HEY! I know another couple of things that diesels can do better than gas engines, and we wouldn't want to forget these;
1. leave you stranded often.
And how do you know this? do you have the numbers to back this up?\
2. cost you 2-5 times more to repair and service.
Possible, but they last longer so you can make up the money that way.
3. get you real friendly with wrecker drivers and service representatives at dealers.
Really? thats funny, the only service rep I know happens to be a LONG time family friend. I dont know any wrecker drivers and Ive had my truck for almost 3 years. Ill ask my dad if he knows any hes had diesels for 5-10 years and never had them towed so I doubt he knows any either.
LOL, it's all in fun right?
BTW: the truck in my sig gets 10-13 mpg.
Your makes me laugh too.
You have it in your sig that you think it will, why arnt you willing to bet? Ill take that bet any day.
You dont need to downshift at 70 with 4.30...I dont have to downshift at 70 with 3.73.
Postmaster
Joined: Jun 2006
Posts: 3,135
Likes: 0
From: Brinklow Md
So you would be ok running 75 with the red line being 85?
The thing about gearing is not rear end gear, it is ALL the gearing put together for what works best for the truck. With 3.73s, I can run second gear at 68 MPH.
With 4.10s, I would have to run third gear and I would put down LESS HP to the ground.
The thing about gearing is not rear end gear, it is ALL the gearing put together for what works best for the truck. With 3.73s, I can run second gear at 68 MPH.
With 4.10s, I would have to run third gear and I would put down LESS HP to the ground.
Fleet Mechanic
Joined: Feb 2007
Posts: 1,852
Likes: 39
There is no point whatsoever in comparing the rear-end ratios between diesels and gassers. They will be different by design, since the engines are so radically different. Diesels have 3.73's (typically) because the HP peak is so low in the RPM range.