That is true too, but you also have to remember that while going with a taller gear will allow it to stay in a lower gear longer, it also reduces the amount of tq it puts to the ground. Without running the numbers, I'm not sure what they would be. I am just giving my input on both types of trucks, both having 4.10 gears and both having the same tranny gearing since that is what is sitting in my driveway.

My 5.4 and 7.3 are pretty close in peak and I have ran them against each other every way you can imagine. At the same rpm in the same gear, it's not even close. The 7.3 comes out ahead any way you look at it. From a dead stop, my 7.3 will pull the 5.4 off the line like you wouldn't believe. The problem is, my 7.3 only turns half the rpms as my 5.4(they have the same rear/tranny gearing), so it can only do half the speed in the same gear. By 12 mph, I am redlining 1st and hitting 2nd in my 7.3. My 5.4 holds 1st until 25 mph. From 0-12 mph, the 7.3 runs off and leaves it. But from 13-25 mph the 7.3 is in 2nd gear and putting less tq to the ground than my 5.4 that is still in 1st gear.

My 5.4 will hold 2nd until about 45 mph. My 7.3, only about 23 mph(yeah, I am already shifting to 3rd in my 7.3 while my 5.4 is still in 1st). That is a huge gearing advantage for my 5.4 and helps it make up ground and pull ahead pretty quickly. At 55-60 mph in 5th gear my trucks are turning 2,000 rpms(peak tq for the 7.3). If I floor both of them, the 7.3 runs off and leaves it. But the problem is, my 5.4 is nowhere near peak tq. I would have to downshift to 3rd to do that. When I floor them then, the 5.4 runs off and leaves it by a mile(more hp, more tq to the ground, better gearing). If I downshift my 7.3 to 4th, it still won't accelerate as good as my 5.4 in 3rd. I could downshift my 7.3 to 3rd too, oh wait, no I can't, because it won't do 55 mph in 3rd gear.....

 

Yup, better than most cummins guys attitude

 

Yeah, the taller gears will put less down, but the engine has more to give. So in the end, they are some what balanced, the V10 with it's 4.10 or 4.30 and the PSD with a 3.31 or 3.55. That's why it really isn't fair to compare the two engines with the same rear end, each needs a different rear end to make the best use of it's engine.

 

You got to remember, one of the huge selling points for the diesel was that diesel fuel used to be so much cheaper than gas. Unfortunately, that edge has been taken away from us. It costs more than gas, and many of us add some type of additive to it, making it cost even more at each fillup. Also, the BTU's in diesel is lower than it used to be, affecting mileage and power in a negative way.

I'm just waiting for the day when they start building gas engines for semi trucks.

 

The BTU per gallon of diesel is still far higher than that of gas, but yes it has decreased.

LOL... I think we'll be waiting quite a while for the gas semi.

 

Whats the grade and elevation?

 

They might, after they put light duty pickup diesel in a class 8 truck.

 

Ok, let's compare them with 3.55's vs 4.30's. From a rolling start with both doing about the same speed and both at peak tq. Both have a zf6. To get them doing the same speed the psd will be in 4th gear(1.0 gear ratio and 3.55 final drive ratio) and the v10 will be in 3rd gear(1.3 gear ratio and 5.59 final drive ratio). The psd will be turning 2,000 engine rpm and 563 wheel rpm (2,000/3.55=563). The v10 will be turning 3,250 engine rpm and 581 wheel rpm (3,250/5.59=581). At 2,000 rpm the psd makes 650 tq at the crank and 248 hp. At 3,250 rpm the v10 makes 457 tq at the crank and 283 hp. Tq to the ground is as follows.

248 hp x5252/563 wheel rpm=2,313 for the psd.
283 hpx5252/581 wheel rpm=2,558 for the v10.

Just for fun let's try 4.10's in the v10. That would be 283x5252/610 wheel rpm=2,437 for the v10.

Looks to me like the v10 is making more hp AND putting more tq to the ground(pulling the load easier) and doing it with 200 less tq at the crankshaft. And to top it off, it didn't have to go screaming up the hill at 5k rpm like most have been arguing. All it had to do was downshift one gear and turn 3,250 rpm.

 

Damn,it's hard to argue with math isn't it. You actually get it. Several of those in the "argument" don't.

JL

 

Interesting analysis. Now if the V10 drops 2 gears...

Although I have tot admit, the difference is only about 10%, which can be lost or gained through many different variables. Heck, the engine might even be +-10% on its actual power output form the factory.

 

Don't get me wrong, I love my diesel, but I will give credit where credit is due and one area that the v10 is not lacking in is pulling power. I have said many times before that my only complaint with the v10 is the mpg's.

 

This thread is getting pointless....So I'll add more to the rant.

I am an advocate of DIESEL technology. I only wish I new more.

Advantages over GAS

Runs LEAN mixtures. This means less fuel.
BIO fuel READY. Who else can say there truck is burning the poop created by Algea?
Easily tuneable. Upwards of 150-350+ HP and 500lbs of TQ from a TUNE. Not counting Nitrous, CNG, Propane (Not recommended).
Diesel TRUCK motors are built with heavy dutier components.
High compressioon ratios are DIESEL. Higher compression equals higher energy...
With the right air intake....you can even run it underwater.
A heavily modified Diesel truck has much better street manners in comparision to a GAS machine making the same power. I'm talking over 500HP here.
Turbos were desiged for DIESELs.
Gas is a solvent. One teaspoon will contaminate 100,000 gallons of water. Oil...just floats. Look at BP. Think you can clean GAS outta the gulf?
Diesel is being used by the Navy in Jets...I'm not aware of any 89 Oct Jets are you? Seriously? I'd like to know.
HP and TORQUE is readily available at LOWER RPM. Who wants to hit 4500RPM anyways to meet max Horsepower?
Vehicle Specifications and Options - Ford Commercial Trucks

6.8 Horsepower 362hp @ 4,750RPM
Torque 457 lb.-ft. @ 3,250RPM
6.4 Horsepower 350hp @ 3,000RPM
Torque 650 lb.-ft. @ 2,000RPM

Granted, I am only looking at Ford and the Scorpion Diesel isn't listed which is why I reference the 6.4.

How many gas fed Freight liners do you see going down the highway at 80MPH?

 

HAHAHA... mpg on the V10 is great. I got 9.7 mpg this winter driving stop and go with the front hubs locked all winter, plus winter gas never helps, and having a V10 run for 20 minutes to warm up for my 4.5 mile adventure to work also does wonders for your mpg. But even then, I was still only using 1 gallon of gas a day where as my friend with a Hybrid Prius was using almost 4 gallons a day.

 

I believe it's 6 to 7% and goes from 7,000 to nearly 11,000. I could be wrong on the lower elevation, but I'm fairly certain it's 10.5+ at the top.

 

11,000' is why your 6.0 can out pull a 3V V10 up that pass. A N/A engine drops 3% of its HP every 1,000'.

At normal elevations, look at the math Josh did.