Hello,

I'm looking for a tow pig with the V10 to tow a 5th wheel down to the coast maybe 6-10 times a year. It will not be my daily, I have a 2024 Lightning for that.

There is not a lot of aftermarket support for these engines, given the split-pin crank limits HP production, of course, there are the PI heads if you have a 99 down. And intakes/cat backs, plus tuning.

I figure these things have enough power to tow well as-is anyway, if they are geared properly to put the engine at an RPM at 65-70 where it is producing at least 80% of peak torque. I'm figuring when I find the clean, well cared for truck that I want, I will go ahead and change out the rear end gears.

Looking at the Dana/Spicer RPM calculator,
https://spicerparts.com/calculators/...rpm-calculator

A 4.88 gear, with a 31.5 inch (stock 17" tire) height, and a .71 final drive ratio, puts you at 64.94 MPH at 2400 RPMs, and 70.35MPH at 2600rpm. To me this seems about right to tow say 10K lbs with the V10, given the torque curve. Goals are to have good acceleration and to minimize downshifting on the freeway. I want to tow in the 65-70 range, probably biased more towards the 65 mph side of that, with the ability to speed up a little if the conditions demand it.

Given this will not be my daily, I don't have to make compromises around wanting reasonable RPM at 75-80 on the local toll roads.

Am I off here?

Some of the older towing charts, list gears up to 5.38 gears for the chassis cab Super Duty V10s. That seems a little extreme for highway use.

 

Yes 4.88 with a 31 inch tall tire is a little to much gear. Now 4.88 with a 35 inch tall tire is just about perfect. It works very well with 99-04 V10s with the 4R100 trans. I will recommend taking a look at 2012 - 2016 with the 6.2 with the 6R140. My son and I installed 4.56s in his 2013. When he keeps his foot out of it he gets a solid 12mpg vs my solid 10mpg on the toll roads.

 

My 2000 V10 DRW with 17" tires and 4.30 gears pulled out 16K 5th wheel all over the country without any problems. Would 4.88 have done a better job maybe but the rpms would have been a problem for me.

Denny

 

I have a 3/99/V10/auto,4x4 ,cc, 3.73 truck, with 285 tires. last good long haul was pulling a 24' cargo weighing an estimated 8000lbs across the US. My observations. #1, no way could I use O/D, unless going downhill only. #2 bucking a headwind of 20/30 mph Id estimate I was lucky to hit 55 and get 6mpg, good flat with no wind 8mpg. Truck is original and stock, free flowing exhaust stock muff, capiche?, no codes, runs smooth as can be, and empty gives 13 mpg. A few have said the truck has something wrong with it and should do way better, dunno??. Ive put 40K on it in 3 years and it never throws a code or skips a beat. Yeah, its a V10 but its only 415CI, what the heck you want is my thought. Now that dodge V10 I had, it ripped like cummins without the clatter....but of course it fell apart like a good dodge. LOL.

 

My 1999 F-53 has a 5.38 differential and is about 17,000 pounds empty and 11'11" tall at the air conditioners. With just the motorhome, a few passengers, and some clothes and food, it is in and out of overdrive on rolling hills all the time, probably 50/50, with no wind and nice weather. Overdrive on flat or downhill or very-slight uphill, 3rd/direct when uphill is steeper than slight, but not steep enough for 2nd. Add a dinghy and/or altitude and/or heat and it spends more time out of overdrive.

My math says a 6.14 would be a good compromise, and it would probably stay in overdrive most of the time, even with a dinghy, and 3rd/direct wouldn't rev too much at 65MPH when it is needed. A 7.17 have it at about 4,950RPM in 3rd/direct at 65MPH and 4,570RPM at 60MPH, which would both be too much for my taste.

The reason I say all of this is that at 65MPH in overdrive it is at about 2,550RPM. At 60MPH it is at about 2,350RPM. Right next to your 4.88 numbers. Both are not loud and doesn't sound like it's stressed. It sounds like it can do that all day and night and day again if it weren't for fuel stops and bio breaks. I usually keep it at about 60 or a little more just to save gas. This is worth almost 1MPG on flat drives versus 65MPH, but exacerbates the downshifting as I'm lower in the powerband.

For reference: My F-53 is a 32' Southwind, dragging two air conditioners through the air on top, and otherwise the usual stuff. It has a Spicer S135 rear axle (hence the available ratios), and 245/70R19.5 tires.

Depending on the weight and height of your 5th-wheel, I think you'd be happy enough with a 4.10 or 4.30, but anything taller would make you proportionately sadder. I think the shortest you can go on an F-350 or F-250 is 4.88 . In my opinion the engine would be perfectly happy, and would turn at pretty much the exact RPMs that my F-53 currently runs at. Let's say your truck is 8,000 pounds empty, and you have 9,000 to 15,000 pounds of 5th wheel + stuff + people, you'll perform just like my motorhome does right now with a dinghy + stuff + people. It's a little slow from a stop, but otherwise fine. If you get one with PI heads or 3-valve heads, you'll be that much better off.

 

PI heads were 2000 and up, not 99 and down.

 

I drove a 99 f250 v10 for several years. It was a great truck but it was gutless. It only had 275 hp and 410 lb/ft of torque. That is not much for a 7k lb truck.

My next truck was the 3V V10 in my 2007. It was leaps and bounds better with 365 hp and 457 lb/ft but always disappointed in empty mpg.

My current truck is the 3.5 in a 2022 F150. I would love to see how the 3.5 performed, and lasted, in my old f250's. It is a torque monster at 400 hp and 500 lb/ft.

Conversely, it would be really cool to see how my 3V V10 would do in the F150. That truck weighs probably 1500 lbs less.

 

It is amazing how far opposite the V-10 and the 3.5EB are from each other in specs, performance, and behavior.