OK. I have been very critical of the 4.6L in my ’06 F-150 Screw. No guts. Can’t tow squat. I had a chance to do some more towing over the weekend, down to Austin and back. About 400 miles round trip. 1300 lbs. flat car trailer empty going down. <4000 lbs. coming back up (added a mint 1960 Falcon). Pretty good head wind going down. Tail wind (of course) coming back.

The trip started out just about how I had expected. The truck could not maintain 70 mph without constantly downshifting. No hills to speak of, just rolling terrain. What a joke. I had to lock out O/D. This is with just 1300 lbs. and no added wind resistance. The truck did hum along nicely at 70 mph, turning about 3000 rpm. But MPGs got shot all to hell.

Coming back, I started out with O/D off, and kept the speed at around 65 – 68 mph. The truck did well. Turning about 2800 rpm. Strained just a bit going up a couple of hills, but did not downshift. Actually was able to speed up a little to pass a couple of bottleneck cars. Can’t complain too much. But on flat ground, wind behind me, running under the posted speed limit and only towing <4000 lbs., I should not have any complaints with a big honkin’ American-made V-8 built Ford tough pickup.

So I did a little investigation, and I think that I understand a little better now. At 70 mph in O/D, the engine was only turning about 2000 rpm. 3.73 rear end. Obviously tuned for gas mileage, not towing. Peak HP (231) in the ’06 4.6 occurs at 4750 rpm. Peak torque (293) at 3500 rpm. Sorry, but at 2000 rpm, that motor just has no guts. You are not going to tow anything in O/D with that motor. 4.10 gears would help, but are not available.

For ’07, Ford upped the HP (17 hp) and torque (1 ft-lb.). So maybe the ’07 will tow better? While I applaud any HP and torque increase, Ford went the wrong direction on this one. Peak torque now occurs at 4000 rpm. My bet is that the ’07 4.6l is even more of a gutless wonder than my ’ 06.

Now I know that the 4.6 in the Explorer has much higher HP (292) and torque (300) ratings. So I have loudly criticized Ford for not using this motor in the F-150, until I checked the specs on that motor. Peak HP occurs at a screaming 5750 rpm. Peak torque occurs at a whopping 4750 rpm. No wonder Ford doesn’t use this motor. You would never get it out of 2nd gear.

I know what you are going to say. If you want to tow, get the 5.4. But Ford rates my truck at 6500 lbs., so I don’t think that a <4000 lbs. trailer should offer that much of a challenge. Also, the truck ought to be able to pull a 1300 lbs. trailer empty, on relatively flat ground, in O/D. At 6500 lbs., I don’t think that the truck would even get out of 2nd gear towing (except maybe going downhill).

Just for kicks, I checked out the specs on the GM and DCX baby V-8s (4.8 and 4.7, respectively). Peak HP (235) and torque (300) on the DCX 4.7 occurs at 4800 and 3200 rpm, respectively. So the DCX motors looks like it might have a few more guts.

The peak HP (285) and torque (295) on the GM 4.8 occur at 5200 and 4000 rpms, respectively. So this motors looks even more gutless than the Ford.

I guess that I am just spoiled by my diesels. Pulling 10,000 lbs. at 68 mph, O/D on, turning about 1900 rpms, up and down, in and around. No muss, no fuss. No offense, but that's the way to tow.

BTW - My diesel at 1900 rpm is quieter than my 4.6 at 3000 rpm.

 

I keep hearing how all these new mod motors make their power so high up in the RPM scale as to make them worthless. Makes me real glad the dealer and I couldn't agree on the 97 F-150 with a 4.6 I was looking at. The truck I have now will pull anything I need and it rarely has to go higher than 3k rpm.

 

These small gas V-8's are tuned for EPA mileage tests (empty) and for "bragging rights" about peak hp and torque. This works well for selling trucks that most people just commute solo in.

My old 1993 V-6 Chebby had more "guts" than the 1994 V-8 Ford because the TBI 4.3 GM V-6 had a torque peak at a diesel-like 1900rpm. Both trucks had similar gearing (3.42 vs 3.55), yet the Ford felt like it needed 4.10's. Both had 4-speed automatics and the same tire size. Surprisingly, the 4.7 Toyota Tundra V-8 that you would think falls short like the others does not. Two reasons, 3.9 standard gearing and variable valve timing, which advances and retards the intake cams, resulting in a "flat" torque curve. It can be done right, but the Big 2.5 would rather sell you a diesel for $5-6k extra if you really need to tow or haul anything.

Jim

 

But that's not a big honkin truck - F350 scab 4X4 w/V10- now that is a.....

 

Not according to Toby Keith.

I have the baddest Hombre out there. End of story.

 

Toyo is 271 HP at 5400 rpm.

313 at 3400 rpm.

So a little more torque, delivered at the lower end of the scale.

 

You should always have the over drive off if your towing. I always do get along fine. Its counterproductive to leave the over drive on. Harder on your transmisssion an engine. Lower gears in that truck would make for a much better tow rig. Over drive is fine if your pulling no load an the terrain is not realhilly.

 

This has been an on-going debate. If you are of the no O/D school. Fine. Won't hurt a thing. It's your gas going out the tailpipe.

But my diesels run all day and all night, pulling 10,000 lbs. and never shift once. That ain't hurting anything either.

 

When I had 3.73s in my truck, I towed my 7200lb camper with OD and without and found I got a little less than .5mpg better in OD than out of it. The difference was about 7 vs. close to 7.5. Now that I have 4.30s, I haven't found any difference at all. I now get 9.5 towing with or without OD. Even though the engine is revving faster, I feel like it's not working as hard. It's kind of like riding a 10 speed up a steep hill. You will pedal slower in 10th gear but may not make it all the way up the top. In first, you will pedal much faster but be able to make it all the way.
These engines are designed to run at higher rpms. and it won't hurt them.

 

All other things being equal, in a higher gear, (like OD), the engine rpm will be lower, but more gas will be injected for a given load. If the gear is reduced (say out of OD), the engine revs up some, but the amount of gas required to produce the higher rpm is about the same. This neglects the slightly higher friction losses of the higher rpm. The fly in the ointment is where those rpm's fall in the torque band. If by going to OD, you drop out of the ideal rpm/torque range, gas mileage will suffer. If the rear axle ratio/tire size is such that in OD the rpms are closer to the best torque rpms, gas mileage goes up.

It's all a trade off, see mu comment in another thread about axle ratio, tire size, etc:
https://www.ford-trucks.com/forums/5...w-power-4.html

 

Agreed. That is why I like to run my CTD at around 1800 rpm. Runs right at 68 mph and pulls like a mule. MPGs are near peak.

And all the more reason for Ford to offer a 4.10 in the F-150. Even with O/D off, and traveling at 65-68 mph, rpms were only 2800, but max torque is not until 3500.

To get to max torque with the 3.73, you would have to get down into 2nd gear.

I do disagree to the comment that the higher rpms do not hurt these motors. Maybe no in the short run, but running 100,000 miles at 3500 rpm wears the motor out more than 100,000 miles at 2000 rpm. Just multiply out the differences in piston travel alone.

Also, let's not forget the noise. Sitting in a truck for 12 hours at a stretch, it's very tiring to have the motor whining away at 4000 rpm.

So all things considered, I prefer to run at the lowest rpms that does not produce a lot of transmission hunting.

 

[QUOTE=jschira]Agreed. That is why I like to run my CTD at around 1800 rpm. Runs right at 68 mph and pulls like a mule. MPGs are near peak. /QUOTE]

If the CTD your refer to is a Cummins Turbo Diesel truck that you own why would you even want to pull a car and trailer with a F150 4.6L and 3.73 gears and not the stronger truck?

 

I own the CTD. The F150 is leased and I am way under on the mileage.

Besides. Pulling a 4000 lb. trailer 200 miles across flat ground, with the wind behind me, should be not any real challenge for a Build-Ford-Tough F150 V-8.

Should it?

 

Are you saying "The truck did well" or it was a challenge?
The 4.6 is made for mileage but you can tow with it. I bet the manual says to lock OD out if it starts changing gears excessively. I wish my dually with a 4:10 rearend got the mileage unloaded your 4.6 gets. Different applications for different truck combinations but I would not call the 4.6 a big honking American made truck. It is what it is. A small V8.

 

Worse mistake in ford history (next to the pinto) was deleting the pushrod motors. Bill jr. Is an idiot. Maybe the new CEO will have a better vision for ford in the future.