OHV vs SOHC?

[slisdexia]

So I used to have a 98 with the 4.0, now I have an 03 with the overhead cams. It seems like the old one had more torque than the new one, at least right off the line. I also got 20-23 mpg out of the old one, now I get nothing but 18 mpg. ?? I put an exhaust and throttle body spacer on(looking for more power), but from the assdyno, nothing has changed. It also seems like the new 4.0 is a racier motor. Nothing until about 3000rpm, then it decides to get after the business. How can I get some torque again? Help! I don't want to race the thing, just some mild off roading, and some work, I need some power down low. Any charts that compare the two motors?

How do I tell what axle it has in back? Or front?

 

[Ranger44]

Over head cam 4.0's are high rev engines...there is really no way around it. No bolt on will change that. As for your axles, the front will be an IFS D35 and the rear a 28 spline 8.8. My only advice is to use low range more often to make up for it.

 

[85_Ranger4x4]

Do you know what the two trucks have for gears? My parents have an '02 4.0 Exploder that gets 21 mpg and is pretty spunky, it has 3.73 gears. Our old '94 with a 4.0 and 3.27's got about 16 and topped out at about the speed of smell. Technecally it should be faster than the newer one but the darn hills send it grabbing for gears.

 

[Wicked_Sludge]

the speed of smell.

all OHC engines tend to be much higher revving than their OHV counterparts.

the OHV makes peak power at about 4200 and peak torque at 2400. the OHC makes peak power at 5250 and torque at 3000.

 

[AllanD]

The SOHC engine actually makes 40ft/lb more torque than the OHV engine, you just have to look higher in the tach scale to find it.

I've said it over and over, people talk about wanting mmore power when what they REALLY want is more torque and they want it lower down...

They just don't KNOW that's what they really want....

The 4.0SOHC's can actually get "acceptable" mileage, provided you didn't get stuck with one of the many trucks that got built with 3.55's or even 3.27's

I've HEARD that the 3.73 trucks are "ok" but that on long highway trips
a 4.10 geared SOHC when CAREFULLY driven can do better...

AD

 

[Ranger44]

Yes, you could do a gear change....

 

[woodyedmiston]

How do you tell?

Jack up the tire. Rotate the wheels one turn- by hand. Having previously placed a mark on the drive shaft count the number of revolutions it makes. The final fraction will be about 1/4, 1/2 or 3/4 of a turn. Therefore you will get 3+1/4, 3+1/2, 3+3/4 or 4+amost 1/4 - that should tell you - with a little Kentucy windage - about what your final drive ratio is.

 

[AllanD]

Woody,

there is no excuse for anyone on these forums to have to resort to
ancient methods for measuring the axle ratio.

the Codes are all well known (open the drivers door and read it)

OR it can be read in plain numbers on the diff ID tag.
(though you gotta crawl under the truck with a flashlight)

AD

 

[gw33gp]

At 1000 to 1500 rpm the OHV engine has from 3-5 lb-ft more torque than the SOHC. At 1600 rpm they have the same torque and after that the SOHC engine holds the bragging rights for have higher torque all the way to 70 lb-ft more torque at 5,000 rpm.

This information comes from the published SAE net power ratings from Ford.

 

[Will]

The maximum torque advantage is about 15ft#. The maximum horsepower advantage is about 45hp. The SOHC is a rip snortin breather compared to the pushrod motor. I don't like all the timing chain tensioners and the fact that I don't posses the ability to reset the cam timing if I even needed to. And I've pulled both motors out and the pushrod motor is a hell of a lot more compact. The SOHC is HUGE due to the heads.

 

[95offroadx]

^^ that is horsepower at the crank

dude id say the 4.0sohc is as much better power,

the 4.0ohv when dynod stock is between 120-130whp, and 170-190lb/ft
the 4.0sohc when dynod stock is between 165-180whp and 200-210lb/ft

But still if you want more power like i do, get a asp crank pulley i hear great things about them.

 

[slisdexia]

Thanks for all your help. And you're right, torque, not power. As for gears, I can, and will eventually check the new truck, I have no idea about the old one. I'd assume whatever it came with from the factory, as the people seemed to be more interested in just driving the thing. Wish I could get it back. Again, thanks for all your help.

 

[Will]

^^ that is horsepower at the crank.

That J1349 rating is the industry standard--the engine is put on the dyno with everything on it exactly as it is installed in the vehicle. The chassis dyno is convinient, but it is no more valid than the J1349 when comparing 2 vehicles that are otherwise the same.

Don't put on a crank pulley. It slows everything down. On the trails when you are basically idling for hours your battery will run down, your truck will overheat and your power steering will be weak. You aren't going to maek any extra power anyway because you aren't going to be spinning your motor fast enough for a long enough period of time for accessory speed to matter.

 

[Will]

all OHC engines tend to be much higher revving than their OHV counterparts.

the OHV makes peak power at about 4200 and peak torque at 2400. the OHC makes peak power at 5250 and torque at 3000.

It only looks that way. In the case of the SOHC motor, the horsepower of the pushrod motor wasn't competitive. The heavy valvetrain limited the speeds they could spin it at. It actually has decent port sizes. Getting rid of the heavy valvetrain, plus the benefit of not having the pushrods in the way of the port design, let them engineer the motor to spin. They could grind a camshaft for that motor that would whip the pushrod motor anywhere on the rpm scale. In fact, it whips the hell out of it everywhere but at an rpm so low you only see it once per time you drive it. Towing, the SOHC motor is much better. Watch your tach and see how often it falls below 1600.

Driving my 4.0 B2 with an M50D, I shift at 3,000rpm. Going from 1-2 the engine drops to 1,800; from 2-3 it drops to 1,900; 3-4 to 2,300; 4-5 to 2,400. Where is the pushrod motor showing its low rpm supremecy? It's non existant. The SOHC motor is better in every way.

Especially if you ARE towing something. When I'm towing something heavy I shift at 4,000 for the first couple of gears because it keeps the motor in a torquier gear longer for better acceleration and the shift points drop close to the peak torque for better pull in the next gear. The SOHC motor has a clear advantage at that 2,400rpm release in second and pulls harder up to the next shift point--something like 30ft# more at 4,000.

 

[Twizzler09]

something we are forgetting though, is that the Rangers that run the SOHC Motor are inherently about a 1000 lbs. heavier.

Acording to most of the information I've looked at, the newer Rangers all seem to weigh 5,100 pounds up to like 5,300.... the Rangers that ran the 4.0 OHV Motor weigh around 4,300. My '96.. its tag says that it weighs 4,369 pounds.

The extra weight of the SOHC Rangers fairly negates most of the power advantage. As a matter of fact, if I'm remembering correctly, Ford says that my Ranger is capable of hauling 7,700 pounds off the ball hitch, assuming I had one strong enough for that.

Look at Ford ratings for towing on the newer Rangers, they aren't that high. mid 6,000 range at most. (this is of course, assuming I remember correctly)

Quote Ford's website (2008 Ranger): "Class III Trailer Towing is available for select Ranger models equipped with the V6 engine, allowing towing up to 6,000 lbs (properly equipped)"

All this put together tells me one thing, the new motor might crank more power, but the truck's increased weight keeps it from properly utilizing it.