OHV More Power

[Robin Hood]

What choices do you have besides programmers do we have to gain some power?

I've been seeing more things for SOHC and just curious what the OHV options are.

[Will]

Switch to a SOHC.

Getting more air into the chambers is the trick. Pretty limited choices on what to do. Headers and a good exhaust might help. There may be some advantage to getting rid of the flat pipe going over the radiator and getting a nicer looking air passage into the throttle body.

Having had a SOHC engine apart, it shows what needs to be done to get that 210hp out of a 160hp motor. The air passages are a straight shot into the chambers with a nice, big, round port. The lack of pushrods allow that, and the lack of pushrods and lack of heavy valve lifters also allows the motor a lot more rpm capability--it's hard to control a heavy valvetrain at higher revs.

[wahlstrom1]

You can do some head work, swap cams, add headers etc. It depends on your application. An OHV will work better in a towing or offroad situation as it developes it's torque at a lower RPM. The SOHC makes high RPM horsepower thats helpful for daily driving, racing etc. Buddy of mine on RPS runs 14.3 Na, 13.4 w/ nitrous with a 4.0L OHV in a 91' ranger in the 1/4 mile.

-andrew

[Will]

Well, if you look at the comparison--really the curves cross at 1600rpm, are parallel to 2000 and the SOHC leaves the pushrod motor in the dust. Below 1600, there's not much difference. If you tow at the Pushrod's torque peak of 2400--the Cammer makes 10ft# more torque there than the pushrod motor does. If you are pulling up to the next shift, you are revving it to 4,000 and the Cammer makes 20ft# more at 4,000. The Cammer is a better towing motor too. And the Cammer is just getting warmed up at 4000. The Pushrod plummets to its death and the Cammer goes like dammit for another 2000rpm. I like the Cammer better. Except, it's too big and too complicated for field overhauls. The Pushrod gets the job done but with much less zing.

[fordwheelinman]

More air in, more air out. Port & polish the heads, port match the upper to lower intake (if possible) and lower to heads. Headers, and some exhaust work. Could try some larger injectors, i.e. higher lb/hr rating than stock. A performance cam will also help the situation. Try some larger diameter plug wires, more current flow equates to more sparking current.

[shadetree]

http://www.moranav6racing.com/catego...?CategoryID=32

http://www.boosthead.com/product.php

shady

[jds3403]

home built turbo

[merc2dogs]

What's involved in an sohc swap?

Ken.

[AllanD]

Originally Posted by Will

Switch to a SOHC.

Getting more air into the chambers is the trick. Pretty limited choices on what to do. Headers and a good exhaust might help. There may be some advantage to getting rid of the flat pipe going over the radiator and getting a nicer looking air passage into the throttle body.

Having had a SOHC engine apart, it shows what needs to be done to get that 210hp out of a 160hp motor. The air passages are a straight shot into the chambers with a nice, big, round port. The lack of pushrods allow that, and the lack of pushrods and lack of heavy valve lifters also allows the motor a lot more rpm capability--it's hard to control a heavy valvetrain at higher revs.

The weight of the valvetrain isn't the only relevant factor to the power band and the inability of the 4.0OHV to rev, the cam timing (lift and duration)
are, but they were chosen to complement the intended use of the
engine, to actually move a TRUCK.

And while those big ports on the 4.0SOHC engine are real "sexy" that wasn't all of the change.... you should study up on the "lightweight rotating assembly" that ford switched over to in mid '97 (yes, on the OHV engines)

Granted the engine wouldn't rev without those big ports, but it wouldn't rev with ONLY those big ports... it would try to fly apart because the 4.0OHV isn't dynamically stable above 4900rpm.

The 4.0OHV engine was actually engineered to work well within
a very specific requirements. it does EXACTLY what it was designed
to do.

the 4.0OHC was designed for a different set of requirements
and it really isn't nearly as good a "truck" engine.

Of course if you are driving a truck as a "Fashion statement" rather than actually using it to tow or haul stuff you probably want the SOHC engine...

Frankly if I really wanted 215-ish hp instead of the 175-ish I supposedly
get from my Borla header equipped 4.0 I wouldn't bother with a 4.0SOHC, I'd put in a 5.0

Frankly I suspect a carefully tuned 5.0 with 3.55 gears might actually get better highway mileage than my 4.0 has with 4.10's

At one point before I put a 4.0 in my truck I was actually toying
with putting in a roller cam 5.8 and 3.27 gears...
My brother was actually tickling 20mpg with an F250 4x4 5sp on 33's
with an EFI5.8, I figuire my Ranger with 3/4 the frontal area and
the better part of a ton lighter could do better...

AD