Yes, the new 4.7 is only 5 lbs short of the last version of the 318,
however, what could the 318 have done with the additional mods the 4.7 got?
(thereby picking up that half liter you refer to)
Realistically, the very thing that limits the pushrod engines in RPM's is
the same thing that gives them good torque. The additional mass in the valve
train means the engine 'lugs' better than an OHC engine. Having experince
with single and dual OHC engines, and comparing them with a pushrod engine,
when you're down in that lug mode, I'll take the pushrod any day of the week.
Also, look at the RPM range the OHC engine's get their maximum torque in, it's
almost always higher than the equivalent pushrod engine. Now these are just
general observations and I'll take an OHC engine for reliability as you have a
less complex and more efficient valve system. Having to pull boats and other
things (especially on those slippery launch ramps), I prefer my power down
low. If I had to wait another 500 to 1000 RPM's to get my max power, it
breaks the wheels loose and mangles tires. I will admit, there comes a time
when the Torque an HP is so high that it's irrelevant if the engine is pushrod
or not. At that point, I'll take the OHC for it's wider RPM band and higher
reliability.
For a "work" truck the pushrod engines are just fine. I also like the cast
iron engines more than the aluminum ones, they can just handle more abuse. I
really wish they would've just kept the 318 & 360 and offered OHC/DOHC (Magnum
II?) options on them. They can plug up the pushrod holes with no problems.
This is an aftermarket mod that is available on the 318 & 360... When you do
that do them their numbers jump WAYYY up on both HP and Torque, but the Torque
ends up higher on the powercurve. (I think someone on the list has a 318/360
modded this way)
My point is, there's not much room left on the 4.7 to improve it (a good
thing?) whereas the older engines could've kept going forward. I certainly
wouldn't put NOS on a 4.7, and a single turbo might be max. Too much
compression increase and that steel sleeve will disintigrate or do nasty
things to the aluminum block. The real reason DC seems to have gone this
route is because they can capitalize on a whole new set of parts and also
create an engine that won't last as long as the cast iron ones. They have the
added benefit of saving weight and increasing fuel economy with aluminum.
Personally, I would've just updated the 318 and 360, but I can understand the
persuit of money. Trucks were one of the last bastions of long lived
vehicles. Now that they are trendy, the last thing a carmaker wants is to
sell a vehicle that has almost twice the lifespan of it's regular car line if
everyone is buying them as regular cars...
If it was just a question of OHC to Pushrod... well, it's a toss-up and
really depends on your application. The problem is, we lost engine size as
well, and in the end, that's what really hurts... as the saying goes: there's
no substitute for cubic inches! (or even: SIZE DOES MATTER!)
Shaun H.
---original message---
Hey Shaun,
The 4.7 produces 295 ft-lbs compared to the 318's 300. That's pretty damn
good IMOH since t's giving up half a litre in size. These numbers are stock
so maybe you're talking about after modding you won't get as much torque.
But if you use your truck for "work" then you probably don't want to mod it
because you need the reliability.
I was a little worried about getting the new engine as well, mostly because
it is fairly new and i was positive that i could rely on it for "work". But
i got the stats on the 4.7, and it's lighter and more fuel efficient, and so
far it's been proved to be quicker.
So, please clarify what you mean by getting more torque out of a 318 than
you can out of the new 4.7.
Frank WJ
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