Everything you say is correct and has been hashed out in the past. I, along with a few others are wrong, Ford went with the 3V.............BUT, imagine taking the same VVT technology and applying it to the already bought and paid for 4 valve heads. (remember, the DOHC heads are around 13 years old!!)

IMO the 3 valve VVT head is about where the OLD 4 valve head already was. I would have to imagine the new castings and design were very expensive. Would rather have seen Ford refine the current DOHC, like Nissan and Toy/Lexus then spend millions more on a whole new design........In an ironic twist, this has always been Ford's down fall when trying to garner any aftermarket support.........always changing stuff.

 

I'm a fan of the Nissan Endurance 5.6. They started off with a clean sheet, used some ideas from the proven VQ series, and came up with an excellent powerplant. Good power, refinement is there, and I've heard it is very solidly built. We'll see how it is doing a few years down the road but I don't anticipate any major problems.

I thought the reasoning behind Mercedes' use of 3-valve heads was for emissions, as it allowed room for two spark plugs per cylinder. They got good power out of it but they can get good power out of almost anything.

 

so far the mod engine has been a proven engine. it runs and runs fleet companies love them because of the low operating costs. there is plenty of modualr engines pushing 300k and some pushing 350k there is a member here who has one. lots of the original v10 engines in e series vans have well over 300k. i would like the other 2 engines to prove themselves as durable. i have driven both while they have more power i don't know if it is reliable power. the biggest problem dodge has is transmissions they only last about 30k.

 

OHV has the crank turning the cam, which moves the lifters, which moves the pushrods, which then move the rocker, which open the valve.
OHC has the crank turning the cams, which move a follower (smaller and lighter than a rocker arm), which open the valve.
There was a PHRTV episode about that a few years ago. I've built both types of engines, OHC engine has less parts in the valvetrain.

 

Ok, OHC has the crank turning 2 or 4 cams.......then there is also preload type hydraulic plunger that acts like a lifter (keeping tension on the rocker or follower if you will) which then acts on the follower which then opens the valve. We must not forget 2 chains creating friction/heat (unless it's belt driven like a Toy motor)


Now, in theory a multi valve motor will have smaller valves with lighter valve springs but again there will be double to deal with.

Nope, OHC does not have less internal friction than a roller tipped push rod motor. And your "less rotating mass" comment is waaaaay off. OHC has 2-4X the cams turning, 1 or 2 more cam sprokets and 4-6X's more chain lenghth

I would ALMOST accept your explanation when talking about an OHC motorcycle engine that uses shims(no preload or rockers on most).........but an automotive motor we'll just disagree

 

Just what I've always wanted, a belt driven 4 valve high maintenence motor. did you forget about GMs 3.4L DOHC 24 Valve motor, or the imfamous quad four, both had great power and both were a complete PIA to do anything to. It was recommended to have the timing belts changes at 40k, that was $400-$600 depending on where you take it every 40K miles. I couldn't hardly find any one to work on my quad four. and the 3.4L V6 sure cost me a chunk of change when I had to replace the alternator, that was another $600 bill. I back ford for staying with a single chain driven cam and 3V heads as they are reliable, have less parts, and are no more maintenence than a 2V mod motor. I do have to say that the 3.4L was impressivly fast for its size though, I even managed to take down my buddies 99' Grand Prix GT, It was close but he was toten a little bit bigger motor and 60k less on the ticker.

 

Forgot to mention if you don't maintain those timing belts and one fails while you're driving the parties over. you might as well plan on spending a the very least a few k for a on a reman.

 

http://www.cartalk.com/content/colum...8/July/03.html

That will help you to understand. If you have any links to show that OHV is more efficeint, please post them.

 

This is probably a stupid question, but am i right when they say SOHC on a v-configured engine that actually means 2 cams because each head has one cam? And dohc is equal to 4 cams?

 

yes you are .

 

LMAO!!!! YOU HAVE TO BE KIDDING ME!!!!


If you base ANY of your expertise on Frick and Frack, you have much learning to do!!


First off, Ford uses rockers, or as you like to call them "followers" on both the SOHC and the DOHC motors. In other words the cam lobe DOES NOT ride directly on the valve stem on the DOHC motors. I even mentioned that to you on DOHC motorcycle engines.......and yes, some of the old europeon DOHC's used shims for adjustment but unless you want to adjust valves every few thousand miles you have to use a hydraulic pre-load (like a lifter) that acts on the end of a rocker (follower if you want)

They do mention less friction which I will argue when put up against a roller lifter/roller rocker pushrod motor. Flat tappet I will 100% agree with you on the friction part.

They/you are wrong on the "rotating mass" that you originally stated. You are now just arguing to save face. You're too smart not to realize there is 2-4X more rotating mass on an OHC motor........if you don't understand, you're just being stubborn.

Please re-read your own link, they also state a SOHC has "slop" which is hilarious because the DOHC uses the same system to activate the valves!!!


Did I ever say a pushrod motor is more efficient? NOPE!!!

What I did say was that OHC was a better way to control valve train at higher RPMS...............just like your heros did. I also will say OHC can make for a cleaner chamber and port running because of no pushrod holes.

But let's take a look at the current offerings by GM and Chrysler......all pushrod V8's that rev as happily and reliably as our OHC motors.

I like Fords and until the 3 valve heads with VVT I really couldn't tell you what advantage our OHC had over the competition.

GM's 4.8 pushrod STOMPED our 4.6 SOHC in the trucks and the 5.3 was at least equal if not higher revving with more HP than our 5.4 SOHC (there's an irony for you......the pushrod motor made more HP and revved higher than the OHC!!!)

So give it up, you misstated...........especially the rotating mass part. I'll forgive you and still respect you in the morning

 

There are no stupid questions...........just stupid people


You're 1000% correct, this is why I'm so dumfounded that someone could think a V motor would have LESS rotating mass with OHC (single or double) than a pushrod motor

 

Jack...See https://www.ford-trucks.com/forums/s...=167301&page=4 Post 59

 

[QUOTE=DOHCmarauder]


.


BTW. The GM LS head has a very modern chamber and port design and is actually a newer design than the OHC wedge type chamber used in the Ford Mod motors by about 6 years!!!
[QUOTE]

Could you please explain the why's and hows of this conclusion? I'm confused by this remark, the recent 3V chamber is totally different from the original 2V chamber, in both design and operation. In what specific ways is the GM LS chamber and port design comparitively modern?

 

From what I see, the biggest advantage of the new 3 valve head is that the spark plugs don't blow out!