Ford has three valves per cylinder!

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Apr 7, 2005
Bay Area, CA
I just saw an ad last night where Ford was bragging about the V8 in their Expedition because it has 3 valves per cylinder. I thought this was kind-of silly since many cars now have 4 valves per cylinder, some even 5 valves. But, then I was thinking about V8's. What V8's have 4 valves per cylinder?
The F-150 has been using the 3 valve per cylinder V-8 for at least a year now. It's good Ford finally upgraded their largest V-8 engine since they had the lowest HP output (based on largest V-8 available) of any full-size V8 truck (excluding Tundra). I'm sure the new 5.4L will be just as good as the one it replaced. Hopefully they will give the 4.6L a similar upgrade.
I believe they also have a 5.4 with 32valves, it is(or maybe was) in the Lincoln Navigator, it made similar power(around 300hp I believe) to the new 3 valves per cylinder 5.4.
Making 3 valves per cylinder does make some sense. The intake can be bigger bc it wont overheat and 2 smaller exaust valves are a good thing for cooling. I assume that's what they are doing
Ford's H.O. 5.4L has 32 valves that went into the upper-line Harley Davidson F150 edition, and I believe the top-dollar Mustang(?) and the Mark VIII at one point.

The V-8 Lincoln LS has 32 shiny valves.

More 32 valver's..
Nissan's 5.6L V-8 in it's new Titan.

I think the only 32 valve V-8 GM offers is the Northstar engine.

Porche 928. (I wish I could drive one of these sometime in my life!!)
Haveing one large intake valve and two smaller exhaust valves helps to improve low end torgue and HP. It is harder to keep the low end torque with a 4 or 5 valve set up. I am guessing the 3 valve set up gave them more turbulance and better scavenging. It is also cheaper to stay with fewer valves. To make a 4 or 5 valve setup worth the time and money to design and build you normaly have to have an engine that you expect to spend a lot of time past 3000 RPM's and usualy well past 5000 RPM's. The other time is if you have a very small displacment engine and you are trying to get as much HP as possable and still meet emissions. If you have the displacment and the application is biased toward torque a three valve arangement truly makes more sense.

Now with Nissan and Toyota they already had I4,I6, V6's and V8's both gasoline and diesel with 4 valve setups. They have been doing 4 and more valve's per cylinder for a long time! For them it actualy makes more sense to do a 4 valve head then it would to do a three valve head. They normal desing smaller displacement engines and they usualy market a number of modular engines basedon a common design globaly. They both tended to in the past reuse as much of their previous R&D results from other projuects as much as possable. It is also what they tend to graveatate to.

In Fords case they had a clean slate and really were not tied by tradition or previous R&D to any set configurtion. I belive that their three valve design was the best choice for their application! I also think that packageing probably played a role! The more valves and or cams you put in a head the larger the head becomes.

P.S. If you compare the output of Toyota's V8 to Chevys 4.8V8 or Dodges 4.7V8 you will see that it is not that anemic at all. Their new Truck V6 is also really impressive as compared to other truck V6's!!!
actually one of the main reasons for using 3 instead of more is simple physics: 3 circles fit easier within the circle formed by the cylinder head.

Originally posted by kenw:
actually one of the main reasons for using 3 instead of more is simple physics: 3 circles fit easier within the circle formed by the cylinder head.

How about simple economics. 3 valves is cheaper than 4 with almost the same results.
Mercedes is phasing out its 3 valve V6 and V8 in favor of 4 valve heads.
VW is also phasing out the 5 valve 1.8 in favor of 4 valve 2.0 FSI.
Mercedes said they did the 3-valve for emissions reasons. Less exhaust cooling with a single exhaust valve. Honda Also had a 3-valve engine made for emissions. One intake was large and let in a very lean mixture. The other was small and located in a small pear shaped chamber, it let in rich air. Supposedly this CVCC design allowed better burning.
I always thought it was two inlets one exhaust.

The inlet only has the atmospheric pressure driving the gasses in, and the better hydraulic diameter offered by two inlets halps volumentric efficiency.

The exhaust has a piston trying to push it out, and as previously stated, there's less wetted area adding heat to the coolant with just one valve.
My old 1985 Honda Accord had a 1.8 liter 12 valve engine (3 valves per cylinder). I thought it was a pretty neat design.

Originally posted by FowVay:
My old 1985 Honda Accord had a 1.8 liter 12 valve engine (3 valves per cylinder). I thought it was a pretty neat design.

That engine is absolutely gutless on the freeway, but just putting around town, it's pretty torquey. My brother's '85 is pretty fun to drive!
Palut, you may have experienced a poor example of this engine. The engine in my Accord performed incredibly well. It wasn't rated for high horsepower (in the 80 hp range I believe) but it seemed to be a perfect compliment to the higher torque output (120lb.ft to the best of my memory).

I do recall that it specified valve adjustments every 30,000 miles which were very simple with the threaded tappet design. Being a design of the 80's era the underhood looked like a bowl of spaghetti with a plethora of vacuum hoses connecting the carburetor to control solenoids.
Doesn't Ford mainly focus on torque not horsepower? I might be wrong but most 4-valve setups gives at low rpms less torque vs hp and more torque vs hp at high rpms. Alot of it may come down to the design the engine, intake/exhaust manifolds though.

And ford fix the plug blow-out in 99 with more threads (PI head) and in 01/02 with new designed spark plugs (more threads).
John Browning sure gave a clear explanation of the trade-offs between 3 and 4 valve engines.

3-Valve - more low end torque, lower emissions.
4-Valve - More Hp at higher RPM's.

While it might be the best solution for their design parameters, it still seems strange that Ford would brag about 3 valves per cylinder in this day and age.
You can have all the threads in the world, but if the heads themselves only have 4, it does you no good. The PI heads are a fix after you shoot out the sparkplugs, and of course, after your warranty is out. Go to any F150 truck forum, you will see hundreds of stories.
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