Ford has three valves per cylinder!

Joined
Apr 7, 2005
Messages
1,904
Location
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?
 
Joined
Dec 20, 2002
Messages
1,197
Location
The coal hills of eastern PA
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.
 
Joined
May 3, 2005
Messages
258
Location
Ft. Morgan, CO
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.
 

Al

Joined
Jun 8, 2002
Messages
19,296
Location
Elizabethtown, Pa
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 [Smile]
 
Joined
Apr 11, 2003
Messages
11,284
Location
Spring HIll
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. [Smile] 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!!)
 
Joined
May 1, 2003
Messages
9,448
Location
USA
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!!!
 
Joined
Oct 10, 2004
Messages
1,979
Location
Houston
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.
 
Joined
Apr 26, 2005
Messages
239
Location
California
quote:
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.
 
Joined
Jan 20, 2004
Messages
4,874
Location
MN
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 dont know]
 
Joined
Dec 12, 2002
Messages
43,676
Location
'Stralia
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.
 
Joined
Jun 2, 2002
Messages
2,993
Location
Georgia/Retired
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.
 
Joined
Feb 12, 2004
Messages
1,309
Location
Western Washington
quote:
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!
 
Joined
Jun 2, 2002
Messages
2,993
Location
Georgia/Retired
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.
 
Joined
Feb 26, 2005
Messages
3,400
Location
Kansas, USA
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).
 

Winston

Thread starter
Joined
Apr 7, 2005
Messages
1,904
Location
Bay Area, CA
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.
 
Joined
May 12, 2003
Messages
7,799
Location
Oklahoma
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.
 
Top