The intersting thing about the three valve per cylinder technology Ford is starting to employ now, is that at low RPMs it only uses one intake valve. So in essence, it has the advantage of a traditional two valve per cylinder motor in the low end. The one intake port that remains in operation at low rpm, has a device in the intake track that induces the the air to tumble into the cylinder. This improves fuel mixing and insures effecient combustion. The combustion chamber is shaped in such away to promote swirl, and the spark plug is located in the exact center like the original hemi or a Boss 429. As engine speeds increase the other intake valve, and it's intake runner, can be brought into operation. This a similar idea to what Fplorer was writing about that V6 motor. It's pretty cool technology, that can be combined with variable cam timing (overhead cams), The intake runners themselves, are long, with a fairly straight run to the intake valves.

A two valve per cylinder cylinder head design must optomize the high rpm flow dynamics, at the expense of the low rpm flow dynamics, or strike a compromise. We can see this is what Dodge had to do with the new 345 Hemi, despite it's novel combustion chamber. It makes 1 HP per cubic inch, and 380 ft-lbs of tourqe, but the peak tourqe comes at 4200 RPM. The Chevy Vortec 5.3 liter motor makes it's peak tourqe at 4,000 RPM using two valves per cylinder.

The new F150's three valve 5.4 liter makes it peak tourqe at 3750 RPMs, but Ford claims that it has 80% of the max tourqe available from almost idle. That means that the tourqe available from almost idle is between 290 and 365 ft-lbs. This indicates a very flat tourqe curve, if we were to graph it, rather than a peaky tourqe curve. The peak tourqe of the Ford three valve is 365 ft-lbs, the same as the Chevy Vortec 6-liter motor's rating.

 

The new 5.4 3V uses variable cam timing. It also has "Charge Motion Control Valves", which I am not sure what they are. They either decrease port size, to increase velocity and swirl, or it is similar to the intake manifold runner control (IMRC) that was on the DOHC Cobras for a while, which basically only opened one runner until you hit 3000 RPM's then the other opened for more air flow.

 

The intresting thing about GM's Gen III (Vortec and LS series) V8's, is that the heads are much more like Ford 351 heads, compared to traditional Chevy small block archetecture. Instead of the siamese exaust ports, with sharp turns, and the obsolete plain old wedge combustion chamber design, that wer'e used to seeing on the old 350..ect..We see a design with evenly spaced exaust ports, with a heart shaped (like a 63 289) "fast burn" combustion chamber.

The Gen III motors were supposed to be based on a never used pushrod V6 prototype not a Fordized 350, but the similarities to both Ford 351 designs are indeed striking. The "fast burn" heart shaped combustion chamber is somewhat inferior to the "swirl" combustion chambers Ford had developed for it's own 16 valve pushrod V8's, before they were superceded by the Modular V8's in the late 90's, but it's rather similar to the original 289 combustion chamber. The large "cathedral ports" are somewhat similar to 351C 2bl ports, although the valves are not canted. We also find better rod/stroke ratios (more like a Ford V8) in the GEN III's, compared to the old 350's.

One of the things we find in the newer GM V8's is a rather high static compression ratio. This will help a naturally asperated motor to make decent tourqe, and perhaps excellant HP, but it also means you need to use more expensive gas, if you don't want the knock sensor to retard your timing all the time.

 

Learn something new every day..

 

Here's some coments on these things by the chief design engineer (Eric Levine) that designed them:

"...the three valve has the capablity to handle what is eqivilent to four valve air flow..."

"...What the Charge Motion Control Valves do is both maximize airflow, and at the same time maximize fuel economy and emissions. The way that it does that, is it acts as, essentially a butterfly valve. It has a small opening when the plate is closed. It closes off a large portion of the port to increase turbulence going into the cylinder head and therfore allow for a better burn, and the ablity to handle higher amounts of VCT....when you get out of the lower speeds and and (to) lighter load conditions, the valves open up and it allows for the full on rush of airflow to allow for that great performance...."

"..the way we utilize variable valve timing on this engine, we are actually rotating the intake and exaust valves events simultaneously. That allows us to both get some improvements in intake manifold filling of capping efficienies, with the intake valves and it also allows us to take advantage of exaust valve closing events to help fuel economy and emissions. Since we have control of both events, it allows us to do a mutitude of things at the same time."

"..the control with the VCT and the cam profiles (that we have) work outstanding for maximizing both tourqe and power in that repect(both F150 and Mustang requirements) it allows us the flexablity to run a truck and performance car using the same camshaft, it works really well."

"..the (centrally located spark plug) is a unique design...that allows us to maximize our valve sizes within the combustion chamber...that allowed us to put in the biggest intake and exaust valves that we could put into the chamber to maximize performance."

 

Take note, U.S. Military HMMWV (Hummers) have four wheel independent suspension. My unit managed to break Only two in 15 months in Iraq. One in a head on collision, and one got t-boned by a bus. If anybody here puts their truck through what those trucks handled, you deserve either a trophy or jail time.