I have been searching the web for info on the forthcoming 3V engine to be used in the 2005 Mustang and read the intake ports are siamesed. Is this confirmed? Are the current 4V high performance and 3v truck heads siamesed on the intake side? Do any high performance engines currently have a similar design-shared intake ports in the heads?

 

Don't know the answer, Felix, but whatever you find on the 3v truck heads applies to the '05 Mustang heads. The castings are identical.

 

Does that mean that when a company like shm starts porting 05 stang heads i will be ab le to ship them my 04 f-150 heads and get the same port job? And what about cams? I am sorry that this is not an 05 stang question but i guess it is related.

 

The ports on the 3V and 4V heads are NOT siamesed.

If you understand anything about how the valves on the 3V and 4V heads are arranged versed normal 2V heads (Chrysler Hemi excluded) you will know that siameased ports do not apply to these types of heads.

What is Siamesed is the cylinder bores. That is the bore liners on the AL block effectively touch each other with no water passage inbetween the bores. This has nothign to do with the heads.

 

Or do you mean siamesed as in there is a single intake port feeding 2 intake valves?

Y'know, I don't know??

I am assuming that the 3v heads have individual ports for each valve (as in 8 ports per head), especially with those intake runner control valves or whatever they are calling them.

Problem with multi valve heads, they have crappy low speed mixture characteristics which has given rise to the notion that mutli-valve engines don't produce as much torque as a single valve engine of comparable displacement depsite the general observation that mutli-valve engines have superior air flow.

with 8 ports and a control valve in one of them, you can increase velocity and tune the airflow (to tumble or swirl, or whatever) to the cylinder so that the mixture remains homogenous promoting a more complete burn in the cylinder which allows the engine to produce more cylinder pressure which translates into more torque.

IIRC, a good port design allows the fuel to tumble into the cylinder at low engine speeds, then as RPM increase it relys more on swirl into the cylinder and the high speed of the piston crashing into the mixture to facilitate the homogenous mixture.

 

there is one large OVAL port feeding both intake valves of each cylinder.

 

The intake manifold on the 3V engine has 2 modes with a valve to switch between them. At lower speeds a longer intake path is used to raise the air velocity and improve low end torque. At some RPM / load combination the manifold switches mode.

The Variable Valve Timing will also help low end torque. At low and high RPMs the intake valve opening (relative to the crank positing) needs to be different to optimize power. On engines with fixed cam timing you have to pick a compromise in valve timing. One of the primary purposes of VVT is to optimize this timing to both low and high RPMs which broadens the torque band.