A very quick and simple answer is that the bottle neck in the 2 valve head is the exhaust valve. I am sure many of you have read "TopGun's" posts and I am willing to bet most you don't and will not spent that type of money to tweek the heck out of the 2 valve head. As for the 4 valve heads as "Ruslow" said the HP and Torque can be there and the RPM level does not have to go through the roof. I am sure that for Stan and for myself this is just a project to have fun with. I learned a long time ago that if your heart is not in it don't do it because you may not finish it and even if you do you will hate every minute of it.

 

Great quote!

-Wayne

 

A torque gain with a 4V engine of equal displacement would mandate either smaller valves and different cam profiles and I still would love to see WHERE the gain would be.Its the power "under the curve" that makes a great engine.It would be hard to beat the almost linear power curve of the lightning as it exists today.A larger blower you ask??Yes that would elevate the power curve but it still would have its wonderful shape!!Improving the exhaust port is a inherited Ford problem dating back as far as I can rembember...and I have a good memory!!

 

NeedFourSpeed,

Now is a good time to start buying all the Boss 302 engine parts you can find. They are getting harder and harder to find and more expensive every day, especially the block and heads. Feel free to e-mail me anytime. I have all the specific casting and part numbers for the Boss.

 

Exhaust valve:
I don't remember seeing anything on exhaust temps being high, even with people running 13-16 lbs of boost. Maybe one or more of the tuners can provide insight as to if they are having to richen the AFR just to keep EGT down? If not, then the exhaust isn't an issue.
Intake valve:
There are guys running over 15lbs boost now without a big decrease in efficiency. So far the increase in boost has brought close to a linear increase in power. If the intake valve was a limiting factor, you would see an increase in inlet temps, and a dramatic drop-off in the power/boost ratio. The intercooler helps disguise this to some extent, but even an IC has it's limits. Again, without some hard data to back this up, this is just theory -- the tuners probably are probably closing in on the limits right now.

The stock bottom end of the 5.4 limits it to around 6k rpm at best without durability problems. Even with a longer rod to slow the accel/deacceleration at TDC, you will have problems without some expensive aftermarket rods. However, Ford devised this engine as a TRUCK engine, which means a high torque/displacement ratio. When they combined that with a positive displacement blower which also builds good low rpm torque, they developed a complimentary system primarily efficient below 5K rpm. The 2 valve heads augment this, and top off an air pump that is extremely efficient at lower rpm. 3 valve heads will help increase efficiency at higher rpm, and with some form of variable valve timing and lift, they might extend the benefit into the lower rpms if they use smaller valves.
The bottom line, is that with the current bottom end, you're not going to profit from a change that swaps high-rpm power for a loss in torque. I think the ideal replacement head will have a slightly larger exhaust valve, and two smaller intake valves with some form of variable timing and/or staging. JMHO

 

With the 4 valve heads there will be 16 exhaust ports, that means you will have to change the exhaust manifolds as well.

 

When ever you force air into something restriction plays little effect on the amount of force ie. intake .But you have to get what you FORCED into the cyl out and that is done by just pushing it out.So IF you increase the area of the exhaust valve and make the exhaust more efficent at scavenging then you would have it.
What people NEED to remember is that this would not be a stand alone mod.You would need to complinent[sp] it to gain the full effect of it.
I know that I have been kicking around the idea of a longer rod that way you can use the same blower system but I needed to find a good exhaust side to make it work and the 4 valve seems to suit my needs.Since I would use an aftermarket rod to begin with the price was not even in the equation.The pistons are the same in the same deal.Stan

 

I am only familiar with the lincoln 4 valve heads, but I don't see why they would completely change the design. As I stated in the previous post, you would have to change the exhaust manifolds also, and I read that the kit was complete with heads , valve covers,and intake manifold. Can somebody enlighten me please.

 

Exhaust is an option. Navigator or headers.

 

Low end torque is more or less derived from the mechanical advantage applied from the undersquare design,, i.e. the long stroke of the engine has a greater moment arm, thus having more "leverage" on the crank throws. The long rod also helps to be more efficient at converting the up down movemwnt into the rotating movement. The 2 valve head will produce a better cylinder fill at low rpm because of the volocity of the air than the 4 valve. I don't think the 4 valve would benefit much under the 4000 rpm range, but I also don't think it will take much away either under 4000. It will move the torque curve up from a low 2500 to somewhere around 3500, but the torque output figure will probably be the same. $.02 Exhaust flow valves do work great though don't they!(CBR929RR)

 

How does the normal exhaust manifold opening designed for 1 exhaust port fit over the larger 2 exhaust port holes exiting the head?

 

Now the winning combination would be BABolts 32v setup with Sal's new blower. HMMMM....

 

I know I'm not the only NY engine remanufacturer/Installation guy on this board. Can anyone tell me how they configured the exhaust port, as per my last post.

 

Lookes simuliar to the Quad 4 motor of GM.Stan

 

kidd2001,
The 4V exhaust valves share the same exhaust port. One exhaust port per cylinder.