Voodoo Child
- Thread starter Tob
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That's a good question because valve size really is the most important factor behind any port. It is the most restrictive aspect and is limited by piston bore/combustion chamber size.
This quote from David Vizard says it all:
“The most important factor in making hp is the circumference of the intake valve in relation to the cylinder's displacement. All two-valve V-8s are under-valved for the cubes those valves have to feed.” David Vizard
Of course I'm not saying that other things are not important but design starts with the question; "how big a valve can we/should we use for the intended application?". Then the rest of the port is designed from there.
To answer your question directly: Two 1.51" valves are equivalent to a 2.14" single valve.
Piston bore spacing/diameter limitations are the reason Ford went with the 4 valve head in the first place. There was no way they were going to derive any semblance of a performance engine with a single intake valve in the tiny 3.55" bore. Imagine trying to stuff a 2.14" single valve in one of our heads. And it's not just huge valve area that provides giant slayer heads for our beloved stangs, it's the valve layout too. With intake and exhaust valves directly across from each other, AND angled toward each other, airflow during overlap is increased dramatically because the incoming air doesnt have to make a 90 degree turn to exit. Of course their are many other benefits to the 4 valve head but I'm long winded enough as it is.
Inside the flanges, there's a fairly "tall" wire fed machine bead that sometimes gets dressed or hit quickly with a carbide cutter. Given the level of detail at every square inch of this engine I have no doubt that they either have no impact or somehow serve a favorable function, beyond just fusing the tubes to the flange.
Regarding this part, a friend of ours who serves as the crew chief for the Daigo Saito pro drift team saw that and said the bead looks to possibly acts as a way to funnel or suction the gasses and cause the exhaust to move faster. That's the best way I can explain what he said but he seemed to recognize why it is there.
I wondered if they had to do with reversion (or anti-reversion) but increasing velocity sounds plausible. After learning how much effort went into these to eek out every last ounce of power it does make sense that any process which proves favorable over another one would be taken advantage of. They look to be machine welded (wire fed or mig) which I thought was interesting given that much of the outside is tig, by hand. Then again, the hand laid mig welds Watson was laying down on the FRPP GT500 headers they did years ago were a bit ugly. The green you see is a trace of the inside of a factory gasket. The 5.2 production headers look much better.
Was there any mention of a voodoo crate motor in the future? I have to have this thing!
Either it cost too much extra cash to run a burr over these for little gain (i.e. is the gain worth the extra money?), or they are left there to help with reversion. My guess is that it is a combination of both.
With the exhaust pulses of an FPC engine, this could possibly be a big help.
Apparently this has been alluded to but nothing formal is my understanding. There's some speculation about balance issues in other cars.
I'll let that thing shake my teeth out if it comes to that.
keep in mind that the GT350 should be hitting the track in IMSA continental tire sports car challenge any time now(multimatic said during the off season that it would be at sebring, 2nd race of the season, but i recently asked them on their FB page when we'll see it and got what was essentially the "it'll be ready when it's ready" answer - not that i would expect anything less from a group as meticulous as multimatic.
anyways, point being, every racing engine ford has used in the last decade(especially in road racing) has been available either through FRPP(FPRP?) or roush-yates(who builds all of them, including blueprinted, sealed factory stock engines for series that require such), so it's all but guaranteed that you'll easily be able to buy this engine if you want.
I wondered if they had to do with reversion (or anti-reversion) but increasing velocity sounds plausible. After learning how much effort went into these to eek out every last ounce of power it does make sense that any process which proves favorable over another one would be taken advantage of. They look to be machine welded (wire fed or mig) which I thought was interesting given that much of the outside is tig, by hand. Then again, the hand laid mig welds Watson was laying down on the FRPP GT500 headers they did years ago were a bit ugly. The green you see is a trace of the inside of a factory gasket. The 5.2 production headers look much better.
I dont have much knowledge on this stuff, but just passing on what he recognized it as. He's Japanese and very knowledgeable and that was just what he recognized it as. He made it sound like it was something the Japanese have done in the past. Just thought I would throw that out there as a possibility.
That's true. I did not think of it from that aspect. I just hope the coyote control pack will work with it with a custom tune or that they release a new one for this engine since its seems like they spent a stupid amount of time get the variable valve timing exactly right for these cams and new firing order.
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