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post #1 of 18 Old 09-05-2007, 07:16 PM Thread Starter
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Which heads do I have?

I'm new to the 32V 4.6 world and, to say the least, ignorant when it comes to what component is in what year of car and so on. I keep seeing the threads discussing the "C" heads and "B" heads. I was curious as to what heads are/should be on my '03 Mach 1. And also, what are the advantages and disadvantages to both?
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post #2 of 18 Old 09-05-2007, 07:45 PM
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you have neither B or C heads...

You have 03/04 Cobra heads...

B heads are any 4-valve pre-99
including lincolns and Cobra's

C heads are 99/01 Cobra

03/04 Cobra heads are any 4-valve 03-up
including Maruader, Aviator, Mach 1, etc.


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post #3 of 18 Old 09-05-2007, 09:29 PM
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Not sure about that.
I consider 99-04 32V heads "C" heads, except Navi and Ford GT/Shelby heads.
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post #4 of 18 Old 09-05-2007, 09:38 PM
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when discussing mustangs, which is all that matters, because other cars suck, C heads usually refers to 99/01 cobra "tumble port" heads. the newer cobra/mach/fr500 heads are all modified versions of this tumble port design.
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post #5 of 18 Old 09-05-2007, 09:51 PM
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Originally Posted by birdman941 View Post
Not sure about that.
I consider 99-04 32V heads "C" heads, except Navi and Ford GT/Shelby heads.
Yes, they are C heads as are the FR500's. But - these casting are different enough, application and flow wise that they should be differentiated along these lines. 99-01, FR500 and 2003-4 mach/cobra.

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post #6 of 18 Old 09-06-2007, 08:43 AM
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This information is paraphrased directly out of the book "How to Build Max-Performance 4.6-Liter Ford Engines" and I do not claim any of it to be my own:

Quote:
'93-'98 Mark 8, '96-'98 Cobra

The early 4-valve head is also known as the B-series head inside Ford. There was apparently an A-series head, with dual round ports, but it did not make it to production. The B-series head has 2 separate intake ports, a primary port that operates up to 3000 rpm, when the computer actuates a valve, opening the secondary port as well. On paper, this seems like a good idea, when in reality, the early heads make good race heads, but suffer from poor cylinder filling at low RPM and lower torque output...
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post #7 of 18 Old 09-06-2007, 08:44 AM
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continued...

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'99-'01 Tumble Port

In 1999, the Cobra arrived with a new cylinder head called the tumble port. This refers to the manner in which the port causes the air to tumble into the cylinder, a different type of air motion than the swirl motion often spoken of. The idea of keeping the air in motion is to prevent the droplets of fuel from condensing on port walls and on the side of the cylinder bore. In addition, in-cylinder motion will keep the air-fuel mixture as homogeneous as possible, promoting an even, controlled burn rate...The exhaust port is marginally better [than B-heads] at lower lift values as well. The engine responded with more mid-range torque, as well as 15 more horsepower at peak...The early heads really had ports that were just too big for the street...For pure race engines, we have some better heads yet to choose from...
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post #8 of 18 Old 09-06-2007, 08:52 AM
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5.4 Tumble-Port Head

The Lincoln Navigator showed up in 1999 with a 5.4-liter 4-valve engine. The cylinder head is a tumble-port design, but the port dimensions are larger, and there is more material available in the ehad to be ported...We have used these heads for several race engines, both forced induction and naturally aspirated (NA), and the results have been very good...
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post #9 of 18 Old 09-06-2007, 08:57 AM
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FR500 Cylinder Head

In 2002, Ford Racing released the FR500 cylinder-head casting, a development of the FR500 Mustang project. The FR500 head flows more air than a production '99-up tumble-port head on the intake at low to medium valve lift...For a pure race engine, this cylinder head is a good starting point. The head mates with the '99-up tumble port intake, or the Ford Racing FR500 intake manifold...When you swap these heads and matching intake onto your engine, you can expect to see up to a 40-50-hp gain...
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post #10 of 18 Old 09-06-2007, 09:00 AM
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'03 Cobra Cylinder Head

This production head mirrors many features of the FR500 head...but the FR500 outflows this head below .250 inches of valve lift. These heads also mark the first time Ford produced dedicated left and right head castings. The water flow has not been equal on both heads for forever...This would make an excellent head to start with for a race engine. The same casting is also used on the Mercury Marauder, the Mustang Mach 1, and the Lincoln Aviator.


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post #11 of 18 Old 09-06-2007, 09:04 AM
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Cobra R Cylinder Head

Unobtanium. This is the best flowing production 4-valve head Ford has produced, but unless you are one of the 300 fortunate people to have purchased a 2000 Cobra R, you cannot get this head. The head was designed by the folks at Ford SVE, and it was produced in limited quantities with soft tooling for the Cobra R program...

Other Designs

Ford also cast a few sets of Rough Rider heads for an internal skunk-works program inside Ford Truck. The Rough Rider heads were used to create 600-hp 5.4-liter truck engines to race in SCORE off road. These heads have unique ports and were fed with individual throttle bodies...
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post #12 of 18 Old 09-06-2007, 09:08 AM
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I hope that answers your question. The book also has tables of each cylinder head with its chamber and intake port volume data, as well as cylinder head flow broken down each .050" increment of valve lift, and a couple pages of pictures of dry molds of each heads port designs. The articles also break down porting techniques and areas of addressing, as well as port thicknesses, guides to valve, valvetrain selection, combustion chamber work, etc.

And this is only the cylinder head section of the book. I strongly advise anyone interested in building a mod motor to pick up a few books on it, especially Sean Hyland's book. While it does seem a little egotistical at times, there is a wealth of knowledge inside it.
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post #13 of 18 Old 09-06-2007, 09:48 AM
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This should clear things up:

4V Head Info
________________________________________
B/Swirl Port: (93-97 Lincoln Mark VIII, pre 99 Lincoln Continental, 96-98 Cobra).
The first and only production Ford head with two (square primary, round secondary) intake ports per cylinder, these swirl port castings arrived first in the ’93 Lincoln Mark VIII. Aptly named, due to the way they promoted the incoming air to swirl into the combustion chambers, much like water running down the drain of a once full sink.
Through the years these heads have proven themselves to be excellent high rpm (8000rpm+) performers—mainly in power adder applications--since their tremendous combined intake port cross sectional area and volume (when combined, a full 55cc more than any other 4.6L head design) provide for exceptional power production in the upper regions of the tach. Ironically, it’s those same big, beautiful, twin ports that also prove to be the B head’s largest inherent design flaw. The extra intake port size has a tendency to kill low/mid rpm intake port velocity and power production—hence the use of Ford’s first IMRC (intake manifold runner control) intake on the 96-98 Cobra. By allowing air to reach only one of a B head’s twin intake valves, velocity, and therefore low/mid range torque production was restored in situations under 3250rpm. Later head designs are clearly superior in this regard, which happens to be the one of the most important considerations for those wanting a stout street motor.
There is also some controversy over the single fuel injector/dual intake port setup. Some claim insufficient air/fuel mixing because of the compromised design, however, others contest that the ability to make 1000+rwhp with only minor porting and some form of power adder is testament to the contrary. Whoever you believe, there is little doubt that even after as little as 8,000 miles, carbon and other deposits tend to form on the secondary ports, causing a major airflow impedance, as there is no fuel present to clean them. B heads feature a somewhat small stock exhaust port that really hinders flow in power adder applications. Major gains from porting come with a quality valve job, some pocket and lots of exhaust work. There really isn’t a lot of material to remove from the intake ports themselves.
The Bottom Line: B heads aren’t the best choice for a naturally aspirated street motor. In order to really shine, they need to be paired with a power adder and a short block that can sustain high horsepower and rpm levels. These, the oldest heads, may still be a great choice for full race applications.

Stock Intake Choices: ‘93-‘97 Lincoln Mark VIII, ‘96-‘98 Cobra.
Aftermarket/Modified Stock Intake Choices: HCI, SSR, PHP.
B head dimensions: Combustion Chamber: 52cc, Intake Port Vol.: 107cc primary (square), 115cc secondary (round). Intake Port Entrance: 1.500x1.300” primary (square), 1.660x1.400” secondary (round), Valves: 37mm Int., 30mm Exh.

C/Tumble Port: (99/01 Cobra, 99 Lincoln Continental).
These second-generation Ford DOHC heads feature a single intake port per cylinder with a smaller cross sectional area that boosts incoming airflow velocity compared to previous years. To understand how C heads earn their “tumble port” designation, try to imagine an Olympic high diver doing repetitive front somersaults before cleanly entering a pool at the bottom. This controlled tumble allows for better air/fuel mixing than in the earlier swirl port heads. The new port design allowed for both substantial increases in midrange torque, and superior horsepower production under 8000rpm when compared with earlier heads. Combustion chamber size is also up 2cc.
The design downfall of C heads, and their larger (5.4L Navigator) cousins, is the relatively flat floor and utter lack of a short turn radius in the throat of the intake port. As such, the incoming air tends to overshoot the valves, making the port think the valves are smaller than they actually are. Some ‘99/’01 Cobra owners reported a “ticking/pinging” noise coming from the drivers side head of their cars. This is due to insufficient cooling around the #6, 7, and 8 cylinders that allowed the valves to overheat and therefore seat improperly. Ford remedied the situation by issuing a TSB to remove and replace the affected heads with a version that featured altered coolant flow.
C heads feature a small exhaust port much like Ford’s earlier swirl port heads, but unlike in B heads, both the intake (throat region) and exhaust ports can see extensive porting work. However, removing too much material from the intake port (mouth region) of a tumble port head will kill velocity very quickly, so make sure your head porter knows what they are doing!
The Bottom Line: C heads remain a viable performance upgrade for those looking for more punch in their street driven 4.6L four valve, without having to pay new part prices for the ’03 DOHC or FR500 versions. The increased midrange torque production and greater overall area under the power curve (when compared to swirl port heads) will enhance the performance of a street/strip driven (8,000rpm and under) modular regardless of application.

Stock Intake Choices: ‘99/’01 Cobra, ‘03/’04 Mach 1 & Aviator, ’03 Marauder, FR500.
Aftermarket /Modified Stock Intake Choices: Al Papitto short runner/ported ‘99/’01 Cobra, MP carb/Sullivan intake, FR500, Aviator
C head dimensions: Combustion Chamber: 54cc, Intake Port Vol.: 177cc, Intake Port Entrance: 1.960”x1.350”, Valves: 37mm Int., 30mm Exh.

Navigator: (98+ Lincoln Navigator)
These 5.4L DOHC heads feature essentially the same intake port design as C heads, however they have a much larger intake port volume than 4.6L castings. Despite the fact these heads feature a relatively small exhaust port, the extra intake port volume could be very beneficial in helping fill a motor of greater displacement—think 5.4L. Expect slightly better midrange torque, and sub 8000rpm horsepower production than even C heads, however the larger intake port size leaves a slim selection of intakes to choose from when utilized on a 4.6L block. Forced induction fans take note, Navigator exhaust ports feature a thicker exhaust divider (while keeping the same overall exhaust port size as B,C, and FR500 heads) that allows coolant to circulate through this vital area. Conversely however, the larger divider can also hurt flow by utilizing additional space in the port.
The real downside to Navigator heads, when used on a 4.6L based motor, is the severe limitation they impose on intake selection. The physically larger 5.4L heads don’t leave a lot of room (when installed on a 4.6L block) between them for an intake plenum to sit—though they do bolt right up. Remember that since Navigator intake ports are essentially clones of those of C heads (just on a larger scale), they too suffer from the same intake port flaws that plague the earlier tumble port design--no short turn or floor in the throat of the intake port.
The Bottom Line: The extra port volume the Navi’s possess could be very beneficial in filling a motor with greater than 281 cubic inches of displacement, or in high rpm N/A street/strip or boosted combinations. Fans of boost should remember the cooled exhaust port divider. Lack of intake availability is the real downfall of this otherwise wonderful casting.

Stock Intake Choices: None (4.6L), 98+ Navigator (5.4L)
Aftermarket/Modified Stock Intake Choices: Al Papitto short runner 99 Cobra (4.6L), sheet metal
Navigator head dimensions: Combustion Chamber: 53cc, Intake Port Vol.: 184cc, Intake Port Entrance: 2.290”x1.400”, Valves: 37mm Int., 30mm Exh.

’00 Cobra R: (’00 Cobra R)
Cobra R heads are bar none the best Modular heads available today. However, their extremely scare supply makes them both ridiculously hard to find, and unbelievably expensive.
Initial performance results are understandably hard to obtain, however Al Papitto reports that with only 25hrs of port work into the his new ‘00R heads, they have already eclipsed the performance of his old Navigator heads with months of labor in them. These heads feature larger intake and exhaust ports, +1mm larger exhaust valves, and a dry exhaust port divider. Cobra R heads also require the use of a specific valvetrain not shared with any other modular application due mainly to their overall physically larger size. Al also claims R heads have too much port volume for a street/strip 4.6L application; only consider them with a larger 5.4L motor or a serious 4.6L race application paired with some form of power adder.
The Bottom Line: The best heads you can or can’t find for a Modular four valve motor.
You are as likely to come across a set of these Modular “Godfather” heads as you are to be Brittany Spears’ next uterus masseuse. Though based on their performance abilities, you may want to start saving, just in case…
Stock Intake Choices: None (4.6L), ’00 Cobra R (5.4L)
Aftermarket/Modified Stock Intake Choices: Sheet metal
’00 Cobra R head dimensions: Combustion Chamber: N/A , Intake Port Vol.: N/A , Intake Port Entrance: 2.370”x1.300”, Valves: 37mm Int. 31mm Exh.
Stock Intake Choices: ‘00R
Aftermarket Intake Choices: Sheetmetal.

FR500: (FRPP)
The sole “aftermarket” offering of the bunch, these high flow heads feature a modified C head intake port combined with the smallest port volume of the group—it seems Ford meant to design these heads for high performance naturally aspirated applications. With the same small standard exhaust port as most other DOHC heads you will still have to remove a decent amount of material from the exhaust ports. Port entrance shape/size remains identical to C heads so finding an intake isn’t hard. These heads are capable of producing power beyond 8000rpm, where earlier versions of the tumble port castings begin to lose their luster. FR500 heads are prone to the #6,7, and 8 cylinder cooling problems as well. Major intake port differences between these and earlier tumble port heads include a raised intake port roof, and a real short turn radius that better directs the incoming air into the combustion chamber; not over the valves like in earlier versions of tumble port heads. These heads also feature a dry divider in the exhaust port, which allows for greater flow, but also higher temperatures. Though improved, the heads can still use some TLC from a quality porter to smooth the roughly finished and newly implemented short turn radius, and the standard exhaust treatment.
The Bottom Line: Outstanding performance heads, with exceptional low and mid lift flow capability. The FR500s only real fault is that the newer ’03 DOHC heads provide near identical performance capability (much better on the exhaust side) paired with a cost differential that is approximately two-thirds less than the FRPP castings. Still a great choice for any application, the heads readily pair to a wide variety of stock and aftermarket intakes.
Stock Intake Choices: ‘99/’01 Cobra, ‘03/’04 Mach 1 & Aviator, ’03 Marauder, FR500.
Aftermarket /Modified Stock Intake Choices: Al Papitto short runner/ported ‘99/’01 Cobra, MP/Sullivan carb intake, FR500, Aviator.
FR500 head dimensions: Combustion Chamber: 53cc, Intake Port Vol.: 160cc, Intake Port Entrance: 1.960”x1.350”, Valves: 37mm Int., 30mm Exh.

‘03 DOHC head: (‘03+ Aviator, Marauder, Cobra, Mach 1, Australian Boss 260/290)
Featuring a nearly identical (though 17cc larger in volume due to the fact that they are also used on the much larger Australian Boss 260/290 5.4L DOHCs) intake port to the FR500 head, but combining it with a newly designed, larger and more rectangular exhaust port, these may be the best all around DOHC Ford heads ever manufactured. The improvements made to the intake port shape over previous years include a raised port roof and the introduction of a short radius turn in the throat of the intake port that helps assure the incoming air charge finds the combustion chamber. For those with a forced induction street/strip motor, these are without question the best heads available, and as with the FR500s, they should produce great power up to and beyond 8000rpm regardless of application. ’03 DOHC heads also feature higher quality head castings from the supplier, which is at least partially responsible for the modest increase in flow vs. earlier castings--chalk that up to Ford’s revised quality control standards.
Early runs of the ’03 DOHC head fell victim to the same #6,7,8 cylinder coolant flow problems as earlier tumble port castings. In mid ’03 Ford made a running revision to the ’03 DOHC heads that allowed for more coolant to circulate through the affected areas. A blue mark on the driver’s side head indicates an updated casting, and there are no additional revisions to the ’04 version of this design.
The Bottom Line: On all accounts these are the best modular four valve heads currently available. They combine the exceptional flow of a slightly larger FR500 intake port with a gigantic new rectangular exhaust port.

Stock Intake Choices: ‘99/’01 Cobra, ‘03/’04 Mach 1 & Aviator, ’03 Marauder, FR500.
Aftermarket/Modified Stock Intake Choices: Al Papitto short runner/ported ‘99/’01 Cobra, MP/Sullivan carb intake, FR500, Aviator.
’03 DOHC head dimensions: Combustion Chamber: 52cc, Intake Port Vol.: 177cc, Intake Port Entrance: 1.960”x1.350”, Valves: 37mm Int., 30mm Exh.

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post #14 of 18 Old 09-06-2007, 02:43 PM
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That was great info. Who wrote that, you?

I want to add something about head porting that the average joe probably doesn't know, but it's importance is hinted to above. Two things greatly affect cylinder head airflow. Size and shape.

Size is the overall port volume of the runner, measured in cc's. This has a drastic effect on how much raw volume of air can go thru the ports. A larger size will feed a bigger inch motor much better, and is great for any type of forced induction usually. The forced induction cars have some type of blower thats pumping a ton of air into the motor, and the only thing that stops that air from actually filling the cylinder is the intake port path (including the intake manifold). When you're talking about an n/a car, too much volume is a killer of low end torque. On a forced induction car, we usually don't have that much trouble with low end torque anyway, unless we have a fairly large turbo for a compressor.

Shape is a different animal. The perfect shape would be a round tube with a valve at the end of it. This tube would be straight up and down, in the same plane as the cylinder bore. For obvious clearance reasons, this can't be done in a car. Besides, there would be no way to actuate the valve from inside the port. [Visualize a 2" plastic pvc pipe with a valve stuck in the end of it, and the valve tip being in the middle of the tube]. So the factory has to bend this tube in a 90 degree fashion towards the intake manifold to get all this to fit under the hood. This also allows the valve tip to stick up thru the top of the port (thru the guide), and be controlled from above by the valvetrain. (Stating the obvious here). The more they bend this intake port, the less straight of a shot the airflow has of going thru the tube. Remember, the air is going thru the tube rather fast, and suddenly it has to make a 90 degree bend to turn into the cylinder, past the valve. When the short turn (the bottom of the port, at the 90 degree bend) doesn't have the right shape, the fast-moving air simply "flies off the cliff", and hits the back side of the bend (the long turn). This makes all of the airflow go past only the long-turn side of the intake valve, which is what he was saying in the post above. That makes the port act like it only has half of the valve to flow thru. The correct shape for the short turn is a quadrant of the valve size. In other words, take the intake valve and carve it's shape into a piece of balsa wood. Now take one corner (25&#37 of that curved balsa wood, and that is a quadrant (1/4) of the valve shape. The short turn of the port should be exactly that same shape. The factory often shortens up that short turn by maybe 10% or so, because they've found that it increases low-lift flow, at the expense of top end flow. With any type of hydraulic cam, low-lift flow is important.

Picture the amount of air between the throttle body and the intake valve that's about to be open, as a set column of air. A train. You want the train not only to go fast, but to accelerate to that max speed fast. Good low lift flow will get the column of air moving faster, while total size and shape will dictate the total amount and speed of airflow once the valve is fully open. Get the train moving faster.

I was told by an expert that any airflow below .300 valve lift is totally decided by the size of the valve (bigger is better for low lift flow), and the angles on the valve job. The less angles, and cuts, such as a 2-angle 30 degree seat works best for low-lift flow. A multi-angle valve job (3 - 5 angles), and a 45 degree seat is better for higher lift flow, as it lets the large amounts of air past the valve faster. Of course, we all have to make that decision on the trade-off there, and that's where a flow-bench comes in handy.

Having the wrong shaped short turn radius will allow a fast-moving column of air to fly off the cliff, and only flow past the back side of the valve. This phenomenon is caused by having the incorrect shaped short turn. This is where a pro head porter has a big leg up on us home-hackers. He understands the shape of that short turn is critical. With a hydraulic cam, we can only pop the valve open so fast without collapsing the hydraulic lifter, so we can't "get to" the high lift flow numbers all that fast. A regular pushrod V8 engine with a solid roller can. So, we have to pay attention to low-lift flow numbers as much as peak airflow numbers, to get the column of air started moving faster. With a higher rpm motor, this column acceleration rate is less critical, because the engine already is turning faster. So what happens is the low-lift flow numbers become a little less relevant.

Now hopefully you can see why the B heads, and their large ports, are not so great for a n/a car at lower rpms. They're big. That's a good thing though, when it comes to racing at high rpms and especially with forced induction. Boost is already pushing that column of air from one side (the throttle body side), and as soon as the valve opens, that boost pushed that air into the cylinder. The air is under pressure, and the physics of a pressure drop take over at this point. So, essentially with a blower (more so than a turbo probably), we don't have as much to worry about by using big heads (large port volume).

Quickly, with respect to swirl vs tumble, think of it like this. There's a ballarina that's spinning her way thru a doorway, or there's a gymnist summersalting his way thru the same doorway. Which one is likely to get thru first, the forward moving one or the sideways moving one? That's swirl, vs tumbleport in a nutshell, although there's a lot more to it in the high tech explanation.

Another noteworthy point is that (and this is important to understand), the size of the bore dictates the size of the intake valve. Less so in a 4V motor, which is just great! The size of the valve dictates the choke point (smallest point) in the intake port. Usually the choke point on a perfectly ported head is about 94% of the size of the valve. The size of the choke point (cross section) determines the overall flow potential of the intake port. The flow potential dictates peak potential horsepower. Normally from the factory, the size of the choke point is much smaller than 94% of the size of the valve, so therefore we can port these heads (assuming there's enough meat left in them at these critical spots) to get to the 94%, and we normally don't have to change valve size. With a mod motor, the bore size is usually 3.55, so we can't fit much of an intake valve in there, and still have room for the exhaust valve. This gets better with a 4V motor, because we have 2 smaller valves to flow into instead of 1 large valve. Now you know why the 2 valve motors will never build much power in N/A trim no matter how much you spend. The bore is too small. Yet a 302 has a 4.00 inch bore, and you can slap some pretty big heads on that motor.

In summary, with a 4V motor and a blower, you don't exactly have to worry about lack of low end torque. The blower will create it soon enough anyway. And with traction at a premium already, a little loss of low end is usually just a benefit. If it's too weak down low, just come out harder.

The tumble port heads redesigned the B head for tumble and velocity at lower valve lift, at the expense of total port volume. This SHOULD mean that, assuming the port shape is correct, the B head will make for a better race head. That may be why you see so many racers running them. In 99, Ford redesigned that new tumble port head to fix the low end torque problem that the B head has. In 03, they had the bright idea to take this already torquey head and put a PD blower on it. The end result: Tire melting. They should have put the PD blower on the 96-98 head in the first place! That would have been a killer combo.

The number one reason why home porters screw up their work is that they enlarge the port in some areas, and leave other areas alone. And they screw up the short turn radius, causing the air to fly off the cliff. Often times, they just kill performance across the board. You would be better off just mildly enlarging the smallest parts of the port you can measure, without getting hog wild.

Take a look at the port volumes listed above, and you'll see that the B head is a rocker already, when it comes to total size. Airflow numbers might still be restrictive, based on choke points and short turn radius (which above was listed as being much better than the newer heads). However, if you port wisely on the B heads, you should be able to get the airflow numbers up quickly, without extensive redesigning of the port. I think they're a race head just waiting to be unleashed. But they'll always be plagued by the single injector, double port design, and also lack of aftermarket intake. I personally think that one reason there aren't many intakes out there aftermarket, is because they can't build one that's much better.

The big turbo cars basically take the runners out of the B manifold entirely, and fill the floor with epoxy to bring it up to the level of the port entrances. While this would kill all low end torque, a drag radial turbo car doesn't care about that anyway. Hope this helps some of you to understand the why's of cylinder heads. Remember too, that the factory usually does a great job of designing a head/intake for it's intended purpose. If they didn't, they probably redesign it within a few years. Case in point is the lack of low end torque on the naturally aspirated B head motors. But with a blower, it's a whole different story.

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post #15 of 18 Old 09-07-2007, 12:32 AM Thread Starter
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Wow, superb information and answered my question completely. Thank you very much. But, in the post made by na_svt, i read that the 03 DOHC driver's side head had a "tick", did Ford recall this issue to where the car does not have to be under warranty to fix this problem?

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post #16 of 18 Old 09-07-2007, 01:48 AM
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Yes, that's why you'll read someone's posting about the "9 thread spark plugs" vs the "3 thread spark plugs". I believe it was the early 03' heads that had this problem. I haven't hear of any 04's suffering from it.
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post #17 of 18 Old 09-07-2007, 10:55 AM
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My understanding s that some early 04's did have the short thread count.
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post #18 of 18 Old 09-07-2007, 04:29 PM
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Quote:
Originally Posted by 95PGTTech View Post
...
how can you tell the difference between right and left by casting numbers. The only reason I ask is because I just bought a set of used 04 mach heads. They have the same casting number. Are they both idential heads just for one side only??
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