Are B headed Cobras "really" that bad?

Discussion in '96-04 - 4V Specific' started by bens4vcobra, Apr 25, 2007.

  1. skmcobra

    skmcobra New Member

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    Maybe this will help. I saved it a long time ago.

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    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+) performersâ€â€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 productionâ€â€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: 1.960â€Âx1.350â€Â, 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 displacementâ€â€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 sitâ€â€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: 2.290â€Âx1.400â€Â, 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: 2.370â€Âx1.300â€Â, 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 groupâ€â€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: 1.960â€Âx1.350â€Â, 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: 1.960â€Âx1.350â€Â, Valves: 37mm Int., 30mm Exh.


    In Conclusion
    Our panel of experts surmised that aside from the nearly unobtainable ‘00R heads, the ’03 DOHC heads are without question the right choice for your Modular four-valve performance application . The combination of a slightly larger FR500 intake port and modified throat region, coupled with a new larger rectangular exhaust port, and a relatively low price (due to it’s widespread use in the Ford organization) makes the ’03 DOHC casting the current head stud of Ford’s Modular stable.
    After porting, the relatively small stock valves/seats become the most serious flow limitation; as such aftermarket replacements should be a serious consideration for those looking to squeeze every last drop of performance from their DOHC heads.
     
  2. DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    With the bad rep that B heads get from those who don't actually know anything the Ultimate Sleeper and Terminator killer would be a 96-98 Cobra with forged internals and a Turbo or 2.
     
  3. bens4vcobra

    bens4vcobra New Member

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    True. I believe that a forged B-head motor with power adder would actually run better times than a terminator with comprable boost/power.
     
  4. fastlane65

    fastlane65 New Member

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    And lighter too.
     
  5. bens4vcobra

    bens4vcobra New Member

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    Yeah, sleeping giants they are...
     
  6. M.O.E

    M.O.E Active Member

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    I love BJ's Oh i mean B - heads :drunk:
     
  7. IMPORTKILLER

    IMPORTKILLER New Member

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    This is a great topic !!! I love the 03-04 cobra. I think Ford hit the nail on the head with a combination of quality and power. Quality meaning forged internals and power meaning a factory supercharger !! The only thing I hate worse than rice racers is 03-04 cobra owners who think that their shit is the best performance car ever built from any company ever. Yes they are a bad ass ride but so are 96-98 cobras.With the equal amount of boost and upgraded internals. NEWS FLASH ....... We 96-98 cobra owners have an aluminum block and if we really wanted to go nuts we can get these cars light as shit. Again if all things remain equal as far as boost/forged internals our redheaded stepchild will beat the shit out of any Abercrombie & Fitch wearing, Justin Timberlake lovin, American Idol watchin, Pink Polo shirt hero on any given day. That is why I love 96-98 cobras because we are always underestimated, and that is to my advantage. Yah your right my 96 cobra is slow and it runs 17.9's all day so I guess I should probably get the hit. I love being underestimated because winning is so much sweeter when no one thought that was gonna happen and the 03-04 cobra guy jus sits there with his mouth on the floor handing you over his Money $$$$ Cha-Ching. The other major part of being the faster car is being the better driver. In my Opinion a real driver who knows how to get every last ounce of power to the pavement is going to win in a " slower " car . As opposed to a " faster" car operated by a nimrod who has no real idea how to handle the horsepower under his ass because the last car he drove was a 98 civic with a performance "coffee can " exhaust pipe until the day daddy ( or sugar daddy for some ) bought him his new 03-04 cobra. Give me a 98 cobra with some basic bolt ons 4:10 gears,pullies,cold air intake,diablo tune, alum flywheel, speck stage 2 clutch , alum drveshaft, Bfg 315 drag radials, upper/lower controll arms, and I will smoke the 18 year old kid with his stock 04 cobra any day of the week. One last thing before I go. You can buy a stock low mile near mint 98 cobra for around 13-15k. If you want to buy a 03-04 cobra you are around 23-25k. Give me the 98 and the extra 10k spent for that stock 03-04 and I will be running 10's all day long while you have spent the same cash and are left with a bone stock 03-04 cobra runnin in the high 12's. Let em talk shit because the look on their surprised face is priceless. DSS Rocks for the Mod motors. Their shop is amazing. Great people better products check em out in MM&FF/ 5.0 OR check out this link.http://www.dssracing.com/ Rock On SN95'S Rock On.
     
  8. scarface

    scarface Guest

    very nice read buddy O0
     
  9. voidfinger

    voidfinger Well-Known Member

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    Well i got a question since we are talking about b heads. I'm thinking of doing the swap and i would like to know what is the difference in flow between the 97-98 Mark 8 intakes and the cobra one. I've heard that the cobra intake is a major problem to since it is one of the killers for the velocity. The 97-98 mark intake looks like the 99 cobra intake and i was wondering if it flows comparable to the 96-98 cobra? thanks

    Mitchell
     
  10. BLWN SN-95

    BLWN SN-95 Guest

    i perfer the B heads to C heads they are better up top IMO, if your gonna work them def go with B heads!
     
  11. rickzcobra

    rickzcobra Guest

    To kill all your torque problems, switch everything to a 5.4 block and get some custom plates made. I got 90lbs more torque to the wheels just switching to a 5.4 block with a retune. And uh, I had my b heads completely rebuilt and Im laying down 458rwhp all motor, but I am also running a 10.9 compression motor with about every bolt on you can imagine.
     
  12. BLWN SN-95

    BLWN SN-95 Guest

    or you can spray that bitch! GOT NX?
     
  13. voidfinger

    voidfinger Well-Known Member

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    lol, that must be a small shot on that thing :p I figure with that kinda flow a 100 shot should put down 130 at the fly :pimp:
     
  14. rickzcobra

    rickzcobra Guest

    Ive wonderd this myself. I could pick up a cheap lower mrk 8 intake and do some modifications to it.
     
  15. voidfinger

    voidfinger Well-Known Member

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    flow it up man :)
     
  16. Cobrar96

    Cobrar96 New Member

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    hmm 96-98 Cobras? Teskid Block ( Made by ferrari ), Solid Axel (not that irs crap), B Head (made for maximum flow..loves centrifucal blowers),...oh yeah the nostrils on the hood are sweet.
     
  17. Paul

    Paul Legend

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    Teskid blocks are not made by Ferrari. Teskid does manufacture some engine componentry for italian automobile makers. Unless something has changed that I don't know about, Ferrari casts their own blocks.
     
  18. Knuckles@Empire

    [email protected] -Never Forget-

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    if your going to build a 4.6 id definetely get a pre 99 4.6 dohc for the flow, theyre great with any power adders tey flow insane numbers with just light porting, if you want a street car with all the low end grunt you could dream of then go the terminator/ roots style / screw style supercharged with the late model dohc heads. my liking of the b series head style has nothing to do with owning one either, i have always seen them perform well in race applications.just my .02 cents ;D
     
  19. voidfinger

    voidfinger Well-Known Member

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    true, b heads with a good centri or turbo and your set :)
     
  20. Shocker98GT

    Shocker98GT Active Member

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    B heads plus a centrifugal or turbo will almost always outrun a 03/04 Cobra with equivalent boost. Just the fact that you don't have to deal with the wheel hop as much, you also don't have the traction issues that a roots/screw charged car has to deal with, as well as the flow at higher RPM.

    For a true street application, though, I'd take the C heads everytime, or FR500 if the wallet permitted. Or those Cobra Rs if I had a 5.4L (I'd much rather find a set of those than be Britney Spears' next uterus masseuse as mentioned above...)