FR500 heads v. ported 03/04 Heads

[305HPCobra]

I've doing some planning now because soon I want to do my engine build on my 99 Cobra. I have done some reading in the past and cannot decide what would be best for my combination. So here goes:

I want to build my engine to hit at a MINIMUM 400rwhp on stock cubic inches, although a forged bottom end. I have read that FR500 heads are one of the best heads for the DOHC engine, but that people have had success with ported 03/04 Cobra heads and ported Mach 1 heads.

So, FOR THE MONEY, which would be best suited for my application? Would stock FR500 heads outflow a good ported 03/04 Cobra head? Would I be better off buying some FR500 heads and having them ported to make the most power possible?

I just want to make the most power possible N/A obviously, but if it's not worth it to buy the FR500 heads when I can make good power with the 03/04heads then that path would be great too.

Thanks in advance

 

[cobraboy169]

I'm pretty sure there have been a couple of threads about this same topic. You may want to try searching for it, but I'm not tto sure. I have heard that the FR ehads are superior but with the right port job on the 03/04 heads they could be very similar to the FR heads as they are stock. But I could be wrong. In any case pm me if you need or want to buy some 03/04 heads. Good luck

 

[droptopsnake01]

a stock Fr500 head will not outflow a ported set of 03/04 heads.

They are the same and flow the same, so one ported will flow more than another.

 

[99COBRA2881]

Good reading below and best of luck with 400 rwhp on stock cubes. I doubt I'll make it there on .020" over 284ci forged 11:1 c/r, ported C heads [email protected] [email protected], FR500 cams, FR500 intake, LTs, Underdrives. I should have done a BIG BORE.

http://www.svtperformance.com/forums/showthread.php?t=367160&highlight=head+comparison

 

[olgreydog7]

Good reading below and best of luck with 400 rwhp on stock cubes. I doubt I'll make it there on .020" over 284ci forged 11:1 c/r, ported C heads [email protected] [email protected], FR500 cams, FR500 intake, LTs, Underdrives. I should have done a BIG BORE.

http://www.svtperformance.com/forums/showthread.php?t=367160&highlight=head+comparison

Why not? Naz did. He had ported FR500 heads though. Someone else did too, I think it may have been the guy in the link you posted.

 

[E. Green Cobra]

a stock Fr500 head will not outflow a ported set of 03/04 heads.

They are the same and flow the same, so one ported will flow more than another.

I wouldn't say they are the same, but they do flow very close to each other. Keep in mind a stock fr500 head won't outflow a ported b or c head either...

 

[droptopsnake01]

I wouldn't say they are the same, but they do flow very close to each other. Keep in mind a stock fr500 head won't outflow a ported b or c head either...

Yea, you know what I mean. I didnt want to go into detail w/ the newb. Just tryin to keep it simple.

 

[99COBRA2881]

Why not? Naz did. He had ported FR500 heads though. Someone else did too, I think it may have been the guy in the link you posted.

I dont really keep up on his combos they change too often but didnt he have a 5.0l Big Bore?

 

[cobrob]

Its not all about flow though. The head design makes the diffrence too. Fr500 have imporved designed ports that flow more straight. It doesn't make sense how 03/04 heads make the same power in a mach with more compression as in a cobra?

 

[01vert]

Debate has been done here quite a bit and many suggest that ported, both flow the same, with similar HP numbers. FR heads have been around a while and the newest design is the C head. The flow numbers have been posted before with a FR set about the same as an 04 set unported, and ported they were about the same.

How you could search this I am not sure, was a while ago.

 

[305HPCobra]

Ok, so I guess my question is, for the money, would ported FR500 heads or ported 03/04 Cobras heads be better? I don't see the point is spending another couple hundred bucks to only gain 2-3 more hp, for example.

Looks like the Terminator heads are next on my mod list!

 

[99COBRA2881]

I've said it before... so this time all I have to do is quote myself.

Why not port your stock C heads?

Here's a good example of how the DOHC heads flow compared to each other. Taken from SHMs "How to build max performance 4.6l engines."

Head Flow Numbers Comparison
INTAKE
______96-98 B heads__ 99-01 C heads__03 Cobra__FR500
.050"____39____________40____________40_______73
.100"____79____________88____________88_______110
.150"____114___________120___________118______137
.200"____144___________152___________151______163
.250"____172___________178___________178______183
.300"____194___________197___________201______200
.350"____207___________211___________211______211
.400"____217___________218___________221______219
.450"____225___________222___________229______226
.500"____231___________225___________233______228

EXHAUST
______96-98 B heads__ 99-01 C heads__03 Cobra__FR500
.050"____34____________34____________32_______35
.100"____71____________74____________68_______73
.150"____97____________102___________97_______98
.200"____119___________123___________120______121
.250"____132___________133___________135______137
.300"____138___________138___________150______147
.350"____141___________140___________158______154
.400"____144___________143___________163______160
.450"____145___________145___________166______159
.500"____146___________145___________169______162

Remember my stock C heads after porting flow very well with no port enlargement/no loss of velocity. Int. [email protected] Exh. [email protected]

Use the money that would be spent buying new heads and have your C heads worked over, just make sure the person doing the porting knows its for a NA app and doesnt hog leg the port just to get good .500 lift numbers.

 

[Tunnelvision]

Keep those low lift flow numbers in mind, big peak numbers don't mean much especially if their at or above .450 lift. I think our stock cams are a .3937" lift. The FR500's do offer significant gains down low over the others (unported).

Porting your stock heads may be the best bang for the buck.

 

[N/Angel]

Why not? Naz did. He had ported FR500 heads though. Someone else did too, I think it may have been the guy in the link you posted.

I dont really keep up on his combos they change too often but didnt he have a 5.0l Big Bore?

Naz made 407rwhp on the stock block with ported FR500 heads, FR500 cams, ported FR500 intake and longtubes... he then made 459rwhp with the 304 big bore

 

[na svt]

The FR heads were also flowed with aftermarket valves which allow more flow than stock valves.

The write-p below is from an old post but the info is still good.

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.

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.


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.

 

[olgreydog7]

03/04 heads ftw! Much better bang for the buck. Yea FR500 are the best, but, for the money, you can beat termi heads.

 

[Cobra925]

03/04 heads ftw! Much better bang for the buck. Yea FR500 are the best, but, for the money, you can beat termi heads.

+1 go 03/04 Heads and be done.

 

[01vert]

Could you just put the money you were going to spend on the 03 heads and porting and put it into porting your set of 01 heads? The flow numbers are not too far apart stock and couldnt a good pro get the 01s to flow the same ported at lift of around .450? Just asking. I know the article mentions the 01s weaknesses but couldnt a guy like Al P get them to flow well?

 

[na svt]

Could you just put the money you were going to spend on the 03 heads and porting and put it into porting your set of 01 heads? The flow numbers are not too far apart stock and couldnt a good pro get the 01s to flow the same ported at lift of around .450? Just asking. I know the article mentions the 01s weaknesses but couldnt a guy like Al P get them to flow well?

Yes, in fact C heads are what Modular Performance use on their Pure Street car.

 

[Nazman]

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