5.4 using 04 cobra c -heads

[cobrasvt57]

would these heads choke a 5.4?
Thanks
joel S

 

[Wildcard]

You have a couple holes on the heads that need to be drilled and tapped, but other than that it's good to go and would be good combo. Make sure you get later model version that has more threads on the spark plug holes. Check to see, the later version has 8 or more threads.

 

[Ironhand]

Depends on cams really. But the intake port on an 03 head is smaller then a 5.4 head. A Navigator head would be a better option. Stock vs. stock the navi head is 17ccs larger IIRC.

 

[cobrasvt57]

I thought the 03/04 were better then the navi due to the navi's exhaust.

 

[Ironhand]

I thought the 03/04 were better then the navi due to the navi's exhaust.

EDIT: Navi exhaust port is the same but it is "filled" by the divider.

 

[4sdvenom]

Have the exhaust side of the Navi heads ported!

 

[cobrasvt57]

the ports on the navi are larger which makes for less velocity which is what the 03/04s have not to mention the exahust side of the 03/04s would flow better and even more once ported. My question is will the 03/04 have the balls to feed a 5.4?

 

[Ironhand]

the ports on the navi are larger which makes for less velocity which is what the 03/04s have not to mention the exahust side of the 03/04s would flow better and even more once ported. My question is will the 03/04 have the balls to feed a 5.4?

Yes the intake ports are larger. However the Navi heads are designed to feed a 5.4 not a 4.6. But the larger intake ports help flow when using forced induction. The Cobra heads wont really be a choke point but the larger ports of the Navi heads are better to have on the larger motor.

I would stack my ported Navi heads against a mildly ported Ford GT head and I bet they would flow more on the intake side and be very close on the exhaust side.

 

[cobrasvt57]

I would think the intake on yours might be close being port to a stock Ford Gt head but the exhaust i'm not so sure. But anyway It's not always about size On a lot of engines it's velocity.This kinda thing is why i wish i had flow benchs for.I'd be in there for hours running and logging test to the point my wife would probably kill me unless i made it my job lol. If you could i'd like to have a link to a couple of your dyno charts.
Thanks
Joel

 

[Ironhand]

I would think the intake on yours might be close being port to a stock Ford Gt head but the exhaust i'm not so sure. But anyway It's not always about size On a lot of engines it's velocity.This kinda thing is why i wish i had flow benchs for.I'd be in there for hours running and logging test to the point my wife would probably kill me unless i made it my job lol. If you could i'd like to have a link to a couple of your dyno charts.
Thanks
Joel

It will be a long time before I have dyno sheets. If you fix the floor and short turn radius on the Navi heads on the intake, then smooth down the divider and port the exhaust side, flow will not be an issue.

Regardless though a Cobra or Navi head will work well. Both have their flaws and arent perfect. It depends on what your doing and what parts your using. If your using something that has the larger Navi ports then your gonna wanna use those heads and the list can go on.