'04 heads on '99 shortblock

[na svt]

my 98 cobra motor lopes like crazy I LOVE IT! C heads + 98 cams = WIN WIN

your car is running like shit if it lopes, get a tune.

 

[Black*Death]

Intakes are different when you try and bolt on 99 heads vs 03/04 heads right?

 

[Jimmysidecarr]

If you get 96-98 cobra cams it would even be better.

This.

You'll probably make about 30-40 HP more in the lower RPM range, with peak torque coming between 3000 and 4000 RPM's. But you'll give up about 500 RPM in the top end. That is, if you go with the heads AND cams. I'm not sure what the power would be like with the 99-01 cams. I noticed a HUGE difference in bottom end power when I swapped to my aviator longblock, but since the motor revved about 500 RPM less, it made less boost.

One other thing to be concerned with is that the exhaust ports are shaped differently in the later heads. To get the most out of your heads, you'll want to swap out your exhaust manifolds for 03/04 cobra manifolds. You can get em cheap, like $20 bucks. Or, you can just get some headers designed for 03/04 cobras or Machs.
Search this forum for head comparisons. There are a few good dyno charts that show the difference.
Homer

I would likely do 03/04 manifolds the ports are bigger, but manifolds are nearly always slightly larger than the port they meet, the old ones will probably not have a lip in the way to hurt flow, they are just smaller.

The 99-01 exhaust cams are the same part number as 03-04. The 03-04 intake cams are the same part# as 99(DOHC)-04 Navigator. They help low end torque, but don't bring the goods up top. N/A I would just change your intake cams over to your old ones if you can't come up with the early B head cams.

 

[na svt]

Intakes are different when you try and bolt on 99 heads vs 03/04 heads right?

no

 

[99Cobra_vert]

they are not the same shape

:shrug:

I don't see a major difference in shape. An enormous change in size, obviously, and the '04 is slightly more rectangular, but they both look oval to me.

'04 on the left; '01 on the right.

 

[Darkc0bra]

You can tell a little bit but I would still take the 03/04 Heads any day of the week.

 

[na svt]

I don't see a major difference in shape. An enormous change in size, obviously, and the '04 is slightly more rectangular...

no major difference in shape, but there is a difference.

 

[fangs99]

Now here's my question, I've heard that the 99-01 cobra heads are a 52cc head and the 03-04 heads are a 54cc how much does that change the compression ratio? Is what you gain in head flow lost in compression?

 

[71catruck]

i have 03 heads on my 99 but i heard that the 99 head is a 54cc and the 03 is the 52cc. not sure how much it would change the ratio but its not enough to mater. and the size of the port isnt the big difference. the 03 has a revised intake runner will less of an angle. on the 99 heads the air tends to overshoot the valve at high rpm and create turbulence slowing down the air.

 

[Darkc0bra]

The 03 has a revised intake runner will less of an angle. on the 99 heads the air tends to overshoot the valve at high rpm and create turbulence slowing down the air.

That is why they are a bit better :beer:

 

[71catruck]

i read that you can port the 99 heads as much as you want and they will still only flow maybe as good as stock 03 heads.

 

[na svt]

i read that you can port the 99 heads as much as you want and they will still only flow maybe as good as stock 03 heads.

Ported 99/01s have a lot more potential than stock 03/04 heads. The difference between the two is that the later heads have a lerger exhaust ports.