03 cobra vs fr500 debate

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54life

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Jul 24, 2003

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Jul 31, 2004

#1

• Jul 31, 2004

• #1

alright here we go....I was looking for heads for my 99 and it boils down to fr500 vs the 03 cobra heads. Which one is the one? What do you think that i'll see from a head swap of this nature? What cams would I want to go with?

 

Beau

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Jan 29, 2000

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San Diego

Jul 31, 2004

#2

• Jul 31, 2004

• #2

I'd assume that the 03 Cobra heads would flow really well and the cams would be more along the lines of a blower grind, but I don't know anything about the FR500 and what setup it had. Personally I'd go with the 03 cobra heads.

 

C

ChrisWeil

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Jun 2, 2003

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#3

• Jul 31, 2004

• #3

According to Sean Hyland, the stock '03 heads flowed a couple more cfm at higher lift, and a tiny bit less at lower lift than the FR500. I'm actually in the same situation, and that's all I've found comparatively.

I know the valvetrain in the FR500 is vastly superior!

Aren't the Mach1/'03 Cobra heads and cams the same? Seems to be a lot of disagreements on that, but I've heard that they're the exact same, even down to the cam specs.

 

S

SnakeBite98

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Jul 11, 2003

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Poway, CA

Jul 31, 2004

#4

• Jul 31, 2004

• #4

I thought that the Mach 1 cams had different cams, gound more for low end and drop off a little on the top?

 

5.0's 4 ever

The #1 Stunna

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#5

• Jul 31, 2004

• #5

The complete assembled head on a 03-04 mach 1 is the same as 03-04 cobra. I would just go with a set of 03-04s over the FR500s, you can pick them up for very cheap fully assembled. You could use them as is or spend the money do some porting and upgrade the valvetrain.

 

5

54life

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Aug 1, 2004

#6

• Aug 1, 2004

• #6

use the factory 03 cams with it or what? I have been looking at those SHM stage 1's and they look kinda decent

 

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03SilverSnake

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Cumming, GA (dont Laugh)

Aug 2, 2004

#7

• Aug 2, 2004

• #7

5.0's 4 ever said:

The complete assembled head on a 03-04 mach 1 is the same as 03-04 cobra. I would just go with a set of 03-04s over the FR500s, you can pick them up for very cheap fully assembled. You could use them as is or spend the money do some porting and upgrade the valvetrain.

Click to expand...

Im not completely sure of this but the 03/04 Machs use 5.4 Navigator cams

 

9

99SVTAddict

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Aug 2, 2004

#8

• Aug 2, 2004

• #8

What's your intent....or how far do you want to go with the car/motor? That's a lot of work and some decent money for marginal power. If you are biulding up an n/a car and plan on porting/cams/higher compression...go for it. Otherwise, there's cheaper things you can do besides the heads.

On another note, if you are going to do the heads....personally, I would port your stock ones (or the 03's if you want to spend the money), upgrade the valves and springs, and go with some agreesive cams and rev that bitch up to 8K RPM's.

 

5

54life

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Aug 2, 2004

#9

• Aug 2, 2004

• #9

I'm eventually going to utilize dual power adders....ati procharger and a 50-75 shot. I just don't feel like tearing the motor down right now that is all. might as well get the heads and cams done.

 

5.0's 4 ever

The #1 Stunna

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Aug 2, 2004

#10

• Aug 2, 2004

• #10

03SilverSnake said:

Im not completely sure of this but the 03/04 Machs use 5.4 Navigator cams

Click to expand...

They all use the same cam setup

 

C

ChrisWeil

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Aug 4, 2004

#11

• Aug 4, 2004

• #11

So for a 5.4L N/A engine, which would you guys think would be the best? FR500 ported/polished, cobra/mach ported/polished, or navigator ported/polished? Whichever I get I'm going to send to Fox Lake for a full p/p job. It'll have radical cams, to be used in street/road racing, and I'm going to use an FR500 intake manifold most likely, again p/p to match, and I think Reichard Racing makes a spacer so the 4.6 stuff will match up to a 5.4. What do you guys think?

What makes the FR500 valvetrain superior, specifically? I know my way around them more than well enough, but I've never found any specs on what the FR500's actually use!

Thanks for the help guys!

 

P

PoorYuppie

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Aug 4, 2004

#12

• Aug 4, 2004

• #12

What makes the FR500 valvetrain superior, specifically?

Click to expand...

They get their gains from two things. The dual runner intake which gives you two torque peaks(giving more area under the curve), and the valvetrain specifically is deisgned to run at higher rpms, where the stock ones can't handle much more than the stock redline. I'm sure they changed the valves and such as well, but I don't know much about them.

 

5

54life

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Aug 4, 2004

#13

• Aug 4, 2004

• #13

2500 for a variable runner intake=stupid s h i t

 

Firme

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Sugar Land, Tx

Aug 4, 2004

#14

• Aug 4, 2004

• #14

the 03 -04 heads are a better design than the FR500. That comming from SVT.

Taking that with a grain of salt since the FR500 heads are a FRPP design, and FRPP butts heads with SVT (now they are under the same umbrella becase of this very conflict), SVT claims design advances in the 03 04 heads over FR00

 

5

54life

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#15

• Aug 4, 2004

• #15

that's pretty much what I have been hearing