03 cobra vs fr500 debate
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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.
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.
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.
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.
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.
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!
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!
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.
Firme
Founding Member
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
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
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