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4.6 to a built 5.4 with 4v heads...Is this worth it, and how much cost am I looking at? I have a 02 GT and I am very unsatisfied with the amount of $$ I have to spend to build a 4.6 motor, put on a blower, then still hit only mid-12's. I would like to know if the 5.4 is worth it, or if I should just scrap this for a crate motor (ie-maybe FoMoCo's 351w stroker)?
 

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The 5.4 will require more work and parts to transplant. It is my understanding that there is no intake unless aftermarket, that will fit the 4.6 block and 5.4 head combo. If you are considering a complete 5.4 then I don't believe it is worth much over a 4.6 4V in a street car. The best bet in my opinion is to build a Billet/Forged bottom end from your block and get some 4.6 4V heads and intake or get a complete 4V 4.6 built and ride till it's done. A combo like that would make enough power to run High 10s to Low 11s with 12-14 PSI. Should go easy 12s all motor.
 

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The 5.4 will require more work and parts to transplant. It is my understanding that there is no intake unless aftermarket, that will fit the 4.6 block and 5.4 head combo. If you are considering a complete 5.4 then I don't believe it is worth much over a 4.6 4V in a street car. The best bet in my opinion is to build a Billet/Forged bottom end from your block and get some 4.6 4V heads and intake or get a complete 4V 4.6 built and ride till it's done. A combo like that would make enough power to run High 10s to Low 11s with 12-14 PSI. Should go easy 12s all motor.
Thanks for the help DOHCtor, I appreciate it. Trying to get this car fast is proving to be VERY expensive, along with time-consuming. Am I understanding correctly that I can put 4v heads on my GT block, with the proper intake assembly? Where do I get an intake for 4v heads on my iron block? What other parts would I need for the swap? If so, what year 4v heads can I use? Can they be off a Navigator, Maurader, Cobra, or other 4v vehicle?

I guess I would have the heads covered, just oder them from Fox-Lake.

Sorry for SO MANY questions, but the idea you are proposing sounds GREAT. Basically a Cobra motor (or better) in a GT...what a sleeper!
 

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The intake depends upon which year model heads you choose. The 96-98 Cobra and 93-98 Lincoln MarkVIII heads will need the 96-98 Cobra intake.The MarkIII heads have different cams but work great. The 99 up heads will need to be paired with the corresponding Cobra intake. This is because of the port design of 4V heads. 96-98 are the same basic heads and I remember correctly 99-01 are the same. Some people prefer the older heads as well as some prefering the newer design. They both have thier strongpoints. You can find intake assemblies from $300 to $500 on eBay. Delete the IMRCs on the 96-98 intake IMRC plates.You will need 4V headers or Cobra exhaust manifolds.

You will also need an Autologic chip and/or change the PCM(engine computer) to the Cobra part. You will also need a front engine cover(timing chain cover) from a 4V and the timing gears, chains, and tensioner assemblies. You can get a stock, aluminum block 4V complete from a Mark VIII for ~$1000 however you will still need a Cobra intake. The Mark VIII engine will use the 6 bolt flywheel from your 2V opposed to the 8 bolt Cobra flywheel.<<< That's what I would do...........
 

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They make a "Cobra" motor in a GT. It's called the Mach1. Same 4V motor as the Cobra. Dont know what the specifics are in difference between the 2, but it's just as capable as far as upgrades as the Cobra is.
 
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