Navigator Cyl heads

[devildog92]

So that the L motor is also Modular, how easy would it be to put a set of 4v heads from the N on our block? I have a chance to p/u these heads and if the swap isn't too much of a ***** i might consider it (if the power gains warrant the expense, after a good port job too). Any ideas?

[J.D. Blackwell]

They will fit, but listen up.....it will cost you out the a$$. I have already checked into it. You might as well get a built bottom end if you choose this route. Make sure you get the timing chains, front cover, etc, also. You will need a different intake for it also, and there is only 1 man that can make you one...JDM. I talked to him about it and you can pick up one of his intakes for around $950, (also that was then and this is now). It cost him alot of $$$ to build them, but it can be done.

Just remember, it will cost you out the a$$.

[devildog92]

So if its, let say, 2.5k to make this happen, what kind of power gains though, and idea? I hate to make that kind of investment for 30hp LOL

[J.D. Blackwell]

I think you may need to speak to a tuner for that question.

But I can tell you this, there is a guy in the DFW area that bought a '03 Cobra and added a filter kit, and cat back and dynoed 400 rwhp. He then changed his upper pulley to a Lightning upper (3# more boost) and then it dynoed at 462rwhp. It is hard to believe. I know they are 4.6L, but they have an Eaton w/ ported versions of the '99&'01 Cobra 4-valve heads. There is also a thread on corral.net with a '03 Cobra dynoed at 499rwhp with just bolt-ons and a chip.

The 4-valve heads seem to be more responsive to bolt-ons, so I can't tell how much more hp you will make. I guarentee you will need a "built" shortblock. It is going to take more then $2,500 to make it happen. I was thinking if you had the heads already it will cost at least $6,500 in parts and that doesn't include your porting and I know you will need to rebuild your tranny too. That is $1,800. Also you will want to change the cams (I would) and there are 4 cams on those heads!

I am telling you it is a never ending situation....just check out my sig. I may switch over to 4-valve heads one day, but it will still cost me $$$$ for the heads, cams, timing chains, front cover, intake, porting, new longtubes, etc... There is at least $4K right there.