i want more HP around 360-400rwhp N/A and i thought that a 5.0 big bore 4v would get me there.......also how would the spray bump my power also because the 96-98 heads flow a lot better then the new ones when adding a power adder
From what I have heard, going with the 5.0 big bore helps alot. A buddy of mine showed me a set of stock 96-98 4V heads and the outside edge of all 4 valves are "shrouded" pretty bad due to the cylinder size. A good valve job and stock or slightly higher compression 5.0 4v kit should bump a 300+ rwhp bolt on cobra to around 340rwhp.
You could figure about 9/10 HP for every 1 cubic inch displacement that you added on the old 5.0's(fully bolted on of course). However, looking at how unshrouded the valves would get with a bigger displacement, I would bet you will get over 1 hp per cubic inch added.
Please note that I am NOT an engine builder and I am NOT speaking from personal experience. This is strictly my interpretation and opinion regarding what I have seen and heard.
BTW, you might want to look into this a little further, because I remember reading something about resleaved 4v's running Hotter than stock bore 4.6.
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