Question: How can I make my Ford Expedition/Navigator go fast?
Answer (Saleen): Put our supercharger on it.
Answer (Me): Buy a used Mustang.
I saw this item on Edmunds Inside Line, about a new supercharger kit that Saleen will be selling for the 5.4L-3V V8 engines used by the Expedition, which are closely related to the 5.4L-3V V8 used in the Mustang GT. Pushing 2200cc of air per revolution, the supercharger kit claims a horsepower boost of 100HP over stock, and 0-60 times of around 7s.
I think this really cool, in an exhibitionist automotive-pornographic sort of way. If you are rich, or if your funds exceed your humility*.
But if you are an average guy with a family to haul, and maybe a jet ski, this is just silly.
Saleen also makes the claim that "this supercharger delivers with minimal effect on fuel economy". I think they need to rewrite that press release, out of embarrasment.
It is physically not possible to add 100HP to an engine with a given displacement without burning more fuel. The whole purpose of the supercharger is to burn more fuel by stuffing more air into the cylinder.
And, if you install this thing, you will have to run more expensive 91 octane (premium) fuel, or risk destroying your engine, according to Saleen's installation manual (here).
I think what Saleen was really saying is that the supercharger kit does not have a big impact on the EPA fuel economy number--which is calculated using a relatively mild speed trace.
But we all know that in the real world, if people are given an extra 100HP to play with, they will, and they will burn a lot of gas doing it. Or, as the EPA likes to say, "Your mileage may vary".
To add 100HP to your Expedition will set you back around $6,000, not including installation. If you upgrade your suspension, brakes, wheels, and maybe glue on some body kit so everyone knows you are packing, you will easily blow through $15,000 or $20,000. Add to that the increased cost of ownership from burning premium gas at an increased rate.
Hence my answer to the silly question: leave the Expedition alone and buy a used Mustang. Quick 0-60, eats regular gas, looks great doing it.
*As soon as I win the lottery, I am going to buy an Expedition, and bolt one on. Hell yeah. Just for the political statement alone.