Background:
The Ford 4.6 2v NPI motor wasn't Fords first attempt at the 4.6. As a matter of fact, they had been building the 4 valve version for a few years, putting the 280hp 320tq motors in their other lines of cars, such as Lincolns Mark 8, police interceptor Vics, as well as some others. In 1996 When Ford switched the mustang over to the 4.6, the motor was a basic transplant for all vehicles, including the F-150 (except for intake), Crown Vic, Marquis, Expedition, ect. These motors were good for torque, producing 290lb in stock form, but as for the horse power, were a sad 215hp at the wheels. Not what you would call a monster. However they started putting the 4v 281 in the Cobra, with much better results. The 96-98 Cobra produced a much better 305hp and 305tq in stock form with fords "B" series head, and also benefited from a much higher redline (7000rpm VS 6250rpm) Both the 2v and 4v were internally balanced, and rode on a 10.5" clutch or flexplate in either a 6 bolt (non forged) or 8 bolt (forged) bolt pattern

In 1999 Ford created the PI 2v 4.6 motor (PI= Performance improved). This increased the sad numbers of the NPI turd motor to 265hp, 300tq in stock form. This was due to different porting on the heads, longer runners on the polly intake as well as a different fuel system and ignition. The Cobra at this time also benefited from Fords improvements by getting its own PI heads, called the "C" head. they were boosted from 305hp to 320hp and 320tq, with the same 7000rpm tach.

Idea for swap:
My current setup being run is Fords NPI 4.6 with a PI intake and Vortech, producing aprox. 360hp at the wheels, and about 360tq. However, the 2v's setbacks are: Mileage (160,000mi), redline (6,250rpm), and power curve of the blower. With a 4v conversion, and basic bolt on modifications, I will be able to achieve what I am getting right now without the snail, and with the addition of some performance cams, would be able to exceed the safe power limit of the Vortech, being able to run close to 400RWHP (450 crank). I will also benefit from better gas mileage, and better power curve. Also, by doing the swap I avoid the insurance increase of buying a Cobra, with the same performance.



Swap Involves:
If you get a MK VIII motor, you start with 280hp. That is the route I am going, however with the addition of a 1999 Cobra intake, cams, and headers, will put me over the 360hp mark. The stock 1997 fuel setup will be run on the motor, as since it is the same generation of motor, I will be able to use all my stock sensors, extending only two wires, and stock radiator. Since the first gen 4vs didn't have a forged crank, I will be able to reuse my Hays performance clutch and flywheel.


I will update this thread as parts start coming in and modifications start occuring

UPDATE-
Further research into the setup, I have found out that using my Stock 2v block and a set of 99+ heads would actually yield more power, and would be cheaper.

Now what I am going to have to do is calculate my compression ratio with the 99 heads, and do a compression test on my current motor to find out how good the rings are in my current engine, to see if it would be worth doing.

Are you still running the stock gears? If so, why not just spend $150 and change to 3.73s or 4.10s and enjoy hitting your blowers power a lot sooner? That car would pull pretty hard with a gear swap.

It will cost you a bit in fuel but if you are building a car for HP don't expect anything over 20mpg.

What is your current setup?

http://www.svtperformance.com/forums/

If you're not a member, take the time to register and look in the SN95 section. You'll find some of the best info there.

Blower is gone- working on getting everything needed to do the swap when the weather gets warmer!