SOHC to DOHC conversion for a 2003 Town Car

CTX-SLPR

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Howdy,

I'm always dreaming and scheming. Particularly every time my daily driver does something not so cool. I drove past a beautiful dark green Town Car 2 days ago and I have to say.... wow. That prompted an Autotrader search and I found 2 2003's well within my price range and with low mileage. However my current daily driver, a supercharged 3.8L V6 Regal GS, makes the same power but with about 500lbs less mass to drag around. While the steeper rear gears and RWD will make some of weight seam to disappear, I'd really like it to actually disappear as well as firm up the ride to a Touring type ride vs the Luxury Cruising of the stock stuff. The suspension stuff is easy the way I see it, Crown Vic Sport/Marauder sway bars and shocks, Maurader brakes and wheels... The power is the taller order. With 240hp pushing 3500lbs in the Regal GS thats a 14.5 lb/hp ratio. To keep this I'd need 275hp. While this might be in the realm of bolt ons I took one glance at how Lincoln did the Aviator and Naviator against thier pedestrian Ford counterparts and said... this thing need a DOHC motor. Call me crazy but driving a premium burning car everyday gets old really fast so I'd like to keep it to 87 octane fuel aswell. Reading around it looks like the Mustang Mach 1 has a ~300hp rating on 87, not sure if the EPA is totally right there since it says I burn 87 despite the supercharger but I'll trust them here. How hard of a swap would it be to put that Mach 1 DOHC 4.6L in using a Maurader intake track and oil pan? Coming from GM world they have editors where you can plug in to the OBDII port and mess with tune on the car to adjust for just this type of thing assuming the DOHC motor runs on the same basic command code as the SOHC motor, does such a thing exist for the Panther cars?

Thanks and sorry for the long post but I can't answer at work and I wanted to spell as much out as possible in the beginning,
 
You can swap a set of DOHC heads... but why not just buy a Mercury Marauder?


usa_2004_mercury_marauder_sdn_4_x_exfrdrvr75_x.jpg
 
Primarly premieum gas... but I'm considering it. What's the camber volumes one the different heads and pistons?

Thanks,
 
All DOHC heads are about 52cc (PI 2V= 42cc). The Marauder is 10.2:1, same as the Mach I heads. Just FYI; you'll be using premium fuel anyway if you put those heads on a SOHC. You'll be pulling 10.5:1 with Terminator heads on the Town Car's block (Terminator heads = DOHC on 03+ Mach I, Marauder, Cobra)
As I've said, you might as well buy the Marauder; or upgrade the drivetrain on the TC...
 
Well by my math here is:
Pistons Chamber Compression
-18.5cc 52cc 8.20:1
-10.5cc 52cc 9.26:1

This is of course with an SOHC short block and a DOHC head and front end conversion. I don't have the numbers on the DOHC shortblock stuff like that Mach 1 but it looks like either way NPI pistons with DOHC heads will give a nice 87 octane friendly compression ratio without dipping too deep into the begging for boost territory. What all does it take to swap DOHC heads and equipment onto an NPI short block?

Thanks,
 

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