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Cheap Performance Mods

2K views 7 replies 4 participants last post by  pvidrummer 
#1 ·
Hey, everyone. After years of owning various, older Grand Marquis (a 1987 and a 1994), I just bought a 2004 Grand Marquis GS Convenience with 21,000 miles on it. I had planned to get something a little older, but my brother, an accomplished Ford mechanic, suggested that I just suck it up and get something as new as I could. $10K later, I've got myself a car that's in practically new shape complete with factory warranty.

The car goes surprising well with the stock 2.73s and the single exhaust. I'd like to eventually do dual exhausts, but I'm wondering if I can get away with some cheaper, under hood mods to the motor before I go laying down that kind of money. What's the best bang for the buck? Besides a Vortec blower, that is.
 
#3 ·
Exhaust is good, but it's only going to gain you around 10-15 horsepower. Yes, it's better, but it isn't spectacular.

I'd recommend doing a rear gear swap up to a 3.27 or even 3.55. That obviously won't gain you any horsepower or torque, but it'll make a huge seat of the pants difference acceleration wise. Depending on what kind of driving you do, you'll either gain a few mpg (city driving) or lose 1-2 mpg (highway driving), but either way the difference won't be terribly significant.
 
#4 ·
My thoughts exactly on the exhaust. I put 2 1/4 inch pipes on my stock '69 Cougar when I owned that, and it increased performance dramatically (the 351W really needs to breathe). Does anyone know if a Marauder exhaust will bolt right up to the GS? I haven't even priced one out, but it would stand to reason that it would be a painless upgrade.

Getting some 3.55s out back is definitely on the list. The one area the car suffers in is off the line performance. I don't even have to get into the pedal to pass once I get up to speed, but under 65 she bogs unless I have the overdrive switched off.
 
#5 ·
The cat back portion of the Marauder exhaust would probably fit, but not the front portions (at least I wouldn't think so). The reason I say that is the Marauder used the DOHC 4.6, whereas your GM has a SOHC 4.6.
 
#6 ·
Yeah, you may be right. The Marauder must have headers of some kind. But as I just had the cats replaced (no cost factory recall), I probably won't be going in that direction right away anyway.

Nathan, I always wanted to buy one of those 351W Interceptors, but I never found one in any kind of good shape. I've owned a couple of 351Ws (in the afformentioned Cougar and a '72 Galaxie) and I think it's one of the best motors that Ford ever produced. I was eating early 80's-era Z-28's with a 2 bbl in my Cougar, and in the Galaxie I was getting somewhere around 21 mpg on the highway (after I replaced the carb and the distributor) with plenty of power.
 
#7 ·
Mine's in good shape mechanically and structurally, though the body's starting to go on it and the interior is semi-shot. Still, for $425, I ain't complaining.
 
#8 ·
You should consider upgrading the following

-exhaust
-air intake
-better gearing

You can replace the cats with high flow Magnaflow cats, and a free flow muffler of your preference. My recommended exhaust tubing size is 2 1/4" where dual and 2 1/2" or 3" if single. It is cheaper to maintain the stock exhaust routing with upgraded cats, muffler, and tubing diameters rather than making it dual. Dual exhaust adds more weight to the vehicle and more weight makes you slower. Performance won't suffer with a single exhaust.

You can spend 200 or more bucks on a KandN intake, or you can make your own with PVC tubing or at the muffler shop. Use your imagination! PepBoys sells Mass Airflow meter adapters and conical air filters, and if you are creative enough you can install the aftermarket air filter in the OEM air box(it ensures colder denser air.) That way you improve air flow the same way the KN kit does for much less.

Gearing is all about sacrifice here gain there kind of thing. If you change your 2.73 for umm... 3.73 you gain acceleration but loose top speed, and since these cars have plenty of top speed...

Your car is now ready for other upgrades. Like, pistons, camshafts, an ecu, nitrous, etc.
 
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