Automobile(s): 2002.5 F55 STS/64500mi, 2004 Ford F150 SuperCab4x4
MD Eastern Shore - Kent Island
Re: added power?
Very, very little can be done to the FWD platform. The GM engineers already did 99.9% of the work and there's nothing made in the aftermarket because there's literally no demand. CHRFAB does some Northstar work for kit cars and sand rails, but none of their custom gear will work in a FWD driver.
The air intake is already a great CAI that flows more than the engine can handle, same for the MAF and throttlebody. The exhaust is the main bugaboo, but the front crossover pipe is the culprit, not so much the rest. rebuilding the crossover is practically impossible and there are no headers and no way to get them in if there were. The PCM is already tweaked as much as possible for each engine/transmission package, VIN Y or VIN 9.
You could gain a few HP at redline with a good mandrel-bent s/s exhaust pipe from the cat back into a 2 1/2" smooth Y and decent mufflers. CORSA makes systems for Seville and Deville, but not Eldorado. Take a look at www.corsaperformance.com.
Read the entire Cadillac Technical Archive up in the black bar ^^^, study the Seville/Eldorado and Northstar Performance sections, keep it clean and maintained, and enjoy what you have.
You're already putting out 300hp. The engine is a 4.6 liter engine which converts to 280.709 cubic inches or basically 281cid. This means that it's putting out more than a horsepower per cubic inch displacement. That's more than most engines can do unless they have forced induction. The only way to really get more horsepower without forced induction would be to tear the sucker apart ($$$$$) and rebuild it with performance parts (stronger, lighter, more balanced) which most don't even exist for this engine ($$$$$$$) and then reprogram the PCM to the best power curve on a dyno (did I mention $$$$$$$?).
I've been trying to find ways to make more power too, but there isn't much out there for us! I've got a 98 ETC that's currently awaiting a rebuilt engine. Seeing the condition of the inside of my old engine, I'm sure this will make the car faster :-)
Best bet is probably just making sure the car is running in tip-top shape. I'm not sure if anyone makes a high-flow replacement air filter, K&N doesn't make anything application specific for us, and I couldn't find anything in their catalog that is close to the dimensions of our air filters (1.69"h X 10.65"l X 7.93"w), but a buddy of mine has an STS and he bought one of the eBay "cold air intake" things for $50 bucks with a cone filter, he doesn't know if it really increased power at all, but he enjoys hearing the engine rev up with the ebay intake (Basically a metal elbow coming off the TB with a cheapie cone filter on the end)
A good set of plugs, wires, a clean air filter, keep up on the oil changes, use good gasoline, and drive the car hard every now and then to blow out any build up (google "Italian tune up")
Keep up with all maintenance (if an o2 sensor needs to be replaced, replace it!), get a good set of tires and make sure they're properly inflated... that kinda stuff is where you'll be able to squeeze every drop of performance out of the car. :-)
Automobile(s): White Diamond '03 DHS (with floor shift)
Re: added power?
The factory air filter is not restrictive and will flow all the air that the Northstar can breath at WOT AND it is already cold air intake. Those cone filters actually draw warm under hood air. They do make a little more noise if that's what you want, but do little else. As a side note, the PCM was placed under the air filter box so as to be cooled by intake air. Rerouting the intake air leaves the PCM uncooled.