Join Date: Aug 2005
Location: Arlington Texas
Options depend on your engine
If you have a 3.5, adding one of the computers from a 250HP car (SXT, LHS, 300M) is a nice upgrade. If you have the 234HP 3.5 you will need an HO plenum (upper intake manifold) and the associated wiring as well. If you have Sentry Key this can become complex. 3.5HO engines top out at around 270-275HP after all mods including exhaust and a JoeKD intake. You can do an intake spacer for more torque and boring the throttle body to 70mm helps a bit. Some have gotten higher with nitrous. Beware..... the transmission is only good for around 300HP!
3.2L: Your pretty much SOL in terms of factory add ons from other cars except a 3.5 swap. The 3.2 already has a short runner valve and a manifold tuning valve, so do a JoeKD intake and exhaust and maybe send in your PCM to B&G Chrysler. Other than that, there are a few more exotic mods like intake spacers and bored throttle bodies, but not much. Don't expect more than about 240HP from this after mods. Nitrous is an option on this as well.
2.7L: You're not going to do much good PCM wise unless you add a Manifold Tuning Valve and PCM that can control this....... do a search, one guy has done this. Some 2.7s have the MTV already. A GOOD intake kit like one from JoeKD works very well. Also, don't forget a well designed exhaust..... the stock one on our cars SUCKS.
DO NOT add nitrous to the 2.7L engine! It may not hold up well, this engine is already fairly stressed and is almost tuned to the max from the factory..... there is only so much you can do with 2.7 liters. Repeat after me: No replacement for displacement! A 3.5 swap is considered to be the BEST course of action for performance and durability. Find a wrecked 300M or LHS and go to town!
NOTE: The HP figures are at the crankshaft, NOT at the wheels. We loose a LOT of HP in the transmission and driveline, all cars do but ours are slightly worse. Wheel HP is around 150 for the 2.7, 165-170 for the 3.2 and 185-200 for the 3.5. This is a little low but not too shabby. If only the rated cars on wheel horsepower..... comparison shopping would be TOO easy.
2004 300M Special...257K miles. Original powertrain!
Last edited by hardwareguy; 01-03-2007 at 07:19 PM.