Rob
I have a 2005 Dodge Durango 5.7L hemi and I've been told that I can increase fuel efficiency by changing out the exhaust system and installing a forced air system (I have no idea what this is). If this is so, can you recommend what type of exhaust system I should get and also advise me on the forced air system?
Dave
The options you mention do increase power and fuel economy. However, you will need to do some math to determine if the costs of these upgrades will be paid back in a reasonable amount of time.
Let's run through each of the two systems to see what they bring to the dance.
Forced air is not really what it sounds like - a more accurate term to use is Fresh Air or Cold Air Induction system. These are replacement parts for the existing air filter and inlet ducting that comes with all vehicles. The main differences are:
Filter design - Replacement filters are very low restriction and often will last the lifetime of the vehicle. K&N filters are arguably the most popular brand. They utilize a reusable filter element that is cleaned with solvent; special oil is then sprayed onto the element and is re-installed in its housing. These filters (there are many other brands), can be fitted to almost any application without the need to replace the intake ducting. Some come with a one-million-mile guarantee.
Ducting - Aftermarket designs tend to smooth out sharp corners and dress up the duct and filter assembly. Sometimes they include a special box that separates the filter inlet from under-hood heat - this gives the fresh or cold air delivery to the engine. This cold air is slightly denser than under-hood air, which theoretically can increase power and fuel economy.
As for exhaust system upgrades, the sky is the limit, Dave. You can go nuts with everything replaceable from the engine to the tailpipe: exhaust headers, larger diameter pipes, low-restriction mufflers, stainless steel pipes and muffler, and on and on. Really, the only limiting factor is the amount of money you have.
Let's consider for a moment that you want to move on intake and exhaust upgrades. Here's the rub: typical cost ranges of an intake system - $220 to $1,200; for an exhaust system - $200 to $3,000.
If cost isn't an issue, go nuts. However, if you're like most of us, some sort of rationalization will be taking place. Figure that a conservative pay-back will be in the range of 2-to-8 per cent in fuel savings, you will have to get out the calculator and do the math. Dave, also figure in the length of time you plan on keeping your Durango, because no matter what you do to it, it is a depreciating asset.
There are a lot of goodies available for your North American iron and there are many parts web sites that will give you an idea of what you need and the costs involved.