Dual Air Cleaners Better?
 

I was just wondering if the Air Cleaners I have noticed on the outside hood of trucks: Are they better than the single air cleaner underneath the hood, or mostly for show?

Plenty of clean fresh cool air is the thing a diesel loves most, besides fuel.
An air cleaner on the inside can't provide more of that fresh air then a truck with 2 air cleaners on the outside. That's my answer.

I dunno...all you're doing is filtering the air outside the hood then piping it into the same space that an internal filter would. I doubt that the small increase in efficiency by the slightly cooler(or not?) air would offset the loss in aerodynamics.
A landline magazine article on fuel efficiency this month states that external air cleaners create enough turbulence to possibly reduce fuel mileage 20% or more. Tho I think that figure is a bit high.

I am not questioning if they help your engine better or not when I ask this question, but are they worth the investment to upgrade to them?

Even though I said what I said. I think it would be personal choice. Although two is better then one. More air means cooler turbo and exhaust temp. This will increase turbo life and some would argue engine life. Also decreased chance of a blown head gasket on big hill climbing when pyrometer temps get too high. Maybe I'm nuts :P

If your not interested if they help your engine then what would be the investment?, besides a very slight increase of value for looks.

Depends on the enviroment too. Where I currently work we have a 2005 Peterbilt roll off truck that has a decent size engine in it considering it's a roll off truck, CAT C13. But it has a dinky under hood air cleaner. Our yard is very dusty in the summer and will clog up a new filter with dirt very quickly to the point that the filter collapses from the engine trying to pull air through it. My truck has dual vortox cleaners and doesn't need servicing nearly as much as the under hood one. However, when we do replace the filters in my truck they are quite expensive. I can't remember for sure but I think they are almost $100 a piece. :) :)

Sidman82, what I meant to say and didn't was I was not questioning what you had posted 1st, but was trying to figure out the good and bad and then decide which way to go.

My truck runs fine now, as long as I blow out the air filter every two weeks as hauling logs is in a dusty environment.

I didn't know if I purchased the dual air cleaners and had them installed it would be worth the money to get this done, and was looking at some way to find out what kind, size, etc.. that I would need to get.

I'm not sure if they even made them for my year model Truck 1985 Freightliner Day Cab.

Papa..Have you talked to a shop to see if it is even possible to had outside filters to your truck? Are you ready to spend the money your going to need to spend, to properly attach 2 filter cans, and add the flow lines to get the air where it needs to be? Does your truck have a charged air system? If so, will it support the volume of air that 2 filters will supply? Things mechanical you might want to ask about.

i would think that it would be a waste of time & money. I too am always looking for ways to improve my trucks performance & prolong it's life. i think that... however a truck was made at the time it was made... has everything on it to perform it's best. i have a 95 cabover with over a mi miles. turbo has never been replaced & i get 6.5- 7.5 mpg. i will say that dual filters on the outside may reduce fuel mileage that is why some trucks have their air filt mounted in rear of cab & i dont see them getting hardly any air there, but the seem to work o.k. cause we've all seen em.. with all the modification & new cost of a new filt i dont see it paying off. mine is a 1 stack, 1 filt design too. it was designed that way..

My guess is that it was a marketing issue to not only sell more trucks but to increase sales on air filter parts. I'm sure the truck was designed to need a certain amount of clean air and that the air filter was designed to at least accommodate that need.

Your sure as Hell not going to get your answer here. Pick a truck, get a dyno and do extensive tests and you'll have your answer.

People on here boast about fuel mileage also but it's crap science. One day you have a headwind or the air density is different. My point is you can't come to any conclusions about anything that has to do with performance unless you have a 100% controlled environment. This was just done with auto manufactures listing fuel mileage. Instead of that Honda getting 50mpg it's getting 38 now. The Feds finally stepped in and said put the cars on a dyno and do your test there setting the dyno at 55mph for highway and 30mph for city with a full stop every 45 seconds, idle for 15 seconds then back up to 30mph.

I guess my point is that these engines were not designed by Billy Bob and his brother but by engineers and scientists in a lab. They didn't pick the size of an air filter out of there AZZ.