K&N / Spectre filter for better mpg?

[Cubey]

I am looking to stretch every gallon of gas as far as I can. Even if it means 1/4 of a mile per gallon better.

I had a 99 F150 4.6L V8 that I put a Spectre air filter in and did a simple intake mod that just used a short piece of PVC pipe and a rubber coupler which allowed for more airflow to enter the intake. I swear that it felt like it had better power. I'm not sure if the larger intake pipe was what helped or the high flow filter, maybe a little of both. It may have also helped the MPG but I really didn't pay a whole lot of attention.

I am wondering if my 360 might benefit from a Spectre or K&N filter. I would probably have to leave the OEM air filter housing since it somewhat helps keep the air being taken in cooler than it would with one of those exposed hamburger bun style housings. So it would solely be an air filter change since there's no real way to do a cold air intake on this van.

I expect the carburetor might need to be adjusted for a higher flow filter since it's not EFI like my F150 was. (I left the truck unhooked from the battery for about 30 mins to clear the computer).

While increased airflow helps combustion, I think perhaps having less air (cooler) coming in might be better than having more air (hotter) going in?

I have read that K&N type filters don't filter quite as well... for example:

Quote:

Well there is a clear pattern on filtration ability compared to both flow and the type of filtration media used. The "high performance" cotton gauze and foam filters do not filter as well as some have claimed. I actually received an e-mail from K&N stating their filters filter within 99% of the OEM filters. This may be true, and 1% may not sound like much. I contend that 1% over many miles, may be important. Really, it is up to each individual to decide. The poorer flowing filters, remove more particles, and the better flowing filters remove less particles. If you think about it, that conclusion passes any and all common sense tests, so it is not surprising. There are many that will be shocked by the results, that should not be though. I've used high performance filters in the past, and I might again in the future. At the same time, I know that the stock OEM type filters perform very well in filtration and don't inhibit flow nearly as much as some think.

Source: http://www.bobistheoilguy.com/airfilter/airtest3.htm


However, in a car that gets 25-35mpg, the driver might say "eh, 1/4 mile more mpg isn't worth my time and the cost for a K&N".

My van on the other hand ventures into single digit MPGs. I need all the help I can get.

This looks Spectre filter looks really awesome but it would be pulling in a lot of heat:

 

[Thax]

It might help the mileage out or it might not. I would make sure that every tune up part on the carbed 360 is fresh and in good condition that will effect mileage way more than any cotton gauze air filter will.

 

[Cubey]

That is very true but I figure a high flow air filter may also help. When I got the van, it had a filter that was too short for the housing so the air intake wasn't really being filtered at ALL! I promptly got a proper sized Wix filter and put it in.

I put in new NGK plugs last year, checking the gap on each one before I put them in.

The dist cap looks in good shape as does the rotor. The air gap might need adjusting as well as timing and carb adjustments which I will leave to a shop to do.

It shouldn't take more than an hour of labor for them to check and adjust the carb settings, timing, air gap on the dist and idle speed. I'll be sure to take off the engine cover first to save about them 5-10 minutes of fighting with it since I know the trick it takes to get it out due to the big captains chairs.

 

[oldhp]

High flow air filters are mostly for WOT/high RPM engines. If it was mine a NAPA Gold would be in it.

 

[Cubey]

Originally Posted By: oldhp
High flow air filters are mostly for WOT/high RPM engines. If it was mine a NAPA Gold would be in it.


Napa Gold air filters might be rebranded Wix. If so, that's what I have in it... a regular Wix brand air filter.

I know Napa Gold oil filters are rebanded Wix.

 

[Tuffy1760]

go for it... look for sales rebates and pull the trigger...
ever think E fan?? throttle body spacer??

 

[Jim Allen]

A well designed aftermarket intake system designed for fuel economy MIGHT add a skosh of economy (depending on how good or bad the OE system is... most OE stuff is biased towards economy) but a filter alone will not. That has been my experience and the study linked below pretty much proves it. INtake restriction has little effect of fuel economy just tooling around because the EFI is constantly trimming the fuel. It will have a big effect on power, as you will read in the study, but not MPG.

On top of that, it's just about impossible to measure fractions of MPGs. The usual margin for error ins about 1 mpg no matter which way you measure so you'll never really know whether you gained anything or not for the money you spent.

But for the sake of argument, lets say that $120 Spectre filter delivers a 1/4 mpg increase. Since you are talking about a 360 you are probably getting 15 mpg on a good day. Let's say you drive 10,000 miles per year and gas is stable at $3.50/gal. You are using 666.7 gallons of gas per year that costs $2333 annually. If you get 15.25 mpg 655.7 gallons per year for $2295 for a $38 savings per year. To recoup your $120 expense, it's going to take more than three years... if indeed you got the 1/4 mpg gain that you really can't measure.

The other thing about the oiled cotton gauze filters is low efficiency. That translates into more wear in the long run and shorter OCIs. How much that effect you long term depends on the area where you live. If it's dirty air where you live, especially with lots of fines in the air (the desert or the big city are the worst places for fines) the more junk the OCG is letting in.

The two things that have helped me with mpg are a programmer with a good fuel economy program and low rolling resistance tires. To that, add synthetic gear oil and you can see a difference above the margin for error. I saw a 2.4 mpg difference in tires between an All Terrain tire and an All Season on my F150 over a measured course, carefully tested Look Tires & Fuel Economy for a test I did on this.

The biggest changes come from how and where you drive. That's the place where most people fall short because they don't want to expend the mental energy to do it or make any changes to their routine but if you concentrate on the driving, you can save 2-3 mpg on just about everything with an engine. Best part of that...it's free.

Intake restriction and Fuel Economy

This 2009 report tests the effect of dirty air filter on fuel economy using standard EPA dyno routines. They used later model EFI cars (2003-2007)and one 1975 carbureted car. The conclusion what that the fuel injection could compensate for the restriction up to the point where the car's performance had deteriorated to barely running and fuel economy decreased only by a percent or so. Performance degraded, of course. The carbureted car was more effected but fuel economy wasn't lowered by nearly as much as "common knowledge" dictates... only 2.5 percent.

In every case lower end performance was unaffected until the restriction reached the level at which insufficient air was being inhaled. Performance dropped mightily but the EFI could trim fuel to keep the mixture about right. They found that in "normal" driving situation, the car was almost unaffected by a clogged filter because the airflow needs were so low. In a few cases, the filters were so clogged that the engine sucked them into the intake tube.

 

[Smokescreen]

- For fuel economy in a carbed engine you want warm air intake.

- You will never recoop $$ spent on an intake in increased fuel economy.

- Tire pressures increased, front air dam,

Visit ecomodder.com. They have many suggestions.

 

[surfstar]

Originally Posted By: Smokescreen
- For fuel economy in a carbed engine you want warm air intake.

- You will never recoop $$ spent on an intake in increased fuel economy.

- Tire pressures increased, front air dam,

Visit ecomodder.com. They have many suggestions.



+1

In a big, heavy, brick of a vehicle, you want to hold your speed - avoid slowing and cruise at a slow rate to save gas. Really kills the driving experience. 55 vs 65 would be quite significant, so it comes down to time vs money on road trips.
I don't mind driving slower on short hwy jaunts, but any road trip and I'm doing 70-80mph.

 

[Cubey]

Originally Posted By: Jim Allen

But for the sake of argument, lets say that $120 Spectre filter delivers a 1/4 mpg increase. Since you are talking about a 360 you are probably getting 15 mpg on a good day. Let's say you drive 10,000 miles per year and gas is stable at $3.50/gal. You are using 666.7 gallons of gas per year that costs $2333 annually. If you get 15.25 mpg 655.7 gallons per year for $2295 for a $38 savings per year. To recoup your $120 expense, it's going to take more than three years... if indeed you got the 1/4 mpg gain that you really can't measure.


15mpg? In a car maybe.. not a 1 ton Class B motorhome. 12 hwy maybe tops but I'm going to be towing (a wild guess) 1000-1500lbs too. While I feel I would probably benefit from a high flow filter, I guess I won't get one due to poorer filtering.

Originally Posted By: Jim Allen

The two things that have helped me with mpg are a programmer with a good fuel economy program and low rolling resistance tires. To that, add synthetic gear oil and you can see a difference above the margin for error. I saw a 2.4 mpg difference in tires between an All Terrain tire and an All Season on my F150 over a measured course,


it's a 78... no progamming possible. LRR tires would have been nice but I had to get a set of 5 which ran me around $1000 for Dunlop Rover H/T LT225/75/16 tires.

Originally Posted By: Jim Allen

The biggest changes come from how and where you drive. That's the place where most people fall short because they don't want to expend the mental energy to do it or make any changes to their routine but if you concentrate on the driving, you can save 2-3 mpg on just about everything with an engine. Best part of that...it's free.


Oh trust me... I watch my driving for sure. I put in a $40 vacuum "mpg" gauge which makes me OCD about going easy on the throttle. I also have a nice portable (120v) 125PSI max air compressor I'll be taking with me to keep the tires aired up to the max pressure, especially on the rear where it carries the biggest load and has the most bounce. I can run it on the van's generator should I need to air up a tire just about any time, any place. I have 12v ones as backups since the generator feeds off the main fuel tank but has a pickup tube that won't reach fuel after it gets below anywhere from 1/2 to 1/4 tank (not sure exactly).

Originally Posted By: surfstar

In a big, heavy, brick of a vehicle, you want to hold your speed - avoid slowing and cruise at a slow rate to save gas. Really kills the driving experience. 55 vs 65 would be quite significant, so it comes down to time vs money on road trips.
I don't mind driving slower on short hwy jaunts, but any road trip and I'm doing 70-80mph.


The way I'm going to be traveling, I won't mind keeping my speed down to 60 in 70 zones to stretch my gas budget when traffic flow allows. As it is, I go about 50-55 on a 55mph 2 lane highway to get home despite there being a parallel running freeway with a 70mph limit and an exit 1/2 a mile from my house. 50-55 vs 70 makes a big difference. Plus the freeway adds a mile or two vs the 2 lane highway.

I'm not going to be limited to a "vacation" time frame where I have to hurry to and from my like I did going to DC in 2009. I had a 91 Corolla though so I didn't mind sticking to the speed limits since it got about 3x the mpg of this van.

 

[surfstar]

It sounds like you're already on top of it for what you can do to maximize MPG w/o spending $$ you'd never recoup.

Maybe you could add rear wheel skirts? Could help by some tiny, small amount, but could also be done for cheap with materials lying around. Similar with a front air dam and side skirts. I'd look for simple aero mods if you'll be doing a good bit of hwy miles.

 

[Jim Allen]

More clear now. When you said "Van" I assumed a real van, not a motor home. I guess I didn't connect the B300 in your sig as the "van" in question. Still, everything applies, more or less in a general way, just not the EFI info.

On a carbureted engine, MPG is more effected by intake restriction but in the one carb'ed engine tested in the study, the MPG difference between a clean filter and one that was so plugged it got sucked into the engine was 2.5%.

Aero loss, weight and rolling resistance are what kills the motorhome, as you already know well I'm sure. Headers and dual exhaust might deliver an extra MPG but might take a long while to pay off. Might be worthing thinking about when it comes time to replace the exhaust system.

 

[ZeeOSix]

This about all you can really do:

• Use full synthetic motor oil
• Keep air filter clean
• Keep engine tuned up
• Keep fuel system & valves clean
• Keep tires inflated correctly
• Keep speeds down when possible
• Accelerate slowly as possible

 

[Cubey]

Originally Posted By: Jim Allen
More clear now. When you said "Van" I assumed a real van, not a motor home. I guess I didn't connect the B300 in your sig as the "van" in question. Still, everything applies, more or less in a general way, just not the EFI info.


One more thing I forgot to mention.. the rear end/differential ratio is a Dana 60 3.54 which is helpful for MPG vs 4.10 or 4.56.

My van is one that came without the "air pump" for emissions (some did, some didn't in 1978) which means a little bit less engine load.

I have one other thing going for me, the height of it.

The first one is mine. The second is another brand of 1978 Dodge B300 chassis motorhome with the same 360 engine.

The low top of mine is unusual and is doable since it has a dropped floor on the right side of the van toward the front so you can fully stand up inside. The other one has a more typical high top roof found on motorhomes. Others may be a bit more aerodynamic but they are still a foot or two taller than mine is.

 

[Smokescreen]

Definitely a front air dam.

Other than:
- removing the running boards
- if you have more than enough power you could try lowering your revs on the highway with taller tires in the rear, but acceleration in town would suffer a bit which would throw off your speedo a bit.
- front tire spats
- rear wheel skirts
- maybe e-fan (not sure if cost will be made up, plus install could be a pain.)

....there is not much more that you can do with it IMO.

Look up techniques like Drive with Load etc http://ecomodder.com/forum/EM-hypermiling-driving-tips-ecodriving.php

Do you have any interior pics, I am interested in layout and the lowered floor you speak of. This makes a sweet bug out vehicle.

 

[Cubey]

Originally Posted By: Smokescreen
Do you have any interior pics, I am interested in layout and the lowered floor you speak of. This makes a sweet bug out vehicle.


Sure. The pics are from over a large amount of time over the past year as I have been working on it so it'll look a bit different in some shots due to me replacing the built in sofa with dinette bench seats. I'll put them in order in which they were taken so you can see the progress/changes.

I'll start out with a floor plan diagram. (The furnace isn't under the seat like someone wrote on it, it's under the closet like it has printed).

I'll post links instead of the images to help keep this thread dial-up/mobile friendly. (Warning, slightly large pictures!)

Prior to buying it, I took photos of the inside through the windows.
http://img.photobucket.com/albums/v222/illiop/78dodge/Hpim4828.jpg

After I got it home. Note the messed up wallpaper. I would have kept it if it wasn't all shrunken/bubbled up. You can see steps up from the dropped floor.
http://img.photobucket.com/albums/v222/illiop/78dodge/Hpim4879.jpg

A general shot of the fridge, stove top and fold-up table.
http://img.photobucket.com/albums/v222/illiop/78dodge/Hpim4880.jpg

After the dinette seats were built. Shows the ugly wall that had the messed up wallpaper. Most of the paper was pulled off by this point. I had to peel off some of that white backing stuff too as it was bubbled up in places too. I reused some of the old wood from the sofa which is why some of the wood is new and some is old. I also used scrap wood paneling around the outside. I'm not the best carpenter but it's sturdy and looks pretty good.
http://img.photobucket.com/albums/v222/illiop/78dodge/Hpim5802.jpg

Picture taken yesterday after I removed the rest of the messed up wallpaper, cut tan auto carpet from O'Reilly and glued it to the wood paneling with craft spray adhesive.
http://img.photobucket.com/albums/v222/illiop/78dodge/Hpim6337.jpg

I am leaving as much original as I can in terms of appearance. I am debating having new cushions made for the dinette from the old sofa cushions material if there's enough to do so, and if it looks like it's not too rotten to hold up to everyday use since I am going to be full timing in it.

The bottom side could be another kind of fabric if need be since it won't be seen. If not, I'll try to find a color that will blend well with the green shag carpeting (in very good shape) and the fabric trim around the top in the front, the fridge's decorative panel, the door panels, etc.

I have a blog over at http://cubey7800.blogspot.com that I *try* to keep updated.

 

[Smokescreen]

Cool.

That has pretty much everything one would need in a very tidy package.

 

[TigerDude]

Jim has it right here. At less than wide open throttle (WOT), the ability of the air filter to pass a large volume of air is irrelevant: the biggest loss of airflow is the throttle. If you let in more air through the filter, then the throttle just closes more.

This is all managed by computer. The mass airflow (MAF) sensor doesn't care about the temperature of the air, either. If the air is hotter, it will just let more in. And regardless, the computer will just put in enough fuel for the air that is flowing.

You might get a little mpg gain with an exhaust system, but intake restriction only matters for maximum horsepower.

 

[Cubey]

Originally Posted By: TigerDude
Jim has it right here. At less than wide open throttle (WOT), the ability of the air filter to pass a large volume of air is irrelevant: the biggest loss of airflow is the throttle. If you let in more air through the filter, then the throttle just closes more.

This is all managed by computer. The mass airflow (MAF) sensor doesn't care about the temperature of the air, either. If the air is hotter, it will just let more in. And regardless, the computer will just put in enough fuel for the air that is flowing.

You might get a little mpg gain with an exhaust system, but intake restriction only matters for maximum horsepower.


What computer? What mass airflow sensor?

 

[FFeng7]

Originally Posted By: Jim Allen
A well designed aftermarket intake system designed for fuel economy MIGHT add a skosh of economy (depending on how good or bad the OE system is... most OE stuff is biased towards economy) but a filter alone will not. That has been my experience and the study linked below pretty much proves it. INtake restriction has little effect of fuel economy just tooling around because the EFI is constantly trimming the fuel. It will have a big effect on power, as you will read in the study, but not MPG.

On top of that, it's just about impossible to measure fractions of MPGs. The usual margin for error ins about 1 mpg no matter which way you measure so you'll never really know whether you gained anything or not for the money you spent.

But for the sake of argument, lets say that $120 Spectre filter delivers a 1/4 mpg increase. Since you are talking about a 360 you are probably getting 15 mpg on a good day. Let's say you drive 10,000 miles per year and gas is stable at $3.50/gal. You are using 666.7 gallons of gas per year that costs $2333 annually. If you get 15.25 mpg 655.7 gallons per year for $2295 for a $38 savings per year. To recoup your $120 expense, it's going to take more than three years... if indeed you got the 1/4 mpg gain that you really can't measure.

The other thing about the oiled cotton gauze filters is low efficiency. That translates into more wear in the long run and shorter OCIs. How much that effect you long term depends on the area where you live. If it's dirty air where you live, especially with lots of fines in the air (the desert or the big city are the worst places for fines) the more junk the OCG is letting in.

The two things that have helped me with mpg are a programmer with a good fuel economy program and low rolling resistance tires. To that, add synthetic gear oil and you can see a difference above the margin for error. I saw a 2.4 mpg difference in tires between an All Terrain tire and an All Season on my F150 over a measured course, carefully tested Look Tires & Fuel Economy for a test I did on this.

The biggest changes come from how and where you drive. That's the place where most people fall short because they don't want to expend the mental energy to do it or make any changes to their routine but if you concentrate on the driving, you can save 2-3 mpg on just about everything with an engine. Best part of that...it's free.

Intake restriction and Fuel Economy

This 2009 report tests the effect of dirty air filter on fuel economy using standard EPA dyno routines. They used later model EFI cars (2003-2007)and one 1975 carbureted car. The conclusion what that the fuel injection could compensate for the restriction up to the point where the car's performance had deteriorated to barely running and fuel economy decreased only by a percent or so. Performance degraded, of course. The carbureted car was more effected but fuel economy wasn't lowered by nearly as much as "common knowledge" dictates... only 2.5 percent.

In every case lower end performance was unaffected until the restriction reached the level at which insufficient air was being inhaled. Performance dropped mightily but the EFI could trim fuel to keep the mixture about right. They found that in "normal" driving situation, the car was almost unaffected by a clogged filter because the airflow needs were so low. In a few cases, the filters were so clogged that the engine sucked them into the intake tube.


I really enjoyed reading this response but I have a question. It states the the city and desert are the worst place for fine particulates in the air. In the desert obviously its sand and silt but what makes the city air so bad? Is it particulates from exhaust or just dirt in general?