From 13.5 to 17 MPG with an Class B RV
 

Does not sound like much but actually is a 22% improvement. All the tips from this website, lots of work, but little expense will save me hundreds of dollars over the next weeks, months and years. Plus I won't be polluting as much. Thanks Ecomodder members.

nice, every improvement helps

A 22% improvement is very impressive.:thumbup:

I noticed in your fuel log notes that the bike trailer drops your FE, have you considered loading the bike(s) into the RV, as opposed to trailering? The only issue might be securing them so they don't knock around while driving.

If the bikes aren't spotlessly clean you could always lay down a tarp on the floor. :)

WOW, that is a big improvement, actually. After looking at your mod list you did some good work on that. That'll pay off long term for sure. Good work!

Very impressive! What engine are you running in that?

Further down my list of projects is the mother of all eco-mods - I want to see how much of a mpg gain I can get in my 84 Pathfinder. 454 Chevy 4bbl carb.


http://i278.photobucket.com/albums/k...hfinder001.jpg

Whoa... carb's are notoriously hard to increase FE due to their "always on nature".

I suggest installing a 2bbl carb with an Edelbrock Performer RPM manifold and a restriction plate. Essentially copy what the NASCAR guys use. Then you are going to want to install miles of cavernous (think the size of a 1" water hose), steel braided transmission cooling lines. The trannies get real hot and reduce your efficiency on those motorhomes. I assume you have a 400 or 350 power glide in there right?

I can't detune it too much because it still has to climb steep mountains. That's always going to be a FE killer, but the power has to be available for when I need it. And the mods have to be cheap. Contrary to what you may have heard from U2 and Jay-Z, traveling musicians don't make much money at all.

I'd like to see if I can work out some kind of adjustable jetting like they have in airplanes, so it can be leaned out once up to cruise speed, but there is a lot of low hanging fruit in the aero department. I can move or enclose the draggy stuff on the roof, build a full belly pan, build a kammback, enclose the wheelwells, and replace the mirrors with rearview video.

This project will take a while, and it won't be done this winter.

All across the United States old Diesel school buses are filling up salvage yards... have you considered making a vegan-diesel bus yet?

You would be spending those hard earned guitar dollars better, getting more room and of course getting a lot of free PR too!

Can you say EcoModder's own version of a Guitar Hero? :D

http://www.fixingtheplanet.com/files/fryerflyer.jpg

If it were about what I wanted, I'd probably go with a electric/diesel hybrid bus like I used to drive, convert it to use veg oil, and cover the roof with high output photovoltaic panels, but in the real world situation, I have to work with what I already have, and what I can afford.

I don't see why you'd suggest a 2bbl; a properly sized 4bbl will be ruuning most of the time on its primaries, which are smaller than the openings on a 2bbl. then, under load, the secondaries open up. a vacuum secondary carb only opens the secondaries when the vacuum signal drops, and this point is adjustable w/ springs.
years ago, I was able to tune my Dad's 460ci F250 for a few extra mpgs by putting a heavier spring in the carb; IIRC, he went from 9mpg to around 12-13.
even better than a carb in this application, there are myriads of fuel injection kits for chevy V8s, from simple TBI setups to full blown laptop programmable rail injectors.
as for the transmission, there are stout overdrive units available as well as modern computer controlled 4 and 5 speed automatics.

Do you have more info on the spring swap? Would this be similar on a Chevy? For me, this sounds like a better starting point than a full induction swap.

on holley carbs w/ vac sec, there is a spring kit available, real simple to swap out. for stuff like that, summit racing is your best bet for product and tech advice. I'm not familar enough w/ other carbs like rochesters or carter/edelbrock to know how they signal the secondary opening.

Increasing FE by 3mpg from 40 to 43mpg is worthwhile, but going from 9 to 12mpg is a 33% increase, and that's HUGE.:thumbup:

it's a trial and error thing; generally, for performance, you would tune the transition to secondary opening so that it couldn't be felt, you wanted it to be smooth. the 'pull' that some would feel means that they are opening too soon, hence a 'bog'.
conversely, you can have them open later. in my Dad's case, it seemed that even at part throttle cruising, the secondaries were partially open.
a vacuum gauge really helps when doing this.

Best bet? Buy a GPS and stay with the 2 lane highways...cruising at 45-50 mph. Use the GPS to find the shortest routes.

Moving all that air out of the way is where your gas is going?

Amazon.com: DeLorme Earthmate LT-40 GPS [OLD VERSION]: Software

To add to the easy aero improvements take that shade canopy off the side if you don't use it. Easier than adding a kammback.

454 mods megasquirt, mpg meter?
 

I have the same Pathfinder as 5bikes. Learned the hard way not to advance the timing on a 454. Now have hypertectic pistons, Thorley double Y headers. Went from 4.5 to 6.5 mpg. Got to beat that. Anybody tried Megasquirt? Also need an accurate real time way to check fuel flow (usage) on a carb.

AFAIK, the best you can get for real-time fuel flow on a carb is a marine fuel flow meter. They're not cheap though.

Yea, it's the silliness with MPG that means I prefer l/100km (or a miles/gallons equiv if you live in the US or UK).

26l/100km to 19l/100km shows how giant the change is from 9MPG(US) to 12MPG. Same reduction in fuel consumption as going from 17MPG to 34MPG.

On that 454-4V above. The Rochester QuadraJet can be tuned to provide excellent mileage. Don't know if yours is the feedback style (electronic carb) or the older all mechanical type (with which I am familiar), but the latter can be adjusted for best cruise/part throttle separately from the other operating systems. See Doug Roe's book on the carb.

BANKS makes performance part which essentially aid efficiency, as does EDELBROCK. Best starting point is to fuel 'er up and take it across the weigh scale for a certified reading. You'll also want rear gear ratio, transmission type, tire height (see manufacturer numbers), intended cruise speed or rpm, and get some cylinder compression readings to go with it in order to get good advice.

See also HOWELL Engineering for TBI retrofit. If the engine still has good -- and even -- compression, then a free-flowing single 3" exhaust after the motor will make the most of what you have.

7-9 mpg is about what is to be expected. 10 mpg is almost impossible. But with numbers this low it is all about percentage increase.

fuel injection is not really that hard to install on an older chevy. used tbi units can be sourced cheap and do really help. the hardest part is getting them to work with your application, for example

my friend bought a jeep grand wagoner. it routinely got between 7 and 9 mpg, no matter how hard he had his foot into it. long story short, we found out some one had swapped the 360 out for a 401..... but we took a tbi system out of a 92 1 ton truck found an adapter plate and adapted the sensors, and it is a really sound truck. starts year round, it now gets a solid 14 on the highway and seems to get 10.5 in town. everything was off of a 454, it also gained a hell of a mid range and kept the low and upper it had before.

now i dont know how much can be attributed to the fuel injection or if the carb was sized or tuned wrong, i never saw the carb, but the easy starts alone were worth it. we skated away with everything for $250. that said for you it might be even easier. like take the whole manifold and bolt it up and everything after that might be plug and play

i remember are one-ton flat bed before we up-graded it.

most RVs ive seen have a simaler engine/trans/gearing set up.

it had a 7.5L460 4V 850CFM, 3sp c-6 auto trans, 4.10 gears and 235/85/16 tires, making for 3,000 revs at 60 mph:eek:, just under 8,000lbs empty granted i admit its MUCH less aro drag than a RV

swaped it for a 4.9L I-6 2V 350CFM with free flowing intake and headers with a granny 5.75-1 and a 0.75% O\D ZF 5sp, still same tire size and rear end.
empty weight of the truck dropped to 7,250lbs yea we put the truck on a diet and it lost 600/750lbs:cool:take that weight watchers:D

dropped rpms to near 2,000 at 60:thumbup: and saves big time in how many sets of front brake pads the truck goes thru having REAL HOLD BACK power with the truck up at its 16,000 GVW

oh and went from 3 to 7 mpg, 8 if its shout down in N gear for a long time LOL
to 7 to 13 that was a massive savings for are pocket book
i was halling off road one time though and i figure i was under the 7 mpg but i was moving 5 ton loads

Nice, good improvements