26.2 MPG in a Toyota Previa minivan

[MK7]

<div class="smallfont">Pretty cool idea here. <br><br>http://ecomodder.com/forum/showthread.php/26-2-mpg-toyota-previa-go-golden-egg-4681.html<br><br><strong>26.2 mpg Toyota Previa. Go Golden Egg!</strong></div><div id="post_message_55155">Just got a record mpg run to Seattle and back with some city driving as well. Was doing average 70mph on the highway as well.<br> <br> Mods so far:<br> 1) No alternator, running on 2 deep cycle batteries.<br> 2) Electric cooling fan<br> 3) All accessory belts off (no p/s, a/c, fan, alt.)<br> 4) All passenger seats out. <br> <br> That's it.<br> <br> Driving habits:<br> <br> 1) Coasting when possible.<br> 2) Drafting at a safe distance<br> 3) Side mirrors in. <br> 4) Windshield wipers vertical when possible.<br> <br> Added: EPA is 20mpg highway giving me 31% over EPA so far.</div>

 

[Cubey]

I doubt an alternator is worth removing for mpg savings but that's just me. Also.. it can eventually ruin your rack not to have power streeing hooked up. Although, when my 91 corolla (i think already smashed on the side) blew out a PS hose, I took off the belt and drove it that way until I got rid of it. But I knew i was getting rid of it fairly soon so I didn't bother.<br><br> I doubt side mirrors in are worth the trouble either. Same with wipers.<br><br>Driving habits are the biggest factor.

 

[MK7]

Seems like removing the alternator is giving the greatest gain. It's a fact that buying underdrive pulleys will increase usable horsepower to the wheels. One of the pulleys is the alternator one.&nbsp; The alternator is certainly running to power the van's electrical system.<br><br>Folding the side mirror and removing the wipers would work. Just a little, and it adds up. Newer cars even tuck the wipers under the cowl when not activated.<br><br>Removing the luggage rack on the roof helps. Some claims 1 MPG on a van. That's tough to calculate though as there's lots of changing variables such as wind, grade, etc. But that carrier does cause drag.

 

[Cubey]

Alternators can be spun easily by hand. I don't see how even a 4cyl engine could be effected by the energy it takes to turn it. It might give at BEST 1/2 an mpg improvement (like 1/10 to 1/4 probably) but I don't see how that's worthwhile when an alternator recharges your batteries for you.<br><br>On the subject of drag, that's one thing I like about my rig. Excluding the very front grill which is flat as can be, the rest has pretty smooth curves. It's also shorter than most Class Bs.<br><br>(I really need a good updated picture)<br><br>

 

[MK7]

Those guys on there are pretty serious about MPG. They claim 10% increase in MPG from just the alternator.&nbsp;&nbsp; <br><br>http://www.metrompg.com/posts/alternator-optional.htm<br><br>The guy with the Previa also disabled his belt driven fan too.

 

[jbhernandez]

I follow that site, and the king IMO is this guy here.

http://www.instructables.com/id/Vehicle-efficiency-upgrades/

He's also been featured on youtube by faircompanies.

 

[highdesertranger]

an alternator is easy to spin when it's not generating power. hook it up and try to spin it. I think it's about 1 horse power for every 25amps. I think a power steering pump takes between 3 to 7 horse power. ac 5 to 7. it all adds up. however I wonder if the extra weight of the batteries isn't off setting some of the gain by not having the alt hooked up. highdesertranger

 

[Simran]

I have a bicycle with a generator hub on the front wheel. There is a world of difference when the generator is kicked in. This is a HUB generator; not a side wall generator. I think the smaller the motor the more you'd gain by eliminating the drag on anything generating power. Anything that produces power is going to cause drag; their is bound to be savings of some kind and the smaller the motor the more savings.
You're right it DOES all add up.

an alternator is easy to spin when it's not generating power. hook it up and try to spin it. I think it's about 1 horse power for every 25amps. I think a power steering pump takes between 3 to 7 horse power. ac 5 to 7. it all adds up. however I wonder if the extra weight of the batteries isn't off setting some of the gain by not having the alt hooked up. highdesertranger

 

[66788]

an alternator is easy to spin when it's not generating power. hook it up and try to spin it. I think it's about 1 horse power for every 25amps. I think a power steering pump takes between 3 to 7 horse power. ac 5 to 7. it all adds up. however I wonder if the extra weight of the batteries isn't off setting some of the gain by not having the alt hooked up. highdesertranger

The old Mopar twin piston air conditioning compressors took 15 HP from the engine.

You are absolutely right about the resistance increasing with the generation power with alternators.

Every accessory on any engine that is belt driven takes power to operate.

 

[masterplumber]

I was talking to my son about this thread - he's a drives truck and also just graduated with a degree in automotive and diesel technology. He was telling me the fans on the big Cummins, Detroits, Cats, etc draw 50 horsepower! the clutches are designed such that when they fail they run all the time so you can get to your destination. He said the mileage just plummets. It's no wonder the manufactures are all going to things like electronic power steering and electric fans. I'm wondering how much I can do though to a 2012 Cummins that runs everything on 1 belt and has so many sensors tied to the computer that even changing to a different factory approved tire size was an issue. Someone on this forum posted pictures of Paul Elkins Toyota pickup camper shell set up - he also did a hyper - mileage Civic if you google his web site. I think all this stuff is great as fuel cost will inevitably continue to rise. I think the biggest issue most of us have is we're not typically driving Civics - we're driving vehicles that are more closely match to pushing a brick through the air. I think I'll do some experimenting with making my pipe rack and topper more aerodynamic, I'll let you know fi I see any improvement.