Land Cruiser Aero dynamic question...
 

Hey all, I posted this on a Land Cruiser board but NEVER got any responses.

I know there are some intelligent chaps on here, as you have all helped me lots of times with my little 911.

my 98 Land Cruiser gets about 12-12.5 MPG and I have been wondering what I can do to it to get better mileage.

I am getting ready to embark upon a 3500 mile road trip out to the redwoods and up the coast of Oregon and if I can increase my mileage i'd benefit by that.

Figure $3.00 a gallon. 300 miles to a tank. 24.5 gallons to fill up. 11.5 tanks at $75.00 a tank!! almost $900 just for gas alone

I was thinking of changing out my rear spoiler:

this is what it has now:
http://www.cruiserparts.net/parts/100/5796_4.JPG

And what I can possibly go to:
http://www.spoilerdepot.com/images/items/Toyota-Land-Cruiser-Spoiler-95.jpg

Or maybe just remove it all together?

ALSO

The new 2010 LC's use a front spoiler to better control the air below it and bumper that channels air away from the wheels for better fuel economy

I was wondering if I added a front spoiler if it would make much of a difference? Lots of big SUV's seem to be using them now.

What do you all think? Do you see much benefit if any?

The only thing different I added really was 33 inch tires from the 31.5"

Drive slower. Lose weight, Drive slower, run highest tire pressure, oh, and drive slower.

I just drove the west coast (2400+ miles) in my relatively aero Cayenne. 60mph got me ~24mpg, whereas 80mph was 17.4mpg

Anyway, aero drag goes up exponentially with speed.

A brick is still a brick no matter what spoiler you put on it. If you want fuel millage, switch to a small diesel.

Heh - just be happy it isn't a FJ62 with a 3FE in it!

I never got that above 10mpg even after a full rebuild (including injectors). You are not going to see any significant improvements.

I sure wish they would have brought in their diesels that get 25-30mpg.

Have fun on the trip

-Jack

My '98 Lambcrusher takes 140L @ $1:45/L and is a brick whichever way you look at it. Hence , my decision to downsize to a 911. I will trade the crusher for an old diesel Hilux or something similar.
The only way I get better mileage is by coasting downhill.

Dang, thats brutal gas mileage.

I get about 20 at highway speeds in my 6.0L desiel Ecursion. It has a small psuedo spoiler looking thingy on the front, but nothing on the rear.

I also notice a difference in mileage between 70 mph and 80 mph.

Have fun on your trip, I have done the drive to northern ca from Denver (I actually went north through Laramie, WYO) and really enjoyed it.

Drive slower (I won't repeat it 3 times like island, but I should), lower it, highway tires, front spoiler, smooth wheel covers taped seams, no wipers, no luggage rack, remove the pass side mirror.

Read this article.
EV WORLD: Free Fuel Riding on the Wind

Read some hypermiler forums articles.

Driving my miata to/from work daily, I normally get 23-25 mpg. If I drive differently, I can get that mileage up to 29-32.

Thanks for the input guys. It's kind of what I thought. I'm leaving at midnight out of Denver and shooting for Reno NV in one straight shot.
Kids should sleep for half that part. Into Sacramento and up to Redding. Then over to Crescent City and all the way up to Seaside. On the way back hoping to see Shoshone falls if the days work out right.
It is a much needed break from the mortgage biz!

I'll just forego any mods to the aero, and try and keep my foot out of it. Last time I drove to San Diego I was averaging 80 MPH til I got on to that long desert strip in Cali. Managed about 300 miles on the tank.

I heard a statistic that lifting it another .75 inch off the ground with the larger tires decreases my fuel something like 5 more percent! Think I'll try and take the advice to go as light as possible too.

Thanks again everyone. take care!

ah, yes, if you can do it, taller skinnier tires should help. --skinnier for aero, taller for lower rev's. Oh, and drive slower :D

12 mpg at 70mph interstate driving is not good. I get about 18 or so if I keep it around 70. I would check the tire pressure. Air filter plugs fuel filter etc etc etc. It should not get that bad of mileage

if it is tuned and you are not pulling a trailor or loaded with tons of gear or have the o/d off or doing 90 then it should get upper teens.

If you are doing all the above and still getting around 12 I would discuss it with the dealer and have them put it on the computer and see if it shows any problem codes.

This is good for a couple more hwy mpg:
http://forums.pelicanparts.com/off-topic-discussions/465923-chin-spolier-fast-easy-cheap-effective.html
http://i184.photobucket.com/albums/x...k%20Up/SP1.jpg

island..you crack me up.

not only driving slower, but use the cruise control to do it. steady, and slow.

Do all the stuff everyone has suggested, especially higher tire pressures and keeping your speed down.

In addition, why not do something to lower your coefficient of drag? Get a little duct tape and close off 3/4s of that upper grille area, some of the lower, and even the area between the top of the bumper and the grille and headlights.

Watch your temp guage and as long as you're not in warmer than usual weather and/or working the engine too hard, you will probably be fine.

Could be a conversation starter at fill up time, too. :)

http://forums.pelicanparts.com/uploa...1268184508.jpg

A mile a minute! The perfect touring speed! (But I've never been able to heed my own advice - )

There was a Mythbutser episode where they drafted behind a semi. The closer they got to the back of the truck, the better mileage they got. Gets dangerous, though.

Rent a minivan?

read..

Aerocivic - Honda Civic modifications for maximum gas mileage - aerocivic.com

apply knowledge..

Beat me to it. I was going to say drafting is your best bet. Find a semi/moving truck that's moving at a good clip, and tuck in behind him for as long as you can. I did that on a recent 1.5 hour drive, and averaged 35+ mpg per the car's computer (vs a typical 25-ish mpg). This was at speeds of 75+ mph.

Fuel injector cleaner. The expensive stuff.

And what they said about tire pressure and weight loss...

Your tires may be part of the problem.

In a Grand Cherokee discussion, bigger tires meant worse highway mileage and MUCH worse in town mileage.

If the tires are wider also (usually are), it really has a negative effect.
Changes the effective gearing.

Drafting works, but the front of your unit will get beat to he!! from small rocks, sand, etc. Surprisingly, the truck's mileage will also impove slightly. Not v. safe.

The answer is no. the all time 4 wheel is what I think its the cause beside it is so flat in the front. The best I ever got on it was 12.5 mpg coming back from Mammoth to LA. I drove across Canada with the thing in the winter and felt great and safe. I am ready to buy my 3rd LC. Love to have a 100 series truck one day. Going soft due to my old age. Good luck with the long drive and have lot of fun.

I like the diesel option...can he not just swap out the gasoline engine for a diesel?? Wiring harness would be a hassle, but there should be plenty of diesel engines out there. I've been wondering myself about this for some time. Possible??

From my reading on ih8mud, you should pretty easily get 18 MPG out of a 100 series Land Cruiser. I get 12 MPG highway with my '91 FJ80 that has 33" AT tires. Sounds like you're in need of a serious tune-up. Plugs, wires, cap/rotor (if no coil packs), oxygen sensor, air filter, fuel filter, fuel injectors cleaned, new fluids, etc. Something isn't quite right.

I'll go ahead and add that you might want to change the front differential, transfer case and rear differential fluids too. It makes a considerable difference. Wheel bearings wouldn't be a bad idea either. I don't get less than 12 on the highway at 70mph up hill into the wind. Then again, I have the bad ass 3FE.

Has anyone successfully converted a LC from full time to part time? I would think disengaging the front axle would free up 1-2 mpg.

BTW, my old '99 GMC Suburban would routinely get 18mpg on the freeway at 74 mph on cruise.

drafting a semi is insane. doing it with your entire family, on vacation to save $100 is way over the top insane....criminal, really.

Kaisen, there are kits available to make an 80 part time 4WD but it's pricey and lot of work. The payback of 1-2 MPG takes a long time to add up.

Going light-weight won't really do anything for you on a long flat trip. If you're going to drive up and over a mountain range it might help. Weight will only affect your mileage when you're accelerating. Once you're at your cruising speed, the affect of weight would be minimal.

Turn off the AC whenever possible. If you are going to open the windows, make sure you aren't creating more aerodynamic drag to offset the less load on the motor. If it is not too hot, simply turn off the A/C, and run the vent fans.

Even things like slipping the car into neutral on long downhills can help.

Also - you should get better gas mileage the closer you get to sea level. Denver's a mile up in the sky - less oxygen up there!

Check out some of the hyper-miler websites - they have tons of recommendations -- some helpful and some downright dangerous - use common sense.

-Z-man.

I guess if you were taking a long trip in dry weather you could always remove the front driveshaft. Can't be too hard.

Yup, I've heard of it being done. You also have to lock the center diff, which wasn't standard on every model year.

I was able to achieve better MPG when I still had my OEM tires. Good tune up, tire pressure could also help, and also by simply keeping your foot off the pedal. Proper maintenance of land cruiser parts is also a factor.