Squeezing more k's from every litre...

[gbcruiser]

After a long highway road test and fill up, I've determined that my HJ60 is getting...piss-poor mileage. I used 62 litres to drive 425 kms. But I'm running 33" tires, which I think means a 10% adjustment. So let's say 467.5 kms from 62 litres.

Based on the niffty Fuel Economy Calculator on Natural Resource Canada's website, that works out to:

Distance travelled
467.5 km
290.5 miles

Fuel Amount
62 litres
16.38 US gallons
13.64 Imperial gallons

Fuel Economy
13.26 litres per 100 km
17.73 miles per US gallon
21.3 miles per Imperial gallon

Like many others, I'm now wondering what else I can do to improve on this. I'm all about driving techniques that can save fuel and I keep my rig pretty well tuned and my tires slightly over inflated on-road.

But is there something else I should check for, or are these numbers fairly common for a large, indestructible, 22 year old brick-shaped mass of metal and glass on wheels?

 

[code 621]

I rode my bike to work today. 13 km '84 BJ 60 parked @ home.

 

[dreko]

Squeezing more k's

Switch to a lower rolling resistant 33" tire??
I was just reading up on the idea "Larger tires = better mileage"

Lots of opinions, but my overall sense:
Larger tires: short stopping city driving: probably not
Larger tires: long distance highway driving: possibly slightly better


???

 

[Towpack]

Larger diameter tyres doesn't necessarily mean more mpg.Yes,you will be pulling less rpm's for any given roadspeed but the engine will be working harder to push the higher gearing.You don't say what pattern your 33's are but even AT pattern tyres offer a lot more RR than a pure road tyre.IMO if economy on the road was No.1 I'd go back to standard size road tyres.

 

[gbcruiser]

Yeah, a second set of 29 or 30" road tires would probably make the most difference, but even still I wonder how much. It's a lot of coin to spend on a marginal mpg increase...but then I'd have to switch wheels at the trail head.

 

[roscoFJ73]

13.3/100 is about normal for a HJ60. You might be able to save a litre ot 2 by careful driving

 

[Dougal]

Easy. Slow down and you'll save fuel.

 

[87 HJ60]

Change your air filter, and possibly have your injectors serviced (cleaned).
On the highway, my HJ60 can go roughly 600 kms on 70 litres of diesel doing roughly 100km/h (2300 rpm).
I'm running the stock 3.70 gearing and 31x10.5x15 BF Goodrich AT tires inflated to 38 psi.

 

[crushers]

normally i do not agree with Dougal but yes, slow down.

if you go from 120 k/h to 90 k/h it will take you roughly 25% longer to get to where you are going but your rpms will drop

using this site for a close est.: Engine RPM Calculator

4.11 gearing, 33" tires at 65 mph = 2176 rpm manual and 1904 auto
4.11 gearing, 33" tires at 55 mph = 1841 rpm manual and 1611 auto

(of course there are better calculators out there that allow you to input the proper gearing but this will suffice for general discussion)

so your rpm will drop 335 manual and 293 auto.

 

[crushers]

depnding on your driving style you should be closer to 28 mpg with the 2H and 4.11 gearing with 33s...

what is your compression readings?
when was the last time it was serviced and how far did they go?

 

[cruiser_guy]

I know my BJ60 is MUCH happier and less thirsty when running at 2000 rpm than at 2500rpm or 3000rpm.

 

[seapotato]

I noticed a big difference when I went from a 33 12.5 to 255/85/16. much easier to spin, much higher tire pressures, and definate increase in mileage. Probably 3 or 4 mpg.

just did 608 km's * on 60 Litres of diesel in my BJ70. and that's as accurate as I can be, until I get a gps in there and correct for the tires. but it's probably around 10% more kms. So I added 50k for the calculator.

used to think this was great mileage, but it is almost entirely highway.


Distance travelled
660 km
410.12 miles

Fuel Amount
60 litres
15.85 US gallons
13.2 Imperial gallons

Fuel Economy
9.09 litres per 100 km
25.87 miles per US gallon
31.07 miles per Imperial gallon

as for driving style , two words..... PUSSY FOOT. I'm slow, and I'm fine with that.

 

[brownbear]

ensure your injectors are clean. They need a service.
might be worth while to try to re-time the injection pump. Go thru the FSM procedure.
adjust the valves.
make sure each wheel spins freely and no brakes are dragging.

Take absolutely everything you don't need out of the vehicle. Including the spare tire. Make sure the truck is very light. Only carry what you need on longer trips.

Slightly over inflated tires help, but they will wear badly. So keep that in mind.

New air filter will help.

Shift into a higher gear at 1500 rpms.

 

[gerg]

I used Liqui moly concentrated injector cleaner. It is used concentrated right out of the bottle conected directly to your injector pump. I didnt notice a difference in performance, but my milage edged up a bit. I always use a diesel additive. I currently am using Stanadyne, seems ok. I also use syntheic oil all around with moly slip oil additive. My bj60 consistantly gets 850km per 80L mixed driving. That is not amazing milage for a 3B, but is on the higher end I do believe. Motor also has 425000k's as well.
Later
G

 

[gbcruiser]

Good ideas all...

I'm running a K&N filter just to test (on road only) but noticed no difference whatsoever, except for the $50 missing from my bank account.

No idea the compression on this engine, or when it was last serviced. It runs well enough and burns no oil whatsoever, but could probably use a tune up/time I imagine.

I've run a few tanks mixed with diesel injector cleaner, and several tanks of B5 bio, again no noticeable difference aside from running a little smoother.

Perhaps the rust holes are causing extra drag...

 

[Dougal]

Perhaps the rust holes are causing extra drag...

They're not rust-holes, they're speed holes.

Has your economy changed recently or is this what your normally get?

 

[brownbear]

running bio.....change your fuel flter too.

 

[exmodlad]

I know my BJ60 is MUCH happier and less thirsty when running at 2000 rpm than at 2500rpm or 3000rpm.

Mine also, the wife says i drive like an old man...i say yes i do...but the truck does get good economy, compared to my 5.7 Liter Tahoe

Best Regards'


Gord

 

[canucksafari]

Yesterday, I tried driving at 90 kms/hr (2000 rpm) for about 10 minutes until it was clear to me that 90 kms/hr is a road hazard. 100 kms/hr is also a road hazard here. Back to 110 on the freeway cause everyone is still passing me like I am standing still. Guess when it comes to speed or economy, speed wins.

My tires are up to 40 psi - not the 32 PSI Kal Tire set them to when they remounted them.

I don't take the Safari out on short runs anymore or by myself. I figure it need to be a solid 15 - 20 miunutes of driving to get it to the correct operating temp to get decent economy. Also, it doesn't make sense to run a big truck for only one person trips. The wife's Tercel is getting used more and more. Its not what I like driving. If the prices keep climb up like in the last 12 months, the next 4x4 will be a JDM Zuk diesel.

 

[Dougal]

Yesterday, I tried driving at 90 kms/hr (2000 rpm) for about 10 minutes until it was clear to me that 90 kms/hr is a road hazard. 100 kms/hr is also a road hazard here. Back to 110 on the freeway cause everyone is still passing me like I am standing still. Guess when it comes to speed or economy, speed wins.

Ain't it funny how everyone moans about fuel prices, but the general public won't slow down to save any?
Here the road rules are different, the car that runs into the back of you is the one at fault. It removes the safety hazard issue of driving slowly, so long as you let other traffic past.