1hdt fuel mileage (2 Viewers)

[bcguy]

I´ve got a new to me 1990 HDJ81, that I´m doing my first road trip with next week.
For the first 2 months i´ve been getting roughly the same mileage in the city and on the highway, approx 10.5 - 12L/ 100kms.
From older posts I´ve searched, seems like that is on the lower side of the spectrum, but no one has really followed up lately on those threads.
Should I expect this type of mileage long term?

 

[sailor]

short answer- yes. unless it's a manual these things get worse 'real world' numbers than legend would have it. Still better than a gasser but it isn't miraculous. gets worse with bigger tires, weight, armour etc.

Fill out your details in your sig line so we know what you have- makes it easier to help with the newb questions.

 

[bcguy]

Well, it is a 5speed, will have an arb front bumper next week, 35¨ Yoko Geolanders, with 3.5¨front/rear lift, kaymar rear bumper.
How many km´s per tank do you get typically?
I´ll update the signature line as soon as i figure out how to do it.
I thought these things were to have some serious distance capabilities.

 

[sailor]

keep it under 90 kph and you have a chance- Big tires, bumpers, gear is a negative.

Auto goes 560k approx per tank.

 

[bcguy]

I'm doing a 15000km road trip over the course of 2 months, so I will track my fuel consumption there.
Any recommendations where I should post my results?
Currently, I'm running between 600-700km's per tank full, but that topped out full to dead empty.
I do notice at the 90-95km mark is where the mileage craps out.
The 35" tires are there to reduce the rpm by a touch.

 

[jamie_scotland]

Yep, I found fitting bigger tyres actually improved my fuel mileage. My 80 is a 5 speed as well so the increase in gearing certainly seems to help.

Remember to take the now inaccurate odo reading into account when you do your calculations!

Jamie

 

[Douglas S]

keep it under 90 kph and you have a chance- Big tires, bumpers, gear is a negative.

Auto goes 560k approx per tank.

That seems low...I'm getting more than that.

 

[wongtsenhin]

I did about 730km for my 1HDT with H55f box. Probably lighter in body weight.

 

[sailor]

Manual is better as is stock tires and light weight. Bigger tires yield dividends on hwy in flat terrain, not so much in the city or on hills... My truck is pretty heavy.

 

[Enigma]

I get a pretty consistent 550k or so per tank. That's with 35's, a lot of extra steel, and a roof rack.

 

[northernrighty]

just posted a thing on this in diesel tech, I found 35 helped my fuel eco too. I get about 700km per tank buy taking it easyish lol, 3" exhaust will help also.

 

[Tapage]

I got 24 city 28 HW km/gal in my 80 with 315 and both bumpers .. mostly flat .. 1HD-T are thirsty ones .. much more than IDI like 1HZ engines ..

 

[Douglas S]

Manual is better as is stock tires and light weight. Bigger tires yield dividends on hwy in flat terrain, not so much in the city or on hills... My truck is pretty heavy.

Everything I've heard tells me that the auto gets better mileage. I've never driven a manual HDJ81, but I seem to remember Crushers saying this was the case.

 

[crushers]

as i posted in the other thread the auto has a much better O/D ratio than the manual and with the lockup torque convertor the auto will give you EITHER a better top cruising speed or better fuel mileage.
the HDJ81 likes 90 - 100 k/h and that is where you will recieve the best fuel mileage.

it seems that for every 10 k/h faster you get 2-3 mpg poorer fuel mileage.

i also recommend you don't go below 1/4 tank but that is just me. especially on a long trip, if you end up thinking cause the GPS says there is fuel in the next town doesn't promise the station will be open for business ...
plus
the closer you get to empty the more crap you might suck up from the bottom of the tank.

 

[marshy90]

i too find 90- 95km/h is a good speed to sit on when traveling the H-way in my 91 hdj80 1hdt. got 600km in one tank with towing a large boat for a large part of the tank last tank i filled up. do all 80 series cruisers have the same size tanks, 90L main and 45L sub? is that correct? cheers

 

[Enigma]

I've been using an app on my 'droid for a bit now called aCar. Been pretty happy with it and just bought the pro version. Anyhoo...

I do not daily drive my 81 anymore, just the odd weekend trips and occasional jaunt around town. My fuel mileage according to the charts on this app are all over the place...
As low as 10.5l/100lm (highway) and as high as 20.41l/100km, with an average of 17.45 l/100. Over the last 3 months that average is 15.89.

These figures do not take into account any calculation for the larger tire size (315 75r16), which is about an 8% difference. Truck also has an RTT brick on the roof and sits quite heavy, think I was 7000 lbs last I weighed it.

 

[Enigma]

Recently completed a 1500 km round trip from Pitt Meadows to Williams Lake BC via highway 1, and from there as much backroad gravel travel as possible towards Barkerville via Yanks peak. Wells Grey park fringes, then to Likely, Barriere, and then finally home.
This was all done with the truck fully loaded with the family, roof rack full (RTT moded to the trailer), and towing my M101 which I guess weighs about 1200 lbs.
I filled up 5 times; once as we left home , in Williams Lake, dumped my 20l gerry can in at one camp site, one more in Likely, and the final fill in Kamloops on the way home, for a total of 290 litres. That's 19.33 l/100km (12.2 mpg) for mixed driving of loaded highway travel/4lo/towing.
Modified aneroid rod, etc and boosted to a max of 18 psi.
Not as good as I originally thought as I just found a receipt for 70 litres I forgot to enter....

But at the same time, was getting the same mileage as a similarly loaded hdj81 leading the pack that wasn't towing.

 

[ozcrusier]

My old 1991 Sahara 1hdt 4 speed auto used to average 12-100 on the hwy and 14-100 city

 

[HillCountryTX]

Just bought an HDJ81 (with the 1HDT) back in November of 2016 and we've seen mileage as low as 12 mpg (us gallons), which is 19.6 L per 100kms, to a best of 16.7 mpg (us gallons), which is 14L per 100kms. We have the stock tire size 31x10.5r15 on the stock 15 inch steel wheels, no lift, a roof rack, an ARB front bumper (no winch) and no modifications as far as I know. It's a 5 spd. manual and we sit at about 3000 rpms going 70mph (112 km/hr), which seems pretty high to me. We do a mixture of city and highway driving, but the mileage doesn't seem to vary very much. The lowest mileage we got (12 mpg (us gallons)) was on a camping trip with three people, gear, bikes on top, and travelling at about 75 - 80 mph on the interstate here in the United States.

I've replaced the injectors recently with brand new injectors and haven't really noticed much of an improvement in fuel mileage (slight, if any), which is disappointing. I've checked the air filter as well and it's clean. Any idea what else to check? I feel like we should be getting in the 18 to 20 mpg (US Gallons) or 10 - 13 L per 100 kms?

Any ideas?

 

[IanB]

For highway driving, larger tires will bring your revs down and should help, if you insist on driving 70mph+ these things will suck back the fuel as they just aren't aerodynamic and get worse as you add accessories.