"The HDJ81 Fuel Consumption Thread"

[83bj60]

Hi Folks,
I thought I'd start a more technical fuel consumption thread for the HDJ81, taking all kinds of factors into account, so as to give more accurate fuel consumption assessments for this vehicle.

Feel free to cut and paste and edit as required, it can be used as a template for your own measurements, and publish your own findings

All record data: distance, speed, consumption is corrected for accuracy based on highway markers for distance and stopwatch measurements with highway markers while driving at a constant speed +/- 1kph for 4km for speed. US Gallon at 3.78 l, Cannuck Gallon at 4.54 l. Mile at 1.609km. Brim to brim fuel filling, engine at operating temperature during filling.

Hope y'all find it useful

Chris




HDJ81 Fuel Consumption Records
Vehicle Specs:
Model: HDJ81 Landcruiser VX LTD
Year: 1991
Mileage: ~83,000km

Drive: Full-Time Four Wheel Drive
Transmission: A442 Automatic, Std valve body, 3 speeds + overdrive
Axles: Lockable Factory Differentials, Lockable Center Differential
Gearing: Factory - Unknown

Engine:
Model: Toyota 1HD-T
Type: Inline-6 Diesel Engine
Displacement: 4.3l
Optimum Torque Region: 1,700 RPM to 2,400 RPM
Maximum Power: 165HP at 4,300 RPM
Fuel Technology: Direct Injection
Valve Technology: Belt-driven Overhead Cam, 2 valves per cylinder
Admission: Single Stage Turbo Charger
Intercooler: none
Propane Injection: none

*************************************************


Record 2 (I will publish the record for my first test in November of last year when I have access to all my data):



Date: May 5, 2007
Engine Temperature: Normal Operating Temperature between Fill-Ups
Driving Conditions:
Road Surface: Dry
Type: Highway
Altitude: 75% 0-300m
25% 300-1000m
Temperature: 10-20C
Speed Travelled: 90% at 97kph +/- 3kph 98% of the time (highway)
10% AT 68 kph +/- 10kph, variable (state/provincial)




Wheels:


Rims: Berg Alloys 16"x8"
Tires: Brand: Bridgestone Dueler A/T
_______Type: Radial, LT, Load Range C
_______Size: 285/75/R16
_______Wear: 90% Worn
_______Actual Diameter: __ 32.25"
_______Actual Tread Width: 9.25"
_______Inflation Pressure, PSI:
___________________________Front: _ 40
___________________________Rear: __ 44




Lubrication:


Engine: Mobil-1 20W50 Racing Synthetic, for 8,000 km
Transmission Lubricant: unknown, presumed OEM
Transfer Case Lubricant: unknown, presumed OEM
Differential Lubricant: unknown, presumed OEM



Speedometer and Odometer Correction Factors, this Vehicle and Conditions, averaged out based on four mesurements:

_________Indicated___Measured____Method___________Corr. Factor___Accuracy

Speed___ 92 KPH _____ 97 KPH ___ Stopwatch _ ______1.055__________+/-0.005
Odom.___ 88.1 KM ___ 59.0 Mi ___ Highway Marker ___1.077__________+/-0.002

calculated OEM Tire Size Extrapolated from Odometer versus Actual Distance: 32.25 / 1.077 = 30.00"

Actual Speedometer Correction Factor Versus Odometer: 1.055 / 1.077 = Speedo Reads 0.98 Times Actual Speed with 30.00" OEM Tire




Actual Results, Corrected from Real Measurements:

Fuel Consumed: 12.697 US Gallons (brim to brim filling) at 3.78l/US Gallon = 47.99466l
Distance Travelled, Actual: 500km




Calculated Fuel Economy:

Metric: 9.6 l/100km
US Measure: 24.47 MPG
Imp. Measure: 29.39 MPG


On my way back from the States, 50% town highways and short stop and go, 50% highway at 97 KPH, I managed 9.7l/100

Tomorrow, when I get to the gas station, I'm going to measure my fuel consumption over the last stretch, which I did at approx. 108-110kph average, just for the heck of it. I did notice the fuel was going down a wee bit faster than at 95-100. I expect the figure to be around 11 to 11.5 l/100, based on the fuel tank needle position.

Bottom line, you can make this beast as thrifty as a camel

My next challenge: break the 30MPG (Imperial) barrier

 

[jfarsang]

Just lurking.

That's excellent mileage !

 

[83bj60]

Thanks, I've always been a fuel consumption freak. I found old records from my first BJ60, where I managed up to 32 MPGs at 85-90 kph with 235/75R15 tires and Rotella 15W40 oil, front axle disengaged (the front axle on the HDJ81 is always engaged) and H55F manual transmission (the HDJ81 has the automatic A442 transmission). I did have a record of 34MPG (using skinny 700/15 Michelin Tires one summer on that same stretch of road) and a short stretch at 39MPG (with a lot of downhills )

I LOVE Diesels!!!

 

[Scott.t]

I haven,t gone into great details with it but i calculate that i get about 10L/100km at 100kph and goes down to about 12L/ 100k At 110kph. But When you drive a vehicle that holds 245L you tend not to get to concerned about a wee drop in mileage. Cheers

 

[83bj60]

Scott, what tires are you fitted with and what engine oil do you use? Have you done any tune-up work?

 

[Enigma]

mileage?

I've done a bit of searching, but the threads that came up were for 60's and 80's.

Does anyone have any factory documentation, or their own findings, of what a bone stock B series 40 got for fuel mileage?

 

[Dougal]

What's your long term average fuel economy?
I've found single tank fills can be out by around 2 km/l.

What I find most interesting is the people in the US and canada claiming fuel economy 4L/100km less than those in Australia and New Zealand.

 

[Martin White]

What I find most interesting is the people in the US and canada claiming fuel economy 4L/100km less than those in Australia and New Zealand.
******************************************************************
The statement above summarizes my feelings exactly. I'm very suspicious of some of the fuel consumption figures posted. The Kiwis and Aussies should for the most part be getting better if not at least the same fuel economy as in North America, yet the numbers posted here tend to be higher, MUCH higher in terms of fuel economy. I also see statements like "the 1HD-T laughs at hills" and so on. Statements that don't make a whole lot of sense and are, to say the least, outrageously optimistic.

Admittedly my truck is now performing markedly better since the 3" exhaust upgrade. However I do not believe at this point there is going to be much of a change in fuel consumption.

I was so concerned about my truck a while back I was convinced I had a problem. Now that I've been able to get the odd tank of near 26 mpg (imperial) under absolutely perfect circumstances, I know it's fine.

It's hard to explain WHY there is such a difference between what we see posted here in North America vs. Aussie and Kiwi mileage, as they do a lot of flat, warm weather driving at speeds similar to what we do here. I, too, wonder why these numbers are so different....

 

[T.Stanford]

I agree with you Martin, when I read of such great fuel economy numbers, I wonder what is wrong with my truck? I drive (most of the time!) for economy and the truck runs like a dream but still some of these numbers on the mud site are >20% better . New injectors, rebuilt pump, going downhill in both directions? I don't know what would account for this variability. Cheers, Tony

 

[Martin White]

If it's any help at all Tony, I know exactly how you feel. I don't know if you have a boost guage but I have found that if you drive at low boost (around 3-5psi) and keep your RPM's low (ie 1800 or so) that you can get phenomenal fuel economy, particularly on the flats. I did a LONG trip on Vancouver Island a few months ago, most of it driving around 80 kph or less, and a large section of that was on dirt and gravel roads (drove out to Bamfield). Unfortunately I ended up getting stuck idling for some time on the lower part of the island, but my mpg number was very high for that trip.

Unfortunately that is not realistic for most of my driving which involves quite a bit of stop and go and idling.

I don't think you have anything to worry about. Just enjoy your truck. I seriously doubt you have any problems with it.

For the record, I was so concerned about my mpg I thought someone had changed the final drive ratios. They hadn't, it is stock (4.11's).

Once I found out the Aussies are getting about the same numbers as I am, I started to have serious doubts about SOME of the numbers allegedly obtained here in North America. I'm also a stickler for details and I KNOW my numbers are accurate.

Again, I can't explain it. I'm not saying anyone posting here is being dishonest. I just don't see how some of these numbers are possible in normal driving.

 

[Dougal]

If it's any help at all Tony, I know exactly how you feel. I don't know if you have a boost guage but I have found that if you drive at low boost (around 3-5psi) and keep your RPM's low (ie 1800 or so) that you can get phenomenal fuel economy, particularly on the flats.

There's a very good reason for that, the amount of boost your engine is putting out is a very good indicator of how much load it's under. If you can drive to a given boost level, you're basically reducing your engines power which dramatically improves economy.

Driving by EGT levels has a similar result.

As far as claimed fuel economy. The kiwis and Aussies I know will give you the fuel economy their vehicle has acheived over the time they've owned it. Over thousands of kilometres and plenty of tanks.
Some of the results posted here tend be be "best ever", rather than long term average.

 

[83bj60]

I just returned from a trip to Maine. The highway I'm using is the 15 south and 10 east in Québec (I average just a little over 100kph there), then 91 south in Vermont and 93 south in New Hampshire (I am usually more conservative there, tend to stay near 100kph) then 202 east for about 80km, at an average 70kph. Oh and when going through the White Mountains we are limited to a max of 45MPH (I stick to about 65 kph on my odo), that is for about 30km or so. There are long hills, but the Beast has no trouble maintaining at least 90-95 there. Mind you, these are mere hills compared to the Rockies, I presume. Maximum altitude the road goes is probably around 2000 feet. So the engine breathes much better than, say, an engine that is stuck at high altitude all the time.

I averaged just smack on 10l/100 for the whole trip, and that's driving at an average corrected speed of about 97 or so kph (speedometer actually measured on a timed run to extract a correction factor of about 5%, another was measured from a road sign radar 'your speed is ...' at 4%). Of course, teh way teh speedometer is built, it is difficult to get any better accuracy out of this instrument (There is a dampening mechanism, presumably to prevent excessive wear).

So the highway only part came to about 9.9l/100 at about 96kph through the mountains with B20, then I got 9.8l/100 at around 100 on dino mostly on flatter terrain, while for short trips to town (8km) and a few at the beach (40km) at 70 to 80kph I averaged about 10.2l/100. Ambient temps were mostly around 20C-25C.

These figures were calculated from accurate odometer measurments as corrected from highway markers. I doubt highway markers are not accurate, they ought to be for financing and maintenance reasons. Also, I re-measured my odometer discrepancy with the worn Bridgestones TWICE and came up once with a factor of 1.0778 and 1.0783, so it's been pretty consistent (Previous measurements gave figures of 1.077 IIRC).

Also when I fill, I fill the fuel to the brim of the filler neck, usually after I reach the 1/3 level mark. I am trying to get the most exact figure I can get!

The ONLY thing I think could induce some folks in error is the actual temperature of the fuel delivered, as this may affect real volume consumed. I know it's "corrected for 15C", but how would it affect end results?

Oh and as far as the B20 in tanked at the Getty in Chichester, NH goes, I did not notice a difference big enough to be certain of my perception that is may perhaps have had a wee bit less 'zing' as a fuel. It could simply have been the type of terrain I drove through after I tanked with it. That particluar B20 was mostly dino with some soy bean derived biodiesel.

In conclusion, I would say that a BIG part in fuel efficiency is how you drive!!! The secret is to pretend there is an egg between your foot and the gas pedal...

Oh and with the old BJ60, I averaged maybe 8% to 12% better. Of course, I could not sustain speeds on hills like I can with the HDJ81, it was with unlocked hubs and front diff with skinnier tires...

I sure would love to get some 800R16s with a road tread pattern!!! (but I would definitely need to finally replace the exhaust to let the turbo breathe better then!)... With taller and narrower tires and better boost the power curve of the engine would probably start a bit earlier, limiting pumping losses a bit, while the narrower tire would have less road friction than the old 285/75/16s... Hmmm... Still looking to beat the magical 30 IMP MPG barrier

BTW, has anyone been able to get the fabled 7 l/100 at 60kph that this truck is advertised in Japan as being able to do?!

 

[83bj60]

The kiwis and Aussies I know will give you the fuel economy their vehicle has acheived over the time they've owned it. Over thousands of kilometres and plenty of tanks.
Some of the results posted here tend be be "best ever", rather than long term average.

I agree. I've averaged about 11l/100 in summer doing my regular runs, and over 12 (up to 14 in certain cases) in winter. 10l/100 is under ideal [=highway at constant speed of 100kph] conditions, of course.

 

[83bj60]

I did a LONG trip on Vancouver Island a few months ago, most of it driving around 80 kph or less, and a large section of that was on dirt and gravel roads (drove out to Bamfield). Unfortunately I ended up getting stuck idling for some time on the lower part of the island, but my mpg number was very high for that trip.

How much? Around 10?

Again, I can't explain it. I'm not saying anyone posting here is being dishonest. I just don't see how some of these numbers are possible in normal driving.

My normal summer driving has so far averaged about 11.2l/100 for runs in the 30km average per 'heat', twice a day, 'cold' in the morning then 30km with a 4 to 6 hour stop then back home.

Winter, the same runs would be about 12.5l/100. Driving gently...

These are of course estimates from my recollections so far. Hope this helps a bit.

 

[Martin White]

Yeah that helps. I'm not sure of the exact figure because I ended up idling at the end of it, barely moving for a very long time, but I'd guess I was around 10.5 l / 100 km on the part of the trip where the consumption was lowest.

 

[dweisger]

My 81 get's about 11-13 l/100km in the summer depending on the type of driving. In the winter more like 13-15l/100km. If certainly doesn't laugh at hills. Don't get me wrong it is really good, but the powertrain has some dead spots. I think the descrepincy between peoples opinions lie with some bad math skills and a different way of driving.
If you have a heavy foot and don't mind winding the rpms out you might think that its great on hills. If your like me and hate seeing the rpms over 3000 you might get a different opinion.

 

[Dougal]

My 81 get's about 11-13 l/100km in the summer depending on the type of driving. In the winter more like 13-15l/100km. If certainly doesn't laugh at hills. Don't get me wrong it is really good, but the powertrain has some dead spots. I think the descrepincy between peoples opinions lie with some bad math skills and a different way of driving.
If you have a heavy foot and don't mind winding the rpms out you might think that its great on hills. If your like me and hate seeing the rpms over 3000 you might get a different opinion.

So you don't get 19mpg when cruising at 130-150km/h either?

 

[83bj60]

I think the descrepincy between peoples opinions lie with some bad math skills

People, why don't we say IMPERIAL in front ot MPG so as to not confuse the yanks... There is BIG difference between a US and an Imperial gallon (either 20% or 25% depending what you compare to what)

So you don't get 19mpg when cruising at 130-150km/h either?

Dougal, I have yet to see many people crusing at 130-150 to give enough credibility to support the (presumably imperial) 19MPG figure that you probably got from Wayne. Not that I don't believe you, Wayne. There are a lot of variables which can affect fuel consumption...

I have also not seen actual figures for low speed cruising (at 60km/h for example). Some Japanese sites claim that at that speed, fuel consumption is around 7l/100.

I'm not sure of the exact figure because I ended up idling at the end of it, barely moving for a very long time, but I'd guess I was around 10.5 l / 100 km on the part of the trip where the consumption was lowest.

Martin, I'm glad you got similar figures to what I get driving gently. Indeed, your truck appears to be fuelled properly, and your lift and large tires appear to have minimal impact on fuel consumption, they compare to mine driving mostly around 95-100kph mostly highway (with some idling stuck in traffic). Also, I noticed that idling doesn't impact fuel consumption much. It's a Diesel, remember, idle= mostly air...

 

[dweisger]

I've never broken 135 km/hr with the truck and I'm not usually up there long enough to check the mpg. I like the 95-100 km/hr range (2200rpm). I'm assuming at 130 km/hr (3000rpm) I'll sucking down fuel in the 15l/100km range or worse.

If I wanted speed I'd be driving a Skyline. I think people drive too fast anyway. Call me Grandpa.....

I recently did a 1000kms for 130l. Travelling from Edmonton to Hinton then to Nordegg on the Foresty Trunk Road and back on the number 2 to Edmonton.
100km/hr max. on the highway (350 km's of Foothill Gravel and 650kms of highway). I made lots of stops and went to the Cardinal Divide and I am pretty happy with the milage numbers.

DW

 

[83bj60]

I've never broken 135 km/hr [...] Call me Grandpa.....

So do my kids (except when I step on it when necessary, and then they're all surprised I can actually do it

But I've tried it all the way up to about 150, no problemo. I did notice it started to flatten out a bit there, but I couldn't try to go a bit faster because the straightaway is very short and ends in a bad curve on my local highway and I would never dare do that on a major highway, too many cops, fines much too stiff, and more importantly, I hate to waste fuel. But I did a run once for about 20km at 140, was following a European client for whom 140 was 'normal' (we were on a highway, but I figured as I was following him he'd be stopped and I'd have the time to slow down). At that speed, the truck behaved perfectly well.

When I first got the truck in November last year, I had a hard time exceeding 120, not anymore... Presumably because the PO never really pushed his engine, resulting in a possibly slightly glazed bore. Since then I have noticed the truck goes faster, and I have also noticed, it uses less oil than it did when I first got it (it has dropped only a quarter inch on my oil dipstick after more than 3,000 km after my last oil change).

But like you said, in a fancy sportscar such as the Skyline or a Porsche, it would be a different story, it's just so easy to go fast and feel you're driving slower. What I remeber most though, was how little the experimental Mercedes Benz C111-3 did back in the late 70s with its 5 cylinder turbocharged diesel: 13US MPG at TWO HUNDRED miles an hour!!! [12US MPG is about 18l/100, not bad for 320kph AVERAGE!]

I recently did a 1000kms for 130l [...] I am pretty happy with the milage numbers.

Hmmm... That's 13l/100... Isn't that a bit high for sedated driving at 100kph? What altitude are you driving at, and what are your tires and inflation pressure? Are you also sure about your odometer readings (larger tires = underestimated distance)?

Drive it hard and fast for a while, it will probbaly help