fuel economy

[incisor]

how many klms do you county owners get out of a std tank?

[wovenrovings]

Mine it depends how i drive. But I get between 12 and 10L per 100km.
Sisters county got 770km out of a tank between Rocky and Longreach, put 77L in it:eek:. Good thing we had a jerry can of fuel with us.
Speed makes a big difference because of the wonderfull streamlining. 95kmh gives me 10L/100km and 105-110 gives me 11.5L/100km. Mine is a 4 speed.
5 speeds are a bit better at the higher speeds.

Hope that gives you an idea.

[kaa45]

http://www.aulro.com/afvb/isuzu-landy-enthusiasts-section/58403-fuel-range.html

[JDNSW]

Standard tank holds 80l, and I get between 10 and 12l/100km, mostly pretty close to 11. Doesn't seem to make much difference load, speed, towing etc as long as I stay below 110. (I have a 60l extra tank, and being diesel, I try my best not to run either tank dry - I reckon on 1100km safely from both tanks)

John

[justinc]

Dave,
My uncle, the original owner of the 110 that my engine came from, had a 5spd 1988 county, and at that time the engine was N/A.
Always did country miles, and returned regularly around 12l/100km. (Lots of hills around where they live...)
On a trip fully laden (3000+kg all up:eek:) it got 15l/100km average from the south west of WA, up the Canning stock route and return to the south west of WA.
He just wished it would pull up hills better:(
I let him drive my RRC after I had turboed and intercooled his old motor, couldn't wipe the smile off his face:twisted:
JC

[Bigbjorn]

Dave, my beast has a 130 litre aftermarket tank and I have never had it below an indicated 1/4 full. Have a look at my posts titled "Went for a drive" of 28/3/2007 and 3/10/2007 for actual economy figures. Both trips were fast and laden. Light laden highway use (me and an overnight bag) returns usually around 9 l/100k's. Round town usage is variable according to traffic conditions and load but is around 11-12 l/100k's

[long stroke]

Our's is a 1985 modal N/A, lt95 gbox running 32" MTR'S with roof racks, and we have just finished reconditioning the motor.
We went away for the weekend last week and returned 10ltr's per 100km's full of camping gear and towing a camper trailer with a bit of low range work and dirt roads included.

CHEERS TIM.

[isuzurover]

Best ever about 9.0L/100

Usual around 11L/100

Drove Bris-Townsville once (non stop each way apart from fuel/food breaks). Averaged 11L/100 on the way up - sitting on the speed limit (incl. speedo error) most of the way. The first leg back down there was a really bad headwind - went up to 13L/100.

Worst I have ever experienced was 16.5. In Dave S's old county (which now lives in canada). NA 5 speed, driving through Wyoming. Headwinds were about 100km/h, so the best we could do was 80-90km/h in 3rd, foot flat to the floor. had 3 people, and a big roofrack with ammo boxes bolted to it - which didn't help our drag coefficient.

[OLR-067]

So far on our trip we are averaging 12.12L/100km. This is with tyre on bonnet, roof rack, roof tent, bicycles on back carrier, 9kg gas bottle on roof and weighing around the 3.2t mark.

Cheers
Paul

[isuzurover]

Just completed a trip - Perth - Adl - Melb - Tas - Syd - Dubbo - Broken Hill - Clare (SA) - Port Lincoln - Perth. Total just over 15k km.

110 County, 4BD1T (see conversion thread for specs), 255/85-16s.
4 people, 70L water, 120L diesel, Engel, usual camping and cooking gear etc, etc on board. Picked up 2x 8274 winches along the way.

Best Economy: 10.2 L/100 Norseman-Corrigin - dirt road!!!
Worst Economy: 17.2 L/100 Sitting on 120+ into a HUGE headwind W-E across the Nullarbor (average EGT was 650+ across this stretch!!!)

Average Economy W-E Across Nullarbor: 14.1 L/100 (sitting on 120 - headwind, EGT 600-700, Boost 6-11 psi)
Average Economy E-W Across Nullarbor: 12.3 L/100 (sitting on 110 - tailwind, EGT 400-500, Boost 4-6psi )

Average Economy WHOLE TRIP: 12.9 L/100

Speedo is 100% accurate with the 33's (well 300m every 100km discrepancy with the GPS). The figures I posted previously were with 32's, so probably a bit better than reality.

[Bigbjorn]

My NA County has a 130 litre tank. Iget 25-26 mpg around town or towing with a load in the back, and 29-30 touring light.

[inside]

Just to bump this I'm seeing 11L/100km out of my 4BD1T. Not bad for an engine that's nearly 4 litres and has such much torque.

[garryseries3]

After reading this thread I am reading that a 4BD1 is generally a tad more economical than a 4BD1T, lets say by may 2L/100kms. Does this appear correct to you all out there. Is this a fare assumption, does the difference decrease with a loaded up vericle say? Am interested to know beacause I always thought turbos made engines more efficient by utilising wasted heat. So I am a tad confused can a turbo motor get better economy than a NA motor? Yes I have driven a few turbo motor landys and they are great but the economy question has head me stumped.
Is it all down to how heavy the right foot is not sure?

regards
Garry

[85 county]

After reading this thread I am reading that a 4BD1 is generally a tad more economical than a 4BD1T, lets say by may 2L/100kms. Does this appear correct to you all out there. Is this a fare assumption, does the difference decrease with a loaded up vericle say? Am interested to know beacause I always thought turbos made engines more efficient by utilising wasted heat. So I am a tad confused can a turbo motor get better economy than a NA motor? Yes I have driven a few turbo motor landys and they are great but the economy question has head me stumped.
Is it all down to how heavy the right foot is not sure?

regards
Garry
Often stated but just not true.

How much fuel ver your foot you shove in is how much you use. Since the NA is a bit lacking at times it is easy to understand that with the extra O available ver the turbo that the foot shoves in a bit more fuel.

Hence the difference

I have been playing around with my rack averaging about 9.6 as a daily to work city drive 3 X 126ltr tanks so far

[garryseries3]

Often stated but just not true.

How much fuel ver your foot you shove in is how much you use. Since the NA is a bit lacking at times it is easy to understand that with the extra O available ver the turbo that the foot shoves in a bit more fuel.

Hence the difference

I have been playing around with my rack averaging about 9.6 as a daily to work city drive 3 X 126ltr tanks so far

The reason I ask is because I am considering putting a turbo on my 120 primarily for economy not for extra torque that it will deliver and would like to know the best way to go about this. In addition I have a sequential 2 LPG system to fit off to the motor. If it delivers extra efficiency for the engine I would think this will translate into increase economy. I have read that the same amount of fuel (diesel & LPG combined) is a result. I have wondered if the burning of what is unburnt fuel in a NA isuzu motor (approx 20%) post combustion will lead to a higher EGT's which in turn may drive a turbo a bit more, pumping in more oxygen. Wondering if this is a realaistic concept, or am I off the track. My 120 get around 9.7 -10.5L/100L which is I think is good, so you have a turbo engine and from what I am understanding its the driving style that results economy gains no matter if the engine has a turbo or not?

regards
Garry

[c.h.i.e.f]

Full tank is gone in about 350-400kms

[85 county]

The reason I ask is because I am considering putting a turbo on my 120 primarily for economy not for extra torque that it will deliver and would like to know the best way to go about this. In addition I have a sequential 2 LPG system to fit off to the motor. If it delivers extra efficiency for the engine I would think this will translate into increase economy. I have read that the same amount of fuel (diesel & LPG combined) is a result. I have wondered if the burning of what is unburnt fuel in a NA isuzu motor (approx 20%) post combustion will lead to a higher EGT's which in turn may drive a turbo a bit more, pumping in more oxygen. Wondering if this is a realaistic concept, or am I off the track. My 120 get around 9.7 -10.5L/100L which is I think is good, so you have a turbo engine and from what I am understanding its the driving style that results economy gains no matter if the engine has a turbo or not?

regards
Garry

wow way off base.
I have LPG fumigation. 28 ltrs that lasts for about 10 hours driving. but I have a NA Isuzu so I use it for a bit more power, taking off at the lights or heading up a hill when i don’t want to change down IE 60klms in 4th ( lt95)

so for me LPG is not an economy thing.

LPG fumigation lowers EGT without lowering boost. It is not heat that spins the fan but gas flow or volume. temp drops but volume increases = net effect about the same.

rule of thumb if your not driving with the boot in all the time. + 2Ltrs LPG = less 1 ltr diesel.

your economy is good, check valve clearances filters. Crack pressure on the top fuel filter and timing for an NA i think about 11 BTDC is good

[JDNSW]

If you add a turbo to an NA motor, you are making use of heat that would otherwise be lost - but you are using it to increase the amount of air that is taken into the motor. This will make virtually no difference to the efficiency of the motor, until you add more fuel than could be burnt without the turbo, when efficiency will be improved because the mechanical work that would be needed to induct and compress the extra air has been replaced by work converted from exhaust heat.

This should make it clear (I hope) that fitting a turbo is unlikely to make any improvement to your fuel economy except by the very indirect effect of not needing to change down - which will rarely have a noticeable effect. What fitting the turbo will do, is provide some extra oomph, available by simply pushing your right foot down. And this, which few can resist doing, will increase you fuel consumption, despite the fact that efficiency may be a little higher; you are using the engine to do more work to propel the vehicle faster.

John

[85 county]

If you add a turbo to an NA motor, you are making use of heat that would otherwise be lost - but you are using it to increase the amount of air that is taken into the motor. This will make virtually no difference to the efficiency of the motor, until you add more fuel than could be burnt without the turbo, when efficiency will be improved because the mechanical work that would be needed to induct and compress the extra air has been replaced by work converted from exhaust heat.


cool, so if I put a turbo in my oven it will spool up? Mass X volume velocity, less backpressure and lack of scavenging.

[Dougal]

The reason I ask is because I am considering putting a turbo on my 120 primarily for economy not for extra torque that it will deliver and would like to know the best way to go about this. In addition I have a sequential 2 LPG system to fit off to the motor. If it delivers extra efficiency for the engine I would think this will translate into increase economy. I have read that the same amount of fuel (diesel & LPG combined) is a result. I have wondered if the burning of what is unburnt fuel in a NA isuzu motor (approx 20%) post combustion will lead to a higher EGT's which in turn may drive a turbo a bit more, pumping in more oxygen. Wondering if this is a realaistic concept, or am I off the track. My 120 get around 9.7 -10.5L/100L which is I think is good, so you have a turbo engine and from what I am understanding its the driving style that results economy gains no matter if the engine has a turbo or not?

regards
Garry

Here's the process.

Fit turbo, set boost to a level safe for the turbo you've chosen (say 15psi), adjust fuelling so at maximum load you aren't going past about 700-750C.

Fit wooden block under accellerator pedal to drive economically.
For those times you need to make more progress, remove the wooden block and store it somewhere safe for future use.
Note this wooden block can have it's thickness tuned for a good balance between speed and economy.

I see no reasons to run LPG on these engines and many reasons not to. If you had 20% unburnt fuel (as some fumigation propaganda alleges) then you would be constantly followed by a cloud of black smoke.

My fuel economy is 10km/l on any given road trip (even including 2000m vertical of skifield roads) and a worst of 8.5 km/l (12 litres/100km) when doing nothing but short trips and offroad.

[justinc]

Just had a chance to test my 110 fuel economy on a biggish run, took tests for 2 tanks, 1300km approx all up, towed a 8x5 trailer from Hobart to Swan hill, then through Healesville back roads to Traralgon, then back to Melbourne, city driving in traffic then back to Hobart again.

Average is 12.5l/100km.

Turbo intercooled, .996:1 gears and 235/85/16 A/T tyres.
Trailer empty on way up, 80% load on way home, bulky not heavy.
sat on 95 to 105km/h, overtook a few times up to 120km/h.

Overall very happy considering engine has almost 600,000km and no recorded injector or pump maintenance other than fuel filters every second oil change, cleaning of sediment bowl and periodic added fuel treatmenst from when donor vehicle was bought new in 1988.

JC

[JDNSW]

cool, so if I put a turbo in my oven it will spool up? No.Mass X volume velocity, less backpressure and lack of scavenging.
To put it simply, the turbo enables you to get more air in than NA, and do it more efficiently than would increasing capacity, but this increase does nothing for you until you burn more fuel. The exception to this would be if you are already overfuelling - in this case, certainly, fuel economy may improve slightly, but only if you do not increase fuelling.

John

[Dougal]

Just had a chance to test my 110 fuel economy on a biggish run, took tests for 2 tanks, 1300km approx all up, towed a 8x5 trailer from Hobart to Swan hill, then through Healesville back roads to Traralgon, then back to Melbourne, city driving in traffic then back to Hobart again.

JC

It's all up and running then? I've got some questions on the performance of that factory Isuzu turbo you are running.

[justinc]

Hi Dougal,

It's a TB25 Garrett, (are those factory?) anyway, manifold is similar to factory one I believe, it is wastegated but that is plugged up and the boost set to 15psi at manifold using the fuel screw. max egt has been about 600 upstream at these settings. The only irritating issue is the idle speed is a bit higher than I would like, and the idle stop screw is out quite far enough, but makes no difference.

Running factory Td5 defender exhaust system from engine pipe back, flows pretty well and is quite quiet.

As I said, I am very happy with overall performance and economy, allround it is a very good set up.

JC

[Dougal]

Hi Dougal,

It's a TB25 Garrett, (are those factory?) anyway, manifold is similar to factory one I believe, it is wastegated but that is plugged up and the boost set to 15psi at manifold using the fuel screw. max egt has been about 600 upstream at these settings. The only irritating issue is the idle speed is a bit higher than I would like, and the idle stop screw is out quite far enough, but makes no difference.

Running factory Td5 defender exhaust system from engine pipe back, flows pretty well and is quite quiet.

As I said, I am very happy with overall performance and economy, allround it is a very good set up.

JC

Justin, your turbo is the factory fitted item from the 94-98 4BD1T and 4BD2T engines. It's a T25 with an Isuzu specific turbine, and a 0.67 A/R turbine housing with a T3 flange.

Should have a 54mm compressor fitted from the factory and I'm looking into upgrades for it, there are a lot of owners in the US of 4BD2T engines who run this turbo and need an easy upgrade for the next step. I have a plan and it should be plug and play.

Can you tell me what the minimum rpm is that you can pull 10 and 15psi boost?

[justinc]

Justin, your turbo is the factory fitted item from the 94-98 4BD1T and 4BD2T engines. It's a T25 with an Isuzu specific turbine, and a 0.67 A/R turbine housing with a T3 flange.

Should have a 54mm compressor fitted from the factory and I'm looking into upgrades for it, there are a lot of owners in the US of 4BD2T engines who run this turbo and need an easy upgrade for the next step. I have a plan and it should be plug and play.

Can you tell me what the minimum rpm is that you can pull 10 and 15psi boost?

ah, good info thanks. when i was looking at turbos waaay back 7 or so years ago, i contacted turboglide who did kits to suit 4bd1 in motorhomes etc. this was the turbo they recommended and the manifold was one of theirs but i have discovered genuine isuzu ones are almost exactly the same, and cheaper. i don't have a tacho, but at these fuel settings and a hill infront of me, i can see 15psi at about 2600 to 2800rpm, and 10 is easy at around 2000 to 2200, under load. these are approx, based on gear that i am in. i will try and get closer numbers by staying in 4th gear for all these tests, watching road speed and hooking up the boost gauge again if it would be helpful? should be easy to calc revs then :)

i am interested in a plug and play solution for more boost, i feel trying to get more out of mine feels as though the little compressor is overspeeding. i could do with a little more as i have a ginormous front mount ic with 3" pipework and could easily take 20+psi....:)

jc

[garryseries3]

To put it simply, the turbo enables you to get more air in than NA, and do it more efficiently than would increasing capacity, but this increase does nothing for you until you burn more fuel. The exception to this would be if you are already overfuelling - in this case, certainly, fuel economy may improve slightly, but only if you do not increase fuelling.

John

So does a NA Isuzu have around 20% unburnt fuel post combustion or is this not true and is this figure much the same for a tubo motor? If it is and LPG increases the fuel burnt as claimed then doesn't this increases the engine efficiency and hence economy?

If I understandit right a turbo adds more air so you can add more fuel to burn with each compression cycle, but the efficiency of the motor to burn the air/fuel mixuture does not alter greatly just the volume. Is this a fair comment?

regards
Garry

[isuzurover]

So does a NA Isuzu have around 20% unburnt fuel post combustion or is this not true and is this figure much the same for a tubo motor? If it is and LPG increases the fuel burnt as claimed then doesn't this increases the engine efficiency and hence economy?

If I understandit right a turbo adds more air so you can add more fuel to burn with each compression cycle, but the efficiency of the motor to burn the air/fuel mixuture does not alter greatly just the volume. Is this a fair comment?

regards
Garry

20% unburnt fuel would see huge plumes of smoke. If you believe that I have a bridge that may interest you... LPG fumigation is simple fuel addition, some adiabatic cooling, and possibly some changes in flame fronts and or flame propagation, however there is no independant research to prove the latter.


Fitting a turbo will be the best mod you ever did...

[Dougal]

ah, good info thanks. when i was looking at turbos waaay back 7 or so years ago, i contacted turboglide who did kits to suit 4bd1 in motorhomes etc. this was the turbo they recommended and the manifold was one of theirs but i have discovered genuine isuzu ones are almost exactly the same, and cheaper. i don't have a tacho, but at these fuel settings and a hill infront of me, i can see 15psi at about 2600 to 2800rpm, and 10 is easy at around 2000 to 2200, under load. these are approx, based on gear that i am in. i will try and get closer numbers by staying in 4th gear for all these tests, watching road speed and hooking up the boost gauge again if it would be helpful? should be easy to calc revs then :)

i am interested in a plug and play solution for more boost, i feel trying to get more out of mine feels as though the little compressor is overspeeding. i could do with a little more as i have a ginormous front mount ic with 3" pipework and could easily take 20+psi....:)

jc

That's the one. I suspect turboglide were selling the genuine Isuzu parts. Quite a good and easy move on their part. Another guy in the US was selling the same Isuzu manifold and turbo for toyota 3B engines, just slotting the holes so the manifold kind-of fit.:(

There is a turbo used on the Isuzu 4HE1 motors which uses the same turbine but a different turbine housing and a bigger compressor. It should fit straight into the turbine housing from the turbo you've got and provide more boost throughout the rev range with no loss of top end. Oil supply/drain are the same but air piping might need small modifications.


So does a NA Isuzu have around 20% unburnt fuel post combustion or is this not true and is this figure much the same for a tubo motor? If it is and LPG increases the fuel burnt as claimed then doesn't this increases the engine efficiency and hence economy?

If I understandit right a turbo adds more air so you can add more fuel to burn with each compression cycle, but the efficiency of the motor to burn the air/fuel mixuture does not alter greatly just the volume. Is this a fair comment?

regards
Garry

Turbocharged engines are more efficient across the whole operating range than non-turbo engines. Even at part load.
In addition, turbocharging allows you to pull higher gears and run lower rpm which can further save fuel.
IMO the only reason non turbo engines are using similar amounts of fuel, is because they are slower and make savings through wind resistance because of this.

The 20% unburnt fuel claim by lpg mongers is complete and utter bollocks.

[JDNSW]

So does a NA Isuzu have around 20% unburnt fuel post combustion or is this not true and is this figure much the same for a tubo motor? If it is and LPG increases the fuel burnt as claimed then doesn't this increases the engine efficiency and hence economy? ....

regards
Garry

Unburnt fuel on a NA is very low, probably well under 1% even at full throttle unless you have the fuelling incorrect. And remember that there is already (a lot of) excess air at all smaller throttle openings, which is where most of your driving is done (well, most of mine, anyway!), so that adding extra air by fitting a turbo will not burn any more excess fuel. I don't know where the 20% came from, but that figure is ludicrous!

LPG may slightly improve fuel burn, but it can still only burn fuel that is unburnt, less than 1%.

John

[c.h.i.e.f]

good to see its all going well justin :)....in regards to the idling problem how far is it until the max fuel cam touches its rest ?

[justinc]

There is a turbo used on the Isuzu 4HE1 motors which uses the same turbine but a different turbine housing and a bigger compressor. It should fit straight into the turbine housing from the turbo you've got and provide more boost throughout the rev range with no loss of top end. Oil supply/drain are the same but air piping might need small modifications.





Thanks Dougal, can you let me know progress on this/ when it happens?

JC

[Dougal]

Thanks Dougal, can you let me know progress on this/ when it happens?

JC

As soon as I can convince someone to buy and try.
Aliexpress.com : Buy GT25/700716 5009S 8972089663 Garrett turbocharger for ISUZU NQR Truck from Reliable turbo suppliers on Rita Li's Turbo Store (http://www.aliexpress.com/store/product/GT25-700716-5009S-8972089663-Garrett-turbocharger-for-ISUZU-NQR-Truck/311588_471016525.html)

[steveG]

Just added up my fuel usage from our recent Cape York trip.
Melbourne-Cairns-Cooktown-Lakefield-OTL-Tip-Mareeba-Cairns.
Coen was the last time I filled the tank completely on the way back as the County is being freighted back to Melbourne from Cairns.

Figures for Melbourne to Coen were 6059km, and 786L, which works out at about 13L/100km.

Vehicle is a 1985 County, 4bd1 with turbo, no I/C, LT95 with .996 transfer and 255/85-16 BFG KM2's, rooftop tent, and the 2 of us in the car.

Driving was a mix of blacktop at 95-105km/h, gravel 80-90 at best (often slower), and plenty of low range.

Steve