12HT Economy

[Ivy4x4]

Hi one and all,

Well I'm looking for some input. I have a HJ61 with a 12HT and I'm thinking that it can do a little better in the economy department. I know that they aren't new engines and I own it for it's reliability but what is disappointing is that I cannot get it better than the very top end of 13's Lt to the 100km (3.7G to 62.5Mi) Those figures don't change, I've been loaded, empty, towing but the figures are nearly the same - mid 13 to low 14 lt per 100km. I don't mind those figures loaded and towing but I would have expected around the 12's when unloaded. I have recently (about 1000km ago) changed the fuel filter and had the injectors done (new nozzles). My question is if there is an adjustment that is done to the injector pump that can alter these figures, is it a simple fix or am I up for some $$$$$$ for a major rebuild. It was Dyno tuned 10,000 Km ago and the figures haven't changed with the rebuilt injectors.

Thanks in advance for your input.

 

[Mountain Goat]

That's about what I get. Any time, any conditions, 17mpg.

I've been similarly unimpressed - expecting to get the 20+ that some people claim. I've just learned to live with it.

 

[maat]

Same here

Begining to think the people claiming those figures are a bit off, or all they do is hwy driving

 

[mun60]

I get 12.5 l/100 Every time, on a recent bucks week I got 14.5 fully loaded with food and piss for 15 blokes and towing the tinny. I have just adjusted the fuel and boost fingers crossed it doesn't change too much. I think this economy is pretty damn good for a large old truck, the old mans lux gets around 12.8l/100 and that's An unladen hilux ute, 2003 turbo d.

 

[Ivy4x4]

I get 12.5 l/100 Every time, on a recent bucks week I got 14.5 fully loaded with food and piss for 15 blokes and towing the tinny. I have just adjusted the fuel and boost fingers crossed it doesn't change too much. I think this economy is pretty damn good for a large old truck, the old mans lux gets around 12.8l/100 and that's An unladen hilux ute, 2003 turbo d.

Thanks for the quick replies fellas, mun60, that's the kind of figures I'm trying to chase. The thing that gets me is that I've kept mine stock, no extra boost or fuel.... The only thing other than the IP that can be against me is that I'm running 31's which keeps the revs up on the Hwy but I try to keep her at 100 km/h. I recon that 110 an hr would still yield 14's for me. The more I think about it the more I'm leaning towards a IP rebuild...

 

[blis]

Last time I checked my consumption it was around 10.2l/100km but that was mostly on highway (80-110km/h)... On allround driving i usually get between 11.5l-13l, thats with 33's and 3" exhaust (basicly freeflow), std boost and fuel... You could always try hammering your car a bit to loosen up the carbon buildup in the engine and drop your consumption a bit, also switch to synthetic engine oil (I use 5w-50 on mine)... That should lower the consumption a bit...

 

[mun60]

I run 31 x 10.5 x 15's which I think are a tad too small, my speedo jumps around a bit so it's a bit hard to tell how fast I'm going. The old fella I bought it off said that it is most economical around 95 km/ hr and if you start pushing it over 100 it will start to chew the diesel. Recently my wife drove the car for 4 weeks and she was getting 11.5, I think this is due to her driving by the speedo which because of the 31's reads a bit high, so she was probably only doing mid 90's. I drive on the highway at 2500 revs which I think is about 104 ish km / hr, this yields the 12.5 litres/100.

 

[dousty]

With H55F, 33's , no roofrack and one on board I get 11.2l on the Pacific Highway. I drive at around 5-10 (indicated) over the limit and ALWAYS try to maintain my speed over hills. While the wagon is not loaded, I am not driving conservatively either. For most of the trip engine speed it at 2400-2500rpm. I drive make one 1000km trip along the Pacific every week (except school holidays).

My auto Sahara with 31's does 11.5 - 11.8 under the same conditions. Although it's engine speed is 300rpm lower.

 

[maat]

I run 31 x 10.5 x 15's which I think are a tad too small, my speedo jumps around a bit so it's a bit hard to tell how fast I'm going. The old fella I bought it off said that it is most economical around 95 km/ hr and if you start pushing it over 100 it will start to chew the diesel. Recently my wife drove the car for 4 weeks and she was getting 11.5, I think this is due to her driving by the speedo which because of the 31's reads a bit high, so she was probably only doing mid 90's. I drive on the highway at 2500 revs which I think is about 104 ish km / hr, this yields the 12.5 litres/100.

To my knowledge 31" is the standard size for the hj61 so your speedo wont be out because of the tyres, with my truck i found 33" mad the speedo read approx 10kmh less than ghe actual road speed when measured next to a new clubsport at 100kmh

 

[roscoFJ73]

I think the manuals will do a little better than the autos around town. I believe there has been a bit of "gilding the lily" on this forum in regard to fuel consumption.
And there are those that just cant do the maths properly.
And there are others who do a long trip on a straight road at 90kph and pass that figure off as their average.

I had a HJ61 for a couple of months and the rough figures were 12-14/100klms with a 5sp.

Ive found the 32 inch tyre is the closest to the 16 inch split rim and tyre

 

[Ivy4x4]

I think the manuals will do a little better than the autos around town. I believe there has been a bit of "gilding the lily" on this forum in regard to fuel consumption.
And there are those that just cant do the maths properly.
And there are others who do a long trip on a straight road at 90kph and pass that figure off as their average.

I had a HJ61 for a couple of months and the rough figures were 12-14/100klms with a 5sp.

Ive found the 32 inch tyre is the closest to the 16 inch split rim and tyre

There is quite a bit of fluctuation in the figures, 10lt to the 100km would be great but I don't expect to get that out of my 12ht, if by some miracle i do someday then that will be a bonus. What gets me is that figures don't really change much loaded or not. When I got this engine about 15,000km ago I tore it down and rebuilt the engine minus the injectors and the IP. The reason I didn't was that it allegedly had 161,000km (I know that it most definitely had been wound down although the engine looked to the contrary, looking really good on the inside)

What do you fellas recon? I'm thinking I'll put the pump in (Once I get the $$$ together) and maybe at the same time the cold morning starts can be corrected with the sensitive throttle as well as the fuelling or am I being too hopeful and wasting cash?

 

[darthvincor]

I don't even own an HJ61, and I'm a bit disappointed by those numbers. I hope to get a 12HT one day, that's why I look in on these threads.
And I too believed they got 10-11 litres per 100kms.

Maybe you can, if you drive granny style?

 

[goldchaser]

I reckon sum of these figures are pie in the sky or bad maths,ive never bothered to check mine but if you get 10-11 you are talking up around 700 klm? out of the
standard fuel tank,i just cant see that. I know i cant get say 600klms then have some in reserve before i refuel,fueling up this arv so ill see howi go this week.

 

[blis]

I don't even own an HJ61, and I'm a bit disappointed by those numbers. I hope to get a 12HT one day, that's why I look in on these threads.
And I too believed they got 10-11 litres per 100kms.

Maybe you can, if you drive granny style?

As said in my earlier post, at highway speeds (90-110km/h) you can push it under 11l/100km... If you drive a lot in the city and drive like a kid on his first car the consumption will be over 13l/100km... During my ownership I've found that driving style affects quite a lot on these engines (+-1l/100km atleast), With sensible driving 11-12l/100km shouldnt be a problem off the highway...

 

[mun60]

Just filled up, did 603 km and added 75 litres of diesel, I find my gauge reads just above 1/2 a tank at 300 km mark and when I hit 600 I fill up its on E for enough, for mine that's 75/6.03 = 12.4172185L/100 km, I think the 31's flatter the old girl a bit as I think the standard tyre is more like a 32 inch tyre. I drive this truck hard all the time and am quite happy with the performance and economy. Standard tank size is 90 odd litres so still 15 left, another 15 x 12.41 = 186 km left, seems like a good buffer to me. Not game to try it though!

 

[roscoFJ73]

What do you fellas recon? I'm thinking I'll put the pump in (Once I get the $$$ together) and maybe at the same time the cold morning starts can be corrected with the sensitive throttle as well as the fuelling or am I being too hopeful and wasting cash?

I asked a really experienced diesel pump mechanic about 12HT pumps a few years back and he said its rare that they need a rebuild and they should be good for 500000klms min.
He said most of those he had stripped down was to do the seals because they were leaking.

 

[Ivy4x4]

As said in my earlier post, at highway speeds (90-110km/h) you can push it under 11l/100km... If you drive a lot in the city and drive like a kid on his first car the consumption will be over 13l/100km... During my ownership I've found that driving style affects quite a lot on these engines (+-1l/100km atleast), With sensible driving 11-12l/100km shouldnt be a problem off the highway...

Mine's pretty well stock (2.5 inch ex is the only mod) does 80% Hwy 20% City driving and I can't get better than high 13's...... Don't worry I drive it like a granny and it still doesn't make a difference.... That's why I posted though, that way I can see if I can do better.

My main reason why I started this thread was that I saw carbon build up in the combustion chambers (not excessive but what I deem is too much for the km) when I put the injectors in to get done. It's only run about 15K since the engine was rebuilt and given my recent trip out west I was a little disappointed with the economy (Expecting 12 - 13 lt per 100 km)

darthvincor, I own my HJ61 for it's reliability not economy. I plan on traveling some remote areas of Aus so I don't want any breakdowns. Being mechanical and older becomes easier to work on if something does go wrong, well that's my logic anyway. In saying the above if I can pick up a saving of 2 lt per 100 km because it's not running at it's optimum I'm am going to chase that figure whatever it may be. You need to decide what you want from your vehicle, no point getting a 12ht if it's going to be a DD and you want economy, probably better to get something more economical.

 

[mun60]

When i got my 12 ht I bought it from Roma western qld and had to drive it 1000 km home to NQ. I really didn't no what to except, the old girl hit the 500 000 km mark about half way home and I honestly had expected about 15 litres / 100 km but was impressed with the 11.5 to 12.5 figured achieved on the way home. I did one long section on the way in the cool of the afternoon with the aircon off which I think achieved the 11.5.

 

[Ivy4x4]

I asked a really experienced diesel pump mechanic about 12HT pumps a few years back and he said its rare that they need a rebuild and they should be good for 500000klms min.
He said most of those he had stripped down was to do the seals because they were leaking.

Yeah, I thought the same Rosco.... Even Mr Toyota said so in the FSM, that's why I didn't put it in to be rebuilt originally but now I'm not too sure.

mun60, I'd love those figures. I dropped short on my way to WA, 5km out of Norseman be be exact . Luckily I had another 40 lt of diesel on board in Jerry's but thought I'd be right and have at least 100 k or 20 - 30 lts in reserve as per my calculations.

Actually here are the real figures (P.S I have a 173 lt tank) : 1235km... run out of diesel, now if I got 12 per 100 that would be 1435.9km out of the same tank (200.9km in reserve or 24 lt)

 

[tim753]

I have a 12HT in my 75 series troopy with H55F. Has steel bullbar, winch, aluminum roof basket. Engine gas 90k km since rebuild, 2.5 inch straight thru zaust and TD05 turbo at 14psi. I do 500kms on the hume freeway at least twice a month, sitting on 90km/h i get 12l/100 on the freeway, sitting on 110km/h i get 14l/100 over the same trip. Around town i get 14 whether I drive it hard or not, offroad low range doesnt really affect my average that much. Troopies are a lot less aerodynamic than 60s and mine isn't standard but 14L/100 is acceptable to me considering a mates 2H 60 gets 12L/100 and I have a bucket load more power