80 series fuel economy

My father-in-laws 4.2 petrol GQ Patrol gets around 5.5 km/L on the highway. My 3 litre petrol does slightly better, but I think that's due to extractors and 2.5 inch free flow exhaust. I fitted a hiclone and didn't notice a change in economy although it did boost top end power (tested before the exhaust mods).

Damien,

The fuel usage (for gas) is about right – nobody would ever call one of these Tojo engines fuel misers!

As you have noticed, the controversy rages around the use of Hiclones with some people getting good returns from it while others seem to get nothing out of it. I would expect that a sophisticated engine like you 4.5 six would not give you any significant improvement from the fitment of a Hiclone, but I am more than willing to be proved wrong.

One thing you should be aware of is that the 4.5 six cylinder engine will have its life (or at least the life of its cylinder head) reduced to the 300,000 klm mark through the use of LPG. If you are getting close to that mark then you should budget for some expensive work soon!

Damian, that fuel economy sounds about right. It's equivalent to 20.8l/100 or 13.6mpg. You might expect a little better from petrol. I had an FJ55 years ago and around town got 12 mpg and the very best on the highway was 16mpg. The only good thing about it is you'll find it won't vary a whole lot if you have more than you in it!! or even a trailer on the back. Also just a word of warning if you ever intend to do any outback travel - gas can be very scarce - you'll need lots of jerries for long distance outback travel!
Enjoy!

Damian, that fuel economy sounds about right. It's equivalent to 20.8l/100 or 13.6mpg. You might expect a little better from petrol. I had an FJ55 years ago and around town got 12 mpg and the very best on the highway was 16mpg. The only good thing about it is you'll find it won't vary a whole lot if you have more than you in it!! or even a trailer on the back. Also just a word of warning if you ever intend to do any outback travel - gas can be very scarce - you'll need lots of jerries for long distance outback travel!
Enjoy!

Damien if fuel economy is important to you I think you've got the wrong vehicle (sorry to be blunt!!) The 80 series are great vehicles but economical on fuel they ain't. The mid size 4wd market is the place to look. The Prado is the best - better performance than the 80 series and half the fuel - expect 9km/litre at least. Probably the only one to avoid is the Pajero as it is quite heavy on fuel.
Cheers
Bob

Damian,
I have a 93 75 series Troopie 4.5lt petrol/gas, its not a aerodynamic as an 80 series. It returns 4.6km/ltr on gas and 5.6km/ltr on petrol (premium).

I have have installed Hiclones in two other previous vehicles that I've had, did not notice any difference in the performance of the vehicle or the pocket.

Damian, I had a 93 80 series running dual fuel (petrol/LPG) until just recently, however it had an arguement with a 4 tonne tip truck and lost. T give you some of my experience, I was getting about 23L/100k on gas and around 18-20 L/100K on petrol. When you consider that to fit the gas tank (115L with 92L usable @ 80% fill) the sub tank has to come out to make way, that you then end up with only a 90L fuel tank. This severly diminishes your range to about 400K on gas and arounr 400 - 450K on petrol.
Someone else replied that you will be up for some expensive repairs to the head around 300k. I can vouch for that. It cost me $1500 and thats at mates rates to get the head refurbished. I also had a Hiclone fitted and would have to say that it was as useless as tits on a bull. I loved the power that it had but I have to say that I am happeir with my Turbo Diesel that I replaced the vehicle with.
Anyway, thats my reply. Hope it is of some help. Happy 4WDing, and see ya in the bush.

Damian that's terrible economy!!! less than 14mpg. With a modern engine or diesel you can get MUCH better than that!!!