Patrol Dilemma
Submitted: Wednesday, Mar 12, 2008 at 13:59
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palmy
Hi all,
Firstly, I've searched and searched and searched some more but can't find what I'm after, although don't seem to be alone with my dilemma.
I have a 4.2TD GU (intercooler model) with 3.9 ratios and 285/75R16 tyres. I really am un-happy with current fuel consumption (high 14s but usual 15-16lt/100km with roof racks and gear on top) and general sluggish nature. The way I see it is I can do one (or combination) of the below options:
1. Go back to 265/75 which I don't really want to do.
2. Change ratios to 4.3 which would certainly help performance and low range and I believe would help with fuel consumption. Am I correct?
3. 3" exhaust, fuel pump mods etc to get some better performance from it.
Ultimately I'd like to do options 2 and 3 but initally I can only afford to do one or the other. I really am leaning towards changing ratios which would also mean less cluth slipping, especially when towing (eventually we'd also like to buy a camper trailer).
I'm after advice from people in the same situation and what they've done, and in what order.... :)
Thank guys.
Mark
Reply By: Truckster (Vic) - Wednesday, Mar 12, 2008 at 14:31
Wednesday, Mar 12, 2008 at 14:31
What fuel consumption are you after from a fully loaded 3+ ton GU with the parachute on the roof?
14s are not uncommon.
Remove the rack and crap when ever you can.
Mine lives in shed until Im travelling.
Anyway down to the 3 options...
Option 1: No real need to as you said.
Option 2: not a bad idea, but can be fairly expensive - $1000+ per end. If you do this, work out of you want lockers, cause now is the time to fit them while its all apart.. saves the fitting costs.
Option 3: Probably
where to start, along with a dynotune and gettin the fuel/pump timing mods done. Which will help with everything, for round 1/2 the price of getting the diffs touched.
Anyway, start with a tune, then see what you think.
AnswerID:
292325
Follow Up By: palmy - Wednesday, Mar 12, 2008 at 14:38
Wednesday, Mar 12, 2008 at 14:38
Thanks. High 14s are without roof rack etc. I only put that on when travelling with oztent and gear... With all that it's easily high 15s to 16s.
Regarding option 2. I already have a rear air locker, and at this stage not too interested in a front locker. But was thinking if I can find some 2nd hand 4.3s and remove the diffs myself and get a mechanic to change to gears over, I was hoping to get that for around the $1000 mark.
thanks again,
Mark
FollowupID:
557680
Follow Up By: palmy - Wednesday, Mar 12, 2008 at 14:39
Wednesday, Mar 12, 2008 at 14:39
Should also mention I've got the speedo accurate by fitting a correction kit from Mark's 4wd adapters and calibrated it against the GPS.
FollowupID:
557681
Reply By: Robin Miller - Wednesday, Mar 12, 2008 at 15:41
Wednesday, Mar 12, 2008 at 15:41
Geez Mark
My 4800 does 16-17lt/100km and is literally twice as fast to 100kmh.
I'm with the others here as my mates have done the big exhaust and tune up mods and it has worked
well provided you can live with some extra noise.
In standard runs (100kmh) they achieve around 12lt/100km
I have put down 1500km on a trip averaging 11.7 lt/100km in a standard one.
The 4.3 ratio will make consumption worse.
I'd personnaly ditch the 285/75 and go for 255/85/16 when the time comes.
AnswerID:
292333
Follow Up By: palmy - Wednesday, Mar 12, 2008 at 16:05
Wednesday, Mar 12, 2008 at 16:05
Hi Robin, thanks.
You say 12lts/100km? Was that with the big exhaust and tune up? Does that also include the bigger tyres, and a
suspension lift? I'd be very happy with 12s as I was getting 11-12s when it was stock standard.
So why 255/85R16? Interesting size.... And why would 4.3 make my consumption worse?
FollowupID:
557689
Follow Up By: Robin Miller - Wednesday, Mar 12, 2008 at 18:49
Wednesday, Mar 12, 2008 at 18:49
Hi Mark
The big exhaust and tune up won't make you cars fuel use worse or better if done correctly.
The driver is the biggest factor here.
Some though ask for max power tune ups which uses more juice.
With
suspension - no real change.
With fatter as opposed to taller tyres generally they use more fuel.
This doesn't need to be as tyre pressure is biggest factor in fuel use, and to elminate the micro-bending in a fat tyre requires high pressure and a harder than necessary ride.
Tyre size is always a trade off of factors I guess, 255/85/16 is a size that I believe is optimum for most big touring wagons particularly underpowered ones like the Patrol diesels.
There is not the range though that there is in 285's but the trade offs of slighter more ground clearance with less drag and lower unsprung weight combined with optimum traction from the available engine power make them worthwhile.
4.3 diffs = more fuel than 3.9 this is because as a general statement over the average useage pattern engine friction is a major cause of fuel consumption.
FollowupID:
557733
Reply By: Member -Dodger - Wednesday, Mar 12, 2008 at 16:46
Wednesday, Mar 12, 2008 at 16:46
Mark,
I have a 4.2td Gu Patrol the non intercooled job.
I was dissapointed with the factory performance and had the stage 2 upgrade done by Motsons.
Link.
It certainly made a big difference to the performance of the vehicle, most notably when under load. I tow a 16ft off road pop top weighing 2.8t Fully loaded plus the Nissan is also fully loaded see
pic below.
My fuel figures are after 7 years of travelling and other motoring for good or bad.
Without van and roof rack but still partially loaded = 13.97 L/100
Van attached and fully loaded average speed 95k = 18.93 L/100
However this is with 265/75 BFG.
AnswerID:
292339
Follow Up By: desert - Wednesday, Mar 12, 2008 at 16:57
Wednesday, Mar 12, 2008 at 16:57
Yes, I concur with those figures.They reflect pretty much what I get. My next mod will be to have the turbine wheels exchanged and the turbo housing machined to accept them, all to aid in pushing more air into the engine which means more fuel can be added therefore more power..... and on it goes. Curious that the GU with the basic 4.2TD engine has never acheived the same fuel economy as the GQ, using essentially the same engine. I guess it all boils down to mass which has to be motivated, and the GU is no light weight. My ST Cab-chassis weighs in at a healthy 2.5 tonne EMPTY. No load, no fuel, no nothing.
FollowupID:
557704
Follow Up By: palmy - Wednesday, Mar 12, 2008 at 17:01
Wednesday, Mar 12, 2008 at 17:01
Yeah it is interesting... GQs do seem a lot better on fuel. Maybe I'll just look at the exhaust and fuel pump/injectors before doing anything else...
FollowupID:
557707
Follow Up By: Member - Duncs - Wednesday, Mar 12, 2008 at 22:58
Wednesday, Mar 12, 2008 at 22:58
The GQ in standard trim is nearly .25 of a ton lighter than the GU
Duncs
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