Patrol Dilemma

Submitted: Wednesday, Mar 12, 2008 at 13:59
ThreadID: 55473 Views:3329 Replies:9 FollowUps:20
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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
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Reply By: Michael ( Moss Vale NSW) - Wednesday, Mar 12, 2008 at 14:12

Wednesday, Mar 12, 2008 at 14:12
What about a proper tune with one of the good diesel guys, it really makes a hell of a difference. Poor spray pattern from the injectors and incorrect timing will change a diesels performance for the worst and then you put your foot into it to get it to go reasonably, using more fuel. I dont mean take it to your Nissan dealer, they couldnt tune a lawn edger!!! Michael
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Follow Up By: palmy - Wednesday, Mar 12, 2008 at 14:21

Wednesday, Mar 12, 2008 at 14:21
Hmmm interesting thought. It's only 78000 so is getting close to a major service. Would it still be required with such low kays? Although never had a 'tune up' it has been well serviced every 5000kms. It does seem like its been getting slower and fuel consumption higher but Ive put that down to the modifications: suspension lift, bigger tyres, roof racks etc....
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Follow Up By: Member - Roachie (SA) - Wednesday, Mar 12, 2008 at 16:29

Wednesday, Mar 12, 2008 at 16:29
I had my 2000GU done by the mob at Berrima when it only had 20,000klm on the clock.........it made a huge difference. There is a hill which leads you off the main Hume Freeway, up into Berrima. I lived at Yass at the time and had to go up that hill to get there on the day of the tune-up. Even having a running start at it, after having gone under the underpass to leave the freeway, I was back to 3rd gear by the time I got to the top of that hill.
They had the truck for the day and when i went to collect it, the older bloke got me to take it for a drive with him in the passenger's seat. We went back down that longish hill to where the underpass is. I did a U turn down the bottom and started back up the hill from virtually a standing start. By the time I got to the top of the hill I was in 4th gear and just about to select 5th. They made THAT MUCH DIFFERENCE!!!! They did the injectors (spray pattern etc), pump timing and calibration and fitted a CAV fuel filter adaptor. They also took out the oiled-up Uni-filter (air filter) and replaced with a paper unit, advising me to steer clear of the Uni-filter in future.

Cost me about $800- from memory; money well spent
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Follow Up By: palmy - Wednesday, Mar 12, 2008 at 16:35

Wednesday, Mar 12, 2008 at 16:35
Wow! Thanks Roachie, that's certainly interesting. I can't believe they're so bad from the factory? That's amazing.

Any recommendations for somewhere in Adelaide? I live in Mt Barker.
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Follow Up By: Member - Roachie (SA) - Wednesday, Mar 12, 2008 at 18:31

Wednesday, Mar 12, 2008 at 18:31
Yep, I had mine done by HiTech Diesel in (I think) Churchill Road a few years after the tune up I mentioned above. I didn't get the same sort of benefit increase that Berrima gave though.

Also, if you fancy a drive to the Riverland, check out the blokes at Berri Diesel Service; they know their craft too and have the dust-free (spotless) workshop required to do a proper job. They also install lots of Patrols with a bigger turbo and exhaust combination.

I should add that my 4.2TD (when I had it) was never very frugal on fuel. Average over the whole 200,000klm I clocked up on it was about 15 l/100km.....but I did have a heavy ARB full-length roof rack, heavy steel rear bar with 2 spares, steel winch bar and winch up front etc etc.....she weighed 3 tonne minimum.

Cheers

Roachie
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Follow Up By: Michael ( Moss Vale NSW) - Wednesday, Mar 12, 2008 at 19:58

Wednesday, Mar 12, 2008 at 19:58
Thats their testing hill Roachie!! I know it well.. Michael
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Follow Up By: Member - Duncs - Wednesday, Mar 12, 2008 at 22:50

Wednesday, Mar 12, 2008 at 22:50
The guys Roachie is talking about in the Southern Highlands have done great work on two of my cars. The GU is due its second trip down there now.

They told me the story of the Nissan production line. 1 big bin full of injectors beside the line, as the motor comes along the injectors are randomly selected from the bin and fitted to the motor. That is the total of the tune up. The tolerance on the factory setting for injector opening pressure is + or - 40psi so there could be as much as 80psi difference in the injectors. I got an extra 150km at least from a tank of fuel after a visit to the tuner.

Even now I get mid 14's around town.

Duncs
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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.
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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
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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.
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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.

Robin Miller

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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?
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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.












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Reply By: desert - Wednesday, Mar 12, 2008 at 15:56

Wednesday, Mar 12, 2008 at 15:56
Giday Mark. If you intend staying with a 33 inch tyre/wheel combo, then the fitment of 4.3's will return gearing/revs to somehere near stock.The fitment of a 2.5" madrel bent exhaust will make ahuge improvement in throttle response, power and improve fuel economy, esp. if you can return the revs/power band back to where it should be with the use of the 4.3's. There is bugger all to be gained by going to a 3" exhaust,over a 2.5 exhaust unless you are running boosts of 12psi or more. They are very heavy and much more expense and troublesome to route. Having said that, fuel consumption levels are never going to be much better than 14's per hundred. However, horsepower levels will be much improved with the above mods.
Cheers.
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Follow Up By: palmy - Wednesday, Mar 12, 2008 at 16:10

Wednesday, Mar 12, 2008 at 16:10
Thanks Desert. So your thinking regarding the ratio change is the same as mine, i.e. will get the vehicle's gearing back to standard. Interesting reading regarding only putting a 2.5" exhaust on. I'd certainly be happier to spend less if I can...! :)

I guess I'd really be happy to get back to low 13s or high 12s and would then accept the fact that it'd go back up when towing a camper trailer but at least I'd have to power to over take when needed. I just think at the moment if I bought a camper, a. I'd have trouble on steep hills, and b. I'd be close to 16-17lts!! Might as well have bought a 4.8 if that was the case.. :)
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Follow Up By: desert - Wednesday, Mar 12, 2008 at 16:48

Wednesday, Mar 12, 2008 at 16:48
Well Palmy, only you know the answer to that question. You'll have to crunch the numbers on 4.8 vs 4.2 consumptions. The whole question of petrol versus diesel is a giant can of worms and intends entirely on your intended driving environment. Whatever worm you pull out of the tin, will not catch the same fish for the next fisherman!

Free pearl of wisdom there........!

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Follow Up By: Member - Davoe (Yalgoo) - Wednesday, Mar 12, 2008 at 17:40

Wednesday, Mar 12, 2008 at 17:40
Palmy I see alot of stuff on the net relating to fuel consumption - - - then you can speak face to face with users or see it for yourself.
trust me get a big 6 (toyota or nissan) petrol and you will be back on here in 6 months asking why you cant get under 20l perhundred when others claim better and why you need to tow a fuel station around as well if towing
Always take consumption figures on the internet with a grain of salt even if genuine they would often have been achieved once in ideal conditions
- Human nature no one wants to remember let alone print the trip from hell when they ran out short after copinfg a head wind uphill and used over 35l per hundred
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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.
I used to have a handle on life, but it broke.

Cheers Dodg.

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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.
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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...
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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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Reply By: Crackles - Wednesday, Mar 12, 2008 at 18:22

Wednesday, Mar 12, 2008 at 18:22
Speak with Darren at ATS in Geelong. He's done a few mods to the 4.2TD Pootrol with oversized tyres & has come away with both excellent consumption & power figures.
Cheers Craig.......
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Reply By: 96 GXL 80 series - Wednesday, Mar 12, 2008 at 19:59

Wednesday, Mar 12, 2008 at 19:59
4.3 ratio is lower than 3.9 so you will be revving like hell and going nowhere.

You should be looking at 3.25 or there a bouts.

Here are some examples of what to expect

4.3 X 100k's = 4300rpm
3.9 X 100k's = 3900rpm
3.25 X 100k's = 3250rpm
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Follow Up By: palmy - Wednesday, Mar 12, 2008 at 20:26

Wednesday, Mar 12, 2008 at 20:26
3.25??

The problem I've got is since the bigger tyres it's harder to get off the line and keep accelerating. 3.25 will make it worse.

I'm thinking that the change to 4.3 will get it as close as I can back to factory specs: 3.9s and 265/70 tyre combo.
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Follow Up By: Member - John - Wednesday, Mar 12, 2008 at 20:54

Wednesday, Mar 12, 2008 at 20:54
3.25's, no such animal for Nissans.
John

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Follow Up By: 96 GXL 80 series - Wednesday, Mar 12, 2008 at 21:42

Wednesday, Mar 12, 2008 at 21:42
I was only using it as an example of the difference in ratio's
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Reply By: palmy - Wednesday, Mar 12, 2008 at 20:30

Wednesday, Mar 12, 2008 at 20:30
Thanks everyone btw... This is all very useful. I'm now leaning towards the the tune-up with a new exhaust.

Still, has anyone out there actually re-geared to suit 33s? I'd just be curious to see what the end result is actually like.

Thanks again,
Mark
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Reply By: Member - John - Wednesday, Mar 12, 2008 at 21:00

Wednesday, Mar 12, 2008 at 21:00
Mark, have a GU 4.2 TD I/cooled, running 285/75/16 and have changed from 3.9's to 4.3 diff ratios, soooooooooo, much better. They can be bought cheapish from Brunswick Diesels in WA. I also have the 3" exhaust and dump pipe and the MTQ turbo mods, bigger wheels both ends. Also have the Marks 4WD o/d fifth gear, at 100 ks, doing 2000 rpm, have to change back to 4th at times or pre empt the hills, but it is a much better truck than with the standard set up and 3.9's. If you are in Melbourne, you can take mine for a drive if you wish. John
John

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Follow Up By: palmy - Wednesday, Mar 12, 2008 at 21:12

Wednesday, Mar 12, 2008 at 21:12
Thanks John, that is a very generous offer! I live in Adelaide though, so won't be able to take you up on it!

So you're happy with the change then by the sound of it? :) Did you change them yourself? I'd still like to pull the diffs out myself if not too difficult. Between Dad and me I think we can do it, unless there's any special tools required.

Didn't know about the o/d fifth that is available, certainly sounds like a nice change, but I would think it would require the other mods you've done as well.

Any fuel figures?

Thanks, Mark
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