Outer Limits 4x4 Board

I originally wanted a 4.2 diesel GQ LWB(mainly for the better fuel economy on a trip).But what i`d like to know is

a)How do the 4.2 petrol & 3.0l petrol engines rate as far as both bush and highway is concerned?

b)I have looked at a 4.2p 5 speed on gas and wondered if they are better on fuel than the diesel.?

BASICALLY what im trying to get at is that i will have to keep whatever i get for a LONG time, so i want to be happy with what i have ,not regret it later thinking that i should have got this engine instead of that engine.Or even think that "o.k. i`ve got this amount of power but it chews fuel like there`s no tomorrow."

Sorry to annoy everyone about this but it is a big decision as i`m not in the position to keep changing vehicles because of a wrong decision.

Many thanks

CB0569 wrote:I originally wanted a 4.2 diesel GQ LWB(mainly for the better fuel economy on a trip).But what i`d like to know is

a)How do the 4.2 petrol & 3.0l petrol engines rate as far as both bush and highway is concerned?

b)I have looked at a 4.2p 5 speed on gas and wondered if they are better on fuel than the diesel.?

Many thanks

3.0 GQ is VL commodore motor - ok if you spend a fortune on it.
4.2 petrol averages 20l/100kms which is shit economy, but if thats no concern, go with it.
4.2 diesel good honest donk that will last 500,000klms if treated properly. Add turbo to make it a worthy contender. Averages 14l/100klms so shits all over the petrol

Apart from the TB42 being thirsty it is a good engine, and i've come across examples that have done well over 600,000kms without a rebuild. But I think you'll find as the government lowers the sulfur content in diesel from the pump there will become more and more issues with the TD42 fuel pump. Thus resulting in an expensive exercise in the long run.

The RB30 is just plain Grimace for a truck that size and it it was up to me i'd still go the TD42 but keep a good eye on the condition of it and the service intervals

TD42 all the way as well..

cant beat reliablity.. just gotta watch the fuel over time..

TOM

GQ wrote:TD42 all the way as well..

cant beat reliablity.. just gotta watch the fuel over time..

TOM

you havent even finished installing the engine properly to be able to drive it

hottiemonster wrote:

GQ wrote:TD42 all the way as well..

cant beat reliablity.. just gotta watch the fuel over time..

TOM

you havent even finished installing the engine properly to be able to drive it

Shush!!!

Now you've spoiled my motivation.. ... you said it.. so u come up and finish it off for me....

Tb 4.2 on gas are cheaper to run than the diesles and you dont have to worry about the fuel pump and or expensive rebuilds.The 3 litre and 2.8 litre motors come with a shit weak gearbox and if I am right to change a clutch on the three and or 2.8 litres it will cost upto $2000 bucks.It also depends on what sort off trips you are going to be taking.

I reckon the piece of mind that comes with the TD42 in knowing that there is no reason you shouldnt get 500000km + if you do the basic maintenance.Also fuel availability.As people say no rocket sip but you know you will get there and back 10 times if you want

If you want power, reliability & strength TB42
If you want economy, reliability & strength TD42
In between, Turbo a TD42
If you're a power fruitcake and own a servo, turbo a TB42

2.8 & 3 litre have weaker gearboxes too.

My TB42 gets 100km out of 14.5 litres of petrol, highway driving, as measured the very day I bought it and drove it from Sydney to Brisbane.

I've never worked it out for stop/start driving but I'd be willing to believe it's a fair bit worse, 20L/100km sounds plausible. But I also reckon there are some badly maintained TB42s that are getting worse economy than they should.

If I'd had the choice of a TB42 or a turboed diesel for the same price, I would have bought the turbo diesel. But they are a long way from being the same price. The normally aspirated diesel is a bit of a slug; I probably wouldn't have bought one of those at any price to be honest.

Anyway, V8 conversion is probably not too far off

Jason

Never owned a petrol 4wd so can't comment.
My TD42 has just ticked over 530,000k's on the original engine.
Only thing I've had problems with has been the starter and have had the injector pump reco'd once.
Other than that has been great.
Can be a bit thirsty but that comes down to how its driven.

myself i have the 4.2L petral and it drinks powers ok not any probs as yet sep for the radiator and still on the orig motor as well far as i know it over 200,000 some where the kms stop working a long while ago

stick to the td42 just my opinon

i have a tb42 with 35's and do about 500 kays a week of mainly windy open road. 22litres per 100kays is a killer. just put it on straight gas and its better but dont put your foot down . should have ditched the petty and put a diesel in it when the head went the first time. or the second time.

i always have this argument with mates. if you were buying a new gu, you would get a turbo deisel (factory or aftermarket) even if its just for the resale. as the purpose of the vehicle is usually different - few brand spankers competeing compared to gq's

but for a roughly 92 gq
a gq with a tb costs $8000 to $10000
a gq with a td costs $13000 to $16000

$5000 difference buys at least 5000 litres of fuel or 30 - 40 000 klms worth. for free effectively. as you still have to put 1/2 to2/3 (petrol eqivalent) in you diesel.

so it takes 100 000 to 130 000klms to break even. then you put up with the lack of power in the diesel.

the petrol is~125kw, diesel ~85. the peak torque of the petty is higher as well as the improved drivability due to higher rev range and reduced gear changes.

this is before you talk deisel servicing costs, injector pump failures, getting the inj's done. then a turbo to bring it to close to petrol power (and fuel consumption) is another $3000.

why people like gq deisels so much i will never know.

my 2 cents

cheers

bru

Have had both a TB42 in a shorty and a TD42 in a LWB. Granted the shorty had more get up and go but no matter how hard i tried i could never get it fully waterproofed, as in drive through water and it would die in the ass. i can now leave the diesel swimming and running smooth while i unhook the winch and tie it to a tree and so on. plus i can also drive into the bush and not have to worry about stupid stuff like dirt in the alternator, condensors and points failing and so on making the petrol pretty much a tow home job.
Want Total Peice of mind, average power and economy go diesel.
Want power, shit economy and the worry of breaking down due to stupid electrical or LPG faults buy a Petrol

There's nothing wrong with the 3ltr RB30 engined patrol's although they are gutless standard.

A freind has one and he fitted it up with a refreshened 0-ringed VL Turbo engine with largish aftermarket ball bearing turbocharger thats good for up to 700hp, external wastegate, aftermarket engine management,injectors, fuel pump, big kenworth intercooler etc..

He took out the original distributor out and fitted in a fully sealed up dummy assembly and ran the crank angle sensor pickup off somewhere down near the front of the crankshaft.

He now runs multi coilpacks tucked right up under the dash and the computers inside tucked away aswell.

Makes 250rwkw(around 350hp at the rear wheels) on 21psi boost and has no problems spinning up a set of 35 boggers on the tarmac without having to jerk the clutch at all.
He just has to cruise off slowly but then when it hits boost there up in smoke.

Yet he has some sort of switch in it that he flicks and boost drops down to about 10psi and its super economical although still plenty fast.
Fast as in it has no problems whatsoever going off the 180kmh mark on just 10psi and probly would get to if not go over 200kmh without breaking a sweat.

Only problem he encountered was clutch's slipping although he has a custom clutch of some sort now and hasnt had a problem since.

Has done a good 50000 k's on this setup in both rugged bush and road and go's as deep as over the bonnet under water with it and has never had it die.not once(has snorkle of course).

He has spoken to castlemaine rod shop about getting an adaptor housing to mount up the TB42 gearbox to the 3ltr engine and is going to purchase a conversion kit he said coz if this gearbox ever stuffs up he is going to put the larger gearbox in it.

Joe

Joe Dirt wrote:There's nothing wrong with the 3ltr RB30 engined patrol's although they are gutless standard.

A freind has one and he fitted it up with a refreshened 0-ringed VL Turbo engine with largish aftermarket ball bearing turbocharger thats good for up to 700hp, external wastegate, aftermarket engine management,injectors, fuel pump, big kenworth intercooler etc..

He took out the original distributor out and fitted in a fully sealed up dummy assembly and ran the crank angle sensor pickup off somewhere down near the front of the crankshaft.

He now runs multi coilpacks tucked right up under the dash and the computers inside tucked away aswell.

Makes 250rwkw(around 350hp at the rear wheels) on 21psi boost and has no problems spinning up a set of 35 boggers on the tarmac without having to jerk the clutch at all.
He just has to cruise off slowly but then when it hits boost there up in smoke.

Yet he has some sort of switch in it that he flicks and boost drops down to about 10psi and its super economical although still plenty fast.
Fast as in it has no problems whatsoever going off the 180kmh mark on just 10psi and probly would get to if not go over 200kmh without breaking a sweat.

Only problem he encountered was clutch's slipping although he has a custom clutch of some sort now and hasnt had a problem since.

Has done a good 50000 k's on this setup in both rugged bush and road and go's as deep as over the bonnet under water with it and has never had it die.not once(has snorkle of course).

He has spoken to castlemaine rod shop about getting an adaptor housing to mount up the TB42 gearbox to the 3ltr engine and is going to purchase a conversion kit he said coz if this gearbox ever stuffs up he is going to put the larger gearbox in it.

Joe

Fun, but how well does it crawl under 800rpm?
21psi boost in a petrol?

bru21 wrote:i always have this argument with mates. if you were buying a new gu, you would get a turbo deisel (factory or aftermarket) even if its just for the resale. as the purpose of the vehicle is usually different - few brand spankers competeing compared to gq's

but for a roughly 92 gq
a gq with a tb costs $8000 to $10000
a gq with a td costs $13000 to $16000

$5000 difference buys at least 5000 litres of fuel or 30 - 40 000 klms worth. for free effectively. as you still have to put 1/2 to2/3 (petrol eqivalent) in you diesel.

so it takes 100 000 to 130 000klms to break even. then you put up with the lack of power in the diesel.

the petrol is~125kw, diesel ~85. the peak torque of the petty is higher as well as the improved drivability due to higher rev range and reduced gear changes.

this is before you talk deisel servicing costs, injector pump failures, getting the inj's done. then a turbo to bring it to close to petrol power (and fuel consumption) is another $3000.

why people like gq deisels so much i will never know.

my 2 cents

cheers

bru

I second that and add my 2 cents . gas is 32 cents and diesel is 1.05. ouch......

Ill third that Ive got 2 GQ petrols on Gas..... Best I get is 20 litres per 100k's, but with LPG at 32 cents, thats $6.40 !! and I do 600k's per week in mine.
Only thing is im not sure about the power aspect... the auto pretty much sucks all the power out of it

I would have to agree with bru21 also. I have a turbo intercooled diesel and while it goes very well there are very large drawbacks. one major one is rebuild maintenence costs. I just don't see diesels being cheeper anymore with the price at the pump being so high. (it is different if you are a primary producer and get tax rebate etc) And if anything goes wrong there are major costs involved. Just look at the guys rebuilding (to a standard level too) 4.2s on this forum. By the time they are finished it will still cost a shit load of $ and that is with no major mods!

I would love more power but to get it from the diesel you sacrifice so much like reliability and longevity which is why you put up with a diesel in the first place. Not to mention costs, and I have a dislike for pumping black smoke into the atmosphere. They really do suck a lot of juice to when you are into them.

I do love diesels but I am seriously thinking of ripping my motor out now while it is in good nick and putting in a petrol. I would no doubt get very good money for it too.

I am not sure what to replace it with yet.

I have huge respect for those that get major ponies from diesels and I love the sound of a higly moded turbo diesel but I just cant afford to play with em!!! lol They have advantages sure but it is not the same as it has been in the past.

Just my 2c

[/quote]

Fun, but how well does it crawl under 800rpm?
21psi boost in a petrol?[/quote]


Crawling under 800rpm in low range is no problems at all.

Idles smoothly on about 600rpm and will crawl just fine.

Whats wrong you sound shocked about a 6cyl petrol running 21psi???

Take a look on the net at some of VL Commodore's running these engine's, they are pushing 40+psi and 800+HP without problems so 21psi aint really nothing for a well prepped engine.Well in a RB30 3ltr anyway.


Joe

I'd say petrol 4.2 as rebuilds and original purchase price on a diesel is way too high.



As far as the RB30 Turbo goes, anything pumping that much power out is gonna have a decent output down low too, so long as it's set up properly. These are new school Turbo technology and not like the laggy old 6-14psi things of the past.

Don't worry, I've suggested dumping the old MQ 88kw L28 for a 160kw RB20 Turbo before and people have responded the same way....

Twice the power means way more power everywhere, not just for a 10 rpm peak.

Joe Dirt wrote:

Fun, but how well does it crawl under 800rpm?
21psi boost in a petrol?[/quote]


Crawling under 800rpm in low range is no problems at all.

Idles smoothly on about 600rpm and will crawl just fine.

Whats wrong you sound shocked about a 6cyl petrol running 21psi???

Take a look on the net at some of VL Commodore's running these engine's, they are pushing 40+psi and 800+HP without problems so 21psi aint really nothing for a well prepped engine.Well in a RB30 3ltr anyway.


Joe[/quote]

I am impressed as the stock 3.0 is gutless down low compared to a stock TB42 and wouldn't have thought a turbo would come on song under idle in rockcrawling conditions. I might turbo my next rebuilt TB42 after all, I am also surprised as AFAIK 20psi is pretty high for even a stock diesel engine to handle. You may run higher but your motor is also not stock, the same money spent on another type motor could also reap large performance increases.

The other thing to consider is if we are expanding to non-standard engines that still bolt in, it would be interesting to compare turbocharged modified TB42's & TB45's & supercharged V8's if anyone has any info.

I realise turbo's are good for certain applications, but also suspect engines of smaller displacement pushed close to limits of their outputs will not survive as long as larger similar or lesser modified engines doing the same job for the long term.

For non-stock engines that bolt in the RB series rock as an L series engine replacement as they bolt up to the normal L series Bellhousing with virtually 0 mods. The engine mounts need to move like 25mm back or so....

That's for a streetcar and I assume the bellhousing for the Patrol L28 is the same bolt pattern as an L28 Skyline or similar... (never bothered checking before).

As far as pushed to the limit 220kw (rear wheel) is more like the limit of an RB20DET without major major expense and then you probably should start again with a RB25DET, 30ET & or even a RB26DETT

For RB30ET... there is NO real limit..... the current drag versions are like 1200hp... same with the RB26DETT (but at insane revs like 11,000 rpm and 40PSI).

In the end capacity is really about how much air and fuel you can get into your cylinders, not how big your crankshaft is.....

If you think about it this way there is no reason why a tricked up ballbearing turbo RB20DET isn't gonna whump a carby Tb42 for torque at idle speed.

My mav had

Phase 1 gas/petrol when i bought it - pain in the arse tuning it for duel fuel, had a miss under load, had to carry more jerry can across the desert, gutless on gas and although cheaper than then petrol when you work out how much upper cylinder head lube it supposed to be getting it didn't seem to work out that cheap (to me anyway), stuffed the carby plus power reduction on gas (i'll stop there)

Phase 2 Petrol only - better, but still thirsty and gutless for the size engine. Put extractors, electronic ignition, k&n filter snorkel, 4.3 diffs hmmm little better but still unimpressed.

Drive a mates gq TD42 Turbo with 1000 foot per pound & 150 horsepower at the rear wheels WOH!

Phase 3 Diesel conversion & turbo very very shortly.

Diesel may be dearer but better economy and I like the reliability.

Diesel all the way - in a gq anyway

The Pajero on the other hand...................

Suzuki Viagra wrote:For non-stock engines that bolt in the RB series rock as an L series engine replacement as they bolt up to the normal L series Bellhousing with virtually 0 mods. The engine mounts need to move like 25mm back or so....

That's for a streetcar and I assume the bellhousing for the Patrol L28 is the same bolt pattern as an L28 Skyline or similar... (never bothered checking before).

As far as pushed to the limit 220kw (rear wheel) is more like the limit of an RB20DET without major major expense and then you probably should start again with a RB25DET, 30ET & or even a RB26DETT

For RB30ET... there is NO real limit..... the current drag versions are like 1200hp... same with the RB26DETT (but at insane revs like 11,000 rpm and 40PSI).

In the end capacity is really about how much air and fuel you can get into your cylinders, not how big your crankshaft is.....

If you think about it this way there is no reason why a tricked up ballbearing turbo RB20DET isn't gonna whump a carby Tb42 for torque at idle speed.

I realise this but how would it go against a tricked ballbearing turbo TB42, to compare apples to apples. The size of the crankshaft is important otherwise a turbo 1 litre engine would kick a RB30's arse

The downfall is the TB42 turbo wouldnt like to rev hard..ie..4500-5000rpm tops.Also there's not much good aftermarket gear for them such as heavy duty steel rod's, off the shelf forged piston's..etc

With the smaller engines like the shorter stroke RB30 you have all that sort of stuff off the shelve's and they have no problems being spun to 7000+rpm all day long on 20psi and in many applications higher boost level's.

The even shorter stroke RB26 head your looking at 8-9000rpm in stock factory form and some very highly modded one's go as high as 12-13000rpm and 1400+hp.


Joe

Exactly... too much weight in metal to spin that hard.

It used to be common in drag circles to use RB30 cranks in RB26DETT's, but the extra weight of the crank even after a lot of work to lighten and balance it dropped the sustainable rev limit down a few thousand revs.

in the end the extra capacity was losing them power rather than gaining it, and costing more money to do so....

But it is that very weight that gives you gobs of torque.

The torquest(?) motors never spin hard ever. Look at big blocks etc.

For 4wd, cubes and torque for me everyday over a high reving power monster.

My Toyota V8 conversion should be ready in a couple of weeks...will post details then.

I was looking for a modern reliable, economic, EFI and V8 (always wanted a V8) after a petrol/gas TB42.

I would also have liked a diesel but could not justify the cost. Had diesels before and cost me a fortune to repair, I am not in the motor industry...

I was unhappy with the TB42 power on gas/petrol and cold weather starts - this is a daily driver for me. Averaged 20-22L/100km. Cost of gas is also getting rediculous - I have seen it over 50c in Brisbane, more up north.

The Toyota 1UZ-FE was a lot cheaper than a Holden/Chev (for me, a non-mechanic) and the fitting costs were not unrealistic.

This motor gets 9L/100 highway in a Lexus, I am looking at maybe 14L/100 in the GQ shorty.
Weighs 79Kg less, has around 75Kw more power and 80Nm more torque (at engine)
I am not doing this for bulk power but these engines can be worked heavily as they are very strong. Toyota (TRD) make a supercharger for it...

Will look at making the electrics as waterproof as possible as I want to do a lot of touring, Cape York, etc.
Cant wait to see how it goes...