Which Engne to replace a worn out 4.5 petrol

Hi guys,
I am looking at replacing the engine in my 99 Gu wagon, it currently has a 4.5 petrol in it but the motor is on its way out.
It is set up for dual fuel and i mostly run it on gas but the fuel consumption is still rediculously high.
On gas i use around 23lt per 100 kms
On Petrol i use around 30lt per 100 kms

It is my work and play car which i drive every day and tow a work trailer which loaded weighs around 800-900 kgs.

On the weekends i either tow a boat weighing around 1.5 tonnes or a caravan that weighs around 3 tonnes, towing either one i go backwards on any incline.
I dont want to sell the car and buy another one because i have it set up just how i want it.

I am not sure whether to replace the engine wth a rebuilt 4.5 or to put an ls1 into it, i know the ls1 conversion will cost another 5k minimum on top of the price of a 4.5ltr but the fuel consumption will make up that cost in 6 months.

I wanted to get some opinions on what would be the best motor of the 2 for towing and for fuel consumption.

Thanks

Forgot to add it is a 5 speed manual

How many kms have you done?

Mine does 300 km city driving on 82 litres of lpg.

Is a td42t conversion out of the question? Going to the ls1 will be good but you will be paying an extra 300 odd dollars for rego and possibly increases in insurance. The ls1 will prob use less fuel while towing and in general i believe but still not quite as good as a diesel.

Just go all out with a 6.6L duramax! ha ha

Go with a common engine I am in the process of doing a VH45 conversion and everything that can go wrong will. Although it is starting to come together now. If you are going to pay someone to do it expect to pay 15k min

Personally i would reco the 4.5
would not even consider using any form of gm junk ever again .

It has done about 230,000 kms

A 4.2 diesel isnt out of the question yet, but i have been told the motor and conversion will cost about 15K, and i can do the LS1 for about 12K, a friend is going to do the engine rebuild and help me do the engine conversion.

What sort of fuel economy would a 4.2D get?

6.6 Duramax, i wish:), but i cant tow around a fuel tanker

My biggest worry is that if i reco the 4.5 and end up with a bit better economy but still not much towing power

Think I second the vote to reco the 4.5. Could do some head work and get some more hp. Otherwise build it to suit a turbo then your laughing. Ive done engine mod swaps and it always costs more and things don't work or come together easily. As said before don't forget extra insurance and engineers costs.
Might cost a bit less if you can keep some parts that are still okay with the 4.5 rebuild.
230k isn't heaps, mine has more ks. My gas consumotion is about the same. What makes you think it's on it's way out?

Gen 3 mmm power
Cheers

$15k for a td42 conversion? what nutter told you this. good running engine can be had for 3-6k then flywheel box etc is $1500. then you pretty much bolt it in and drive away. only need to change minor things. no major mods need to be done to anything.

Recon stick with TB45.
Add turbo and you'l have all the power you want and then some.
You should find fuel economy improvement to.
Providing you don't think your D Johnson.
Turbo will help you get up to speed much quicker.
as it simply breathes better turboed than the stock TB45.
These stock engine slog things out, that's why they are heavy on fuel.
look at it another way.
XR6T is similar capacity and make excellent HP figures. Better then XR8 I hear.
you add a turbo to a torque designed engine and bucket loads of power and torque will follow.
WITH PROPER EXHAUST, ECU CHANGE OR TWEAK AND DYNO TUNE BY REPUTABLE TUNER.
Look at BIGRIG thread on his GQ what he's got after doing TB42 turbo conversion.
Cheers

Quote:

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Originally Posted by Robo

Recon stick with TB45.
Add turbo and you'l have all the power you want and then some.
You should find fuel economy improvement to.
Providing you don't think your D Johnson.
Turbo will help you get up to speed much quicker.
as it simply breathes better turboed than the stock TB45.
These stock engine slog things out, that's why they are heavy on fuel.
look at it another way.
XR6T is similar capacity and make excellent HP figures. Better then XR8 I hear.
you add a turbo to a torque designed engine and bucket loads of power and torque will follow.
WITH PROPER EXHAUST, ECU CHANGE OR TWEAK AND DYNO TUNE BY REPUTABLE TUNER.
Look at BIGRIG thread on his GQ what he's got after doing TB42 turbo conversion.
Cheers

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X2 Robo. Rebuild and convert to petrol only with a new turbo setup. You'll get more power than an LS2 or equivalent conversion and outlay half the money if done right. Your fuel consumption will drop significantly also - both through being able to tune the engine to one fuel, and the control of a new ECU (sequential ignition; fuel over cut when off the pedal; more power early so less right foot required to achieve same job; etc; etc - BUT, stick your foot into it and expect to need a BP tanker to have to follow you everywhere as it will throw it in there if your not frugal when normal driving).

And it keeps it relatively standard from a wiring etc perspective so everything still "looks and smells" Nissan (makes it easy to work on for me).

Good luck with it mate.

Thanks for all of your help guys.
After reading what everyone has said i think for now i will just go with a rebuild on the 4.5 and look into adding a turbo.
Seems to be the easiest way out and probably end up with about the same power for towing, so long as i keep the lead out of my right foot.
I'll let you all know the verdict when i get around to doing the rebuild

Quote:

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Originally Posted by JuzGU

Thanks for all of your help guys.
After reading what everyone has said i think for now i will just go with a rebuild on the 4.5 and look into adding a turbo.
Seems to be the easiest way out and probably end up with about the same power for towing, so long as i keep the lead out of my right foot.
I'll let you all know the verdict when i get around to doing the rebuild

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Good call IMHO mate.

I have been searching the net trying to find a pic of a gu 4.5 with a turbo just to see how it is setup in the engine bay but not having much luck.
Is anyone running a turbo on a 4.5 petrol that can give me an idea of some fuel figures and maybe a pic of their engine bay Plleeeeeaaaaassssseee

Yep, I think your making the right choice. Just don't put too much boost in it and it'll give your reliability. If you rebuild the 4.5 put in bigger rods from the 4.2 and then you can boost away.
I read elsewhere that someone with a turbo is getting 350 - 400 ks from LPG. I'm lucky to get 350 without a turbo.

It's just nice reading about 4.5s no matter how old the thread :)

When its time for my 4.5L rebuild I will most certainly be going down the turbo path.

I agree with using one fuel, but if its already dual fuel like many 4.5 are why not set it up for straight gas.

Quote:

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Originally Posted by NP99

It's just nice reading about 4.5s no matter how old the thread :)

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I agree.. :) especially as I'm currently doing what the OP was advised to do..

an old thread but with the price of Gas ATM is it really worth running gas.
I ran gas for 400,000ks and now hate it with a passion, Melted carbies, air box back fires.
Burnt out headers even after ceramic coating them inside and out, at great expense.
All fixable but what a PITB. Gas was only 18c a ltr with my last 4x4.
I did a few Simmo trips with the help of an Aux tank [highly recommend] just left the gas full
in case I holed a tank. IMO I think gas has run its race, based on the price these days

I and I'm sure a few others tend to agree with you 3D. One day I'll get rid of my gas