Thread: V8 or TD5

Originally Posted by Rok_Dr

Having traversed a similar path to PhilipA I have to agree with everything he says, the TD5 is far better for towing and you'll get further on a tank. Likewise I'm more than happy with the performance of the standard tune engine and pulling a 1.8 tonne van.

Steve

Now, can I ask about the towing thing? On paper, the V8 has better power and torque than the TD5. So why is the TD5 better for towing? Is it just the fuel, or is there something else I'm missing?

I don't own a petrol V8.

Given you know the car, the low kms, it's set up, it's a no brainer. Stay with the v8. You will pay a lot of money for an equivalent Td5.

Now, can I ask about the towing thing? On paper, the V8 has better power and torque than the TD5. So why is the TD5 better for towing? Is it just the fuel, or is there something else I'm missing?

What is important to me anyway is holding speed on long hills on the highway.
The TD5 makes more torque than a v8 at about 2000-2200 RPM which is around the 100-110Kmh on the highway in locked top.

Now the result of this is that if you hit the enormous hill north of Buledelah going southbound you start at the bottom at 110Kmh and you are still doing 100 or so in locked top at the top of the hill towing 1000Kg.

My V8, even though tuned for torque was doing less than 100Kmh (maybe 90) and had changed back to third by the top and revving its head off.

To be fair if you get thwarted by some goose at the bottom of a hill in a TD5 you cannot regain speed up the hill as you don't have the revs to accelerate,vs the V8 where you can accelerate strongly by giving her the berries.
But it is far more prevalent that the TD5 will sail up the hills that the V8 will struggle on.
That is also a reason that I always discourage people putting hot cams in V8s.


Regards Philip A
I did all the mods on the V8 as I got sick of passing people on the flat only to be passed up the hills then having to pass again and so on. It helped a lot and a Thor D2 is maybe better than a RRC but still diesel is the Go and doing say 12L per 100Km vs the V8 doing about 16-17lper 100Km ( after mods and O2 sensors)..

I followed all the work you did on yours Phillip,,
but as you know, at 2200rpm the V8 would be making around 95% of its max torque,, which will still be more than the max put out by the TD5,, and torques are torques,, whether diesel, steam or LPG, if the weights, gear ratios, and speeds are the same, up that hill, the car with the most torques will win,,
my green cars 4L was a beauty,, but this silver one was useless. bought at roughly the came kays too,,

I remember testing a brand new TD5 when I had my 3door,, and remember keeping my 3 door,,

In my case the comparison was between a bog standard 94 soft dash classic and a 03 td5 auto. The 3.9l V8's torque is 314nm at 3100rpm, while the td5 auto is 340nm at 1950 rpm. More torque lower down makes all the difference. Plus 15l/100km vs 25l/100km towing in the V8 was a no brainer. The d2 auto also has lock up on 3rd and 4th as well.

That said the std v8 d2 is 340nm at 2600rpm so the difference between it and the td5 would be a lot less.

Cheers
Steve

That said the std v8 d2 is 340nm at 2600rpm so the difference between it and the td5 would be a lot less.

Weeell, my 3.9 really mirrored a Thor and I believe I had MORE torque at 2600 than a Thor , and I have to say that the torque RISE to 2600 is an issue.

On the open road in top locked you are never doing 2600 unless you are going very fast. Remember V8s are artificially restricted at low revs because of the need to limit NOx, thus all the criticism of engines like Gen111 of poor low down torque.

The old TD5 has its shoulder well into the torque curve at 2000 and the turbo is pushing hard . You are over the curve so shouldering back into the Max torque at 1950RPM.

I have to say they are like chalk and cheese, and I was amazed the first time I sailed over that hill. At the time I thought why did I waste my time and effort of many years on the V8.

Always the caveat that if you are baulked at the bottom it is a sloow trip to the top . When I am going up the Hume ( from Sydney to Canberra) I am always planning for the next bigun by ensuring if possible that I am clear of trucks and caravans at the start of the climbs.
Regards Philip A

Of course you can always go the 4.6... Cheers

Thanks Gents,
And yes, a larger V8, say a Disco 3, is an option for the next rig. Although they seem pretty rare compared to the 4L 6 petrol model.