Let's talk Torque!

Having been shot down for mentioning the higher torque of the D40 being 403Nm@2000rpm and apparently not understanding the delivery of power to torque blah blah blah

These are the figures for a 2002 4.2 litre TD patrol motor -
114 kw @ 3600 rpm, 330 Nm @ 2000 rpm

So by your reckoning on figures alone, the 2.5 litre Navara motor should shit all over a 4.2 litre TD Patrol. Maybe on the highway, but certainly not in the bush.

The numbers mean very little if you don't understand how the power and torque are delivered. The 2.5 may have higher numbers, but it is a spikey torque curve, meaning that it is harder to find your max torque, and harder to keep it there, especially with larger tyres fitted. The hunt for big numbers in little engines is for one thing and one thing only......sales

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Anyone want to enlighten me?

Cheers Brad

I see what your saying, I got a mate with a GU coil cab and another mate with a QD32 powered D22.

Off road I am using low range way more often then they are, the TD42 and the QD32 run a compression ratio of 22 to 1 because they need it being indirect injection motors.

The ZD and the YD being direct injection motors run less compression and more boost to give them similar figures.

Off boost the ZD and the YD cant make the torque that the higher compression motors can.

On road the ZD and the YD crap all over a standard TD42 and QD32. On boost to the ZD and YD are out of there while the old tech motors are blowing losts of smoke to get to the speed limit.

You win some you lose some, Id rather drive my ute everyday then my mates GU coil cab. The ZD30 is much easier to live with in everyday driving.

Dave.

Who said that to you?

What are you wanting to know about it? The search for bigger numbers in smaller motors is more about fuel economy, weight, cost and emissions, it's easier to boost your sales numbers fitting a 6.5L diesel V8 to everything if you can do it cheap.

Thanks Dave! There is only so much I know about motors etc. being a plumber an all!! But the way you explain it makes plenty of sense!

Pro-Nav, I responded to a statement without thinking

Poster,
The 2.5 litre engines are not known for their amazing bottom end torque, so you'll be looking for some higher gear ratios. .
Me,
With 403Nm@ 2000rpm it's top of it's class!!

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Nevyn said:

Having been shot down for mentioning the higher torque of the D40 being 403Nm@2000rpm and apparently not understanding the delivery of power to torque blah blah blah

Anyone want to enlighten me?

Cheers Brad

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That's correct, the flatter the torque curve the better, peak torque numbers don't really mean that much but rather where and how the torque is delivered in the rev range. The 2.5 is not a user friendly offroad engine especially with the tall gearing. (D40) it may be better in the D22.

No worries Brad, I picked your brain pretty well when it came to the solar hot water system.

Everyone has there own specialties.

Dave.

Now we're on the subject, is this where putting a bigger exhaust on and blocking off that other thingo (EGT??) brings turbo boost in a bit earlier thus giving us a little bit more offroad punch???

A bigger exhaust will help, haven't looked into the EGR on the YD25. Blocking it may or may not trigger a fault.

Low range and the right gear will help to, next step is some reduction gears.

I wouldn't bother chipping after seeing the results posted a few days ago.

Dave.

That's the thing Dave, I'm completely happy with the performance of the Nav both on and off road. Though I'm still getting used to driving a turbo, the rev thing (when you don't want the revs). When I put the 265/75's ST's on it I was expecting big power loses etc. but it just diddn't happen! Maybe it's my driving style.
As for low range 1st gear going down hill (rutted) is comfortable for the Mrs and 1st & 2nd coming up the same track is good.

Cheers Brad

I really do think that the actual numbers are pumped out for sales, but they also have significant meaning.

For average driving - not the extremes of climbing up the side of the 3 Sisters, or wading across the Tasman, or rock-sliding on Uluru - I'm talking *average* driving - the better the torque and power developed, the better the vehicle moves along with its cargo for a given amount of fuel.

Larger engines are always going to have more power. When was the last time you heard of a podium position on Mt Panorama by a Briggs & Stratton powered beast? Brute force is one thing, but clever development of power is something else.

For average driving, cleverly developing that power is important for economy (and for saving the planet too, but I didn't want to bring whales into it). Your Navara can pull the same amount of weight and reach its destination as a larger-engined beast - but if you can drive it in its sweet spot (read "2000rpm for the D40") then you'll use much less fuel compared to the larger-engined vehicles.

It's simply advancements in technology and finding a good balance. Unfortunately for us D40 drivers, that balance point is rather narrow - the torque band is not very wide at all, so once we move outside of it, we're either using too much fuel or simply not keeping up.

But that's where we come back to averages. For the average driver, doing the average things, these cars outperform the larger, heavier, bigger-engined vehicles.

In truth, the numbers don't really matter. A D40 driver who doesn't use the power curve to their advantage could easily use more fuel than someone in their Patrol who knows where to do what with their car.

That's why comparing fuel economy is interesting and gives us opportunity to discuss methods of improving our own, but at the end of the day doesn't amount to a lot because we're all different people driving different cars (minor variations in production and servicing = different) doing different things in different ways.

And THAT is what's so bloody interesting. Not these numbers!

I suppose newer engines have the technology of having stronger but lightweight internal components fitted inside them that gives them the edge of making the same amount of power as a bigger old engine.

SOLID D22 said:

I suppose newer engines have the technology of having stronger but lightweight internal components fitted inside them that gives them the edge of making the same amount of power as a bigger old engine.

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Electronic fuel control, better atomisation of diesel through the introduction of common rail, and things like variable timing and variable turbos are the main improvements.

Pro-Nav2.7TDi said:

Electronic fuel control, better atomisation of diesel through the introduction of common rail, and things like variable timing and variable turbos are the main improvements.

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Thats true.