Isuzu torque - numbers

[Trolley]

Hello all.

I am the proud owner of an 03 D2 with a lovely td5, that LR states put out 300nm at 1950rpm. I have had the perentie bug for about five years now, and everywhere I look people remark on the isuzu motor being a "torque monster" and such. Isuzu say the 4bd1 puts out 245nm at 1900rpm. Td5 has it beat purely based on numbers, so what am I missing? There aren't too many people raving about Td5 torque.

I can see that the 4bd1t or 4bd1 with a turbo fitted is a torque monster, but the NA doesnt post big numbers.

I am curious as to what I am missing here.

Thanks all.

[Vern]

Its a large capacity diesel, it will pull from idle. Its like a tractor! I guess you just have to drive one to see.
Mine would be around 650-700Nm.

[Trolley]

Yeah I figured that, but why dont the numbers reflect it? That's huge, how did you get so much out of it?

[BadCo.]

Chuck any old turbo on and wind the fuel out and they outperform TD5s

[Ashleylipus]

My understanding is that Those figures are the peak torque. Lots of vehicles have a high peak torque output but have a steep torque curve meaning they have a small amount of torque threw the rev range right until the last moment. Perentie motors reach a high torque output early and maintain a smoother torque curve right up until the peak

[Vern]

Yeah I figured that, but why dont the numbers reflect it? That's huge, how did you get so much out of it?

Turbo and fuel. 4bd1 has 66kw @ the flywheel stock, last time mine was dynoed it was 102kw @ the wheels!
Has since had further tuning.

[87County]

....

[87County]

To add to what others have said...

If you drive a standard 4BD1 you'll notice that it has a natural "anti-stall" feature

If you add one of the turbo kits you'll find it quieter, smoother and pulling like a freight loco.

It is only when you actually drive one that you understand why we have wide smiles .....

[Phil B]

Definitely chalk and cheese
The difference na to turbo is unbelievable
They pull from idle to the limiter
Best part is you don't have to rev them
They pull the same across the rev range

[JDNSW]

Same as the others have pointed out. The peak torque is the same, near enough, but as stated, the Isuzu has good torque all the way down to stalled, where the TD5 torque drops off as the engine slows and the amount of exhaust available to spin the turbo drops. Or to put it another way, the slower the Isuzu is turning, the more air gets into the cylinder and so more fuel can be burnt, whereas the TD5, with half the cylinder capacity needs to still have twice atmospheric pressure to get the same amount of air in at low speed, and with the engine turning at that speed there simply is not enough exhaust to get that much boost. (OK, I've simplified, it, the TD5 has more cylinders, but that doesn't affect the situation much)

The driveability depends not so much on the peak torque as the shape of the torque curve, especially down low.