Thread: are these industrial engines suitable for automotive use?

Originally Posted by isuzurover

Those JCB motors look like they are optimised to operate at 1200-1600 rpm. And the curves only go to 2200. (they are also a bit dodgy - note the change in scale?!?!).

The 4BD1 revs to 3400-3600 rpm in stock form. It also has a flat torque curve from ~1200 to ~3000 rpm in na form (turbo is a bit peakier).

The sharp decrease in torque above 1600 rpm in the JCB engine would make that motor pretty useless in a vehicle IMHO.

Certainly, but my money is on the torque and power being tuned to take a dive to encourage the drivers to use higher gears. Thus saving fuel.

If we can get an aftermarket tunable commonrail ECU for less than new vehicle prices then it's something that's easily fixed. I'd expect most commonrail diesels to keep making more and more power until about 3500-4000rpm given the chance.

I would say that most of the "industrial" motors you are looking at would last a lot longer than anything in a car. I would definitely say that this is the case because of RPM. Engine wear is accelerated at the square of rpm. So if you could fit an overdrive and bought some longer ratios from Ashcroft, you could potentially have a car that would not rev over 2500rpm and last forever. Your car may not be very nice to drive though, as it would now become more like a truck. I mean that it is now geared for torque then more so power. Your best option would be to find something that is controlled via an ECU.. At least this way you would have some hope of changing the rpm limit... However, this now presents another issue of weight and compatibility of bell housings. This could be your second biggest hurdle... The major issue that I think that you will face is emissions. Some of the younger stuff should be okay i.e. EURO 5 etc... I just don’t know how you would go taking a motor that is meant for mobile plant use and then putting it in a production car...

Are these quoted engine data on an engine dyno or real world figures at the road wheels on a vehicle dyno?

Am I correct that we should be looking for max torque to be developed at final drive for desired highway speed? i.e. 100 KPH

Originally Posted by Lotz-A-Landies

Are these quoted engine data on an engine dyno or real world figures at the road wheels on a vehicle dyno?

Am I correct that we should be looking for max torque to be developed at final drive for desired highway speed? i.e. 100 KPH

Everything automotive is quoted flywheel. Max torque at 100km/h is the best for drivability, most factory diesels hit this.

Originally Posted by Dougal

...... Max torque at 100km/h is the best for drivability, most factory diesels hit this.

Not sure I agree with this except as a very rough rule of thumb.

As a rule of thumb, you would want maximum torque at the speed you normally drive at, in the gear that you normally drive in. But this assumes that there is sufficient power available at that engine speed, which is not necessarily the case. For driveability, it is probably more important to have a wide spread of torque, in other words, not a sharp peak. This often means peak torque at quite low rpm, at which rpm there would be insufficient power to drive the vehicle at 100kph. (remember, power is torque x rpm, and power required goes up roughly as the square of the speed). A rather extreme example would be the 2.25 diesel, which produces maximum power at 1750rpm. if geared to do this rpm in top at 100kph (it is nearer 3000 at 100kph), you would never reach 100! Not in top, anyway, maybe third.

My view is that the key torque consideration for driveability, at least with a manual box, is the torque available at normal clutch engagement rpm. This figure is rarely if ever quoted, and you have to guess at how good it is from where the peak is, unless you have the complete curve.

John

Originally Posted by JDNSW

Not sure I agree with this except as a very rough rule of thumb.

As a rule of thumb, you would want maximum torque at the speed you normally drive at, in the gear that you normally drive in. But this assumes that there is sufficient power available at that engine speed, which is not necessarily the case. For driveability, it is probably more important to have a wide spread of torque, in other words, not a sharp peak. This often means peak torque at quite low rpm, at which rpm there would be insufficient power to drive the vehicle at 100kph. (remember, power is torque x rpm, and power required goes up roughly as the square of the speed). A rather extreme example would be the 2.25 diesel, which produces maximum power at 1750rpm. if geared to do this rpm in top at 100kph (it is nearer 3000 at 100kph), you would never reach 100! Not in top, anyway, maybe third.

My view is that the key torque consideration for driveability, at least with a manual box, is the torque available at normal clutch engagement rpm. This figure is rarely if ever quoted, and you have to guess at how good it is from where the peak is, unless you have the complete curve.

John

After reading that, I'm not sure what you mean.
There's nothing remotely close to the old 2.25 diesel on the market at the moment so it's an example we can safely ignore.
All modern diesels are geared to be right in their max torque (which is usually flat over a good range) at 100km/h cruising. They have more than enough torque and power at this speed to do the job. If a diesel has a peak it's usually 1800-2000rpm. Often these days it's flat over a range centred about that (like constant torque from 1500-2500rpm). The advantage of electronic control, get the most from the engine while respecting the drivelines torque limits.

It only takes about 30hp to cruise a landrover at 100km/h. 30hp at 2000rpm is only 105Nm, I can't think of any current diesel vehicle putting out less than 200Nm.

If you want a good rule of thumb for clutch engagement torque, go for displacement in litres x about 60 for a diesel.

Originally Posted by Dougal

After reading that, I'm not sure what you mean.
There's nothing remotely close to the old 2.25 diesel on the market at the moment so it's an example we can safely ignore.

I used this example to point out that the rule of thumb only applies to more or less current diesels - it has not applied in the past, and there is no reason to assume it will in the future.

All modern diesels are geared to be right in their max torque (which is usually flat over a good range) at 100km/h cruising. They have more than enough torque and power at this speed to do the job. If a diesel has a peak it's usually 1800-2000rpm. Often these days it's flat over a range centred about that (like constant torque from 1500-2500rpm). The advantage of electronic control, get the most from the engine while respecting the drivelines torque limits.

It only takes about 30hp to cruise a landrover at 100km/h. 30hp at 2000rpm is only 105Nm, I can't think of any current diesel vehicle putting out less than 200Nm.

If you are quoting the flywheel horsepower, I find this rather difficult to believe, by a factor of about two. A Series 1/2 diesel at full throttle at rated maximum power rpm (52hp) cannot reach 100kph, certainly not a loaded 109, and a 2a with another 10hp can barely do so, and then only on the level.

If you want a good rule of thumb for clutch engagement torque, go for displacement in litres x about 60 for a diesel.

I was not suggesting any figure for clutch engagement torque, merely commenting that this figure is more important for driveability than the position in the rpm/top gear speed range of the peak torque.

John

Originally Posted by JDNSW

I used this example to point out that the rule of thumb only applies to more or less current diesels - it has not applied in the past, and there is no reason to assume it will in the future.

If you are quoting the flywheel horsepower, I find this rather difficult to believe, by a factor of about two. A Series 1/2 diesel at full throttle at rated maximum power rpm (52hp) cannot reach 100kph, certainly not a loaded 109, and a 2a with another 10hp can barely do so, and then only on the level.

When has automotive technology gone back to old designs or theories (excluding a brief flirtation that japanese had with revised IDI designs). Current designs are optimised using FEM/CFD. Modern diesels have much higher outputs and much better fuel efficiency than old designs - easily an order of magnitude.

Every healthy 2.25D I have driven can hold 100km/h on a flat road while loaded.