The engine of my Chery J3 has poor fuel consumption, poor torque and poor power, compared to other engines of the same capacity.

My father in law says that that’s because it’s oversquare, but could it be as simple as that?

Capacity 1.6 L
Bore x stroke 81*77.5

The low power tends to be because the automatic gearbox changes down whenever the rpm hits 3000 rpm, and this happens at freeway speeds on even the slightest hill. This also contributes to the poor fuel consumption, the fuel consumption is only relatively bad, 6.7 L/100 km on flat freeway, up to 7.7 L/100 km or above when the freeway has hills.
Is there any way an engine tune could improve torque

it’s undersquare. good pick-up at the expense of torque. hard to “tune” modern engines.

from my understanding, it’s not so much torque that suffers in an oversquare motor, than Hp.

you can’t really tune it out of the motor without spending big $ porting, polishing, oversize valves, etc..

sorry it is oversquare.

mollwollfumble said:

The engine of my Chery J3 has poor fuel consumption, poor torque and poor power, compared to other engines of the same capacity.

My father in law says that that’s because it’s oversquare, but could it be as simple as that?

No. Engine stroke and bore/stroke ratios have virtually nothing to do with torque output. For a cylinder with the same capacity and pressure on top of the piston, a big bore/short stroke engine will make exactly the same torque as a small bore/long stroke engine; pressure/area x lever ratio ends up being exactly the same.

I’m sorry to say that the reason you get poor fuel economy is because the engine just isn’t very good.

torque is affected that is why 4wd motors were long stroke and why putting a red motor into a landrover was a waste of time.

ChrispenEvan said:

torque is affected that is why 4wd motors were long stroke and why putting a red motor into a landrover was a waste of time.

Nope.

Capacity gives torque, not stroke.

ChrispenEvan said:

torque is affected that is why 4wd motors were long stroke and why putting a red motor into a landrover was a waste of time.

Why would you have done that?

dunno, but it was quite a common practice.

ChrispenEvan said:

dunno, but it was quite a common practice.

cheaper maintenance and easy to find replacement parts?

probably, plus they thinking was that the landy would go faster. though why you would want to go fast with recirculating ball steering i don’t know.

Spiny Norman said:

mollwollfumble said:

The engine of my Chery J3 has poor fuel consumption, poor torque and poor power, compared to other engines of the same capacity.

My father in law says that that’s because it’s oversquare, but could it be as simple as that?

No. Engine stroke and bore/stroke ratios have virtually nothing to do with torque output. For a cylinder with the same capacity and pressure on top of the piston, a big bore/short stroke engine will make exactly the same torque as a small bore/long stroke engine; pressure/area x lever ratio ends up being exactly the same.

I’m sorry to say that the reason you get poor fuel economy is because the engine just isn’t very good.

Can you say more about what constitutes “isn’t very good”?

ChrispenEvan said:

probably, plus they thinking was that the landy would go faster. though why you would want to go fast with recirculating ball steering i don’t know.

ChrispenEvan said:

dunno, but it was quite a common practice.

Yes. That’s true. I have seen it before.

mollwollfumble said:

Spiny Norman said:

mollwollfumble said:

The engine of my Chery J3 has poor fuel consumption, poor torque and poor power, compared to other engines of the same capacity.

My father in law says that that’s because it’s oversquare, but could it be as simple as that?

No. Engine stroke and bore/stroke ratios have virtually nothing to do with torque output. For a cylinder with the same capacity and pressure on top of the piston, a big bore/short stroke engine will make exactly the same torque as a small bore/long stroke engine; pressure/area x lever ratio ends up being exactly the same.

I’m sorry to say that the reason you get poor fuel economy is because the engine just isn’t very good.

Can you say more about what constitutes “isn’t very good”?

Head airflow, frictional losses, rotational inertia, fuel & spark management, etc.

Spiny Norman said:

mollwollfumble said:

Spiny Norman said:

No. Engine stroke and bore/stroke ratios have virtually nothing to do with torque output. For a cylinder with the same capacity and pressure on top of the piston, a big bore/short stroke engine will make exactly the same torque as a small bore/long stroke engine; pressure/area x lever ratio ends up being exactly the same.

I’m sorry to say that the reason you get poor fuel economy is because the engine just isn’t very good.

Can you say more about what constitutes “isn’t very good”?

Head airflow, frictional losses, rotational inertia, fuel & spark management, etc.

The Japs made heaps of crossflow four cylinder motors before the American giants had to get Aussies to show them how it could be done to Fords.

Spiny Norman said:

mollwollfumble said:

Spiny Norman said:

No. Engine stroke and bore/stroke ratios have virtually nothing to do with torque output. For a cylinder with the same capacity and pressure on top of the piston, a big bore/short stroke engine will make exactly the same torque as a small bore/long stroke engine; pressure/area x lever ratio ends up being exactly the same.

I’m sorry to say that the reason you get poor fuel economy is because the engine just isn’t very good.

Can you say more about what constitutes “isn’t very good”?

Head airflow, frictional losses, rotational inertia, fuel & spark management, etc.

To give you an idea of how much difference it can make, the engine I use in my old racing car is from a late 80’s earl 90’s Suzuki Swift GTi.
It makes 100 hp from the factory.
My race engine uses the same compression ratio, same rev limit, but larger cams, different manifold, etc, and I get up near 160 hp from mine. We worked hard at reducing the losses and making it pass as much air as possible as efficiently as possible.

Gotta go now …

Before I say anything else bad about the Chery J3 engine I’d better check claimed torque and power.

Power 93kw 6150rpm Torque 160Nm 4300rpm

How does that compare with other 1.6 litre four cylinder engines? My other car (1.5 litre) has

PERFORMANCE
Maximum power (kW rpm) 886600
Maximum torque (Nm rpm) 1454600

But that other car actually has a lot more acceleration off the traffic lights and the power to go up hills at speed than the Chery J3.

mollwollfumble said:

Before I say anything else bad about the Chery J3 engine I’d better check claimed torque and power.

Power 93kw 6150rpm Torque 160Nm 4300rpm

How does that compare with other 1.6 litre four cylinder engines? My other car (1.5 litre) has

PERFORMANCE
Maximum power (kW rpm) 886600
Maximum torque (Nm rpm) 1454600

But that other car actually has a lot more acceleration off the traffic lights and the power to go up hills at speed than the Chery J3.

what’s the difference in kerb weight between the 2.

Your issue also may be more in gearing

mollwollfumble said:

Before I say anything else bad about the Chery J3 engine I’d better check claimed torque and power.

Power 93kw 6150rpm Torque 160Nm 4300rpm

Okay I take back what I said – It’s not a real performer but looks like a good average one.
As Stumpy said, it might be the gearing. There’s other factors, such as aerodynamic drag, weight, etc. The engine management might also not have good cruising maps.

the economy is dictated by an average based on how the car is tested

maybe your normal driving route is different to the way they tested the car for economy in the first place – lots of stop starts etc

Spiny Norman said:

mollwollfumble said:

Before I say anything else bad about the Chery J3 engine I’d better check claimed torque and power.

Power 93kw 6150rpm Torque 160Nm 4300rpm

Okay I take back what I said – It’s not a real performer but looks like a good average one.
As Stumpy said, it might be the gearing. There’s other factors, such as aerodynamic drag, weight, etc. The engine management might also not have good cruising maps.

Aerodynamics – good, better than average, I know both from my aerodynamics experience and from the fact that performance at 100 km/hr is identical to that at 110 km/hr (unlike any other car I’ve driven).

Weight: 1350kg
Other car 1048kg so that would make a noticeable difference.

Is engine management mapping something that can be cured?

it could be your tyres

mollwollfumble said:

Is engine management mapping something that can be cured?

Yep, though probably no so easily with that engine as it’s not a popular one, I suspect.
As Wooks mentioned have you checked the tyre pressures? Up around 40 psi is usually the pressure you should have.

ChrispenEvan said:

sorry it is oversquare.

OK, can you have an overround engine too?

bob(from black rock) said:

ChrispenEvan said:

sorry it is oversquare.

OK, can you have an overround engine too?

If not, then this is blatant shapeist didcrimination.

bob(from black rock) said:

bob(from black rock) said:

ChrispenEvan said:

sorry it is oversquare.

OK, can you have an overround engine too?

If not, then this is blatant shapeist didcrimination.

Who would want to be a didcriminal?