Here, we will investigate the characteristics of this engine by referring to the data of the K3-VE2 naturally aspirated engine installed in Toyota’s M111A duet 1.3S 2004/04 model.
K3-VE2 Engine Specifications
Toyota’s M111A Duet 1.3S
|Vehicle model||LA-M111A type|
|Car name & grade||Duet |
|Inner diameter x stroke||72.0 mm x 79.7 mm|
|Bore stroke ratio||1.11|
|Single cylinder volume||324.5cc|
|Intake method||Naturally aspirated|
|Fuel used||High octane gasoline|
|Maximum output||110PS / 7000rpm|
|Maximum torque||12.8kgm / 4400rpm|
First of all, as a basic structure, the K3 type engine is a long stroke type engine with a bore (inner diameter) of 72.0 mm, a stroke (stroke) of 79.7 mm, and a bore stroke ratio of 1.11 (the stroke amount is larger than the piston diameter).
When the displacement and the number of cylinders are the same, the engine has better torque characteristics in the low rpm range than the short stroke type and is easy to handle, but in the high rpm range, the filling efficiency deteriorates and the sliding resistance increases. There is a concern that the output will drop.
Moreover, when the number of revolutions is the same, the average piston speed tends to be higher than that of the short stroke type, so the load on the engine tends to be heavier.
On this site, the model equipped with the K3-VE2 naturally aspirated engine is the first duet [M111A type | 2004/04] released from 1998/09 , and there are 4 NA models, turbo / All 4 models of 0 models are registered as SC cars.
Evaluation from the viewpoint of transient characteristics and liter equivalent horsepower
|Image of engine performance curve|
|Changes in horsepower||78.6PS → 110PS|
|Transition of torque||12.8kgm → 11.3kgm|
|Liter horsepower||84.81PS / L|
|Liter torque||9.9kgm / L|
Duet’s in-line 4-cylinder 1297cc engine with a compression ratio of 11.0 and a high-octane gasoline specification naturally aspirated engine, which is the reference vehicle this time, produces a maximum output of 110 horsepower at 7,000 rpm and a maximum torque of 12.8 kgm at 7,000 rpm.
If you know the horsepower and the number of revolutions, you can know the torque, and if you know the torque and the number of revolutions, you can know the horsepower. The torque at 7000 rpm is 11.3 kgm.
The horsepower per liter of displacement is 84.81PS / L and the torque is 9.9kgm / L, and the horsepower per cylinder (single cylinder volume 324.5cc) is 27.5PS and the torque is 3.2kgm.
When the K3 type naturally aspirated engine is applied to a 10-step evaluation based on the deviation value aggregated from all NA vehicles registered on this site, the evaluation is ” quite good” with a converted horsepower of [ 8 ] and a converted torque of [ 7 ]. It is categorized as ” high power engine “.
Displacement increase, compression ratio increase, bore stroke ratio change
|Normal displacement and compression ratio|
|Bore||Stroke||Displacement||Compression ratio||B / S ratio|
|Displacement expansion by bore up|
|Displacement expansion by increasing stroke|
There are three factors that determine the engine displacement: the number of cylinders, the bore diameter, and the stroke amount. By increasing or decreasing these, engines with various displacements are created.
Here, regardless of whether it is actually possible or not, the displacement when the piston diameter is expanded from the genuine 72.0 mm to 75.0 mm in 0.5 mm increments and when the stroke is extended from the genuine 79.7 mm to 84.7 mm in 1 mm increments. And, the change of the compression ratio when it is assumed that the combustion chamber volume does not change is listed.
* It is easy to say stroke up, but if you want to make a long stroke, you need a crankshaft and a compatible connecting rod, and if you can not use it as a genuine product, you have to make it in one-off, so it is expensive anyway. It is a menu that requires considerable preparedness to put out.
Regarding the compression ratio, in most cases, the uneven capacity of the top surface of the piston changes as the diameter of the piston increases, so the compression ratio values in the list do not match, but the displacement. Please enjoy the atmosphere that the compression ratio will naturally increase as you increase the size.
B / S ratio is an abbreviation for bore stroke ratio, and as the bore diameter is widened, the characteristics of the long stroke type, square type, or short stroke type are approached. In the case of K3 type engine, the ratio changes from 1.11 to 1.06 when the bore is increased by +3.0mm from the genuine piston.
Increased displacement with engines with similar piston diameters
There are 45 engines with pistons that are similar in size to the K3 type engine with a piston diameter of 72.0 mm, so as a side note, let’s calculate the displacement when the piston is diverted and the bore is raised.
|Eg model||Piston diameter||Displacement|
For engines with similar piston diameters, Honda: L15B type 1496cc 73.0mm mounted on RW1 type CR-V, Mitsubishi: K12C type 1242cc 73.0mm mounted on ZC83S type Delica D: 2, Honda: RU3 type Vezel LEB type 1496cc 73.0mm mounted on Honda: L15A type 1496cc 73.0mm mounted on GE8 type Fit, Mitsubishi: K12B type 1242cc 73.0mm mounted on ZC72S type Delica D: 2, Honda: ZF2 type The LEA type 1496cc 73.0mm mounted on the CR-Z is applicable.
(Although the number of people who find pleasure in such a quest has decreased) No matter how close the diameter is, there are factors such as the diameter of the piston pin, the height of the piston, and the convenience of valve recess, so if possible, the same manufacturer, If possible, if you choose the same fuel and the same intake method, and if possible, the one with a similar displacement, the possibility of genuine diversion may increase.
Average piston speed
Next, let’s look at the average piston speed. The average piston speed at 7000 rpm, where an engine with a stroke of 79.7 mm produces maximum output, is 18.6 m / s , which is a piston speed that travels a distance of 18.6 meters per second (67.0 km / h at speed). It means that is moving up and down.
The average speed is 11.7 m / s at 4400 rpm, which generates the maximum torque, and 19.9 m / s when the rev limit is assumed to be 7500 rpm, which is 500 rpm higher than the 7000 rpm where the maximum output is generated.
For reference, I calculated the change in piston speed when a K3 engine with a stroke of 79.7 mm is rotated up to 10000 rpm. Looking at this, it seems that the speed increases by approximately 5.33 m / s as the number of revolutions increases by 2000 revolutions.
Considering only 20.0 m / s, which is a guideline for a general engine premised on mass production, it is mechanical to set the upper limit of high rotation to about 7530 rotations (whether it turns or not). It seems to be preferred both mentally.