Here, we will investigate the characteristics of this engine by referring to the data of the K3-VET type turbo engine installed in Toyota’s J102E type Camisole Q Turbo Aero-Version 2004/04 model.
K3-VET Turbo Engine Specifications
Toyota’s J102E type Camisole Q Turbo Aero-Version
|Vehicle model||TA-J102E type|
|Car name & grade||Cami |
Q Turbo Aero-Version
|Inner diameter × stroke||72.0mm×79.7mm|
|Bore stroke ratio||1.11|
|Single cylinder volume||324.5cc|
|use fuel||Regular gasoline|
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.
Evaluation from the viewpoint of transient characteristics and liter equivalent horsepower
|Image of engine performance curve|
|Changes in horsepower||80.4PS → 140PS|
|Transition of torque||18.0kgm → 15.7kgm|
Cami’s in-line 4-cylinder 1297cc, compression ratio 8.5 and regular gasoline turbo engine, which is the reference vehicle this time, produces a maximum output of 140 horsepower at 6400 rpm and a maximum torque of 18.0 kgm at 6400 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 6400 rpm is 15.7kgm.
The horsepower per liter of displacement is 107.94PS / L and the torque is 13.9kgm / L, and the horsepower per cylinder (single cylinder volume 324.5cc) is 35.0PS and the torque is 4.5kgm.
When the K3 turbo engine is applied to a 10-step evaluation based on deviation values aggregated from all turbo cars registered on this site, the evaluation is ” standard ” with a converted horsepower of [ 6 ] and a converted torque of [ 5 ]. It is categorized as ” engine with high output (upper middle) “.
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 12 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 type||Piston diameter||Displacement|
For engines with similar piston diameters, Honda: L15B type 1496cc 73.0mm mounted on RW1 type CR-V, Honda: LEA type 1496cc 73.0mm mounted on ZF2 type CR-Z, Honda: FK7 type Civic L15C type 1496cc 73.0mm installed, Suzuki: K10C type 996cc 73.0mm installed in WB42S type Valeno, Suzuki: K14C type 1371cc 73.0mm installed in ZC33S type Swift Sport, Toyota: EL31 type Corolla II The installed 3E type 1456cc 73.0mm etc. 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 6400 rpm, where an engine with a stroke of 79.7 mm produces maximum output, is 17.0 m / s , which is a piston speed that travels a distance of 17.0 meters per second (61.2 km / h at speed). It means that is moving up and down.
The average speed is 18.3 m / s at 3200 rpm, which produces the maximum torque, and 18.3 m / s when the rev limit is assumed to be 6900 rpm, which is 500 rpm higher than the 6400 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.