Category Technical Talk

The S55 engine-equipped 2015 BMW M3 and M4 has been for sale for a while.

However, before looking at the below two technical documents from BMW, I bet you do not know the M3 and M4 in such depth. These two official documents provides precious details about these M cars and its heart: the S55 engine.

For example, some of the major differences between the S55 engine and the N55 engine (which is found in all BMW *35i models), are: 1. the S55 has closed deck crankcase, and the N55 is open deck; 2. the S55 has LDS-coated aluminum cylinder liners, while the N55 is using cast iron liners.

Download the documents for more insights.

M3/M4 Technical Document

S55 Engine Technical D...

Yesterday’s news that Mazda is planning a 449hp rotary engine for the RX-9 attracts many attention.

Now let us take a look at some interesting facts about the rotary engine.

Advantages about the rotary engine

1. Because there is no crankshaft, valves, pistons etc., the rotary engine is lighter, runs with less vibration;

2. Longer strokes, less prone to knocking and less pumping loss, which is more suitable for turbocharging, direct injection and lean burning;

3. Quicker throttle response;

4. Less moving parts such as pistons, valves, so rotary engine has less probability of sudden failures when compared to other traditional internal combustion piston engines.

Below is an ...

Continuously Variable Transmissions (CVT) have two major types: one does not use a belt to transmit power, such as Toyota’s Hybrid Synergy Drive, which uses mechanical gears; another type of CVT uses belts connecting two pulleys.

The first type has the advantage of real mechanical hard connections, high efficiency and high capacity (can handle large torque), but one limitation is that the Toyota Hybrid Synergy Drive, its mechanical structure can only be used in hybrid powertrains, that transmission will not work in a traditional internal combustion engine powered car.

For the belt type CVT, it can be used in all cars with different types of power sources, and it has unlim...

In the previous sections, we examine one type of factor that determines the location of a car’s brake calipers.

We may have several questions:

1. Is the design of the suspension solely determines the location of the brake caliper?
2. Is one type of the brake layout better than another, from the performance aspect?

Before we diving into these questions, let me first introduce a key concept: the roll center. In this article series the term is for each wheel, it does not mean the roll center of the whole car. Below I am going to explain what the roll center of a car’s wheel is.

For each wheel of a car, it is linked to the car body by the suspension system...

In this section, we will examine the rear wheel braking system.

Similar to the front wheel, one factor that affects the location of the brake caliper is the geometry design of the car’s rear suspension.

For some cars, there are control arm that connects to the rear part of the wheel hub, which takes up places that can fit the brake, therefore the brake caliper must be located in front of the rear wheel axle. For example the Lexus GS350 with rear wheel steering option, the control arm is located behind the wheel hub, therefore the brake must be placed on the other side.

For some other cars, the rear suspension control arms are in front of the wheel axle, therefore the bra...