Technical terms

[Acemundo]

yeah same idea.

 

sprinter must have muscular legs.

 

long distance runner better to have longer legs.

[Acemundo]

wow, thanks for the info.........clears up a lot of the confusion i had. in fact i also wanted to ask what is bore and stroke and u answered me before i asked

[Acemundo]

makes sense....

 

engine must fit the gear also.

 

so smaller cc engine should have lower gearing ratio?

[Acemundo]

does turbo cars make it more explosive by altering the compression ratio or making the combustion more spontaneous by allowing more oxygen?

[E36UDM]

Turbo pumps pressurized air

[Acemundo]

so more spontaneous combustion?

[E36UDM]

Yup more air but have to introduce more fuel in the process as well Better to upgrade fuel injectors to get better results

[GDIzen]

Nowadays rainy days makes the air cooler and more combustible... engine seems more TORQUEY...

[E36UDM]

ur rite but then floor wet cant go all the way

[GDIzen]

Have some wheelspin fun and drifting moves....

[E36UDM]

If only its RWD

[Tiger156]

Errr... Anyone called me???

 

Let's start the lesson with gear ratios. The ratios are there for comparison purposes when buying cars. Ratios determine how much the rpm will drop during gear change, and at what rpm will you be cruising at the highest gear. There are 2 types of gearing, namely tall and short. If you are looking for a car goes fast from start and through all the gears, you do not want your rpm to drop so much between gear change and therefore, you want a closely matched gear ratios. However, this will also mean that you will be cruising with a louder engine because the final ration will be smaller and therefore higher rpm. As such, you will notice that a 4AT will cruise quieter than a 5MT.

 

Compression ratio has not much meaning to end users like us, unless you are thinking of modding your car. Theoretically, higher compression ratio means higher power output. However, the limitation to this is engine knock, i.e. pre-combustion of air-fuel before ignition, that can kill the engine over time. You will notice that for normally aspirated cars, the compression ratios are around 10, and performance engines like Hondo Euro/Type R engines have a much higher ratio and thus higher output. Turbo or supercharged cars are lower ratios, like 8, simply because the air/fuel are pre "compressed" before entering the chamber and do not require high compression.

[Acemundo]

wow, well explained. so closely matched gear ratios means the ratios at particular gears at all within close bandwidth?

[Genie47]

Not necessarily leh. The Kenyans are so small in stature and yet can run any marathon. Must be the low pressure mountain air in Kilimanjaro. But the analogy is quite correct.

 

Efficient heart and lungs = Big bore

Long stroke = strong leg muscle

[Tiger156]

GEAR 1st 2nd 3rd 4th 5th Final

 

5MT 3.416 1.842 1.290 0.972 0.820 4.388

 

4EAT 2.816 1.497 1.000 0.725 - 4.416

 

Yup, tat's rite.

 

If you look at the comparison above, you will notice that this 5MT is not close at all because it is setup to provide better fuel economy by compromising pulling power. This can also be seen by looking at the final ratio of 4.388. A lower final drive ratio equates to better fuel economy, and a higher final drive ratio gives a better pulling power. The final ratio simply means that the drive shaft turns 4.388 times for every turn of the wheel.

[Yttrium]

does turbo cars make it more explosive by altering the compression ratio or making the combustion more spontaneous by allowing more oxygen?

 

 

 

 

Turbocharing and supercharging work by forcing more air/fuel mixture into the combustion chamber. More than what would naturally be drawn into them in a naturally aspirated engine. Thus, more power is produced. The fuel mixture then has to be richer than an NA engine, coz under higher pressure the mixture is more likely to detonate or pre-ignite. So actually the mixture is less explosive.. there is a higher ratio of fuel to air than normal.. (stoichiometric ratio)

[Acemundo]

ur explanation very good. makes me understand much better.

[Acemundo]

any diagreams on the bore and stroke?