Charging theory questions

[Guest tony78_280z]

Turbocharged and Supercharged is basicaly the same thing in that it crams more air/fuel into a smaller space. It basicaly makes the motor behave as though it has a greater displacement without increasing the displacement. But..

 

Question 1: A theoretical 1 liter displacement engine would require how much boost to cram in 2 liters volume?

 

Question 2: Would this boost level be the same boost level required to cram 4 liters of volume into a 2 liter displacement motor, or does the boost rate need to be increased with the displacement?

 

Question 3: In the above theoretial motor, with the 1 liter engine burning 2 liters of air/fuel, wouldn't the power output and fuel consumption be the same as a 2 liter NA motor?

 

Thanks

[yo2001]

1. 1 bar over ambiant should cram 2 times as much air if you ignore all the laws of physics.

 

2. yes but you would need more turbo to create same kind of airflow.

 

3. no because you are getting compressed air which is more dense hence slower burn, less timing less power output.

[Guest tony78_280z]

1. 1 bar over ambiant should cram 2 times as much air if you ignore all the laws of physics.

 

2. yes but you would need more turbo to create same kind of airflow.

 

3. no because you are getting compressed air which is more dense hence slower burn' date=' less timing less power output.[/quote']

 

1. What is 1 bar over ambiant? and supose we don't ignore all the laws of physics?

2. You mean a larger CFM turbo, but at the same boost level?

3. Interesting. (I also understand that a boosted motor can not have as high compression ratio but that is besdie the point.) So how much boost would the 1 liter motor need motor need to equal the power out put of a 2 liter motor. I know an exact number is not possible, but would the boosted 1 liter motor need to consume something like like 2.2 liters of air/fuel to equal the power output of a non boosted 2 liter motor? And if so, then would it be a safe assumption to say that a boosted motor is not as efficient as a greater displacement motor?

[yo2001]

1. 1 bar over ambiant = 14.5psi. Suppose if you don't ignore the physics, you would have to deal with thermal dynamic and effeciency of the turbo plus IC effeciency, air restriction, heat on and on.

 

2. yes, since you wold need about twice as much cfm on 4 liter than 2 liter. A

t3 is not going to keep up well on 4 liter as well as 2 liter.

 

3. well, under WOT, you would need more fuel to feed a boosted engine but you would need alot less off throttle (like cruise) on boosted engine since off boost the engine is smaller than N/A large displacement. Also there are factors like revlimit and power peak. if you get a 1liter boosted with peak power of 15000+rpm and 2liter with 6800rpm peak power, the both might make similar power and 1liter might be more effecient. So many factors.