for every 1 lbs of boost on an engine what cubic inch does the engine act like?

EX

350 cuin engine + 15 lbs of boost comes out to a 700cuin N/A motor whats the 1lbs to 1 cube conversion?

 

For every twinkie you eat how many turds do you make?

 

No relation. 15 pounds of boost from a 61mm turbo is a lot different than 15 pounds of boost from an 88mm turbo.

 

hmm then how does banks get this idea from?

http://www.bankspower.com/Tech_twinturbo.cfm

 

Banks = over PRICED

Banks = Gay

 

ok, thanks banks is junk that was for reference purposes only.

 

That is not true, 15psi is 15psi. It has nothing to do what turbo it comes from. The only difference in a 65mm turbo and a 88mm turbo is how fast and hard hitting that pressure will be built and the final amount that the turbo can build. What Banks is talking about is kind of a simple minded explanation but what they are trying to say is that its not the size of the cylinder that determins cubic inches, its the amount of air that can fill that cylinder. The earth's atmosphere is 14.7 psi on any N/A motor. So by there thinking, if you compress 15psi from a turbo in the cylinder you are doubling the amount of air in the cylinder and by there explanation you are doubling the size of the motor. This as everyone else has said is a terrible explanation of turbo charging and as far as im concerned should not even be given a second thought or used to try and figure out how to build your motor.

 

Oh, so you mean to tell me that a 61mm and 88mm turbo will make the same power at the same boost levels?

Thanks for clearing that up

 

So efficency has nothing to do with boost and turbos then right?

 

ofcourse it does, all I said was boost is boost so 15psi is 15psi. no matter what turbo it is

 

Rubbersdown is correct. At least if he's making that observation from the correct perspective.

Ultimately, what forces air into the cylinder is the pressure differential between the volume inside the cylinder and the volume outside the cylinder. (there has to be a force that causes the kinetic energy) Keep in mind that air is not drawn or "sucked" into a cylinder. It's ok to think of it that way sometimes, but in all actuality air is not "sucked," it is pushed by the air molecules behind it, and there is a direct correllation between that intermolecular force and pressure. In fact, it's the same thing. So, twice the force will result in twice the volumetric flow regardless of the type of turbo causing that force.

Many of you crying foul are correct from your perspective, as well. The problematic issue with the above explanation is that often times a larger turbo is more efficient than a smaller turbo at a given rpm, displacement, and boost level. So, there are other considerations that must be made. The biggest consideration is the temperature of the air, which from an inefficient turbo will naturally be higher than the temperature of air from a more efficient one. Temperature affects the mass of air and/or its pressure in a given volume. Thus, with higher temps and equal absolute pressure the mass air flow will decrease even given the same volumetric flow.

That is not to say that a larger turbo will always be more efficient, and hence powerful, than a smaller turbo at a particular rpm, displacement, and boost.


Still in response to the initial thread starter, there is no direct correlation between boost and a supposed equivalent displacement size. There are several other factors to consider before an accurate answer can be given. In an ideal environment (read: 100% efficiencies, and no chage to wave propogation, or initial kinetic energy of the intake air) 2 bar (absolute) would make an engine's equivalent displacement twice that of 1 bar. In correct turbod/intercooled applications, this rule of thumb isn't far off, and I would venture to guess that the actual guage pressure that would double the car's gross output and hence its equivalent displacement is somewhere between 16 and 18 psi. It's hard to say for net output because no additional power is required to spin any of the accessories at a given rpm, and they vary from one car to the next. So you would notice double the net engine output at less guage pressure.

I'm sure what I've written here reads somewhat like a textbook, but I wanted to ensure that my exact wording was both precise and accurate. I hope it's informational to somebody.

Chris

 

PV=nRT

and don't you forget it, boost is boost, if temp is the same.

 

lmao.. Banks may be over priced.. But it's hard to call a man who's accomplished as much as he has, gay. Jealousy is thick in here.

 

His first name is Gail after all

No seriously, he's a f'ing legend, I don't think anyone was attacking him personally just the company and their products.

 

As long as back pressure is the same.... And engine has to flow air in AND out to make HP.

 

true, I was trying not to hurt their brains yet

 

To answer the question more directly, the rule of thumb you stated is sound. If the system is reasonably designed 7.5 lbs of boost is about like 50% more displacement, 15psi is about like 100% more displacement, etc.

 

1 twinkie to 2 deuces wild

 

If you take into account the atmospheric pressure of my house I would have to say on an average day with an average temperature with only 30% humidity I take around 3 shits per twinkee. Taking into account the efficiency of my ass of course.