ok here is my question. i wanted to know if psi is psi for example 12psi will always be 12psi like if i put a smaller turbo and it makes 12 psi on an engine but then i take a big turbo and limit it to 12 psi will it be the same?

thanks, phill

 

no it will be different. 12 psi on a big ass turbine will flow more cfm then 12 psi on a smaller lower flowing turbine

 

why is that?

 

psi just means pressure, the important thing is airflow or cfm, and i bigger turbo will move more air at the same psi

 

to me that makes no sense cuz wouldent you have to flow a certain amount of air to make the psi in the tubes? so i dont understand why it would be different.

 

hhmm let me explain it like this.

take a 50 gallon sprayer for instance. you have a 1 inch sprayer head on it and a 2 inch sprayer head. naturally, which is going to spray the 50 gallons faster?

the 2 inch head is going to spray it faster because its got a bigger "housing" so to speak.

like wise a turbo housing at .63 is naturally larger than a turbo housing set at .48 sizing simply because it has more size(volume), so therefore it will push more cfm than a smaller housing will

 

i understand that. so im incorrect at where psi is measured? is it not measured in the like overall tube? i dont see why 12 psi out of a smaller housing wouldent be the same as 12 psi out of a large housing.

 

psi is simply a set pressure. it determines when a bov decides to open. naturally you would think that psi would dictate power, but as said its simply a pressure level. cfm is how fast you flow something. you can flow air a 50 cubic feet per minute(distance/speed it travels) at a set 12psi(pressure) and have it be totally different than a faster flowing 60 cubic feet per minute setup running at 12psi(once again a dictator of pressure)

 

ok i think im understanding this more. so 12 psi either way will be 12 psi but how fast the 12psi is moving is different?

 

These guys speak the truth.

 

exactly youve got it. take a piece of pipe for instance. you can put enough pressure on it to equal 12psi. now take cfm. cfm ishow fast that 12 psi pocket of air is traveling(as well as how large it is)

 

yep these guys are right.

 

awesome. then why dose the speed affect it? is it because the fast the 12psi is moving the more of it can get shoved into the cylinder?

 

well the psi isnt moving more of it, the cfm is. but your onto it. a bigger turbine will spool more air pushing more into the cylinder per combustion cycle as opposed to a smaller turbine.

 

cfm=cubic feet per minute. if you can push more air, you can increase volumetric efficiency into the cylinder

 

i believe the psi is more indicative of the pressure at which air is packed into the cylinder. 50cubic feet of air packed into a soda can at 12psi is different than 40 cubic feet packed in a can at 12psi

 

ok i think im getting it. excuse my awkward wording but is it sorta like a bigger turbo will push more of the 12psi into the cylinder?

 

in a sense, yes. basically exactly the concept

 

yea i get the ve part im trying to understand i guess the physics of it all.

ahhhhhhhhhhhhhhhhhhhhhhhhhh perfect!! lol totaly werid but i totaly get it now.

 

hehe its pretty simple. always helps to understand the basic physical concepts of how it works.

 

A bigger turbo will have a greater lag time, due to the greater energy required to get the spool going to produce the additional psi

 

yes indeed. so to compensate a little would the lease amount of charge piping possible for the smaller turbo help at all? or is that a totaly differnt thing

 

but properly sizing a turbo for your application and needs is the most important.

ic piping diameter has something to do with it. but remember turbo's operate off of exhaust volume. learn how to read compressor maps. they will be your friend. lol

 

:P the sizing is fine i dont need a huge turbo im doing it mainly for a nice boost in power and then reliability. and to make all my ignorant ******* friends jaw drop.

 

give me a minute so i can calculate the essential "perfect" turbo for your set-up. whats you power goal?