Air Intake
Air Intake
(OP)
Remembering what I have learned in physics, that air flowing through a pipe or tube can increase or decrease in speed and pressure based on size changes in the tube. According the calculations and live tests this is true, but what about turbocharging engines?
I am working on turbocharging on engine right now, and if I were to say have a 3" pipe come off the turbocharger and into the intercooler, then have it decrease in size coming out of the intercooler to say 2.5" and gradually decrease in size again to 2.25" or even 2" at the intake manifold, would there actually be an increase in speed here and thus more power?
According to my calculations there would be an increase in flow, by almost 300cfms, and a pressure drop of .01 psi.
Pressure from a turbocharger though comes from restrictions in the path of the air from the turbo to the combustion chamber, would the decreasing pipe size be such a restriction that boost pressure would increase and ultimatly hurt the reliability of my engine vs increasing power by increasing air flow by basic physics?
I am working on turbocharging on engine right now, and if I were to say have a 3" pipe come off the turbocharger and into the intercooler, then have it decrease in size coming out of the intercooler to say 2.5" and gradually decrease in size again to 2.25" or even 2" at the intake manifold, would there actually be an increase in speed here and thus more power?
According to my calculations there would be an increase in flow, by almost 300cfms, and a pressure drop of .01 psi.
Pressure from a turbocharger though comes from restrictions in the path of the air from the turbo to the combustion chamber, would the decreasing pipe size be such a restriction that boost pressure would increase and ultimatly hurt the reliability of my engine vs increasing power by increasing air flow by basic physics?
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RE: Air Intake
Use those equations, and consistent units. The adiabatic assumption is a big ask, but will do for rough calculations.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Air Intake
Also an increase in pressure will result in an increase in temperature which will have a negative effect on potential maximum power output
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Air Intake
I am not an engineer but am going to school to become one, and am a very serious engine builder. If I should hold off until I am finished with school and have some experience under my belt before posting on this forum let me know and I will not trouble you all any more!
RE: Air Intake
Yes, you should wait till you've graduated, and understand the conservation of mass, before posting on this or any of the Eng-Tips forums.
Also if the turbo can only flow 678ft^3 of air (unit time)(at 7psi) how do you expect to have available 1061ft^3 (?at 6.99psi?) at the other end of a very long tube. Where is the extra 383ft^3 of air going to come from? The pressure will definately drop more than .01psi. (That might be the pressure drop due to the tubing, the volume increase is going to be a bit more though.) From Pv=nRT you cna get: (ooops looks like my typing was way ahead of my calculator on that one) 4.47psi (I may have done that wrong. I am very out of practice with gas law thermo... Sorry Dr. Lifer)
Nick
I love materials science!
RE: Air Intake
You cant learn if you dont ask questions. Take the suggestions these gentleman offered, try them out and provide some feed back on numbers. This way you will learn how to apply the formulas. This is a must in the engineering profession. All the while you will also gain knowledge in what could and could not work.
Good luck!!
Quote: "Its not what you know, its who you know" - anybody trying to find a decent job
RE: Air Intake
thats what these forums are for, finding answers.
I heard from my engineering profs that "the difference in a smart man versus an intellegent man is the intellegent man knows where to get the answers"
Keep plucking away, some of lifes greatest finds have been on accident.
Alex
RE: Air Intake
Unless of course you plan on have a water injection system. There is a book out there called TurboCharging, and I remember it has a twin turbo Banks motor on the cover. Awesome book for learning about turbos and tweaking them. I actually read the book twice from cover to cover, loved it.
Alex
RE: Air Intake
Another way around the problem of added head is to utilize methanol injection. Does wonders for cooling the intake charge. As for you calculations, think of things in a logical progression. Decreasing the tube diameter will increase the flow velocity(as well as pressure and temp.) but the overall quantity of air in the system does not increase. You would want to maximize the flow numbers while minimizing flow losses and heat buildup. Keep researching and reading and you will pick these things up. And don't get discraged as there are always people who can't act professionally when asked questions as you will learn more when you work in the industry!!
RE: Air Intake