My friend at work swears he as a super charged Pontiac Grand Prix that also has ram air. I argue that this is not even possible. Of course right now he has the super charger off because of maintenance and would not even pop his hood.
My major concern is the moron who overheard the argument and swears he knows it is possible to have both. I am almost certain you cannot have ram air with a super charger but I would like some back up. Ramming air into a compressor just doesn’t make any sense at all to me. So, help me fight ignorance and let me know what you guys/gals think!!
One more thing, I could be wrong. I just wanted to say that…
That is a fairly common mod for the Grand Prix. If the supercharger is starved for air it won’t pump as much, but I believe that the ram air helps primarily by providing cooler outside air to the supercharger. I’ve seen people claim around a 15 HP increase.
My credentials: My brother has a similar option on his Grand Prix. It’s an SLP (supercharged) with the GTX (ram air) goodies. I also run around with a guy who is considered a supercharged grand prix guru. I’m also a colelge student living in an apartment, all I can do is think and learn about automotive systems and the underlying theories of operation.
Ram Air alone is generally a forward facing ‘scoop’. At low speeds its simply a better flowing intake. At higher speed* ram air will, theoretically (it varies based on design), force a wee bit more air than ambient pressure allows. The car travels forward and ‘rams’ more air into the intake, hence the name.
With a roots type supercharger (as with the Eaton m-90 on your friends car), ram air is simply a free-er flowing intake. The supercharger makes the ‘ramming’ effect redundant, as it is drawing in (sucking) and compressing more air than the ram air system would. Its like blowing into the hose of a vacuum cleaner. On a minute physics scale there would be some benefit, in reality youd be out of breath and have some funky marks on your lips.
With a centrifugal supercharger or a turbocharger, ram air may have some benefit. These systems not only have to pressurize the air in the intake manifold, they also have to pressurize the air in the tubing, intercooler, and the manifold. This causes a ‘lag’ while the 'charger ‘spools’, it takes some time for the whole system to build enough pressure to signifigantly add power. A ram air sytem will, probably , at higher speeds* help these 'chargers spool faster.
So, your friend does get a tad of a power benefit with the Ram Air rig on his SLP Grand Prix, but not from the ‘ramming’ effect. The power comes from a free-er flowing intake.
*higher speeds = car speed NOT engine speed (AKA RPM)
Compressors, fans, pumps, or any similar devices create pressure differential. If you supply air at atmospheric pressure and the compressor adds 50 psi, you get output at 50 psig (gauge). If you supply air at 5 psig, you get output at 55 psig. Ram Air would definately help although the effect might be very small. I agree that cold air is probably more important than pressurization.
yoyodyne is correct. The idea is to get more air into the engine to allow it to burn more fuel. This means increasing the density and/or volume of incoming air. Cold air is denser as is compressed air.
I agree with the posters but what is total BS is:
“Of course right now he has the super charger off because of maintenance and would not even pop his hood.”
You said “at work” so I assume the car is at work - meaning it is being driven. I find it extremely hard to believe that your friend has taken off the SC and installed a normally aspirated intake and modified the computer so that the car can be used without the SC.