http://www.vetteguru.com/ramair/

Its true.

 

wow, flashbacks to junior year. i need a beer...

his reasoning is sound...

 

This is some serious bs from a probable mustang owner This guy obviously doesn't know the purpose of ram air. The purpose of Ram Air, like exemplified on the WS6 and SS, is to assist the air into the intake tract in an effort to take some of the load off of the cylinders during their intake stroke--Ram Air's task is Not to compress the air so that more air is squeezed into the cylinder as is the task of a super/turbocharger. Ram Air benefits the power making process in the same way that a better flowing intake or freer flowing exhaust does---Meaning these two "free up" power from the engine by allowing the engine to work less on getting air into and out of the cylinders-that is how you can gain power from these mods---Remember the engine is a big air pump--any modification that allows for less strain on pumping this air into and out of the engine will allow for more power output from the engine---this Includes Ram Air.

 

the phenomenon that introduces A/F into the cylinder is a lower pressure in the cylinder than that of the intake manifold. the only way to increase the A/F flow rate into the cylinder is to increase the partial pressure of air in the intake manifold. what this guy is saying is that ram air will not increase static air pressure in the manifold because air is typically considered incompressible below 0.3 mach (that's where i disagree with him, he states 0.5 mach).

 

You are looking way too deep at this matter. It is Much simpler than you are perceiving it to be. Ram air does not aid the power making process via increasing pressure into the combustion chamber, it simply assists the air in getting to the cylinder. This doesn't have any effect on a/f ratios. It is like when you replace your exhaust with a better flowing one or your air box/lid with a better flowing one--it simply frees up power--allows engine to produce at its potential.
Think of it like this: Say you have a vacuum cleaner--you turn it on and its sucking away--take your hand and place it over the end of the hose to block its induction of air--notice the vacuum changes tone--the sound indicates that the motor is struggling--remover your hand and the vacuum runs like normal. Now think of a plain non- ram air firebird/camaro and liken it to the exapmple of the vacuum with your hand blocking the end of the hose---then you have a ram air firebird/camaro-it would be analogous to the vacuum running without your hand blocking the end.

*Note----The benefit of the ram air obviously doesn't take effect until the car is in motion--the faster you go, the higher the benefit.

 

don't want this to turn into a 5 page post, so, i hope you don't think i'm trying to argue. it's just that i enjoy these technical discussions. makes me feel like my schooling wasn't a complete waste. i really enjoyed my fluid mechanics class, so the article was an interesting read for me.

i agree that as the air enters the intake system at higher velocities, the engine has to perform less work to pull air into the cylinder. this benefit is obviously better at higher speeds. however, i don't think you can neglect air pressure at the intake manifold. that is the driving force behind air entering the cylinder (in conjunction with the cylinder creating a negative pressure during it's downstroke). i do believe that higher air velocities create higher stagnation pressures when the air's kinetic energy goes to zero, or close to it. the air intake system is not a constant flow, it is in pulses as intake valves open and close. so at some point, there is stagnation of air in the intake manifold. so a higher velocity of inlet air would create a higher stagnation pressure.

although air is theoretically incompressible below 0.3 mach, there will be some slight compression noted since we don't live in a theoretical world.

i also believe that pressure losses across the intake ports and valves is much higher than any other pressure losses in the intake system. so any increases gained by higher stagnation pressure are small compared to the losses across the valves.

i guess what i'm saying is that gains would be minimal at best. i think we agree there...

there's also throttle position to consider, which, at any other position than WOT would create a choked flow condition, but i've said enough. this post could go on forever. i'll just stop now...

 

the term "minimal" is subjective. 10 hp from a catback is probably considered minimal, but it is still a gain--and I believe that ram air would realize this margin.

True, but if anyone needs power, it is when they want to go fast--and when they want to go fast, they go WOT. So, the choked condition isn't an issue imo.