Ram Air Box

[HLSASS]

Not sure where to stick this but I was looking at the Ram Air box as a way to bring some good air to the 383 stroker with a 750 cfm carb I have. Anybody use this before?

[importkiller69ss]

i was looking into it b/c it is so hot here...but i was hesitant b/c they are not that good looking i wish i could see some custom ways to get fresh air to the carb rather than the traditional open eliment air cleaner

[Zee]

I like mine:

[importkiller69ss]

did you actually notice a difference in performace or anything

[Zee]

I have not driven it so I can't tell for sure but I can't imagine it not working. Mine has a clean shot at fresh air from the grille.

[importkiller69ss]

humm i was almost going to buy that i think it was around 250 or so im interested in hearing what you have to say about it let me know

[Zee]

It's not cheap but my car has the ram air hood but I'm missing the factory air cleaner. I decent original air cleaner for a ram air car is well over $600 plus special brackets etc. Repos are available now but they still are expensive. Since originality was not a big concern for me, the airbox represented a functionally superior set up that I think looks pretty trick.

[chirizo007]

hello,

I am new on this forum. I am french so I will try to write in a good english (I hope everybody could understand).

Just to be sure I have well understand what is the RAM effect in an airbox:
it is when the inlet catches and “stagnates” (ie stop) the airflow and converts all its dynamic pressure (kinetic energy) into static pressure (potential energy) from which the engine can benefit. that is done by using a divergent shape.

I post that because I am making an airbox for an engine which has nothing upstream the throttle body (a 2l honda) and I would like to make a performant air box.

so I would like to know if it is possible in practice to use the ram effect on a road car which has only ONE throttle body, and in my case 4 in line cylinders. because if I use a little inlet (so as long as it’s large enough to supply more than the engine needs) and I diverge in a big plenum to stop the flow (convert dynamic pressure to static), after the air flow need to accelerate when it pass through the throttle body to enter in the intake manifold, so it will losse its static pressure and convert it in dynamic pressure (venturi). and the pressure in the inlet pipe will not be increased.

So in short, Ram air works if you have an intake with separeted trompets and a butterfly for each cylinders (like formula 1 engine). But that doesn't work if you have one (or 2) butterfly for all the cylinders.

I am right? I am young in aerodynamic so I would like to be sure I have well understand the ram effect.

All your knowledges and experiments are welcome.

thank you

[WS6]

True Ram Air on a street car is not possible due to the fact that you will not get the car going fast enough to ram the air in as the name suggests. What it does typically is provide a very short and straight intake tract for the air into the engine. This is a good thing regaurdless of if the system actually rams air into the engine. I have never heard the two buttflies throttlebody remark before so I have no idea if that is true or not.

Another option for any engine is to do what is known as a cold air intake. The idea is to get the intake inlet down as low to the ground as possible so that it may take in colder more dense air. This can be a problem if space is limited as you need the intake tract to be as smooth and straight as possible. If it has to twist and turn all over the place, it will not function as well.

Welcome to our peice of the internet, and your english is fine. I just hope you can understand ours

[chirizo007]

hello,

thank you, just if I can allow me : it is not really good to put the inlet as low to the ground as possible because in some case the tarmac is much hotter because of the sun so the air around it will has less density. and if you are on gravel you will catch lots of dust on you air filter.

My "prototype car" will have a max speed of about 280 km/h ( 175 miles/h) so I could think that the dynamic pressure will be interessant at this speed.

so if I put a duct of 2.8inch diameter which catches the air flow and put this duct on the throttle body. will I increase the pressure in my intake manifold at 175 miles/h?

because the theory of "RAM effect" is that you need to convert the dynamic pressure into static pressure with a divergent. and I use a simple duct.

So if there is no divergent shape, is there ram effect?

is someone who know that? or a book or website which talk about ram effect?

thank you

[WS6]

I should have been more clear. People usually put the inlet towards the bottom of the car. Which can be low to the ground. This gets the inlet away from engine heat and allows cooler air to enter the engine. This can be a better source for air versus on top of the hood which may get stagnant air due to the aerodynamics of the car itself. The dust isn't something to worry about if you run a K&N style oiled filter. You'll have to clean it more often obviously though.

As for your speeds, if built right you could benefit from a ram air style intake. However, I would simply build it as a short straight shot into the engine more so than trying to get air rammed in.

good luck. Try a google search on ram air and you should find some more scientific info