Article topic: Does ram air work?

Yeah i would wanna see 5-10 runs averaged with and without that intake before i'd give 8HP ona 400HP motor and legitimacy...

I think ram air does make power but not from raming air in and causing positive pressure, it does however make a smoother intake, cool air, and any speed the direction of the car adds is a plus, but i doubt its causing positive pressure anywhere in the intake tract, what COULD possibly tell you is a Vac gauge in the intake prior to the TB than you can compare vac reading in each gear at a given RPM/SPEED....

If the 8HP gain on that intake was measured via a standard dyno run, then by definition that 8HP does not come from the ram-air effect.

Say you put this car on a wind-tunnel dyno, and do a standard run, fans off, and get 408HP vs. the stock 400HP. That 8HP is from intake path differences. Now say you fire up the fans for a 60MPH wind and get 418HP. That 10HP gain would be from the ram-air effect (at 60MPH).

bigbens6 wrote: ... but not from raming air in and causing positive pressure...

Why not? Positive pressure does provide a greater volume of air, which if used correctly will increase power. The real question is how much?

bravenrace wrote: Why not? Positive pressure does provide a greater volume of air, which if used correctly will increase power. The real question is how much?

Because the potential positive pressure increase that could be caused by the forward movement of the vehicle does not exceed the negative pressure created by the sucking of the engine whether or not the car is moving, so there is not a gain in pressure.

Ever put your hand over the intake of a running car?

It does, however, make more fresh air available for the engine to pull in, as I noted earlier.

SVreX wrote:

bravenrace wrote: Why not? Positive pressure does provide a greater volume of air, which if used correctly will increase power. The real question is how much?

Because the potential positive pressure increase that could be caused by the forward movement of the vehicle does not exceed the negative pressure created by the sucking of the engine whether or not the car is moving, so there is not a gain in pressure. Ever put your hand over the intake of a running car? It does, however, make more fresh air available for the engine to pull in, as I noted earlier.

-10 psi to -8 psi is a positive pressure increase. I think that has to happen to cause any gain. Think of it as less pressure drop.

In reply to SVreX:

Yeah, of course there wouldn't be any positive pressure, but it would help the air flow by numerically lowering the negative pressure.

As noted earlier, I agree.

And, as I noted earlier, it worked on my car.

Haters gonna hate!

ask the NHRA Pro Stock guys what the ram air effect does- i don't know about now, but about 20 years ago i read an interview with Warren Johnson that said that they actually get an increase in trap speed with a head wind of up to 20mph thanks to the design of the scoop, but even back then he was lobbying the NHRA to let them go to efi so they could lose the big ugly scoop and go with a lower profile rear facing cowl induction setup..

now for my experience with a home brewed setup i did on my 71 Nova.. i had a dual snorkel air cleaner from which i ran dryer ducts down below the front bumper.. it was worth a solid 2mpg over a 14X4 open element air cleaner, but wasn't worth any trap speed on a 1/8 mile drag strip compared to the same housing with no hoses, a single snorkel with and without a hose hooked up, and the 14" air cleaner with a 3" and 4" tall element. i made 3 runs with each of them back to back to back on the same night at a "grudge race" night over a period of about an hour and a half with no other changes to the car.

with the hoses on the car, i had to replace a few elements because bees, large flies, and dragonflies would get rammed into the housing hard enough to poke holes in the paper element, so there was some ram air effect going on there.

my first experience with a similar setup was on a 76 Monte Carlo that i had back in '92 and '93.. i pop riveted a second snorkel onto the stock air cleaner housing and added a second stock air intake above the radiator support.. i "rebuilt" the engine with a $159 kit from Northern that came with the smallest cam they had, added headers, and changed to a really old WEIAND dual plane intake with an adapter to run the stock quadrajet. the trans was the stock TH350 3 speed auto and it had the stock 2.56 gears. i don't know how much power the dual ram air setup added, but i could get 30mpg with that car and the carburetor would be cold to the touch and have water dripping off it on 100 degree humid days..

i'm hoping for a similar effect on my Camaro with this ram air setup that uses some of the factory engineered GM stuff to pull air from the high pressure area in front of the radiator:

but when talking about later model air boxes, the biggest effect you will see is by opening up the airflow path into the air box.. my 94 Caprice was forced to breathe thru a baffle that was less than an inch high and about 3" wide.. i removed that baffle and attacked the lower part of the air box with a 1" hole saw and my utility knife to open it up.. even without adding a cold air pickup or any ram air setup, it gained a noticeable amount of power and about 3mpg's- plus it just sounded so much better.. the same experiment on my 97 Cavalier with a 2.2 and a 5 speed resulted in a little less torque, a stupid sound, and no gain in mileage so i plugged the holes i made with some sheet aluminum and self tapping screws..

Sport Rider Magazine Dyno test article

Sport bikes are designed to take advantage of 'true' ram air at high speeds.

Here's a better link with actual air box pressure plotted vs. mph: linky

cghstang wrote: Sport Rider Magazine Dyno test article Sport bikes are designed to take advantage of 'true' ram air at high speeds. Here's a better link with actual air box pressure plotted vs. mph: linky

Good find!

bravenrace wrote: Why not? Positive pressure does provide a greater volume of air, which if used correctly will increase power. The real question is how much?

Because i dont think you can achieve a positive pressure above ambient in a street car practically.

SVreX wrote: Because the potential positive pressure increase that could be caused by the forward movement of the vehicle does not exceed the negative pressure created by the sucking of the engine whether or not the car is moving, so there is not a gain in pressure. It does, however, make more fresh air available for the engine to pull in, as I noted earlier.

this essentially, RAM AIR is not less vacuum air, it implies (to my ear) a positive manifold pressure almost like a small turbo effect. be it .5PSI above ambient, it implies to me a positive Pressure ratio.

tuna55 wrote: -10 psi to -8 psi is a positive pressure increase. I think that has to happen to cause any gain. Think of it as less pressure drop.

Yeah a change from -10 to -8 would be an improvement worth noting and striving for, my point was that ram air is not going to net a positive pressure ABOVE AMBIENT, I agree fully that it could being intake vac closer to 0 vac for sure but... By that standard of simply vac, any SRI or CAI probably does this, does it make it ram air, i would argue not it does not.

cghstang wrote: Sport Rider Magazine Dyno test article Sport bikes are designed to take advantage of 'true' ram air at high speeds. Here's a better link with actual air box pressure plotted vs. mph: linky

I am not claiming it is not possible to get RAM air on a car, but the ducting on a bike vs engine size is much more practical than a car, and as engine size goes up so must inlet volume or speed for a given HP plus you have to account for losses in the rest of the intake tract and bikes tend ot have a much shorter and direct path to the intake than a car....

Dude you are picking at nits. We're all talking about the same damn thing (less pressure drop), it's just called "Ram Air". If you really have a beef with that, you need a time machine to go beat down some marketing suits at Pontiac in 1965. Yeeesh!

In reply to bigbens6:

I think you are only considering something ram air if it provides a positive pressure. But it doesn't have to in order to increase power. It only needs to reduce negative pressure enough to make a noticeable difference.

novaderrik wrote: ask the NHRA Pro Stock guys what the ram air effect does- i don't know about now, but about 20 years ago i read an interview with Warren Johnson that said that they actually get an increase in trap speed with a head wind of up to 20mph thanks to the design of the scoop,

Given the open and free design options on a drag car this does not shock me, now do it on an accord or modern day mustang, thats a different animal.... and again was that 20mph due to less vacuum or some form of positive manifold pressure? im betting it was less vac, freer flowing, just cause the wind did not have ot change direction f\to go into the custom designed purpose built intake on a dedicated race car with a massive budget..

Ram-air is simply insignificant at automotive speeds and atmospheric conditions. It's just too easy for the air in the ram-air 'chamber' to spill back out the inlet as more air is pushing in.

Picture your faucet filling up a soda bottle. When the bottle gets filled, the water flow gets a little chaotic at the mouth; the faucet stream is trying to 'ram' in, and the contents of the bottle are pushing back out. For convenience, the intake air and airstream can be visualized as behaving similarly to a fluid.

11110000 wrote: Ram-air is simply insignificant at automotive speeds and atmospheric conditions. It's just too easy for the air in the ram-air 'chamber' to spill back out the inlet as more air is pushing in. Picture your faucet filling up a soda bottle. When the bottle gets filled, the water flow gets a little chaotic at the mouth; the faucet stream is trying to 'ram' in, and the contents of the bottle are pushing back out. For convenience, the intake air and airstream can be visualized as behaving similarly to a fluid.

I find it simpler to picture an engine consuming air. unless the throttle closes, it does not "fill up", it is sucking in air and the power required to do that is a pumping loss. If the engine spends less energy sucking in air because of a pressure drop decrease at the inlet valve the engine gets to spend that energy elsewhere. results may vary depending on speed, NA vs FI, inlet track length volume and shape, yada yada yada, but it is a measurable and known area of design.

The engine does not suck air. Atmospheric pressure tries to fill the vacuum.

Just being picky.

If the vacuum (ergo, "sucking") didn't exist, then the atmospheric pressure wouldn't be filling anything it hadn't already filled.

Engines suck.

Turbos blow.

YOU CAN'T EXPLAIN THAT!

bigbens6 wrote:

novaderrik wrote: ask the NHRA Pro Stock guys what the ram air effect does- i don't know about now, but about 20 years ago i read an interview with Warren Johnson that said that they actually get an increase in trap speed with a head wind of up to 20mph thanks to the design of the scoop,

Given the open and free design options on a drag car this does not shock me, now do it on an accord or modern day mustang, thats a different animal.... and again was that 20mph due to less vacuum or some form of positive manifold pressure? im betting it was less vac, freer flowing, just cause the wind did not have ot change direction f\to go into the custom designed purpose built intake on a dedicated race car with a massive budget..

they are actually pretty restricted on what they can do to a Pro Stock car- they have very strict rules in place for the scoops and other aero pieces.. actually, the whole car is pretty closely regulated.

and the performance gain with a 20mph head wind is compared to no headwind or even a tail wind.. i think you might have misread me as saying that they gained 20mph in their trap speed, when i was talking about the amount of wind as measured standign on the track... i can't remember where the article was- probably Hot Rod- and it was at least 20 years ago..

See? It's doing it again. Having concrete numbers would make these arguments much better

gh0st wrote: See? It's doing it again. Having concrete numbers would make these arguments much better

only because someone doesn't know that "vacuum" and "pressure" are two sides of the same coin..

For our next argument, which is faster, a turbo or a supercharger?

(yes, I said faster, not more efficient at a given RPM, etc)

In essence a ram air system allows the engine to use less of its power to fill the cylinders with cold fresh air. Less parasitic loss, more power to the wheels