ram air/ direct flow air

[Reaper0001]

lol i was drunk when i drew that one
lol

[Mysuzyq]

Wouldn't ram air be really hard to tune for? It would lean out the faster you went...

According to an old motorcycle mag, Honda tried this before ram-air was in vogue (for motorcycles, anyway), with exactly that result. I recall the article included a pic of Freddie Spencer aboard a race CB750 OR 900, featuring two ducts that ran from the intake to the front of the bike, underneath the tank.
They finally got the bike to run acceptably (in true Honda fashion) by running tubing from the carb bowls, to the mouth of the air intake scoops.....then scrapped the idea altogether.

[loud et]

Wouldn't ram air be really hard to tune for? It would lean out the faster you went...

Btw am I the only one who chuckled at this?

no, I saw it and had to do a double take to make sure what I was seeing! ha ha funny stuff

[landspeedrich]

Ram Air Myths?

The Brit 1327 cc old skool gs bike at Speedweek had to yank off the the ram air tubes and air box sides last week.Couldn't get enough air for the 44 mm lectrons to work properly!180 hp on the chassis dyno,but not on the great white dyno?
We experience 3 to 4 psi of ram air boost,depending on temp and air density.This is with an 280 mph belly tank(maybe mach .3 to .4)Inlet size and air box design pretty important,and maybe running FI simplifies air density issues at 4400 ft elevation with a density altitude of over 7000 ft.
Thinking about trying to pickup scooped up air under motor and routing it towards SA then up to an stockish size air box.Nice radiused 2-3 inch alm tube with a automotive style rect. air filter inline at entrance to air box.Thinking this for my miler bike (Wilmington Oh). Rich

[Griffin]

Quoted from The Ram Air Myth by Dave Rodabough

Technical errors abound in this article. I'm a fluid power engineer, this guy doesn't know what he's talking about. He's read some articles and is trying to regurgitate them to "prove" his assertion.

I'll list the most blatant and easiest to understand error here:

A good example of this is Newton’s famed “law of action and reaction”, the mathematical expression of which is a succinct F=MA.

Uh.....no. F = ma is Newton's second law of motion (he doesn't even have the commonly accepted upper and lower cases of the symbols correct). That law is stated as:

"The measured net force on an object is equal to the mass of the object multiplied by the acceleration of the object through space."

He's referring to Newton's third law of motion, which is stated:

"All forces in the universe occur in equal but oppositely directed pairs. There are no isolated forces; for every external force that acts on an object there is a force of equal magnitude but opposite direction which acts back on the object which exerted that external force."

Unfortunately, the rest of the article has several other inaccuracies as well. I won't get into a dissertation about fluid dynamics at low pressures, but I will ask one thing:

Why do motorcycles equipped with "Ram Air" make more horsepower going down the road at speed than they do when strapped to a dyno?

For those who don't believe that an air intake pressure increase of 0.5 psig can make a large difference in the fuel to air mixture, you're wrong. Modern air filters are considered clogged when the differential pressure across them reaches about 15-20" H2O (which converts to 0.5-0.7 psig). If you start out with higher static pressure on the inlet of a filter, you will have higher static pressure at the filter's outlet (carb intake), with essentially the same differential pressure across the element.

Which is why racers forgo intake filters for "velocity stacks". They gain an additional 4-8" H2O inlet pressure by doing so. They can then rejet the carbs (or reprogram the fuel injection program) for the proper air/fuel mixture for the higher intake pressure.

For most vehicles ridden/driven on the street, "Ram Air" is indeed a gimmick. The intakes aren't designed correctly, and the vehicles don't travel fast enough to build enough static pressure at the intake to affect the air/fuel mixture to any noticeable extent. However, high performance motorcycles and race cars with properly shaped intakes can benefit from it at high speeds, so long as they have electronic fuel injection with sensors adjusting the fuel feed rate to match the air intake to achieve a proper air/fuel mixture.

And no, they do not need to achieve "mach 0.3" (Which is 228 mph at sea level. The author uses the "mach" term to make it seem unreachably fast.) to see an increase in static intake pressure that is needed to gain a benefit. The air in the throat of the ram air intake needs to achieve that velocity, which is doable at somewhat lower ground speeds than "mach 0.3" if the intake is designed correctly. One other thing to consider. Ram air ducts draw in cooler, denser air from the front of the bike, which is better than airboxes located behind and over engines. That alone will aid in increasing static pressures at the intake.

For example, Kawasaki has succeeded in attaining a noticeable ram air effect on their ZX12 and 14 motorcycles once they attain about 160-170 mph.

The GS1000 that this whole thread started about will see no benefits of a ram air system. If it did attain higher intake pressures at speed, it would not run properly throughout the speed range due to a changing air/fuel misture with essentially no way to "tune it on the fly".

[Steve]

This may fall into the "common sense" school of thought (which was shot down in that linked article), but my thinking is that any increase of "ram air" effect would be dependant on the size of the intake.

For example: let's say you have a nine square inch opening (a 3" by 3" square) that feeds your tube that goes to the airbox. This is going to provide a certain amount of air flow at a given speed. If it happens to gather exactly as much air as the engine is pumping, the pressure in the tube will basically be "atmospheric" (OK, it's going to be a little bit less because it's moving, but you get the idea). If you were to enlarge the opening to a 4" by 4" square, it would try to force a bit more air through the tube. If the engine could not handle any more air (due to obstructions elsewhere), would the pressure in the tube not be just a little bit higher?

Yeah, the added airflow might push a little more through the engine and pressure might not go up, but more airflow through the engine is more power, right? And wasn't that the point of this whole exercise? Not necessarily to increase pressure in the intake, but to enhance airflow through the engine.

Or we could just stick with the larger-bore, higher-compression pistons.

.

[Griffin]

This may fall into the "common sense" school of thought (which was shot down in that linked article), but my thinking is that any increase of "ram air" effect would be dependant on the size of the intake.

For example: let's say you have a nine square inch opening (a 3" by 3" square) that feeds your tube that goes to the airbox. This is going to provide a certain amount of air flow at a given speed. If it happens to gather exactly as much air as the engine is pumping, the pressure in the tube will basically be "atmospheric" (OK, it's going to be a little bit less because it's moving, but you get the idea). If you were to enlarge the opening to a 4" by 4" square, it would try to force a bit more air through the tube. If the engine could not handle any more air (due to obstructions elsewhere), would the pressure in the tube not be just a little bit higher?

Yeah, the added airflow might push a little more through the engine and pressure might not go up, but more airflow through the engine is more power, right? And wasn't that the point of this whole exercise? Not necessarily to increase pressure in the intake, but to enhance airflow through the engine.

Or we could just stick with the larger-bore, higher-compression pistons.

.

Steve, what you're trying to accomplish is an increase in the velocity of the air going through the intake, then dead head the air into the airbox for an increase in pressure [cramming 5 lbs. of poop into a 3 lb. box]. Using a smooth, rounded edge orifice in front will create increased laminar flow, cause less turbulence, and therefore more air molecules will make it ''into the tunnel''. The tunnel then needs to narrow down to increase velocity [think of a narrow river channel and how the current increases], then open into an expansion chamber where the air molecules deadhead against the air filter itself, causing an increase in pressure.

Larger bore, higher compression pistons obviously are a simple way to increase horsepower. But modern bike engines that could benefit from ram air are designed much closer to the limits on bore and compression than our GSes were. In the modern day horsepower wars, even a 2 percent increase at the upper, unusable end of the spectrum can give one manufacturer bragging rights for the year, and increase sales.

[Reaper0001]

now yall are catching on this thread is to figure out exactly what needs to happen to the air box to make more power without super or turbos
4 1 inch pipes on the carbs is stock and one 11/4 inch filter
im looking at puting a 2' filter on a 2 inch pipe that conects the 1 inch carbs together
i have another drawing for you all that yall might like even better than the first few

[Reaper0001]

sorry it took so long but here is the first ram air prototype

[Steve]

Since the whole idea here is to increase power, what are you using as your comparison tool?

Do you have a chassis dyno available or are you going to the dragstrip?

.

[Griffin]

You're not going to accomplish any performance increases by doing what you're doing here.

You will give your bike a "Mad Max" look, though.

[Reaper0001]

i have a drag stip kind of
im gonna do 0-60 tests when my new r1 throttle tube comes in and im going to do 0-100 drag tests for time im going to look at rpm gains and anything i can think of any ideas guys

[Reaper0001]

what does the mad max bike look like anyway

[Steve]

i have a drag stip kind of
im gonna do 0-60 tests when my new r1 throttle tube comes in and im going to do 0-100 drag tests for time im going to look at rpm gains and anything i can think of any ideas guys

What are you going to use for RELIABLE and REPEATABLE timing?

Not going to settle for "seat of the pants" timing or dyno runs, WE WANT NUMBERS, and make them accurate, if you dont mind.

You realize, of course, that this means before and after numbers?

.

[Steve]

what does the mad max bike look like anyway

Click HERE, take your pick.

.