GStwin.com GS500 Message Forum

Has anyone designed or though up a way to get ram air on a GS?

I'm trying to think of a good way to do it and would like some other opinions.

Thanks

I heard somewhere that ram air can damage the engine if it is not set up properly.  

I was going to put some scoops to create ram air but after a little investigating it looked to be too much of a hassle and worry.

why?

R.A. is a marketing tool....

no real effect until 100-120 mph

Quote from: werase643why?

R.A. is a marketing tool....

no real effect until 100-120 mph

werd, speaks the truth..

Quoteno real effect until 100-120 mph

true for most part, Ram air doesnt really work below a certain airspeed. its basicly a funnel that scoops air and crams itself down the intake track.  its also very dependant on DISPLACEMENT.   smaller engines dont need quite as much forward speed (airspeed) as they dont breath as much.   take a moped (peddle type) intake carb faces the back of the bike, turn it around and put a scoop on it, sure dirt will get in but so will alot more air  after about 25mph and its a noticable differnce.

the biggest problem is jetting ram air isnt allways a constant and really works better on FI then carb engines to keep the mixture right.  the same principles apply if you were using a turbo with low boost, say 3lbs you still have to seal area;s of the carbs or vents into airbox,  the low boost from ram air might not need a fuel pump to overcome the airpressure pushing the fuel back up the line but then again, it might , then your talking pressure regulation as well.

you could do it, and it might show some gains but not sure it would be worth the headache of trying to figure out the fuel curve needed for a CV carb. FI would be alot easyer for sure

Ram air works.  It effects intake charge at ANY airspeed but starts to have its most impact at higher airspeeds.  It doesn't increase air flow so much as increases the air pressure within the airbox so that the intake stroke draws more mix.

The tricky part is that there is a 10% or so in volumn between 0 airspeed and max effect. Jetting for that difference is the hard part. Jetting for that can be hard and one of the reasons carbed bikes were rare or had elaborate intake plumbing to compensate.

The GS is difficult to rig for ram air because its an aircooled side draft engine. The ramair can't block the cooling air to the engine. You have to get high velocity air around the engine and into the airbox.  I've thought might beable to place a scoop under the forks and run a duct up over the cylinder agains t the tank and into the airbox.  Never got around to trying it, but it should be doable.

perhaps a k&n lunchbox would be better worth your time, I'd place my money on the fact that ram air would not surpass the noticeable difference on a GS as a lunchbox would....

tuned properly, you would loose your money.

Quote from: werase643

R.A. is a marketing tool....

no real effect until 100-120 mph

Your a Marketing Tool.   Im  Joking!!!    

Ram air is not just a marketing tool.   Here is a example:  The honda CBR 600 F2 does not have ram air. The F3 does.  When comparing the two bikes,  the F3 walks all over the F2.  Same displacement...  The F2 is lacking so much power that is can be compared to an SV650.  

Im sure there are other improvements to the motor that contributed to this but not that many.     It is like comparing an Carborated motor to a bike with F. I.  There isnt much comparison.  

Why do people port and polish heads?  To get air in/out of the cylender faster.   Any pressure pushing air into the cylenders will help.  Hence the compression gets higher and with the right jetting... More power.

Will it be much help?  I dont know.   I do know that it will help some. It is on my race bike and any increase in performance will help.    The only thing that I know is that EX500's and Monster 620 have about 10 HP on the GS and anything that I can do to decreas that gap I will do.

Just routing a pair of hoses from the front to supply cooler air would be a benefit over sucking hot air off the motor. How much benefit...dunno?

[quote="falcon0321" ]


 The only thing that I know is that EX500's and Monster 620 have about 10 HP on the GS and anything that I can do to decreas that gap I will do.[/quote]

10 hp in your dreams
try 15-25

ever wonder why ram air was used by kawasaki first.....
they built airplane engines....
you gunna need a big friggin airbox
and a straight shot from the high pressure point to the big friggin air box
also need to pressurize the carbs and fuel tank
or get a fuel pump

lots of R & D there skippy.....
but hey bust a nut if you want

The "ram" effect at 100MPH is equivalent to about 4.94" WC at standard atmosphere and water density.  That's about .17 PSI.   ;)

Total power increase assuming zero loss would be on the order of 1.1%.  Now, ram effect increases as the square of the change in airspeed.  Double the airspeed, quadruple the ram effect.  At 200 MPH, the ram effect is about .68 PSI.  Total power increase:  about 4.6%.  Still no substitute for a turbo or blower.

Best case I could see a power gain of 5% over the stock configuration with careful design.  i.e. not much more than the K&N lunchbox.  You wouldn't see anything under 100MPH though.

Do you have a reference for your figures?

Not that I don't believe you, but yours are a bit... pessimistic than those I've seen.

oh yeah baby i want to see a gs go 200mph....with a 5 % increase in power.....

Quote from: werase643

10 hp in your dreams
try 15-25

Im pushing 53 HP as I sit right now.  Ive race 2 seasons on this motor and it has no signs of letting go yet.

2 mil over high comp pistons, cams, shaved head, timing, K&N pod filter, V&H oval, ...

Quote from: GeePThe "ram" effect at 100MPH is equivalent...

Not to bust your balls or anything but do you know or could you figure out what that would relate to compression changes?   (As in 130psi  increase to 140psi with ram air...)

Up to 120 mph when the boost hits 20mb, we're only talking about the odd bhp. From then on it gets progressively stronger. As the effect is speed relative, it's at its most pronounced at very high velocities; the faster you go, the stronger the boost. But, hey, how many of you ride at 150 mph on the street? Never mind, don't answer that.


and this is on a 125 HP zx-9.....

other article below....
4-7 hp gains on 600-1300cc bikes.....translateed to a GS......at 38-42hp
back to my first response.....why?
....1- 1.5 HP MAX!!!!!


i did a quick search....

http://sportrider.com/tech/146_9910_ram/

http://sportrider.com/tech/146_9912_ram/

http://sportrider.com/tech/146_9508_ram/

Quote from: werase6434-7 hp gains on 600-1300cc bikes

Ja, so when a bike of that size is racing in superbike, seeing 100+ a lot, and you're not allowed to turbo... and 5hp will make a difference... it makes sense.  Beyond, well, as you say.  :)

Quote from: werase643
back to my first response.....why?
....1- 1.5 HP MAX!!!!!

Racing.  Riding ability can carry you only so much.  When your talking about a bike with lets say 40 Hp, thats 2.5-3.75 % increase in power.   That is a pretty good jump.

Quote from: Roadstergal

Quote from: werase6434-7 hp gains on 600-1300cc bikes

Ja, so when a bike of that size is racing in superbike, seeing 100+ a lot, and you're not allowed to turbo... and 5hp will make a difference... it makes sense.  Beyond, well, as you say.  :)

it makes no diff when everybody is doing it....
heck they don't even advertise it anymore, do they? :dunno:

Quote from: falcon0321

Quote from: werase643
back to my first response.....why?
....1- 1.5 HP MAX!!!!!

Racing.  Riding ability can carry you only so much.  When your talking about a bike with lets say 40 Hp, thats 2.5-3.75 % increase in power.   That is a pretty good jump.

and another great racing furmula.... 1 HP = 7 lbs
you can push a lighter bike just as fast with less power

get off your butt and start running
or
even better stated by a friend.... "i'll take a dump before i hit the track and gain a HP"

Im pushing 53 HP as I sit right now. Ive race 2 seasons on this motor and it has no signs of letting go yet.

2 mil over high comp pistons, cams, shaved head, timing, K&N pod filter, V&H oval, ...

so a built GS is still down on a stock EX500....55HP

and i have seen a fat man on a FAST EX600+ pumping 96 hp
he replaced the cases every 2-3 races...wear item!!!!!!

named Stromann, ya might have heard of him
they changed the rules in WERA because of him

hope you dont have to race with a 10 mph tail wind.

Quote from: JamesGDo you have a reference for your figures?

Not that I don't believe you, but yours are a bit... pessimistic than those I've seen.

No problem.  I'm glad to share.

First off, I provide this link to pitot-static airspeed measurement.

To estimate the dynamic pressure "ram effect" we use a simplification of Bernoulli's theorem.  (At least, that's how I like to remember it.)  This will work to roughly 220 MPH.  Above this speed, compressibility needs to be considered.

q = (1/2) (rho) (V squared).

Where:

q:  Dynamic pressure, Water Column (WC)
rho:  Density of air at standard atmosphere, .002377 slugs/cu.ft.
V:  Velocity, feet per second.

So...  At 100 MPH (146.67 FPS) the dynamic pressure is equal to .5(.002377)(146.67 squared) or .17PSI

To determine the zero loss power gain is straightforward.  The ISO standard atmosphere is 14.696 PSI absolute.  Air density is directly related to pressure, volume, and temperature.  If we assume volume and temperature are constant, the amount of combustible air available is directly proportional to the delivery pressure.

A GS 500 with no ram air has a maximum possible induction pressure of 14.696 PSI.  A GS 500 with zero loss ram air at 100 MPH will have a maximum induction pressure of 14.696 + .17 = 14.866PSI.  That's an increase of 1.15% of available combustible air in the cylinders.  Therefore, if the fuel scheduling is increased accordingly the engine should put out 1.15% more power not accounting for mechanical losses.

This simple computation works because it's relative.  We know how much power the GS puts out under a standard atmosphere.  Therefore we can, within reasonable limits, "scale" the effect of air density.  

Errors:  I assume in my calculation that the speed of the airflow through the intake is 0.  Obviously, this is not the case.  I do this because the cross-sectional area is unknown.  The larger the cross-sectional area of the intake duct, the lower the speed through the duct, and therefore the more ram air recovery.  To get a closer figure you need to subtract the speed of the air through the intake duct from the forward velocity of the motorcycle.

It can be argued that the change in relative density affects the viscosity of the working fluid and results in a slight error due to fluidic drag.  This is true.  The error is negligable.

i was searching on ram air...but couldn't find it

KEWL
thanks for posting source!!

i was also looking for the info on air box resonance design / theory....
quick ugly.....  http://www.chrysler300club.com/uniq/allaboutrams/ramtheory.htm

there is more to it than duct taping on some drier hose.

No problem.

Couple other things that came to mind...

To recover as much ram air as possible you need to have total stagnation around the inlet to the duct when the duct through velocity is zero.  An efficient ram air recovery system might be a tube up to several inches ahead of the stagnation point on the front of the fairing and aligned with the "direction of flight" like a pitot tube.

An inefficient design might be an inlet flush with the fairing and aligned with the "direction of flight".  It's less efficient because the air never stagnates in front of the inlet when the through velocity is zero.  That's because the fairing has "deflected" it to some angle less than 90 degrees before it passes the inlet.  The velocity of the potential inlet air is no longer in-line with the "direction of flight".

The NACA technical server could be of interest.  http://naca.larc.nasa.gov/  NACA technical notes are notes and reports on actual testing of all kinds of things aircraft-related.

Pipe flow is a very complicated subject, even for something as simple as a round tube.  Changing area compound curve ducts are impossible to calculate without software.  Even then, I hear it's hit-and-miss.  However, all you need to develop a duct empirically is a calibrated air source and 20 ft of plastic tubing.  (Water manometer.)

Quote from: werase643i was also looking for the info on air box resonance design / theory....
quick ugly.....  http://www.chrysler300club.com/uniq/allaboutrams/ramtheory.htm

there is more to it than duct taping on some drier hose.

Most certainly!

I can recommend:  http://www.bentleypublishers.com/product.htm?code=g309

Quote from: werase643
and another great racing furmula.... 1 HP = 7 lbs

I completely agree.  I heard it was around 10lbs though.  I like your number better.    

I have already made the bike as light as I can and I am pretty thin myself ( there is always room for improvements).  As it currently sits, I have the bike fully faired and I am even debating if the extra weight is worth the better aerodynamics.   I could feel that it hurt my braking so I added a 2nd rotor to fix that.  

We predominately race at BIR where the front straight, turn 1, and turn 2 can be taken at full throttle.  It is about 1.5 miles and aerodynamics do play a facter.   This, all out part of the track, is mainly why I am debating RA.   1.5 mi at 120+ mph is definately worth looking into RA.

guess you could set it up anyway, if nothing else, it will add cool air in the low to mid range and alittle bump up top where the GS peters out.  why not give it a shot anyway

The 636 sees a 9rwhp max gain with ram air.

The biggest problem with ram-air on a carbed bike is keeping the pressures equal throughout the carb.  High pressure in the vortex + and low pressure in the bowls = no fuel.

one would need to put a vent tube with a check valve into the tank so the takn can be presureized, OR use an electric fuel pump with a regulator to maintain a constant pressure.

Quote from: Blueknytone would need to put a vent tube with a check valve into the tank so the takn can be presureized, OR use an electric fuel pump with a regulator to maintain a constant pressure.

That wouldn't work, and you'd need more.

Ideally, you would need to pressurize the float bowls...they'd actually be best fed off their own seperate ram-air tube.  You don't want a pressurized fuel system.  What you want is equalibrium between the vortex and the bowls.

On top of that you would need stronger floats.

Kawasaki had the BEST ram-air systems on any carbureted bike.  You should look into that.

Sure is nice to see someone present a fact-based conclusion vs. emotion based he/she/my uncle said.

:cheers:

The simple way is to enclose the carbs within the pressurized air box.

You usually don't have to worry about the pressure differental from the tank. Gravity overcomes it.

To make things simple, yes, the fuel system probably needs to be pressurized.

The carburetor on the GS as built is not designed to work with an induction pressure higher than the surrounding air.  The best solution is to pressurize the float bowls and fuel tank.  Alternatively, a carburetor change could work too.

It's not possible to just pressurize the carburetor float chamber.  That may solve the metering problem but it won't solve the fuel supply to the carburetor.  With 1" of gas in the tank the GS has about 6" of head.  If we assume the density of fuel is 6.14 lbs per gallon, a 6" head of gasoline will be about .16PSI.  This is a rough estimate of the head a GS will have with 1" of fuel in the tank.  

So, at a pressure of .17PSI in the float bowl fuel is going to flow back into the tank.  Not good.  This is why the tank needs to be in equilibrium with the float bowls and the induction pressure.

figure it wouldnt be much differnt then the turbo bikes, the carbs are sealed in a way that the bowls see the same atmosphere the Plenum box see's and the fuel is pumped via electric pump, regulator and return line.


if the tank and floatbowls are pressurezed to the same psi even if its low, then the gravity flow fuel system will still work like normal. IF your just pressurizing the bowls and not the tank, then the fuel flow will slow down as airpressure is trying to make its way from the bowls past the float needles and up the line into the tank.    Putting a pump inplace with a regulator would be more then enough to over come the built up in pressure.

These are all really good ideas.  Thanks for the help.  

One thing that has not been discussed is the slides.  They also operate on the vaccum that is created.  With the forced air creating a "lower" vacume force,  do you think it would be sufficient changing the air/fuel mix or should that be looked futher into as well.

From the sounds of it. It might be easiest to get some carbs that are from a ram air bike and set up tubing just like the factory's...or look into FI...