Cold air intake / ram air?

[txironhead]

Then it would seem that the simplest, most effective way to get "cool" (cooler at least) air to the carbs would be to create a heat shield between the engine and the carbs. A sheet of stainless or aluminum with some stick-on heat shield like is used on race car firewalls and floorboards should work. I just don't see a workable way to create "ram air" with the same amount of air going to each carb without it being very cumbersome, difficult, and just plain goofy looking.

One thought that came to mind was to create a box that covered all four carb intakes, similar to the "tin pan" air filters of the 70's, with an inlet pipe that was ducted to create the ram air effect. The box should regulate and disperse the air pressure evenly, and then you'd only need one pipe for the ram air. Couple that with the heat shield, and it might actually be a beneficial system.

Of course, that still leaves the problem of where to put the ram air duct. Downwards would pick up water and debris, to the side would cause leg placement issues, and there's just no room between the top of the engine and the tank. Routing it back might get you to some slightly cooler air (would still be somewhat in the cooling fins' backlash) but no ram effect.

Okay, I have a headache now. I'll let the master fabricators, carb experts and insane Einsteins have at it for a bit.

[Clone]

Thinking of starting pretty simple with a cold air intake. Colder air = denser air = more oxygen = more fuel can be added = more POWER. Right?

The design would be pretty simple to start, much like the cold air intakes you see on cars. Take a straight tube or hose, clamp it to the intake of the carb on one end, and clamp a pod air filter on the other. Make the tube is long enough to get cooler air than would be available via a standard pods setup (ie not right by the engine). Richen the jetting a bit to suit.

Kinda like this. Imagine one tube/hose and one pod filter "feeding" cooler air into each carb.



Is this a stupid idea or could this actually have some benefit?

Stupid Idea. Why do you want to use hot air that has already gone through your radiator!! A cold air intake is to pull air from outside the engine compartment. I got the best results with the New Beetle, by taking off the U shaped portion of the air intake and connecting it to the grille by the fog light with ridgid suction hose, COLD RAMMED AIR, better jam on the highway and the intake noise was way out front.

But on a bike, speed would determine your airflow, and then you would need to rejet to handle the different flow.

[chef1366]

Just get a turbo. MR.Turbo
:-D\\/;-)

[first timer]

here is your heat shield

http://yoshimura-shop.netmove.co.jp/ap/dtcat?p=6/7/8&s=39/115/120&l=en&t=/c_carb1_e/c_carb1_e/c_carb2_e/c_carb3_e&d=326

[txironhead]

Here's a thought: would the increased drag nullify the benefits of the cold air?

[Mark M]

Here's a thought: would the increased drag nullify the benefits of the cold air?

Given that bikes (especially unfaired bikes) are such aerodynamically dirty machines I can't imagine you could even measure an increase in drag. You can easily gain 5% or more in HP just with cooler air. It will have almost no effect on top speed (power required for any speed is proportional to speed cubed, so 5% amounts to almost no change), but you would feel a noticeable difference around town in acceleration. And that's where all the fun is, isn't it?:-D

Mark

[txironhead]

You know, you'd think that motorcycles would benefit greatly by reversing the head, allowing the carbs access to the cool air from the front of the engine and allowing the exhaust to be closer to it's exit point. However, from what I've learned, it has been attempted many times by different manufacturers and met with dismal failure. The "why" has never been convincingly answered, just that they tried and failed.

I understand that having the carb inlets at the front exposes them to rain and debris, but look at the "ram air" intakes many Harleys and V-Twins are running now, basically just a snorkel facing the front of the bike. They meet with the same problems.

[Ironriot]

I was wondering the same thing about the whole flipping the head thing also but figured if it worked the manufactures would already be doing it. Maybe they don't do it because of turbulence? I know that on high speed cars you can't just have an open scoop because at top end the air is too turbulent and would screw up the whole induction thing. I dunno I'm just thinking outloud. As for the whole ram air thing, it has to work. Kawasaki has it on their bikes and people claim that they can actually feel the ram air effect

[Mark M]

I was wondering the same thing about the whole flipping the head thing also but figured if it worked the manufactures would already be doing it. Maybe they don't do it because of turbulence? I know that on high speed cars you can't just have an open scoop because at top end the air is too turbulent and would screw up the whole induction thing. I dunno I'm just thinking outloud. As for the whole ram air thing, it has to work. Kawasaki has it on their bikes and people claim that they can actually feel the ram air effect

Don't think that everything is on our bikes because it works better. There is a strong conservative, traditional esthetic involved in a lot of the design elements. The "reversed" head makes a lot of sense on a liquid cooled engine and has been tried a number of times. I think a lot of the failures have nothing to do with the configuration, but with other design/manufacturing/quality issues with those bikes. It certainly seems to make a lot of sense from a packaging standpoint, but none of the big 4 Jap makers have bit on producing a mass market version. Our loss, I think.

No one says that ram air doesn't work (or they shouldn't), just that the effects are very small and you need very high speeds to realize even those small gains. The gains made from a properly tuned airbox system and the cold air intake setup used on current sport bikes are much higher than ram air pressure gains, even at stupid high speeds.

Mark

[Suzukfan78]

I rememberd I read an article online in the past that tested a few different modern sport bikes and how much Hp was actually attributed to Ram Air. The Busa was one of the bikes...it didnt do the best in the test; however I was surprized how little Hp difference it made...were talking under 5Hp at significant speed. Bike manufatures ads really hype up the ram air thing. Futhermore the stock busa air box sat right on top of the throttle bodies and obvioulsy it would heat up from rising engine heat inside the fairing at legal speeds. So Im thinking that performance gains would be minimal and possibly imagined just like high octane fuel in an 87 octane machine. I will try and find the article to post...Its really interesting.

[racer54]

Just another idea...years ago, racers would take a plain piece of aluminum and mount it to the frame right behind the carbs(like on the cross braces in above picture). Idea was that it stopped the air from swirling right behind the carbs and basically create a dead(or calm) air area that the carbs could use. Supposely worked to some degree as the pro-stockers used it before they went to pressurized air boxes. Use some heat barrier of some type between head/block and carbs along with the shield and that should help.

[Mysuzyq]

IIRC, the Honda racing guys experimented with this idea, before the Kawasaki 'ram-air' trend....some might recall a pic of simple ducts running from the airbox to the front of Freddie Spencer's superbike. I think at high speeds they found it created a very lean condition, and somehow solved it by venting the carbs via tubes to the same intake duct to equalize pressure ....no, dont argue or ask for details....this I recall from an issue of 'Cycle' in my schoolboy days, so may or may not be entirely accurate.

Tony.

[Dink]

Tony you are absolutely right, if you manage to get anysort of pressurised feed to the airbox, you will also need to run your bowl vent pipes to the airbox to pressurise the floatbowls or you will run lean.

Dink

[drhermanstein]

The air close to a bike is extremely turbulent. In order to get a consistent even cool charge of air one would have to place the intake well away from the bike. The phenomenon of laminar air flow coupled with extremely odd surfaces on the bike makes it tough to get "clean" air close to the bike.

[Mysuzyq]

Tony you are absolutely right, if you manage to get anysort of pressurised feed to the airbox, you will also need to run your bowl vent pipes to the airbox to pressurise the floatbowls or you will run lean.

Dink

Thanks for confirming, Dink....it's weird how some info gets retained eh......other times, I can't seem to locate my car, in the Walmart parking lot.

Tony.