When f4i gets tested, or any other bike with ram air induction, on a dyno for HP rating, it usually rated at 95-98HP.
I was wondering how much HP boost ram air adds in higher speeds.
Since the bike is stationary during dyno tests, ram air gain wouldn't be reflected on charts. Do you guys happen to know?
Thanks for the feedback guys!

 

any dyno should have fans to keep the 'cool'ant cool. High end dynos prob have speed matching type fans. My guess is 100hp tops.

 

I think you misunderstood the question. Hes not asking if the fans keep the bike cool or not, hes asking if their is a power gain to the ram air (natural forced induction).

 

The actual "Ram Air" function usually only adds a few hp. I remember a story in motor trend about the ram air functionality of the firebird V8. Seems like it is only 5-10 hp on those big engines. Problem was that it was just such a miniscule amount of air that is actually pushed into the engine by travelling through it. Then the air had to go through an air filter which slows things down a lot. You'd only see real hp gains at 50+ mph. A turbo or supercharger is much more effective.

On our bikes we don't really have functional ram air either. The air goes in from the front and then goes through constrictive air ducts, then through a restrictive air filter, then into the engine. At freeway speeds there may be a small hp gain from having the air inlet facing the front. Over freeway speeds I'd say definitely. The engine by itself is very, very good at sucking air in. Every time that piston travels downward it sucks in air. It doesn't need to be force fed to perform well enough for daily use. One of the real benefits of any vehicle getting a lot of air from the front is that the air coming from the front is usually some degrees cooler than the ambient air around the engine.

Since no one tests their bikes at speed I'd say that they really don't count on much extra hp from a Ram Air function.

Sorry, that went a bit long....

 

No misunderstanding... The purpose of the fans is to keep air flowing through the radiator to cool the coolant. As a result, air is also being blown into the ram air ducts. Keep in mind bikes are designed to go much faster than even big hp cars. Therefor, much more pressure being forced into cylinder. On the flip side, bikes have much higher redlines than cars and therefor would 'suck' air more times per second. Back on the original side though, cars have higher displacement and would require much more air per 'suck' (Welcome to endlessly debateable). And any system has to go through restrictive ducting and filter. The design of the ducts is also critical. Much like in the cylinder head, a longer, narrower duct will create higher velocity to smash the air into the cylinder. Where a wider shorter duct would allow more air to be available for the cylinder to suck in. The former creates more low end power, the latter more high end. And of course cooler air/fuel is always better. Regardless, you are not going to get to 100% volumetric efficiency (amount of air space in cylinder vs. how much actually gets in there) and beyond without a super/turbocharger. Thats where you see REAL power gains. But that comes along with bigger injectors, fuel pump, pressure regulator, yada yada yada...

I feel like ive gotten WAY off topic.

Still, we're talking about less than 5% gains most likely. That is...Until you start reaching speeds around the sound barrier.

My bad for rambling. No disrespect meant. This is why I try to keep from posting...

 

All the specs I find on our bikes state they have 108 - 110hp, tho I am sure thats at the flywheel and not at the wheel.

 

I remember reading somewhere Honda claiming about +5 HP gain with RAM air at high speed.
Anyway, thanks for the input again guys!
-Ben-

 

all the testing honda does is on a engine dyno with forced ram air thats why they say 110 hp not whp a stock f4i has about 91 whp i know a f4i with full exhaust race filter and PC3 makes on average 103 whp no ram air. one with a ported head cams full exhaust and race filter made 118whp and the head was milled down and tuned on 110 octane. on 100 octane it make like 116whp also no forced air. just remember 2-3hp gain on a bike can be noticed.