Ram Air Effect - Page 3 - Yamaha R6 Forum: YZF-R6 Forums
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post #21 of 35 (permalink) Old 05-25-2009, 01:41 AM
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Re: Ram Air Effect

does the shape of the air intake have any effect on the ramming or compression of the air coming in is that a function only of the car speed relative to the air??
does the ram air effect sort of function like a turbo charger??
how do the variable trumpets (now banned) work
do the adjust length automatically through the cpu or is it links to the timing, cams, etc. ?? does the trumpet vary over 1 cycle or only a few occasions during varying conditions during the race (humidity, temperature)?? or does it vary with throttle position??
what is the point of variable trumpets?? does the exhaust have variable trumpets??
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Last edited by Emmanuel; 05-25-2009 at 01:51 AM.
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post #22 of 35 (permalink) Old 01-15-2010, 10:28 PM
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Re: Ram Air Effect

Well from my understanding of FI engines. It has a MAS ( mass airflow sensor ) after the air box telling the ECU how much air is going in. It also has an O2 sensor to tell how much of the fuel was left unburnt and there for telling the ECU if it was lean or rich. It also has a Temp sensor to tell the ECU how dense the air is. Ram air does work better on a FI engine. The MAS is the one sensing pressure and air flow and how much actual air is going into the engine. You can also get more HP be getting a bigger housing for the MAS and reprogram the ECU for that size housing. A bigger housing lets more air get to the TB and the Engine.

PS I am new to R6-Forum. HEY. this is also my first post.
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post #23 of 35 (permalink) Old 07-01-2010, 06:47 PM
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Re: Ram Air Effect

The variable intakes are used to adjust the intake length. Over 14,000 RPM the YCCI opens and lifts the intake open. It makes the intake shorter thus increasing intake velocity and increasing HP. Longer intakes are better for producing better torque figures. When did they ban variable intake lenghts.

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post #24 of 35 (permalink) Old 07-17-2010, 08:28 AM
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Re: Ram Air Effect

Quote:
Originally Posted by Motor10 View Post
...Over 14,000 RPM the YCCI opens and lifts the intake open....
Actually that stacks lift when the RPM > 13,700 AND the throttle > 48%. They drop when RPM < 13,500 OR throttle < 48%

They also lift when you turn off the bike, probably to extend the life of the seals when it is sitting.
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post #25 of 35 (permalink) Old 07-17-2010, 09:18 AM
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Re: Ram Air Effect

Quote:
Originally Posted by penfold View Post

Theory

The basic concept behind ram air is that a moving bike will stuff air into its forward-facing intake runners, resulting in a free supercharging effect. As speed increases more air is forced in, resulting in more power and, in turn, more speed. The faster you go, the faster you'll go. The first impression upon viewing the gaping maws of some ram-air-equipped bikes is that an enormous amount of pressure must be built up at high speeds, but this is not so. As air is jammed into the opening, the high-pressure area that is created builds outward, effectively stopping more air from entering. Picture a balloon being inflated with an air tank. If the balloon is sealed to the nozzle, it will expand easily. Hold it slightly away from the nozzle, however, and the balloon will only inflate so far....
Thats where I stopped reading
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post #26 of 35 (permalink) Old 07-17-2010, 09:41 AM
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Re: Ram Air Effect

Quote:
Originally Posted by Nikonforever1 View Post
Well from my understanding of FI engines. It has a MAS ( mass airflow sensor ) after the air box telling the ECU how much air is going in. It also has an O2 sensor to tell how much of the fuel was left unburnt and there for telling the ECU if it was lean or rich. It also has a Temp sensor to tell the ECU how dense the air is. Ram air does work better on a FI engine. The MAS is the one sensing pressure and air flow and how much actual air is going into the engine. You can also get more HP be getting a bigger housing for the MAS and reprogram the ECU for that size housing. A bigger housing lets more air get to the TB and the Engine.

PS I am new to R6-Forum. HEY. this is also my first post.
Most if not all bikes use Manifold Absolute Pressure (MAP) not Mass Air Flow (MAF) to meter fuel. To use a MAF you need to run all the air through a single point to measure it. This is easy to do on a car with an intake manifold and single throttle plate. Whether it is having four throttle bodies, the cost, or size limitations either way every motorcycle, personal water craft, or snowmobile I've ever seen uses MAP.

To meter the correct air-fuel ratio the ECU needs to know how much air mass is moving through the engine. A MAF measures it directly. MAP is used to calculate it. Mass is Density x Volume. The ECU as a Static Air Pressure sensor (SAP) that measures the ambient pressure (altitude) and an Inlet Air Temperature (IAT) sensor. With these the ECU can calculate Air Density.

To calculate volume they actually look it up in a table or map. The ECU has an Inlet Air Pressure sensor (IAP). The ECU subtracts the IAP from the SAP to get MAP or the difference in pressure from outside the engine and inside the manifold. Now you can't calculate flow volume with this number but it does change with flow so they use it with rpm to look up flow.

At the factory they take a stock motor and stick it on a dyno with very expensive instrumentation, including a MAF, and run it. They then record how much volume the engine flows at a given RPM and MAP. The idea of course being if they build thousands of engines to the same spec, same pipe, same air box, same filters, etc. that it will flow the same as the test stand engine. These are called the Speed Density maps.

Now actually the bikes have two sets of base fuel maps. Speed Density and Alpha-n. The Alpha-n fuel maps are RPM x Throttle position. You can think of them as Low Load (speed density) and High Load (Alpha-n) maps. Most bikes switch from Speed Density to Alpha-n around 10-15% throttle.

Here are the Speed Density and Alpha-n Maps for the 2008 R6 (13S-20). On both RPM is down the left side. On the S-D map across the top is MAP voltage (SAP - IAP) left to right it goes from partial vacuum to 0.00 or SAP=IAP

The Alpha-n is Throttle Position across the top displayed as percent range.


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BTW if your wondering why both maps cover the full operating range when each is only used for a portion of the hi/low load it is because they are used as back up maps for each other.

If the IAP sensor should fail and the ECU becomes unable to calc the MAP then the ECU will use the Alpha-n map for both low and high load. The reverse is true if the Throttle Position sensor should fail but given these Throttle by wire bikes have redundant TPS that is not very likely.
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post #27 of 35 (permalink) Old 09-05-2010, 04:05 PM
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Re: Ram Air Effect

I havent looked into this enough to know how the air intakes are designed on the R6, but I do know that on cars, ram air does virtually nothing. Mainly because on a car the "ram air" is inside the boundary layer of the air flowing around it, but also because for there to be positive pressure built up, the intake must be designed as a diffuser (small cross-sectional area widening to a larger cross sectional area inside the intake box), yet most intakes are designed as a nozzle with a large opening, funneling down to a smaller intake tube. Im guessing that to get these results, the intake is designed as a diffuser and because it’s a bike, it can take advantage of short intake runners being placed directly in the path of the incoming air, thereby eliminating the boundary layer issues that cars have.

Either way, I am curious as to how a carbed bike meters fuel properly with increased pressure as my limited understanding of how carburetors work tells me that fuel delivery increases as air velocity through the venturi increases, which is not dependent on pressure. Although there have been supercharged and turbo charged carbed engines for decades, Ive just never understood how they “self correct” for higher boost pressure. I tuned my WRX using speed density instead of using the mass air flow sensor and I think it works a lot better under high boost applications. I do love fuel injection, but I’m beginning to love my carbed bike just as much, street turning an FI engine requires a lot of expensive stuff!
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post #28 of 35 (permalink) Old 09-06-2010, 10:50 PM
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Re: Ram Air Effect

I've got a python script I wrote that works out boost if anyone wants it?

It's currently written for metric units only, but I'm just adding to it now as my own wee coding test to include imperial for you silly silly americans
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post #29 of 35 (permalink) Old 09-06-2010, 11:58 PM
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Re: Ram Air Effect

you'll need python stuff to get it to work, google is your friend.

edit: fixed a problem before anyone noticed.

edit 2: my flatmate is a bit slow, when it asks for pressure Pa or psia, please put in the current atmospheric pressure (or any pressure you wish to know about) DO NOT put "Pa" or "psia"...
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Last edited by Davenzl; 09-07-2010 at 01:05 AM.
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post #30 of 35 (permalink) Old 01-01-2011, 08:52 AM
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Re: Ram Air Effect

Yec ECU is the only way you can adjust RAM air effect ...in fact the ECU has RAM air compensation...you could put any piggyback but with no AFR reading ON TRACK you are out of the game....
Note...O2 sensor on any commercial bike is not a WIDEBAND....will correct fuel ONLY to meet EPA restrictions!
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