Tuning With Ram-Air?

danath 34

danath 34

Registered
So I am a complete newbie when it comes to tuning... I have only ever adjusted jetting on a carb, and have never done any kind of tuning in any way/shape/or form on a fuel injected bike... But I was thinking today, and have a question...

How do you accurately tune a bike with a ram-air intake, like the busa? Because to my knowledge, when a tuner does his magic on the bike, it is on the dyno, and thus the air pressure at the intake is just ambient pressure. Now you can tune it and get great numbers on the dyno, but when you actually take off down the road, you are going to get more air pressure (and thus more airflow) at the ram air intake. Now even if you perfectly tuned the bike on a dyno, wouldnt the nature of the ram-air make it go lean when you get up to speed?

Is there any accurate method of tuning so that you account for this extra air, short of setting it up in a wind tunnel?

Someone please educate me :bowdown:
 
What alot of tuners do on the dyno is shoot for a 12.8:1 A/F at WOT for a ram-air bike. When on the road, it ends up around 13.0:1-13.2:1 which is right where you want it.
The best way to do it is on the road with a wideband a/f meter, but this is VERY time consuming, not to mention dangerous running up and down the highway at WOT all the time...
 
Birdoprey said:
What alot of tuners do on the dyno is shoot for a 12.8:1 A/F at WOT for a ram-air bike. When on the road, it ends up around 13.0:1-13.2:1 which is right where you want it.
The best way to do it is on the road with a wideband a/f meter, but this is VERY time consuming, not to mention dangerous running up and down the highway at WOT all the time...
Click to expand...

interesting... so they typically tune it a bit rich at WOT, so that when you are on the road it hopefully falls where it should be...

I wonder... and this is just the engineer in me thinking... Why hasnt someone put a pressure sensor on the intake, made some high speed WOT runs, and get that pressue... Then you could build a blower that hooks right up to the ram air intakes, and set it for the pressure you saw at the top speed in each of the respective gears... Then you could replicate the same amount of air flow on the dyno...
 
Birdoprey said:
What alot of tuners do on the dyno is shoot for a 12.8:1 A/F at WOT for a ram-air bike. When on the road, it ends up around 13.0:1-13.2:1 which is right where you want it.
The best way to do it is on the road with a wideband a/f meter, but this is VERY time consuming, not to mention dangerous running up and down the highway at WOT all the time...
Click to expand...

+1 They just set it up a little fat (rich) to compensate for the ram air.
Posted via Mobile Device
 
The air metering system should adjust the fuel mixture for different pressures. Minor changes in pressure are detected by the MAP sensor. The ECU can easliy calculate how much fuel it needs to add or take away to compensate for this.

Ram Air is kind of a gimmick from what I understand. It does a real good job of getting cool air in but doesn't actually compress it. Their is a certain speed required for the air to actually compress and I can't remeber what that speed is but I think it is around 200mph or so.
 
danath 34 said:
interesting... so they typically tune it a bit rich at WOT, so that when you are on the road it hopefully falls where it should be...

I wonder... and this is just the engineer in me thinking... Why hasnt someone put a pressure sensor on the intake, made some high speed WOT runs, and get that pressue... Then you could build a blower that hooks right up to the ram air intakes, and set it for the pressure you saw at the top speed in each of the respective gears... Then you could replicate the same amount of air flow on the dyno...
Click to expand...

Would be terribly complicated. You would need to get pressure readings from different rpms AND throttle positions in EACH gear. Then you would need to find a fan that would put out enough air to simulate 180 plus MPH AND be able to variably control it on down.
Even with all that effort, it will NEVER be perfect. Air density changes and also winds and such change even on a short ride. Your never gonna simulate all that nor be able to perfectly compensate.
There are those that have run a pressure sensor and read their a/f on the road. Setting the A/F at 12.8:1 ish is close enough and puts MANY a smile on the riders face:thumbsup:
 
fastblackblur said:
The air metering system should adjust the fuel mixture for different pressures. Minor changes in pressure are detected by the MAP sensor. The ECU can easliy calculate how much fuel it needs to add or take away to compensate for this.

Ram Air is kind of a gimmick from what I understand. It does a real good job of getting cool air in but doesn't actually compress it. Their is a certain speed required for the air to actually compress and I can't remeber what that speed is but I think it is around 200mph or so.
Click to expand...

+1 on the first part.

Ram air actually works. I believe you start seeing pressure in the airbox around 100mph and its actually helping around 120mph on up. Not alot of pressure, but every little bit helps. IIRC, the pressure at max speed is just under 1/2psi. Good enough for 5+hp to the wheel.
 
Birdoprey said:
Would be terribly complicated. You would need to get pressure readings from different rpms AND throttle positions in EACH gear. Then you would need to find a fan that would put out enough air to simulate 180 plus MPH AND be able to variably control it on down.
Even with all that effort, it will NEVER be perfect. Air density changes and also winds and such change even on a short ride. Your never gonna simulate all that nor be able to perfectly compensate.
There are those that have run a pressure sensor and read their a/f on the road. Setting the A/F at 12.8:1 ish is close enough and puts MANY a smile on the riders face:thumbsup:
Click to expand...

yeah it would take a bit of engineering to put together, but I think it could be done. I have done quite a bit of work with analytical wind tunnels, and controlling the wind speed would be easy. I think if one were to persue this, they would definitely need to have some data logging... A pressure transducer, a GPS for speed, and log the rpms. Then you could controll the blower with a PLC that will vary the power put to the fan according to the RPM's and gear. And of course, this will all be relative to the geographical location you are tuning in, so you would have to create a wind speed/pressure vs rpm profile for your specific location...

But if you did so, you could really fine tune the machine and know for sure you have the proper a/f... for those nit-picky types, that is... :laugh:
 
fastblackblur said:
here's an older article on it from sportrider.

Sport Rider-ram air induction test for sport bike motorcycles

something about .4psi at 150mph...
Click to expand...

Great read!! Wow! Thanks! Very interesting. Definitely the most scientific test I have EVER seen in any motorcycle magazine... Thats the exact sort of method I was thinking about...


As I expected, the pressure wasnt all that high... Even below ambient in a lot of places. But you do get a lot more airflow. So essentially, it is increasing the pressure, but the engine just gulps all that excess flow right up. Notice on the hayabusa dyno chart... It wasnt above positive pressure until 145mph... but there is quite a substantial boost in horsepower and torque throughout the range... So yeah, you dont have to build pressure, but just increase flow (I guess technically you do build pressure... Just a higher negative value, really)...

And I bet with better seals on the ducting, and possibly refined ram air scoops, you could make even larger gains, too!

:thumbsup: :bowdown:


*edit*

oh god now I am wanting to take some aluminum tape to all the air ducts/air box seals...
 
fastblackblur said:
The air metering system should adjust the fuel mixture for different pressures. Minor changes in pressure are detected by the MAP sensor. The ECU can easliy calculate how much fuel it needs to add or take away to compensate for this....
Click to expand...

MAP sensor does adjust fuel mixture for pressure changes...but this is due to ALTITUDE changes not ram air...sea level vs. living in the mountains.

I live at about 70 ft above sea level...I can be in Lake Tahoe in about three hours. Tahoe is over 6,000 ft above sea level and on the way there I will get to almost 8,000 ft above sea level...without the MAP sensor making adjustments for the change in pressure...the bike would run like crap as the elevation changes.
Posted via Mobile Device
 
BA BUSA said:
MAP sensor does adjust fuel mixture for pressure changes...but this is due to ALTITUDE changes not ram air...
Posted via Mobile Device
Click to expand...



Are you saying that ram air doesn't exist or that the map sensor doesn't account for the changes ram air incurs?

The map sensor adjusts for pressure regardless of what is causing the change in pressure. I would agree that on the average sportbike altitude has a far greater effect on engine performance than ram air ever will.

Unless the bike is running in an alpha-n mode the map sensor is feeding the ECU data in real time.
 
I've seen tuners set blowers up in front of the bike to mimic moving through the air. Was that bogus and they were just providing air flow to help cool the bike ?

Also, my understanding is that on the Busa at higher speeds a dead air space forms several inches away from the nose cone. That's the whole reasoning behind the ram extensions.
 
fastblackblur said:
Are you saying that ram air doesn't exist or that the map sensor doesn't account for the changes ram air incurs?

The map sensor adjusts for pressure regardless of what is causing the change in pressure. I would agree that on the average sportbike altitude has a far greater effect on engine performance than ram air ever will.

Unless the bike is running in an alpha-n mode the map sensor is feeding the ECU data in real time.
Click to expand...

MAP sensor is on the bike for changes in evevation...not the ram air...ram air has little to no effect below speeds of 120-140 mph.

The MAP sensor can only do so much...at high speed the ram air leans down the mixture...the MAP sensor will fatten it up a bit, but the ECU is getting signals from...gear postion sensor, speed sensor, crank sensor (rpms), and throttle position (TPS)...they all work together to let the ECU richen up the bike @ speed...MAP sensor plays a small part overall.
Posted via Mobile Device
 
dadofthree said:
I've seen tuners set blowers up in front of the bike to mimic moving through the air. Was that bogus and they were just providing air flow to help cool the bike ?

Also, my understanding is that on the Busa at higher speeds a dead air space forms several inches away from the nose cone. That's the whole reasoning behind the ram extensions.
Click to expand...

Fans are there to keep the bike from overheating...they don't offer enough to make the ram air work...also they help to keep the dyno operator from passing out.
Posted via Mobile Device
 
BA BUSA said:
Fans are there to keep the bike from overheating...they don't offer enough to make the ram air work...also they help to keep the dyno operator from passing out.
Posted via Mobile Device
Click to expand...

yeah... you definitely need a high power blower to get 150mph winds...



man... like I said, I am a real tuning newbie... So if the map adjusts for varying pressures, why doesnt it fully adjust for the ram air? I dont quite understand... ???
 
Isn't Petrik or Smith working on(or already has) an ECU Editor function that you can put your laptop in a backpack or tankbag and it will make adjustments to your air/fuel as you ride(or chart them so you can change them)? It would be the perfect way to tune.
I recall reading something about that.
 
danath 34 said:
man... like I said, I am a real tuning newbie... So if the map adjusts for varying pressures, why doesnt it fully adjust for the ram air? I dont quite understand... ???
Click to expand...



It does. Think about it. The pressure in the intake manifold is constantly changing as the RPMs change and the throttle opens and closes. The argument would be is the change from the ram air even large enough for ecu to care about?

How do you tune for your ram air? Well it's easy, you get a data logger with wideband O2 sensor capability and log what your sensors are telling you. If the engine's AFR is too far off adjust the corresponding cells in the fuel map.

Has anybody ever blew up a bike because they didn't account for ram air?
 
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