supra5677
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posted May 17, 2007 08:19 AM
Measuring Ram Air Pressure
My buddy is a prototype tester for Ford, Nissan and GM. He put a pressure meter in his ZX11 C model and was able to measure 1.5psi maximum on the meter. Incidently his bike was used to make the first Factory Jet Kit for the ZX11. There were 2 tubes used on the zx11 1 tube to balance the pressure , 1 for the float bowl and the air box for the overall pressure.
Is there a balancing pressure issue withe the ZX12r as it relates to the injectors. Does the ECU add fuel when ram pressure is increased? How is this done if there is no oxygen sensor?
Can anybody weigh in... Doug?
Supra
   
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rac4it
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Bergie
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posted May 17, 2007 10:05 AM
a pressure sensor attached to the airbox during a run at Maxton should do it
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TRNorBRN6001
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posted May 17, 2007 10:28 AM
Entropy has done a touch of logging in the 1/4mile, but I do not think anything at the Texas Mile yet. Some old Sport Rider mags did a little testing as well. It would be very interesting to see the pressure results at 200mph
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Y2KZX12R
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posted May 17, 2007 10:45 AM
The bike has a manifold absolute pressure sensor and a barometric pressure sensor.
It uses these two sensors to change fuel delivery.
So it knows how much ramair pressure the engine is seeing.
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supra5677
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posted May 17, 2007 11:10 AM
is it possible that the stock fuel map is leaned out at highest pressure?
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rac4it
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Bergie
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posted May 17, 2007 11:49 AM
possible, anyone with a datalogger and wideband like an Innovative LM1 could tell you for sure if the factory ECU does its job to compensate. I would like it probably does, the question is does the powercommander map changes interfere with its ability to compensate... hmmm
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supra5677
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posted May 17, 2007 12:29 PM
exactly.. when I figure out how to down load RR's fuel maps then I can see if fuel is being addes or subtracted at high throttle positions and rpms.. does the powercommander map recomend or does it overide? at 180 plus mph seems like a lot of fuel would be added.
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rgeorge
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posted May 17, 2007 04:00 PM
My understanding is that the ecu doesnt know that the powercommander is there.
The ecu makes calulations for fuel and ignition based on all the sensor inputs. It then ouputs signals to the injectors and coils. The PC intecepts theses signals and changes them by the amount in your PC maps. The modified signals are then sent from the PC to the coils and injectors.
This is just my understanding, correct me if Im wrong.
Next time I have my bike apart I will hook my logger to the MAP sensor.
I'll log rpm, MAP and AFR and make some colorfull graphs- just give me a week or two.
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entropy
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posted May 17, 2007 09:20 PM
quote:
Entropy has done a touch of logging in the 1/4mile, but I do not think anything at the Texas Mile yet. Some old Sport Rider mags did a little testing as well. It would be very interesting to see the pressure results at 200mph
I logged MAP, AF, RPM, TPS, Oil Pressure, and airbox temp at the last 2 Texas Miles, but i'm not at all sure what the question is here.
MAP increases from 29.3 to about 30.3 "Hg @190mph. AF stays steady.
What was the question again??
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supra5677
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posted May 18, 2007 07:33 AM
how many millibars of boost are in the air box at 190mph..? Does the ecu add fuel as air box pressure increases?
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supra5677
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posted May 18, 2007 07:35 AM
If there is 1.5psi max boost in the air box on a zx11c, I would expect the 12r to be at least that much or more..
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supra5677
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posted May 18, 2007 08:03 AM
The ZX11 air box is measured at a capacity of 15 litres.. has anybody measured the volume of the zx12r's air box?
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TRNorBRN6001
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posted May 18, 2007 09:04 AM
I guess that would be around .49 psi, so roughly a 3.3% increase in HP at 190mph for your monster A/F swilling motor. So if your motor normaly puts out around 220HP that would be around a 7HP gain. I am probably wrong with my calculations, but it is a very interesting topic.
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dougmeyer
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posted May 18, 2007 09:51 AM
 Edited By: dougmeyer on 18 May 2007 10:53
The available ram air pressure is strictly a function of the air density and speed- That's how an airspeed indicator works (pitot tube).
The reason there is a float bowl pressure balance tube on the 11 is BECAUSE THERE ARE FLOAT BOWLS.
If the pressure in the float bowl is not the same as the pressure at the carb inlet, the venturi effect which draws fuel up through the main jet is completely negated. Think about it - if the pressure in the carb throat is higher than the pressure on top of the fuel in the bowl, the main jet would just blow bubbles instead of draw fuel. Injected engines do not require this consideration.
There is no reason or mechanism for a 12 to have a higher ram recovery than an 11. I know it's counter intuitive, but it has nothing to do with the size of the inlet, or the size of the airbox for that matter. Shape of the "lip" or edge of the inlet has a minor effect on the efficiency of the duct. Speed and density, that's it.
Remember Pressure and Flow are different. (See my posts on fuel pumps)
I wrote post after post on the topic of how ram air works in 2000 when the 12 first hit. Please do a search, there is alot of info there (is it still, Fish?) and I don't want to re-educate if I don't have to, but I will dammit!
Doug
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supra5677
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posted May 18, 2007 10:38 AM
" There is no reason or mechanism for a 12 to have a higher ram air recovery than an 11."
If I'm correct ram air recovery is how much ram air is available after the air has gone through the runner, air filter and into the throttle bodies correct? How does one improve ram air recovery? I will go educate myself further these kids have a history test anyway 
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supra5677
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posted May 18, 2007 11:28 AM
Question: The zx12s' throttle bodies flow 149cfm each that means each runner must flow 298cfm per minute.. Is this happening in each zx12r runner?
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dougmeyer
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posted May 18, 2007 12:59 PM
No, it does not mean that, as only ONE cylinder is "consuming" air at a time. Think of a firehose being alternately squirted at each TB.
No , "ram recovery" is an aviation derived term for how much air pressure is "regained" or increased over ambient. Your explanation is correct except for the part about the TB's. I'd call ram pressure the pressure at the inlet of the system and that compared to the pressure at the TB entrance would describe the efficiency and integrity (leak proof-ness) of the duct system. All that really matters is the mass flow entering the TB throat which is a function of the density (which is effected by pressure) and the efficiency of the ductwork ("volume" of flow).
Make sense?
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aughtsix
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posted May 18, 2007 05:15 PM
Edited By: aughtsix on 18 May 2007 21:10
quote:
Originally posted by Supra5677 Question: The zx12s' throttle bodies flow 149cfm each that means each runner must flow 298cfm per minute.. Is this happening in each zx12r runner?
Supra - For what it's worth, if you're right about each throttle body being able to flow 149cfm, I would think it's more than enough:
To convert cubic centimeters to cubic inches you multiply by .061 (1cc = .061ci) so 1200cc = 73.2ci.
73.2ci @ 11,500rpm ingests 841,800cim (cubic inches per minute). Remember though, that the intake valve opens only once per two engine revolutions, so we divide by 2 = 420,900cim. To convert cubic inches per minute to cubic feet per minute we divide again by 1728 = 244cfm and to find out what each cylinder flows we divided by 4 = 61cfm -- and this is at 100% volumetric efficiency.
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supra5677
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posted May 18, 2007 07:29 PM
yes Doug.. thanks it makes sense..except how a zx11 and zx12r have equal ram air systems is interesting.
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Y2KZX12R
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posted May 19, 2007 07:37 AM
quote:
zx11 and zx12r have equal ram air systems is interesting.
I think what Doug was saying is that there is a maximum that is achievable and exceeding that is impossable. But it doesnt mean that all are just as good as eachother and develop the same airbox pressure.
I know from a sportrider test in 99 that different bikes ramair systems perform very differently are not all good performers. Some were actually horrible and almost useless.
If you took several bikes with ramair they will all produce different pressures at different speeds due to design. See the test in sportrider. But none can exceed the maximum for a given speed.
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ridgeracer
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posted May 19, 2007 08:36 AM
Here is the RPM vs Adjusted Inlet AP Fuel map for the ZX-12
I don't know how to convert the AP units into something meaningful like millibars. Also note that the AP scale is nonlinear. The left side starts out with about 6 units per column and by the right side is only 0.6 units per column.
In general terms it shows an increase in fuel as air density increases.
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supra5677
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posted May 19, 2007 10:43 AM
68.9 millibars equals 1 psi..
from the 1999 Sport Rider Magazine part 1 the zx9r makes 2.6bhp for every 10 millibars of pressure..
don't think the powercommander can adjust to the ram air, can it?
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supra5677
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posted May 19, 2007 11:18 AM
found some excellent articles on ram air: negative pressure, positive pressure etc..
www.autospeed.com/cms/A_0663/Article.html
www.autospeed.com/cms/article?&A=0637
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