I got the extender kit with the paper air filter and a K&N that I'll sell anybody if they're interested...
Air Cleaner
- Thread starter hoat
- Start date
Yep, turn that spike up. Once you do that it's time to tune your intermediate jet. I would buy a new set of plugs and take her out for a nice cruise and see how the plugs are burning.
desldog
Member
So, if I turn the spike up this will create a leaner environment, thus tune the mid jet...Thanks!!
Loafington
Active Member
I am not sure where the figure of 310 cfm requirements came from, but I figured the airflow requirements at 6000 rpm and 100% VE and it comes out to be 203.125 cfm. Now I am sure most of the people on here have a average understanding that practically no normally aspirated engine will develop 100% VE. Add a supercharger or a turbo and you will exceed that VE number easily. On a good day and maybe the stock set up, 6000 rpm at 85% VE, the requirements for 117 cubic inches is 172.656 cfm.
I am not trying to start any shit with anyone here, just perhaps trying to help some people from buying more than they have to in order to achieve the results that they are looking for.
Get an intake that flows 203 cfm and that will be more than enough for any 117" engine most of us will ever have under our nuts.
VE = Volumetric Efficiency (basically how much air can be sucked into an engine in a given time)
I am not trying to start any shit with anyone here, just perhaps trying to help some people from buying more than they have to in order to achieve the results that they are looking for.
Get an intake that flows 203 cfm and that will be more than enough for any 117" engine most of us will ever have under our nuts.
VE = Volumetric Efficiency (basically how much air can be sucked into an engine in a given time)
Fibersnake
Banjo Playing PsychoBilly
Loafington,
You bring up a good point, however would the figure not be for a perfect enviroment as far as the air flow. With our bikes having the air cleaner/intake setting out there being effected by different factors, the VE of the engine would not directly relate to what is needed for the filter since there will portion of the filter that have a negative pressure and other parts having a positive, which will effect the amount that is able to flow in at the particular situation.
If you go with minimal CFM rating based on a the Swept Volumn and VE of the engine, IMHO, you could have situation (and more than likely will) where the needed air will not flow to the rate designed and thus possibly end up starving the intake.
An example would be the spike filters-pointed forward, the will be area of the filter that have a negative pressure to it due to pd of the flow thus not allowing air to fully flow at rated. If the filter is set to minimal CFM as per the engine, you could have less actually flow going to intake due to the design, palcements and constant change of pressure across the filter.
Having a larger filter flow rating, will allow for these decrease in flow through and still allow for enough to insure that the engine needs are being met as well as allowing for a gradual decrease in flow as the filter becomes more restricted from dirt and particulants.
Another factor is that with certain situation, your can induce more air due to the higher pressure of moving at speed. In short there is so many variables going on with a constant change of enviroment that having a filter rated based on VE and Swept volumn alone, would be pushing it.
Just my 2 cents
You bring up a good point, however would the figure not be for a perfect enviroment as far as the air flow. With our bikes having the air cleaner/intake setting out there being effected by different factors, the VE of the engine would not directly relate to what is needed for the filter since there will portion of the filter that have a negative pressure and other parts having a positive, which will effect the amount that is able to flow in at the particular situation.
If you go with minimal CFM rating based on a the Swept Volumn and VE of the engine, IMHO, you could have situation (and more than likely will) where the needed air will not flow to the rate designed and thus possibly end up starving the intake.
An example would be the spike filters-pointed forward, the will be area of the filter that have a negative pressure to it due to pd of the flow thus not allowing air to fully flow at rated. If the filter is set to minimal CFM as per the engine, you could have less actually flow going to intake due to the design, palcements and constant change of pressure across the filter.
Having a larger filter flow rating, will allow for these decrease in flow through and still allow for enough to insure that the engine needs are being met as well as allowing for a gradual decrease in flow as the filter becomes more restricted from dirt and particulants.
Another factor is that with certain situation, your can induce more air due to the higher pressure of moving at speed. In short there is so many variables going on with a constant change of enviroment that having a filter rated based on VE and Swept volumn alone, would be pushing it.
Just my 2 cents
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Loafington
Active Member
Oh boy. The numbers that I got were not to determine what a filter will flow, they are based on the engine's consumption of air at a given RPM. The forward movement may or may not have an effect on the intake of air into the engine (ram air). However, one can achieve 6000 rpm in 1st gear at which ram air effect would be minimal, but at highway speeds, there is some ram air effect. The CFM numbers are figured with no other installed components like air filter, intake, ect. it's just the airflow required to fill the cylinders to their capacity at a given RPM. We add intake components and carburetors that need to flow as a minimum what an engine requires for airflow for the RPM range that it will operate. As far as running into a problem wih starving the engine of air, it is very difficult to get 100% VE due to the simple principle of operation for internal combustion engines and physics of moving air, ect.
I am running an intake set up that is rated for 223 cfm. My K9 pulls strong throughout the entire RPM range. I selected the intake set up with a little overkilll in mind. I know my engine will never see 100% VE, therefore never needing the ability for an air filter to flow 223 cfm. The reason why I went bigger was for the dirty filter factor.
When I first read your reply, I immediately felt like the caveman in the GEICO commercial. The one where he was being interviewed in some debate and the host asked him for his response and his reply "uh, what."
I am running an intake set up that is rated for 223 cfm. My K9 pulls strong throughout the entire RPM range. I selected the intake set up with a little overkilll in mind. I know my engine will never see 100% VE, therefore never needing the ability for an air filter to flow 223 cfm. The reason why I went bigger was for the dirty filter factor.
When I first read your reply, I immediately felt like the caveman in the GEICO commercial. The one where he was being interviewed in some debate and the host asked him for his response and his reply "uh, what."
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barhopper
Another round please
If you were to dyno a bike with the spike and a large K&N airfilter, you will see the difference. I saw it on my bike. Thats why I removed it, put on the K&N. Problem fixed. The K&N still dropped me 5 HP than with no airfilter at all. Thats why drag bikes have zero air filters. They need all the air they can get.
Fibersnake
Banjo Playing PsychoBilly
Loafington,
Sorry about the Geico thought, but to be honest depending on my beard I could be confused with such at times. That and I tend to be wordy.
To keep it short though, I understand what you are saying and though it has been along time, have used detail calculations in the past to come up with good carb combination and other intake consideration.
That all said, on the filter, I have always gone with the least restrictive filter that meets the design and purpose regardless of what the CFM rating is.
One of these days when I get smart and have time, I have a FEA program that I would love to put some drawings in and see how air is being flown over various scenarios. For now though I will concentrate on pryaing for good weather and taking the time to finish the polishing of the billet.
Safe riding to you and all.
Sorry about the Geico thought, but to be honest depending on my beard I could be confused with such at times. That and I tend to be wordy.
To keep it short though, I understand what you are saying and though it has been along time, have used detail calculations in the past to come up with good carb combination and other intake consideration.
That all said, on the filter, I have always gone with the least restrictive filter that meets the design and purpose regardless of what the CFM rating is.
One of these days when I get smart and have time, I have a FEA program that I would love to put some drawings in and see how air is being flown over various scenarios. For now though I will concentrate on pryaing for good weather and taking the time to finish the polishing of the billet.
Safe riding to you and all.
barhopper
Another round please
Need to do mine also.:bang:
Loafington
Active Member
I hear ya. I wish I had money for all the time and effort spent in working the correct combo, it pays off though. I would like to see the info you get. I bet there will be some surprises as to what flows better and whatnot.