I'm planning to build a custom intake consisting of a pipe running from each throttle body out the gap left by removing the stock airbox and placing a K&N cone filter on each pipe (maybe offsetting them a little, details are sketchy) any opinions on how this would flow compared to a VBAK or to stock. the pipes will be of similar diameter to the throttle bodies. I'm hoping to get near VBAK performace from something I can build myself. I have access to a pipe bender and a plater so I think this could turn out very cool. Would appreciate any input at all. thanks.
dragstar
Flow on a custom intake
2 reading
Hi Dragstar,
I wish it was that simple, but it is not. Intake tract tuning is based on pressure pulses and valve timing. There is some pretty heavy math needed to do it right.
I won't write a book on this here, although it is complex enough that you could write a pretty long chapter.
Basicly, air is compressable, so the air within an intake track acts like a spring (actually more like the child's toy the Slinky). A properly tuned intake tract has a negative pressure pulse that is caused by the suction of the cylinder when the intake valve opens. This negative (less than ambient) pressure pulse travels (always at the speed of sound) to the open end of the intake tract (air filter or opening of the velocity stack) where it "bounces" back as a positive pressure pulse (greater than ambient).
Now the trick is to have the length of the tract cause that positive pressure pulse to be right at the back of the intake valve just before it closes after bottom dead center. The energy in the moving air pulse (actually enertia) then rams extra fuel/air charge into the cylinder, thereby greatly increasing the volumetric efficiency (VE) - which increaces power much like a turbo or supercharge does.
To make all this even more difficult, the air actually bounces back and forth several times within the intake tract while the intake valve is closed. We number these pulses because the air loses energy with each bounce. The pulse with the most energy is the 2nd pulse. It also requires the longest intake length to use. So you must determine what is the practical limit to intake length and pick the stongest pulse that you can use.
Next you must determine where you want max VE (power) in the powerband. The engine changes the velocity of the intake air as RPM changes. RPM is therefore varible, but the intake track is fixed (as in length and diameter). Generally, I try to tune for the middle of the RPM range. But in the case of the Warrior, I shoot for max VE at about 3000 RPM. You may want to go for more bottom or more top end, so it is for you to decide.
OK, for the math. To find a starting point for intake tract length for each air pulse, use the following: (the result will be the tract length in inches from the back of the intake valve, to whatever opening to outside air is used, and RPM will be your chosen powerband mid point):
2nd Pulse:
L = 132000 / RPM
3rd Pulse:
L = 97000 / RPM
4th Pulse:
L = 74000 / RPM
5th Pulse:
L = 54000 / RPM
You could go on, but after about 5 pulses, there really isn't much energy left to extract, so why bother.
Once you have the length, you then mock it up on a dyno and adjust the length with spacer blocks to obtain max VE. The math gets you to within an inch or two.
The plenum box under the fuel tank does all this also, but the uses both cylinder's pressure pulses to increase VE.
Hope this helps with your design.
Snake
I wish it was that simple, but it is not. Intake tract tuning is based on pressure pulses and valve timing. There is some pretty heavy math needed to do it right.
I won't write a book on this here, although it is complex enough that you could write a pretty long chapter.
Basicly, air is compressable, so the air within an intake track acts like a spring (actually more like the child's toy the Slinky). A properly tuned intake tract has a negative pressure pulse that is caused by the suction of the cylinder when the intake valve opens. This negative (less than ambient) pressure pulse travels (always at the speed of sound) to the open end of the intake tract (air filter or opening of the velocity stack) where it "bounces" back as a positive pressure pulse (greater than ambient).
Now the trick is to have the length of the tract cause that positive pressure pulse to be right at the back of the intake valve just before it closes after bottom dead center. The energy in the moving air pulse (actually enertia) then rams extra fuel/air charge into the cylinder, thereby greatly increasing the volumetric efficiency (VE) - which increaces power much like a turbo or supercharge does.
To make all this even more difficult, the air actually bounces back and forth several times within the intake tract while the intake valve is closed. We number these pulses because the air loses energy with each bounce. The pulse with the most energy is the 2nd pulse. It also requires the longest intake length to use. So you must determine what is the practical limit to intake length and pick the stongest pulse that you can use.
Next you must determine where you want max VE (power) in the powerband. The engine changes the velocity of the intake air as RPM changes. RPM is therefore varible, but the intake track is fixed (as in length and diameter). Generally, I try to tune for the middle of the RPM range. But in the case of the Warrior, I shoot for max VE at about 3000 RPM. You may want to go for more bottom or more top end, so it is for you to decide.
OK, for the math. To find a starting point for intake tract length for each air pulse, use the following: (the result will be the tract length in inches from the back of the intake valve, to whatever opening to outside air is used, and RPM will be your chosen powerband mid point):
2nd Pulse:
L = 132000 / RPM
3rd Pulse:
L = 97000 / RPM
4th Pulse:
L = 74000 / RPM
5th Pulse:
L = 54000 / RPM
You could go on, but after about 5 pulses, there really isn't much energy left to extract, so why bother.
Once you have the length, you then mock it up on a dyno and adjust the length with spacer blocks to obtain max VE. The math gets you to within an inch or two.
The plenum box under the fuel tank does all this also, but the uses both cylinder's pressure pulses to increase VE.
Hope this helps with your design.
Snake
quote:Originally posted by Dragstar
I'm planning to build a custom intake consisting of a pipe running from each throttle body out the gap left by removing the stock airbox and placing a K&N cone filter on each pipe.
Dragstar,
I had the same thought. I wanted to bring the intakes out and bend them forward do that the K&N's would be pointing toward the front. Thought it would look pretty sweet. Maybe not though, after Snake's explanation.
I'm planning to build a custom intake consisting of a pipe running from each throttle body out the gap left by removing the stock airbox and placing a K&N cone filter on each pipe.
Dragstar,
I had the same thought. I wanted to bring the intakes out and bend them forward do that the K&N's would be pointing toward the front. Thought it would look pretty sweet. Maybe not though, after Snake's explanation.
Snake – Do you think anyone who has made any of the BAKs has paid any attention to the level of detail you presented and if so which ones?
Dragstar – I think you've got a really good idea and I say go for it. I was thinking of a similar setup with a pipe coming out each side and maybe use rubber hose under the tank. I figure I could find pre-molded hose at a parts store that might work. If you want perfection after making the setup, it could be tuned on a dyno by changing the length of the straight section up front.
Dragstar – I think you've got a really good idea and I say go for it. I was thinking of a similar setup with a pipe coming out each side and maybe use rubber hose under the tank. I figure I could find pre-molded hose at a parts store that might work. If you want perfection after making the setup, it could be tuned on a dyno by changing the length of the straight section up front.
Snake,I'm a lil lost here (no surprise). If you want the tube to be the proper length for the strongest pulse, number 2, why are you bothering with the math for numbers 3-5? Also, unless my calcuguesser is way off, I come up with 44 inches for pulse 2. Sounds a bit unrealistic to me. What am I missing?
Immara writes:
"Snake – Do you think anyone who has made any of the BAKs has paid any attention to the level of detail you presented and if so which ones?"
I have lots of experience with velocity stacks on Hilborn fuel injected straight line cars & with sprints. The V-BAK was developed with overall drivability in mind not peak HP. I do not know of any Warrior that runs at 5000 rpm at all times however you can expect a 6 to 8% increase in peak HP over the stock configuration.
"Snake – Do you think anyone who has made any of the BAKs has paid any attention to the level of detail you presented and if so which ones?"
I have lots of experience with velocity stacks on Hilborn fuel injected straight line cars & with sprints. The V-BAK was developed with overall drivability in mind not peak HP. I do not know of any Warrior that runs at 5000 rpm at all times however you can expect a 6 to 8% increase in peak HP over the stock configuration.
quote:Originally posted by cbwarrior
For what its worth I dynoed 5hp better without churchkeys's volicity stacks. I have 42mm throttle bodies and his stacks seemed smaller (more restrictive). I think I'll try it again with larger diameter stacks.
Everybody has the 42MM size on the inlet side of the throttle bodies. Besides the length, tubing diameters both internal & external were tested for the best OVERALL performance. See my reply to Immara.
If you have lost 5 hp you have done something wrong or the dyno you were on was not functioning properly.
For what its worth I dynoed 5hp better without churchkeys's volicity stacks. I have 42mm throttle bodies and his stacks seemed smaller (more restrictive). I think I'll try it again with larger diameter stacks.
Everybody has the 42MM size on the inlet side of the throttle bodies. Besides the length, tubing diameters both internal & external were tested for the best OVERALL performance. See my reply to Immara.
If you have lost 5 hp you have done something wrong or the dyno you were on was not functioning properly.
Ok Snake, I've had some extensive physics background, so I do understand how air does move like a slinky and I do understand the refection of the air pulses, but I've never had it related to an engine intake. Carrying out your calculation I see that your lengths are 44in for 2nd pulse, 32.3 for 3rd pulse, 24.6 for 4th pulse and so on. If this is true, why are the VBAK velocity stacks effective when they are only a couple in. long? I think I may still give it a try. I think it will look cool as **** even if it doesn't perform that well. I'll be sure to post some pics.
quote:Originally posted by dkpickard
Hi Dragstar,
I wish it was that simple, but it is not. Intake tract tuning is based on pressure pulses and valve timing. There is some pretty heavy math needed to do it right.
I won't write a book on this here, although it is complex enough that you could write a pretty long chapter.
Basicly, air is compressable, so the air within an intake track acts like a spring (actually more like the child's toy the Slinky). A properly tuned intake tract has a negative pressure pulse that is caused by the suction of the cylinder when the intake valve opens. This negative (less than ambient) pressure pulse travels (always at the speed of sound) to the open end of the intake tract (air filter or opening of the velocity stack) where it "bounces" back as a positive pressure pulse (greater than ambient).
Now the trick is to have the length of the tract cause that positive pressure pulse to be right at the back of the intake valve just before it closes after bottom dead center. The energy in the moving air pulse (actually enertia) then rams extra fuel/air charge into the cylinder, thereby greatly increasing the volumetric efficiency (VE) - which increaces power much like a turbo or supercharge does.
To make all this even more difficult, the air actually bounces back and forth several times within the intake tract while the intake valve is closed. We number these pulses because the air loses energy with each bounce. The pulse with the most energy is the 2nd pulse. It also requires the longest intake length to use. So you must determine what is the practical limit to intake length and pick the stongest pulse that you can use.
Next you must determine where you want max VE (power) in the powerband. The engine changes the velocity of the intake air as RPM changes. RPM is therefore varible, but the intake track is fixed (as in length and diameter). Generally, I try to tune for the middle of the RPM range. But in the case of the Warrior, I shoot for max VE at about 3000 RPM. You may want to go for more bottom or more top end, so it is for you to decide.
OK, for the math. To find a starting point for intake tract length for each air pulse, use the following: (the result will be the tract length in inches from the back of the intake valve, to whatever opening to outside air is used, and RPM will be your chosen powerband mid point):
2nd Pulse:
L = 132000 / RPM
3rd Pulse:
L = 97000 / RPM
4th Pulse:
L = 74000 / RPM
5th Pulse:
L = 54000 / RPM
You could go on, but after about 5 pulses, there really isn't much energy left to extract, so why bother.
Once you have the length, you then mock it up on a dyno and adjust the length with spacer blocks to obtain max VE. The math gets you to within an inch or two.
The plenum box under the fuel tank does all this also, but the uses both cylinder's pressure pulses to increase VE.
Hope this helps with your design.
Snake
Nice short story pretty good gramer and spelling.
I love a good fiction based on a true story only the facts have changed.[8D]
Hi Dragstar,
I wish it was that simple, but it is not. Intake tract tuning is based on pressure pulses and valve timing. There is some pretty heavy math needed to do it right.
I won't write a book on this here, although it is complex enough that you could write a pretty long chapter.
Basicly, air is compressable, so the air within an intake track acts like a spring (actually more like the child's toy the Slinky). A properly tuned intake tract has a negative pressure pulse that is caused by the suction of the cylinder when the intake valve opens. This negative (less than ambient) pressure pulse travels (always at the speed of sound) to the open end of the intake tract (air filter or opening of the velocity stack) where it "bounces" back as a positive pressure pulse (greater than ambient).
Now the trick is to have the length of the tract cause that positive pressure pulse to be right at the back of the intake valve just before it closes after bottom dead center. The energy in the moving air pulse (actually enertia) then rams extra fuel/air charge into the cylinder, thereby greatly increasing the volumetric efficiency (VE) - which increaces power much like a turbo or supercharge does.
To make all this even more difficult, the air actually bounces back and forth several times within the intake tract while the intake valve is closed. We number these pulses because the air loses energy with each bounce. The pulse with the most energy is the 2nd pulse. It also requires the longest intake length to use. So you must determine what is the practical limit to intake length and pick the stongest pulse that you can use.
Next you must determine where you want max VE (power) in the powerband. The engine changes the velocity of the intake air as RPM changes. RPM is therefore varible, but the intake track is fixed (as in length and diameter). Generally, I try to tune for the middle of the RPM range. But in the case of the Warrior, I shoot for max VE at about 3000 RPM. You may want to go for more bottom or more top end, so it is for you to decide.
OK, for the math. To find a starting point for intake tract length for each air pulse, use the following: (the result will be the tract length in inches from the back of the intake valve, to whatever opening to outside air is used, and RPM will be your chosen powerband mid point):
2nd Pulse:
L = 132000 / RPM
3rd Pulse:
L = 97000 / RPM
4th Pulse:
L = 74000 / RPM
5th Pulse:
L = 54000 / RPM
You could go on, but after about 5 pulses, there really isn't much energy left to extract, so why bother.
Once you have the length, you then mock it up on a dyno and adjust the length with spacer blocks to obtain max VE. The math gets you to within an inch or two.
The plenum box under the fuel tank does all this also, but the uses both cylinder's pressure pulses to increase VE.
Hope this helps with your design.
Snake
Nice short story pretty good gramer and spelling.
I love a good fiction based on a true story only the facts have changed.[8D]
quote:Originally posted by VR-4man
Hey Snake,
That's quite an interesting explanation! I suppose this would apply to the BAK's (that so many here have) as well.
I'm curious, have you modified you intake? If so, what did you do?
Hi VR,
I don't know what effort was put into the various BAKs. Keep in mind that reducing intake flow resistance has a benifit all it's own. So in theory, you should get some improvement by that, even if you don't fully tune the intake tract. A problem that can occur is if the tract length of the BAK ends up placing a negative pressure pulse at the back of the intake valve instead of a positive pulse. This would have the effect of actually decreasing VE.
I use tuned velocity stacks.
Snake
Hey Snake,
That's quite an interesting explanation! I suppose this would apply to the BAK's (that so many here have) as well.
I'm curious, have you modified you intake? If so, what did you do?
Hi VR,
I don't know what effort was put into the various BAKs. Keep in mind that reducing intake flow resistance has a benifit all it's own. So in theory, you should get some improvement by that, even if you don't fully tune the intake tract. A problem that can occur is if the tract length of the BAK ends up placing a negative pressure pulse at the back of the intake valve instead of a positive pulse. This would have the effect of actually decreasing VE.
I use tuned velocity stacks.
Snake
quote:Originally posted by lmmara
Snake – Do you think anyone who has made any of the BAKs has paid any attention to the level of detail you presented and if so which ones?
Dragstar – I think you've got a really good idea and I say go for it. I was thinking of a similar setup with a pipe coming out each side and maybe use rubber hose under the tank. I figure I could find pre-molded hose at a parts store that might work. If you want perfection after making the setup, it could be tuned on a dyno by changing the length of the straight section up front.
Hi lmmara,
I think the Speedstar stacks and possibly the PR kit. Can't say for the others, but most likely not. Keep in mind that tuned tracts are helpful, but not the only thing to consider. Like exhaust pipes, less restrictive flow plays a major part in increasing VE. By the way, properly tuned exhausts use the same principles, just in reverse -- that is, the goal is to have a negative pressure pulse at the back of the exhaust valve to help pull the spent gases out of the cylinder.
Snake
Snake – Do you think anyone who has made any of the BAKs has paid any attention to the level of detail you presented and if so which ones?
Dragstar – I think you've got a really good idea and I say go for it. I was thinking of a similar setup with a pipe coming out each side and maybe use rubber hose under the tank. I figure I could find pre-molded hose at a parts store that might work. If you want perfection after making the setup, it could be tuned on a dyno by changing the length of the straight section up front.
Hi lmmara,
I think the Speedstar stacks and possibly the PR kit. Can't say for the others, but most likely not. Keep in mind that tuned tracts are helpful, but not the only thing to consider. Like exhaust pipes, less restrictive flow plays a major part in increasing VE. By the way, properly tuned exhausts use the same principles, just in reverse -- that is, the goal is to have a negative pressure pulse at the back of the exhaust valve to help pull the spent gases out of the cylinder.
Snake
quote:Originally posted by OldMan
Snake,I'm a lil lost here (no surprise). If you want the tube to be the proper length for the strongest pulse, number 2, why are you bothering with the math for numbers 3-5? Also, unless my calcuguesser is way off, I come up with 44 inches for pulse 2. Sounds a bit unrealistic to me. What am I missing?
Hi OldMan,
You are correct that use of the first few (and most energy laden) pulses may require unreasonably long intake tracts, so you just keep going to you find the lowest number pulse that you can fit into your design. Also keep in mind that the measurement is from the center of the intake valve stem to the outside edge of the velocity stack or airfilter, so you add up inches pretty quickly.
Snake
Snake,I'm a lil lost here (no surprise). If you want the tube to be the proper length for the strongest pulse, number 2, why are you bothering with the math for numbers 3-5? Also, unless my calcuguesser is way off, I come up with 44 inches for pulse 2. Sounds a bit unrealistic to me. What am I missing?
Hi OldMan,
You are correct that use of the first few (and most energy laden) pulses may require unreasonably long intake tracts, so you just keep going to you find the lowest number pulse that you can fit into your design. Also keep in mind that the measurement is from the center of the intake valve stem to the outside edge of the velocity stack or airfilter, so you add up inches pretty quickly.
Snake
quote:Originally posted by Dragstar
Ok Snake, I've had some extensive physics background, so I do understand how air does move like a slinky and I do understand the refection of the air pulses, but I've never had it related to an engine intake. Carrying out your calculation I see that your lengths are 44in for 2nd pulse, 32.3 for 3rd pulse, 24.6 for 4th pulse and so on. If this is true, why are the VBAK velocity stacks effective when they are only a couple in. long? I think I may still give it a try. I think it will look cool as **** even if it doesn't perform that well. I'll be sure to post some pics.
Hi Dragstar,
I didn't mean to dismiss your idea -- just wanted to add another element to be considered in your design.
Your idea should work well on several levels. First, it is low restriction, so you will pick up VE that way.
Next, if you tune the length, you could pick up a lower number (more energy laden) pulse as your intake tracts will naturally be longer than we could stuff under the tank.
Lastly, because we use fuel injection, ram air is our friend. /emoticons/emotion-1.gif The faster you go the higher the appearent "ambient" pressure. The only thing that should be looked at is how to feed a valid ambient air pressure measurement to the ECU. I haven't thought this out fully, but perhaps intergrating the intake pressure sensors into the intake tracts would produce a measurement that the ECU could act on to "trim" or tune the injector pulses. This part is a nightmare on a carbed bike, but the FI ECU can do all the adjustments for the various air speeds (and related pressure changes) for us.
Snake
Ok Snake, I've had some extensive physics background, so I do understand how air does move like a slinky and I do understand the refection of the air pulses, but I've never had it related to an engine intake. Carrying out your calculation I see that your lengths are 44in for 2nd pulse, 32.3 for 3rd pulse, 24.6 for 4th pulse and so on. If this is true, why are the VBAK velocity stacks effective when they are only a couple in. long? I think I may still give it a try. I think it will look cool as **** even if it doesn't perform that well. I'll be sure to post some pics.
Hi Dragstar,
I didn't mean to dismiss your idea -- just wanted to add another element to be considered in your design.
Your idea should work well on several levels. First, it is low restriction, so you will pick up VE that way.
Next, if you tune the length, you could pick up a lower number (more energy laden) pulse as your intake tracts will naturally be longer than we could stuff under the tank.
Lastly, because we use fuel injection, ram air is our friend. /emoticons/emotion-1.gif The faster you go the higher the appearent "ambient" pressure. The only thing that should be looked at is how to feed a valid ambient air pressure measurement to the ECU. I haven't thought this out fully, but perhaps intergrating the intake pressure sensors into the intake tracts would produce a measurement that the ECU could act on to "trim" or tune the injector pulses. This part is a nightmare on a carbed bike, but the FI ECU can do all the adjustments for the various air speeds (and related pressure changes) for us.
Snake
quote:Originally posted by Churchkey
Immara writes:
"Snake – Do you think anyone who has made any of the BAKs has paid any attention to the level of detail you presented and if so which ones?"
I have lots of experience with velocity stacks on Hilborn fuel injected straight line cars & with sprints. The V-BAK was developed with overall drivability in mind not peak HP. I do not know of any Warrior that runs at 5000 rpm at all times however you can expect a 6 to 8% increase in peak HP over the stock configuration.
Hi Churchkey,
I am sorry if I wasn't clear about the RPM target. You pick a RPM that is at the midpoint of the area you want to increase in VE. For example, on a sport bike is would pretty high but on a crusier it would be lower. This is the same basic consideration you make when picking a cam profile. You can go for top end at the expense of the bottom end (for example in drag racing), or give up a bit of top end for more "usable" power and ridability (as for the street). You could tune for idle RPM if you wanted to -- it just wouldn't be very useful.
Please understand that my comments to Dragstar wasn't in any way intended to dis any of the BAKs. He is talking about adding ram air to the mix and I was just trying to discuss the tuning aspects for his design. He will have an advantage in that he will have room for a longer intake tract than anything we can put under the tank, so intake tract tuning would be more of a major contributor to his design.
Snake
Immara writes:
"Snake – Do you think anyone who has made any of the BAKs has paid any attention to the level of detail you presented and if so which ones?"
I have lots of experience with velocity stacks on Hilborn fuel injected straight line cars & with sprints. The V-BAK was developed with overall drivability in mind not peak HP. I do not know of any Warrior that runs at 5000 rpm at all times however you can expect a 6 to 8% increase in peak HP over the stock configuration.
Hi Churchkey,
I am sorry if I wasn't clear about the RPM target. You pick a RPM that is at the midpoint of the area you want to increase in VE. For example, on a sport bike is would pretty high but on a crusier it would be lower. This is the same basic consideration you make when picking a cam profile. You can go for top end at the expense of the bottom end (for example in drag racing), or give up a bit of top end for more "usable" power and ridability (as for the street). You could tune for idle RPM if you wanted to -- it just wouldn't be very useful.
Please understand that my comments to Dragstar wasn't in any way intended to dis any of the BAKs. He is talking about adding ram air to the mix and I was just trying to discuss the tuning aspects for his design. He will have an advantage in that he will have room for a longer intake tract than anything we can put under the tank, so intake tract tuning would be more of a major contributor to his design.
Snake
Snake, Good explanation of the technical aspect of VE. I enjoyed it & did not interpet it as a slam/flame directed at any intake system.
My replies were directed to those that had opinons or questioned the topic.
Take care
My replies were directed to those that had opinons or questioned the topic.
Take care
Snake, old worn out mind here, not firing on all cylinders. You're telling me this is somewhat similar to tuning an antenna? Best results will be with a full wave length but if you can't do that you drop down to 1/2 wave or 1/4 wave etc? So with the intake you work your way down to which ever pulse you can fit in the space you have? The exact length needed for say pulse 7 or 8, or whatever number, would be better than a length that falls between any two pulses? If I'm correct on this, how does the air filter effect all this or does it come into play at all?
quote:Originally posted by Dragstar
I'm planning to build a custom intake consisting of a pipe running from each throttle body out the gap left by removing the stock airbox and placing a K&N cone filter on each pipe (maybe offsetting them a little, details are sketchy) any opinions on how this would flow compared to a VBAK or to stock. the pipes will be of similar diameter to the throttle bodies. I'm hoping to get near VBAK performace from something I can build myself. I have access to a pipe bender and a plater so I think this could turn out very cool. Would appreciate any input at all. thanks.
A suggestion:Change your stock air filter elements for any aftermarket and test. Then build a custom intake of plastic (that resist heat) material and install then into the openings of each intake and TEST! Good Luck!
I'm planning to build a custom intake consisting of a pipe running from each throttle body out the gap left by removing the stock airbox and placing a K&N cone filter on each pipe (maybe offsetting them a little, details are sketchy) any opinions on how this would flow compared to a VBAK or to stock. the pipes will be of similar diameter to the throttle bodies. I'm hoping to get near VBAK performace from something I can build myself. I have access to a pipe bender and a plater so I think this could turn out very cool. Would appreciate any input at all. thanks.
A suggestion:Change your stock air filter elements for any aftermarket and test. Then build a custom intake of plastic (that resist heat) material and install then into the openings of each intake and TEST! Good Luck!
[/emoticons/emotion-5.gif]Remember to bump the ecu a little too to compensate for the extra air. If you change the stock pipe for a better slip-on the combo will gain extra horsepower and torque. Good Luck![/emoticons/emotion-5.gif]
quote:Originally posted by OldMan
Snake, old worn out mind here, not firing on all cylinders. You're telling me this is somewhat similar to tuning an antenna? Best results will be with a full wave length but if you can't do that you drop down to 1/2 wave or 1/4 wave etc? So with the intake you work your way down to which ever pulse you can fit in the space you have? The exact length needed for say pulse 7 or 8, or whatever number, would be better than a length that falls between any two pulses? If I'm correct on this, how does the air filter effect all this or does it come into play at all?
Hi OldMan,
You know, I never put the two together, but you make a good point. It does seem that they both share some of the same wave behavior. I not an expert on standing waves, just know a bit from CB tuning, but it makes a lot of sense to me.
Yes, the goal would be to use the strongest wave pulse that is practical -- the same way you tune a CN antenna.
Snake
Snake, old worn out mind here, not firing on all cylinders. You're telling me this is somewhat similar to tuning an antenna? Best results will be with a full wave length but if you can't do that you drop down to 1/2 wave or 1/4 wave etc? So with the intake you work your way down to which ever pulse you can fit in the space you have? The exact length needed for say pulse 7 or 8, or whatever number, would be better than a length that falls between any two pulses? If I'm correct on this, how does the air filter effect all this or does it come into play at all?
Hi OldMan,
You know, I never put the two together, but you make a good point. It does seem that they both share some of the same wave behavior. I not an expert on standing waves, just know a bit from CB tuning, but it makes a lot of sense to me.
Yes, the goal would be to use the strongest wave pulse that is practical -- the same way you tune a CN antenna.
Snake
quote:Originally posted by cbwarrior
I think churches stacks are fine on 102 warrior but on 108 warrior with bored throttle bodies you can see the torque curve fall off as rpms increase causing the loss in hp. I'm going to try to fabricate larger diameter stacks to see how this effects torque/hp.
Hi CBWarrior,
That makes sense. When you increase the cylinder volume with a bigger bore, if you keep the intake tract the same diameter, you increase the air velocity. While we want a good amount of air velocity to keep the fuel air charge mixed, if it is too high we start building resistance, especially through the filter.
What may be happening in your case is that there is now a transittion area between the size of your bored (enlarged diameter) throttle bodies, and the size (stock diameter) of the stacks. There could be an area at the point where the diameter changes between the throttle bodies and the stack that has become turbulent (as the velocity changes). That turbulance would disrupt the smooth flow you are trying to get to the engine. In fact, if it is bad enough, the turbulent area can begin to actually reflect some or all of the pressure waves back toward the intake valve at unpredictable timings. My guess is that if you bring the diameter of the stack up to match the size of the throttle bodies, you would get some of the power back at the top. This assumes that the filter surface area is large enough not to have too much restriction for the 108 at high RPMs.
Snake
I think churches stacks are fine on 102 warrior but on 108 warrior with bored throttle bodies you can see the torque curve fall off as rpms increase causing the loss in hp. I'm going to try to fabricate larger diameter stacks to see how this effects torque/hp.
Hi CBWarrior,
That makes sense. When you increase the cylinder volume with a bigger bore, if you keep the intake tract the same diameter, you increase the air velocity. While we want a good amount of air velocity to keep the fuel air charge mixed, if it is too high we start building resistance, especially through the filter.
What may be happening in your case is that there is now a transittion area between the size of your bored (enlarged diameter) throttle bodies, and the size (stock diameter) of the stacks. There could be an area at the point where the diameter changes between the throttle bodies and the stack that has become turbulent (as the velocity changes). That turbulance would disrupt the smooth flow you are trying to get to the engine. In fact, if it is bad enough, the turbulent area can begin to actually reflect some or all of the pressure waves back toward the intake valve at unpredictable timings. My guess is that if you bring the diameter of the stack up to match the size of the throttle bodies, you would get some of the power back at the top. This assumes that the filter surface area is large enough not to have too much restriction for the 108 at high RPMs.
Snake
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