RPM triggered valve?
08-16-2009, 02:15 AM
#1
Racer
Thread Starter
RPM triggered valve?
I tried searching the internet for this but got nothing: What cars use an rpm triggered exhaust valve or where am I able to purchase one? I believe I was told the Z06 uses them, or their just butterfly valves after the muffler for noise range. Some others have thought of this idea as well and I think its a great idea, a resonator (maybe try one from a 928) with an RPM valve system and a Supertrapp for the best of both high/low power. But what RPM range is considered low/high?
Thanks to all who reply
Thanks to all who reply
08-16-2009, 02:19 AM
#2
Nordschleife Master
search Jegs for an exhaust cutout.
They have manual ones you control with a cable, and electric ones. You can put the switch on the dash, so its either open or closed. Or, you can put the switch under the gas pedal, so its only open at WOT.
They're not hard to find, if you use the right words....
They have manual ones you control with a cable, and electric ones. You can put the switch on the dash, so its either open or closed. Or, you can put the switch under the gas pedal, so its only open at WOT.
They're not hard to find, if you use the right words....
08-16-2009, 02:24 AM
#3
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Triggering the valve would be tricky. You could use a reverse valved wastegate off of the vacuum but that corresponds to load and not RPM. Backpressure tuning is based off of RPM.
You could electronically control a valve but not off the gas pedal. That would be a "load" setting more than RPM as well. You would have to trigger the electric valve off of some kind of tach.
The whole deal is probably more trouble than it is worth. Just stick with the stock exhaust and keep a good balance of high and low RPM power.
You could electronically control a valve but not off the gas pedal. That would be a "load" setting more than RPM as well. You would have to trigger the electric valve off of some kind of tach.
The whole deal is probably more trouble than it is worth. Just stick with the stock exhaust and keep a good balance of high and low RPM power.
08-16-2009, 02:28 AM
#4
Rainman
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some are RPM dependent, others are simply throttle dependent.
like on a lambo gallardo once you pass iirc 4000rpm the valves open because it figures to go that high without shifting you arent just dawdling in traffic. however a corvette will cruise around all day silently until you put the throttle down and then it barks at you.
personally id use the throttle one because itd be easier to do, you could use a vacuum signal to open or close the valve (google a "bypass valve", this is exactly what it does) which would actuate a butterfly.
thing is you may have to have two pipes in the area where you install the butterfly, otherwise you could choke the engine off entirely. or maybe have the butterfly in the pipe but smaller than the ID of the pipe so that sufficient air could get by while cruising
like on a lambo gallardo once you pass iirc 4000rpm the valves open because it figures to go that high without shifting you arent just dawdling in traffic. however a corvette will cruise around all day silently until you put the throttle down and then it barks at you.
personally id use the throttle one because itd be easier to do, you could use a vacuum signal to open or close the valve (google a "bypass valve", this is exactly what it does) which would actuate a butterfly.
thing is you may have to have two pipes in the area where you install the butterfly, otherwise you could choke the engine off entirely. or maybe have the butterfly in the pipe but smaller than the ID of the pipe so that sufficient air could get by while cruising
08-16-2009, 02:30 AM
#5
Rainman
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Triggering the valve would be tricky. You could use a reverse valved wastegate off of the vacuum but that corresponds to load and not RPM. Backpressure tuning is based off of RPM.
You could electronically control a valve but not off the gas pedal. That would be a "load" setting more than RPM as well. You would have to trigger the electric valve off of some kind of tach.
The whole deal is probably more trouble than it is worth. Just stick with the stock exhaust and keep a good balance of high and low RPM power.
You could electronically control a valve but not off the gas pedal. That would be a "load" setting more than RPM as well. You would have to trigger the electric valve off of some kind of tach.
The whole deal is probably more trouble than it is worth. Just stick with the stock exhaust and keep a good balance of high and low RPM power.
on the ford supercoupes there is a bypass valve installed before the intake to the supercharger that depending on vacuum signal would open or close a butterfly valve. when the car was just cruising the valve would be open, and incoming air would go straight into the intake manifold without even touching the supercharger. once the pedal went down then the valve would close and the air would be forced through the blower.
you could, actually, use that exact unit for your exhaust system. something like $35 online.
08-16-2009, 02:41 AM
#6
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Nope, again that is load based and if you are looking for any type of backpressure tuning on the exhaust it has to be RPM based. It is somewhat like the later style 993 variable length intake runners but on the exhaust side.
In a perfect world you would be able to adjust the backpressure of the exhaust actively over an infinite range corresponding to the engines RPM and not just an on/off.
But... the gains from all of this are not worth the time/$$$ it would take to implement it correctly. Like I said in the other thread, if you have a single application that requires only low or high end, adjust accordingly. Otherwise, stick with he stock exhaust for the best happy medium.
In a perfect world you would be able to adjust the backpressure of the exhaust actively over an infinite range corresponding to the engines RPM and not just an on/off.
But... the gains from all of this are not worth the time/$$$ it would take to implement it correctly. Like I said in the other thread, if you have a single application that requires only low or high end, adjust accordingly. Otherwise, stick with he stock exhaust for the best happy medium.
08-16-2009, 02:46 AM
#7
Racer
Thread Starter
some are RPM dependent, others are simply throttle dependent.
like on a lambo gallardo once you pass iirc 4000rpm the valves open because it figures to go that high without shifting you arent just dawdling in traffic. however a corvette will cruise around all day silently until you put the throttle down and then it barks at you.
personally id use the throttle one because itd be easier to do, you could use a vacuum signal to open or close the valve (google a "bypass valve", this is exactly what it does) which would actuate a butterfly.
thing is you may have to have two pipes in the area where you install the butterfly, otherwise you could choke the engine off entirely. or maybe have the butterfly in the pipe but smaller than the ID of the pipe so that sufficient air could get by while cruising
like on a lambo gallardo once you pass iirc 4000rpm the valves open because it figures to go that high without shifting you arent just dawdling in traffic. however a corvette will cruise around all day silently until you put the throttle down and then it barks at you.
personally id use the throttle one because itd be easier to do, you could use a vacuum signal to open or close the valve (google a "bypass valve", this is exactly what it does) which would actuate a butterfly.
thing is you may have to have two pipes in the area where you install the butterfly, otherwise you could choke the engine off entirely. or maybe have the butterfly in the pipe but smaller than the ID of the pipe so that sufficient air could get by while cruising
This is getting a bit complicated lol, maybe I'll just stick with with the idea of msds headers, 928 res and a magnaflow, and possibly a dash controlled valve so I can bypass it when I'm in the mood. But Im thinking of still using the valve your talking about, I am still confused on how it works though.
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08-16-2009, 02:49 AM
#8
Rainman
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Nope, again that is load based and if you are looking for any type of backpressure tuning on the exhaust it has to be RPM based. It is somewhat like the later style 993 variable length intake runners but on the exhaust side.
In a perfect world you would be able to adjust the backpressure of the exhaust actively over an infinite range corresponding to the engines RPM and not just an on/off.
But... the gains from all of this are not worth the time/$$$ it would take to implement it correctly. Like I said in the other thread, if you have a single application that requires only low or high end, adjust accordingly. Otherwise, stick with he stock exhaust for the best happy medium.
In a perfect world you would be able to adjust the backpressure of the exhaust actively over an infinite range corresponding to the engines RPM and not just an on/off.
But... the gains from all of this are not worth the time/$$$ it would take to implement it correctly. Like I said in the other thread, if you have a single application that requires only low or high end, adjust accordingly. Otherwise, stick with he stock exhaust for the best happy medium.
maybe a crank trigger wheel with a certain RPM set to open fully a modified VANOS butterfly...
this is getting too complicated for my tiredness lol.
dont bother!
08-16-2009, 03:03 AM
#9
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lol, if you wanted to implement it on the cheap you would hook up an electronic selinoid valve triggered by an aftermarket Tach off of a programmable shift light via some relays.
I agree, a long way to go for small gains. It would be fun to play with if you had some available dyno time. It would be cool to see the torque curves with more restriction, no restriction and then with the RPM controlled valve active.
I agree, a long way to go for small gains. It would be fun to play with if you had some available dyno time. It would be cool to see the torque curves with more restriction, no restriction and then with the RPM controlled valve active.
08-16-2009, 03:11 AM
#10
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travis, i just made a reference to something in my previous post about a bypass valve; you might be more familiar with a specific example.
on the ford supercoupes there is a bypass valve installed before the intake to the supercharger that depending on vacuum signal would open or close a butterfly valve. when the car was just cruising the valve would be open, and incoming air would go straight into the intake manifold without even touching the supercharger. once the pedal went down then the valve would close and the air would be forced through the blower.
you could, actually, use that exact unit for your exhaust system. something like $35 online.
on the ford supercoupes there is a bypass valve installed before the intake to the supercharger that depending on vacuum signal would open or close a butterfly valve. when the car was just cruising the valve would be open, and incoming air would go straight into the intake manifold without even touching the supercharger. once the pedal went down then the valve would close and the air would be forced through the blower.
you could, actually, use that exact unit for your exhaust system. something like $35 online.
08-16-2009, 03:28 AM
#11
Racer
Thread Starter
Supercharged MR2's use this exact system as well. I think if you got a cutout and a simple Nitrous Controller Brain, you could do an RPM dependant "on-off" setup. Just wire the system up like you would for nitrous, but instead of using it to control giggle gas, it just opens the cutout.
