Cam gear adjustment??
Am I below my max potential or doesn't have to be adjusted
Mar 18, 2009, 12:50 PM
#2
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hello mate ive got worst trouble with my evo 9. the car was pushing 460whp with stock cams. now that i have put 272 bc cams and a biger turbo the car has dropped to 372whp.
i need help ajusting my exaust cam pulley. any ideas?
i need help ajusting my exaust cam pulley. any ideas?
Mar 18, 2009, 01:01 PM
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Second, set your cams back to zero, go get bigger injectors and a fuel pump and find a "GOOD" tuner.
Mar 18, 2009, 06:09 PM
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When it comes to cams and cam gears it is all about personal preference. The options are limitless. Dialing in cams can't be done without proper measuring devices any how. (degree wheel, and dial indicator)
I have revolver cams and stock gears. With proper tuning the power can be extracted without the use of cam gears.
Mar 19, 2009, 01:56 PM
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hi guys ive taken the cams off today and put my std cams back. i havent retuned the car yet but it feels like ive got my lost power back . it took me 3 hours to set the correct decrease with the srocket tools but in the end it was a waist of time
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Mar 20, 2009, 11:05 PM
#10
Apr 7, 2009, 08:00 AM
#15
Here is some help :)
It looks like there is some confusion as to what the benefits and uses are of cam gears as well as what they are expected to do in terms of improving/changing your power levels.
I have a masters degree in mechanical engineering and work full time as an automotive engineer specializing in combustion and performance. As such I have a decent understanding of some of these issues and will attempt to outline some basics for you guys.
Basically cam gears will allow the tuner to adjust the phasing of the intake and exhaust cam by +- a few degrees in what would otherwise have been a fixed nonadjustable cam.
What are the benefits of this? Well as you adjust the phasing of the cams, you change when the intake and exhaust valves open and close in relation to the position of the piston and crank.
This sort of mechanical tuning is ALWAYS a trade off. Physics does not allow for "Free lunch" where you will get the best of everything with no negative trade offs.
here are a few of the simple effects of phasing:
If you:
retard the intake cam. You have effectively delayed how late the intake valve is open and you do what is called Late Intake valve Close. This IVC is one of the most important valve events and is a favorite of tuners and OEM's to play with.
Advancing the intake phasing will cause some valve overlap, meaning that there is a couple of degrees when your intake and exhaust valve are both open at the same time. This will destabilize the delicate idle combustion and cause a lumpy uneven idle. (Think 280 race cams!) Intake reversion occurs and some exhaust can backflow into the intake and mix around and generally cause less that ideal mixing for stable combustion.
So why would you want late IVC? Because at HIGH rpm, when the intake mass flow has a lot of momentum, the incoming air can "Stuff itself" into the intake valve just before it closes. so closing the intake valve late allows for a bit more fresh charge to squeeze in using its momentum, even as the piston starts to rise up for compression.
Valve overlap at this time, will also allow the intake air to "flush out" the cylinder more effectively (this is called scavenging) pushing the burnt exhaust gasses out of the cylinder and introducing a cleaner cooler new charge by evacuating all the exhaust gas more effectively. = more power.
more valve overlap tends to cause worse idle. But with late IVC you can gain better top end power. (very simplified)
Playing with the exhaust cam phasing will also have impacts on the valve overlap events, but it its main impact is how well the cylinder is evacuated of burnt gasses after combustion and how much of the expansion stroke is used to actually generate work at the crank. In order to make the most power possible, we have to get all the hot burned oxygenless combustion gasses out of the cylinder as quickly and completely as possible.
An early exhaust valve open event will allow the built up pressure of the late expansion stroke to "shoot" the exhaust gas out of the exhaust valve. This is called Blowdown. And combined with late intake valve close can be effective at scavenging. The downside is, the energy left in the cylinder is lost to the exhaust the instant the valve opens, and no more power is being transferred to the crank as a result. If you open the exhaust valve too early, then you loose a bunch of potential work that could be pushing down on the piston for a little bit longer.
On the other hand, you could wait really late for a exhaust valve open event. This will phase less valve overlap and offer a smoother idle, as well as allowing the engine to complete a full expansion stroke getting as much power as possible out of the expanding combustion. This is good for fuel consumption, efficiency, and low end torque/response. Not so great for high end power.
There are many many other factors that affect and have impact on cam phasing, but these are some basic tips to get the ideas flowing. Upgraded cams play their role by increasing how quickly the valves are pushed open (ramp rates), how long they stay open (duration), and how high they are pushed (lift). The bigger the valve, the higher the lift, the longer the duration, the more aggressive the cam and the more potential there is to flow air (which is the key to making power).
People think that bolting cams into a car should magically add power. It might, but thats not how its meant to work. After installing ANY mods that affect air flow in any way, you MUST MUST MUST retune the car. Making power requires a balance of fuel and air and spark timing. These are the MOST valuable tools you have to make power, no amount of boost or cams or giant turbos will do you any good if you haven't tuned your ECU to take advantage of this increased potential.
To get the most out of your mods always have your car retuned professionally after any upgrades that affect air/fuel in any way.
I have a masters degree in mechanical engineering and work full time as an automotive engineer specializing in combustion and performance. As such I have a decent understanding of some of these issues and will attempt to outline some basics for you guys.
Basically cam gears will allow the tuner to adjust the phasing of the intake and exhaust cam by +- a few degrees in what would otherwise have been a fixed nonadjustable cam.
What are the benefits of this? Well as you adjust the phasing of the cams, you change when the intake and exhaust valves open and close in relation to the position of the piston and crank.
This sort of mechanical tuning is ALWAYS a trade off. Physics does not allow for "Free lunch" where you will get the best of everything with no negative trade offs.
here are a few of the simple effects of phasing:
If you:
retard the intake cam. You have effectively delayed how late the intake valve is open and you do what is called Late Intake valve Close. This IVC is one of the most important valve events and is a favorite of tuners and OEM's to play with.
Advancing the intake phasing will cause some valve overlap, meaning that there is a couple of degrees when your intake and exhaust valve are both open at the same time. This will destabilize the delicate idle combustion and cause a lumpy uneven idle. (Think 280 race cams!) Intake reversion occurs and some exhaust can backflow into the intake and mix around and generally cause less that ideal mixing for stable combustion.
So why would you want late IVC? Because at HIGH rpm, when the intake mass flow has a lot of momentum, the incoming air can "Stuff itself" into the intake valve just before it closes. so closing the intake valve late allows for a bit more fresh charge to squeeze in using its momentum, even as the piston starts to rise up for compression.
Valve overlap at this time, will also allow the intake air to "flush out" the cylinder more effectively (this is called scavenging) pushing the burnt exhaust gasses out of the cylinder and introducing a cleaner cooler new charge by evacuating all the exhaust gas more effectively. = more power.
more valve overlap tends to cause worse idle. But with late IVC you can gain better top end power. (very simplified)
Playing with the exhaust cam phasing will also have impacts on the valve overlap events, but it its main impact is how well the cylinder is evacuated of burnt gasses after combustion and how much of the expansion stroke is used to actually generate work at the crank. In order to make the most power possible, we have to get all the hot burned oxygenless combustion gasses out of the cylinder as quickly and completely as possible.
An early exhaust valve open event will allow the built up pressure of the late expansion stroke to "shoot" the exhaust gas out of the exhaust valve. This is called Blowdown. And combined with late intake valve close can be effective at scavenging. The downside is, the energy left in the cylinder is lost to the exhaust the instant the valve opens, and no more power is being transferred to the crank as a result. If you open the exhaust valve too early, then you loose a bunch of potential work that could be pushing down on the piston for a little bit longer.
On the other hand, you could wait really late for a exhaust valve open event. This will phase less valve overlap and offer a smoother idle, as well as allowing the engine to complete a full expansion stroke getting as much power as possible out of the expanding combustion. This is good for fuel consumption, efficiency, and low end torque/response. Not so great for high end power.
There are many many other factors that affect and have impact on cam phasing, but these are some basic tips to get the ideas flowing. Upgraded cams play their role by increasing how quickly the valves are pushed open (ramp rates), how long they stay open (duration), and how high they are pushed (lift). The bigger the valve, the higher the lift, the longer the duration, the more aggressive the cam and the more potential there is to flow air (which is the key to making power).
People think that bolting cams into a car should magically add power. It might, but thats not how its meant to work. After installing ANY mods that affect air flow in any way, you MUST MUST MUST retune the car. Making power requires a balance of fuel and air and spark timing. These are the MOST valuable tools you have to make power, no amount of boost or cams or giant turbos will do you any good if you haven't tuned your ECU to take advantage of this increased potential.
To get the most out of your mods always have your car retuned professionally after any upgrades that affect air/fuel in any way.
Last edited by ktk; Apr 7, 2009 at 12:28 PM.