Cams
#1
08-28-2010, 07:28 PM
Cams
Just a few questions that I am SURE most of you can answer for me about cams.
What do the numbers mean for duration, lift, etc. and what do they equate to?
I saw two comp comps and one had a rpm range of 1600-5600 or so and the other had 2000-6000. What does the range mean? Does it mean the range of it's usability? It moves the powerband? So the second cam won't really let the car "take off" until 2000rpm as opposed to the first's 1600?
And the numbers, why would you want a cam with a longer duration or a higher lift and whatnot? What differences do they have?
I understand that cams allow the engine to breath better but am not positive on all the numbers. I know I can search google but I think by posting on here I can get more detailed explanations for our cars specifically.
Thanks for your answers guys, I know I can come here without get flak.
What do the numbers mean for duration, lift, etc. and what do they equate to?
I saw two comp comps and one had a rpm range of 1600-5600 or so and the other had 2000-6000. What does the range mean? Does it mean the range of it's usability? It moves the powerband? So the second cam won't really let the car "take off" until 2000rpm as opposed to the first's 1600?
And the numbers, why would you want a cam with a longer duration or a higher lift and whatnot? What differences do they have?
I understand that cams allow the engine to breath better but am not positive on all the numbers. I know I can search google but I think by posting on here I can get more detailed explanations for our cars specifically.
Thanks for your answers guys, I know I can come here without get flak.
#2
08-29-2010, 10:01 AM
Durations is the number of crankshaft degrees of engine rotation in which the valve is off the seat, the bigger the duration the bigger the horsepower gained
Lift has to do with how far the valve rises from it's seat
Cams can change the powerband level of your car, my VT Stage 2 N/A cams had a lot less power in the low RPMs but it came ALIVE up high and I also upgraded my valve springs (it can be necessary depending on the cams) and I was able to shift at 6500 RPMs.
More aggressive cams can cause you to have to upgrade the internals of your car, so you want to be sure the cams you pick are supported by factory internals or be prepared to do some upgrades.
Lift has to do with how far the valve rises from it's seat
Cams can change the powerband level of your car, my VT Stage 2 N/A cams had a lot less power in the low RPMs but it came ALIVE up high and I also upgraded my valve springs (it can be necessary depending on the cams) and I was able to shift at 6500 RPMs.
More aggressive cams can cause you to have to upgrade the internals of your car, so you want to be sure the cams you pick are supported by factory internals or be prepared to do some upgrades.
#4
08-30-2010, 08:15 AM
5,500 rpms is the best rpm for a n/a 2v with bolt on's. If you have boost its a different setup.
#5
08-30-2010, 01:50 PM
In general:
a longer duration will operate with peak efficiency at higher RPM than a shorter duration.
Lift and duration combine to affect PTV clearances. Duration would probably be the part you have to worry about with 4.6's as they're an "interference engine" meaning that the pistons and the valves occupy the same space at different times which sets you up for an easy time finding a cam that can deliver PTV interference.
LSA and intake centerline have quite a bit to do with how the motor behaves with a given cam. Lift and duration are just part of the thing.
The RPM ranges they give you are the boundaries of the power band. The motor will be kinda laggy from a stop with a cam designed for 2000-6000 operation where it'll have more grunt off the line with one set up for 1500-6000. The stock cams are setup for 5500rpm hp peaks with peak tq at 3500 and about 80% of the tq available just off idle. Something with a 2k-6k rating would be intended to bump performance between those two but you'll likely lose a little under the low number and above the high number.
If you're going to pick a cam, decide what else you're going to do first. Cams should be among the last things you do. Return on investment is pretty low considering a 600 dollar buy-in for the parts plus about 8-10hrs of labor at your local tuner's shop rate ($80/hr). All that for 15-20hp.
Cam science is a bitch. It takes a lot of time to learn the realities of what's happening and there's still a bit of black magic to the whole thing.
a longer duration will operate with peak efficiency at higher RPM than a shorter duration.
Lift and duration combine to affect PTV clearances. Duration would probably be the part you have to worry about with 4.6's as they're an "interference engine" meaning that the pistons and the valves occupy the same space at different times which sets you up for an easy time finding a cam that can deliver PTV interference.
LSA and intake centerline have quite a bit to do with how the motor behaves with a given cam. Lift and duration are just part of the thing.
The RPM ranges they give you are the boundaries of the power band. The motor will be kinda laggy from a stop with a cam designed for 2000-6000 operation where it'll have more grunt off the line with one set up for 1500-6000. The stock cams are setup for 5500rpm hp peaks with peak tq at 3500 and about 80% of the tq available just off idle. Something with a 2k-6k rating would be intended to bump performance between those two but you'll likely lose a little under the low number and above the high number.
If you're going to pick a cam, decide what else you're going to do first. Cams should be among the last things you do. Return on investment is pretty low considering a 600 dollar buy-in for the parts plus about 8-10hrs of labor at your local tuner's shop rate ($80/hr). All that for 15-20hp.
Cam science is a bitch. It takes a lot of time to learn the realities of what's happening and there's still a bit of black magic to the whole thing.
Last edited by r3dn3ck; 08-30-2010 at 01:52 PM.
#6
09-01-2010, 04:18 PM
Adding to this topic..
I totally agree with the statement above, you need to know your goals of the car. For example don't go installing N/A cams if you want to supercharge down the line, it's a WASTE.
I had 4.10 gears in my 2003 and that helped it pick up in the low RPMs since my cams were so aggressive up high.
With all my mods (LT headers, O/R X-pipe, catback, u/d pulleys, 75mm tb and plenum, cai) and the cams I made 296 rwhp on 93 octane gas. It's always been one of the higher numbers I've seen for those mods.
Cams will change a lot of things about your car, I had a buddy who copied a lot of the mods I did and he even went as far as getting the cams, and he grew to hate them. He hated the way the car shook (it never bothered me). The biggest thing is it makes the car sound so ******* badass. Forget the horsepower gained, the sound alone made it all worth it to me. I never heard another mustang sound like mine did and every one could tell it was my car from the sound, I got so many compliments on it from strangers.
Here for the hell of it, here's a video of the install that was a PITA, the camera never did the sound of the car justice though
http://www.csledd.com/ellie/cams/cams-install.wmv
I totally agree with the statement above, you need to know your goals of the car. For example don't go installing N/A cams if you want to supercharge down the line, it's a WASTE.
I had 4.10 gears in my 2003 and that helped it pick up in the low RPMs since my cams were so aggressive up high.
With all my mods (LT headers, O/R X-pipe, catback, u/d pulleys, 75mm tb and plenum, cai) and the cams I made 296 rwhp on 93 octane gas. It's always been one of the higher numbers I've seen for those mods.
Cams will change a lot of things about your car, I had a buddy who copied a lot of the mods I did and he even went as far as getting the cams, and he grew to hate them. He hated the way the car shook (it never bothered me). The biggest thing is it makes the car sound so ******* badass. Forget the horsepower gained, the sound alone made it all worth it to me. I never heard another mustang sound like mine did and every one could tell it was my car from the sound, I got so many compliments on it from strangers.
Here for the hell of it, here's a video of the install that was a PITA, the camera never did the sound of the car justice though
http://www.csledd.com/ellie/cams/cams-install.wmv
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