Basics of a Cam
10-19-2003, 08:16 PM
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Basics of a Cam Alright, this should be basic.
I know that putting a more aggressive cam in your car will give it the lumpy, mean idle, and I know it is supposed to add more power...but what exactly is a cam? Is it the same as a camshaft? How does it add power, and is it the lobes on the camshaft that give the cars the disticntive idles? Thanks in advance,
Ed
I know that putting a more aggressive cam in your car will give it the lumpy, mean idle, and I know it is supposed to add more power...but what exactly is a cam? Is it the same as a camshaft? How does it add power, and is it the lobes on the camshaft that give the cars the disticntive idles? Thanks in advance,
Ed
10-19-2003, 08:22 PM
#2
Re: Basics of a Cam the cam is the heart of the car. heres a small overview from jmX's site.
By far, one of the best mods you can possibly ever do to your LS1/LS6 is to install an aftermarket camshaft in it. Gains from various camshafts can range anywhere from 20rwhp to 60+rwhp for more radical cams. For gains this amazing, it must cost an arm and a leg right?!? Well, the beauty of swapping in a new cam is the hp/dollar ratio. A good cam package can range anywhere from $650 up to $1000 depending on what components it includes.
The great price, the great gains, AND the fact you can install all these parts yourself in your own garage make this modification probably one of the most popular ones done on LS1/LS6 based engines.
When deciding which camshaft is right for you, the best you can do is try to make an educated guess based on previous experiences or other's experiences. There are countless books about camshaft design and theory, so trying to explain what all to choose is pointless and this is why vendors are out there to see what works well in the LS1 for us. They do the research, and thus, they get our money.
When buying a cam, you'll see specs like "220/224 0.550/0.558 114lsa". The first two numbers are intake duration (in degrees) followed by exhaust duration (in degrees). The next two numbers are valve lift for the intake (in inches) and valve lift for the exhaust (in inches).Finally, the last number is the Lobe Separation Angle.
Duration:
Duration really plays a big factor in how the cam will drive and idle. The bigger the duration, the longer the valves stay open, and generally the 'lopier' and worse driving the cam will be. The numbers you'll usually see are the duration in degrees that the valve is open MORE than 0.050" of an inch. Cam cards will also list duration at 0 lift, and that will be a number like 270-290'ish. Cams that have the same duration for intake and exhaust are symmetrical, cams with more intake than exhaust are called "reverse split", and cams with more exhaust than intake are sometimes referred to as "traditional split".
LSA (Lobe Separation Angle):
Lobe Separation Angle, usually referred to as "LSA", is the angle of separation between the exhaust peak and intake peak. The lower the angle, the more the lobes will overlap, and that means more lope, gas smell, and drivability issues...however, the lower LSA can also mean more power and you get it sooner in the RPM range to boot. Duration and LSA are 2 very important items in clueing you into how a cam will idle and drive, although there is a LOT more to a cam than this.
Lift:
Cam lift, in my opinion, is less of a complicated matter on these motors. There's not much of a reason to run less than 0.550" of valve lift, so anything between 0.550 and 0.600" is probably going to be fine. If you have ported heads, it may be best to lean towards cams with 0.570" lift and up as most ported heads will just keep flowing more and more as that valve lift increases. Note that a cam card will show lobe lift, which is the actual lift of the cam lobe. Once you take lobe lift and multiply it by the ratio of the rocker arm (stock is 1.7), you get valve lift.
Lobe Profile
The Lobe profile of a cam basically is the curve at which a valve is opened and closed. Some lobes are very EXTREME and will snap a valve open very quickly and then slam it shut, while others are "softer" and slowly open and close valves. The more extreme the lobe, the noisier your valvetrain will be and the harder it is on your valve springs...however, a more extreme lobe will generally idle better than a less extreme lobe with the same duration at 50 thousandths. If your cam has very aggressive lobes and your cam lift is up there, I'd suggest you try to lighten your valvetrain by getting titanium retainers if possible.
Choosing the cam for you
For cars that need to stay stock sounding and driving, but still want a kick in the pants for horsepower, something between a 214 and 220'ish duration would probably be best. For the majority of the cars out there, anything in the 221-227 range is probably a better selection, and for the guys that want all they can get 228+ duration cam shafts are generally the minimum. As a novice all you can do is ask around, listen to cars, look at track/dyno results, and make your best guess. As long as you pick a cam close to what might fit you (i.e. mild, average, or extreme given the criteria above) you really can't go wrong. It's not a life or death decision here. A few degrees here and there isn't something you should sweat about until you've gotten a few cams under your belt and know more about what you want.
Choosing the valvetrain upgrades:
Now, you can't just throw a cam in and call it a day. At the BARE minimum your valvesprings *must* be replaced with stiffer ones. Whoever sells you the cam can also recommend a spring to go along with it...this is what vendors/shops are for, so you don't need to worry about being an expert on this (although it's not very complicated if you want to learn). Some springs will require aftermarket retainers (it's kind of a hat that sits on top of the spring), some won't, but in general if you go with a very aggressive cam and plan on spinning the engine up past 6600rpms I'd recommend getting Titanium retainers to help reduce the moving mass and keep the valvetrain moving crisply.
Next there are spring seats and valve seals....some spring setups may require you change the spring seat and install new valve seals as well. If your vendor requires you install this, I will cover their install in this document as well. Hardened pushrods will also be highly recommended, although quite a few have just stuck with the stock pushrods and not had issues.
By far, one of the best mods you can possibly ever do to your LS1/LS6 is to install an aftermarket camshaft in it. Gains from various camshafts can range anywhere from 20rwhp to 60+rwhp for more radical cams. For gains this amazing, it must cost an arm and a leg right?!? Well, the beauty of swapping in a new cam is the hp/dollar ratio. A good cam package can range anywhere from $650 up to $1000 depending on what components it includes.
The great price, the great gains, AND the fact you can install all these parts yourself in your own garage make this modification probably one of the most popular ones done on LS1/LS6 based engines.
When deciding which camshaft is right for you, the best you can do is try to make an educated guess based on previous experiences or other's experiences. There are countless books about camshaft design and theory, so trying to explain what all to choose is pointless and this is why vendors are out there to see what works well in the LS1 for us. They do the research, and thus, they get our money.
When buying a cam, you'll see specs like "220/224 0.550/0.558 114lsa". The first two numbers are intake duration (in degrees) followed by exhaust duration (in degrees). The next two numbers are valve lift for the intake (in inches) and valve lift for the exhaust (in inches).Finally, the last number is the Lobe Separation Angle.
Duration:
Duration really plays a big factor in how the cam will drive and idle. The bigger the duration, the longer the valves stay open, and generally the 'lopier' and worse driving the cam will be. The numbers you'll usually see are the duration in degrees that the valve is open MORE than 0.050" of an inch. Cam cards will also list duration at 0 lift, and that will be a number like 270-290'ish. Cams that have the same duration for intake and exhaust are symmetrical, cams with more intake than exhaust are called "reverse split", and cams with more exhaust than intake are sometimes referred to as "traditional split".
LSA (Lobe Separation Angle):
Lobe Separation Angle, usually referred to as "LSA", is the angle of separation between the exhaust peak and intake peak. The lower the angle, the more the lobes will overlap, and that means more lope, gas smell, and drivability issues...however, the lower LSA can also mean more power and you get it sooner in the RPM range to boot. Duration and LSA are 2 very important items in clueing you into how a cam will idle and drive, although there is a LOT more to a cam than this.
Lift:
Cam lift, in my opinion, is less of a complicated matter on these motors. There's not much of a reason to run less than 0.550" of valve lift, so anything between 0.550 and 0.600" is probably going to be fine. If you have ported heads, it may be best to lean towards cams with 0.570" lift and up as most ported heads will just keep flowing more and more as that valve lift increases. Note that a cam card will show lobe lift, which is the actual lift of the cam lobe. Once you take lobe lift and multiply it by the ratio of the rocker arm (stock is 1.7), you get valve lift.
Lobe Profile
The Lobe profile of a cam basically is the curve at which a valve is opened and closed. Some lobes are very EXTREME and will snap a valve open very quickly and then slam it shut, while others are "softer" and slowly open and close valves. The more extreme the lobe, the noisier your valvetrain will be and the harder it is on your valve springs...however, a more extreme lobe will generally idle better than a less extreme lobe with the same duration at 50 thousandths. If your cam has very aggressive lobes and your cam lift is up there, I'd suggest you try to lighten your valvetrain by getting titanium retainers if possible.
Choosing the cam for you
For cars that need to stay stock sounding and driving, but still want a kick in the pants for horsepower, something between a 214 and 220'ish duration would probably be best. For the majority of the cars out there, anything in the 221-227 range is probably a better selection, and for the guys that want all they can get 228+ duration cam shafts are generally the minimum. As a novice all you can do is ask around, listen to cars, look at track/dyno results, and make your best guess. As long as you pick a cam close to what might fit you (i.e. mild, average, or extreme given the criteria above) you really can't go wrong. It's not a life or death decision here. A few degrees here and there isn't something you should sweat about until you've gotten a few cams under your belt and know more about what you want.
Choosing the valvetrain upgrades:
Now, you can't just throw a cam in and call it a day. At the BARE minimum your valvesprings *must* be replaced with stiffer ones. Whoever sells you the cam can also recommend a spring to go along with it...this is what vendors/shops are for, so you don't need to worry about being an expert on this (although it's not very complicated if you want to learn). Some springs will require aftermarket retainers (it's kind of a hat that sits on top of the spring), some won't, but in general if you go with a very aggressive cam and plan on spinning the engine up past 6600rpms I'd recommend getting Titanium retainers to help reduce the moving mass and keep the valvetrain moving crisply.
Next there are spring seats and valve seals....some spring setups may require you change the spring seat and install new valve seals as well. If your vendor requires you install this, I will cover their install in this document as well. Hardened pushrods will also be highly recommended, although quite a few have just stuck with the stock pushrods and not had issues.
10-19-2003, 08:41 PM
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Re: Basics of a Cam Wow...Thanks for that reply jrp. I am still a little confused though...is a cam just the camshaft then or is is everthing including special valves and such?
Thanks
Ed
Thanks
Ed
10-20-2003, 10:36 AM
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Re: Basics of a Cam And then you have Stealth Cams. like mine 220/220, .581/.581, 115 lsa
Stealth cams iddle almost like stock and have a strong pull acrosss the curve all the way till 6500 rpm.
Stealth cams iddle almost like stock and have a strong pull acrosss the curve all the way till 6500 rpm.
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10-20-2003, 05:46 PM
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Re: Basics of a Cam That said this is something you can do in your garage? Don't you basically need to pull the motor out to put the new cam in?
I'm also looking at getting a new cam but thought it would be something that might be just outside my abilities.
Also what kind of cam would you recommend with a good lope, strong pull but with alright driving characteristics? It doesn't need to be completely stock feel but at least able to drive it without causing too much attention.
I'm also looking at getting a new cam but thought it would be something that might be just outside my abilities.
Also what kind of cam would you recommend with a good lope, strong pull but with alright driving characteristics? It doesn't need to be completely stock feel but at least able to drive it without causing too much attention.
10-20-2003, 06:10 PM
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Re: Basics of a Cam
That said this is something you can do in your garage? Don't you basically need to pull the motor out to put the new cam in?
I'm also looking at getting a new cam but thought it would be something that might be just outside my abilities.
Also what kind of cam would you recommend with a good lope, strong pull but with alright driving characteristics? It doesn't need to be completely stock feel but at least able to drive it without causing too much attention.
I'm also looking at getting a new cam but thought it would be something that might be just outside my abilities.
Also what kind of cam would you recommend with a good lope, strong pull but with alright driving characteristics? It doesn't need to be completely stock feel but at least able to drive it without causing too much attention.
http://ls1howto.com/index.php?article=23
keep in mind i had never even changed oil or spark plugs before so its not like i had loads of automotive experience. you just need the right tools and patience and it can be done.
look at that chart thats in the 2nd post, that'll give you an idea of the kinda cam you should go for. it depends on alot of things though. you sound like a 220-224 112-114lsa kinda guy.
10-20-2003, 06:27 PM
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Re: Basics of a Cam Thanks for posting (and not saying "do a search")the great info jrp! Wow, cam swap before oil change, huh. Got more self confidence than I did. Started to do mine a couple months back but stopped because it was gonna take more time than I had. Now the oil looks like tar. Is it time to change it??? J/K all! I meant the cam!!! 
10-20-2003, 07:07 PM
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Re: Basics of a Cam Yeah that helps a lot, really appreciate it.
One more question, how much difference is there in a 224/224 with 114lsa than a 224/224 with 112lsa?
One more question, how much difference is there in a 224/224 with 114lsa than a 224/224 with 112lsa?
10-20-2003, 07:48 PM
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Re: Basics of a Cam jrp, you are the man, helped out a lot of people with your info. I hate the standard...do a search answer people give. Thanks for taking time out to help out.
10-20-2003, 07:56 PM
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Re: Basics of a Cam Yeah I would agree, this has been a lot of help with deciding on a good cam to start with. Don't want to keep changing them out every other month till you find the right one.
So thank you for all the help.
Nick
So thank you for all the help.
Nick
10-20-2003, 09:16 PM
#15
Re: Basics of a Cam no problem guys. i did alot of research on cams too before i picked mine. theres alot of info out there and with stuff like cams its best to get all the info you can so you can make the right decision for your application.
z289899 - the tr224 on the 112 and 114 will make similar power, the 114 will have less lope and a broader powerband while the 112 will have more lope at be a little bit peakier.
i like lope as you can see by my choice. if you have to pass smog the 114 will be the best bet as it has less overlap then the 112. the 112 could probably pass with a good enough tune but the 114 has been proven already. also if you have an a4 a 114 will be a little easier on drivability and idle then a 112. but again, tuning can help.
z289899 - the tr224 on the 112 and 114 will make similar power, the 114 will have less lope and a broader powerband while the 112 will have more lope at be a little bit peakier.
i like lope as you can see by my choice. if you have to pass smog the 114 will be the best bet as it has less overlap then the 112. the 112 could probably pass with a good enough tune but the 114 has been proven already. also if you have an a4 a 114 will be a little easier on drivability and idle then a 112. but again, tuning can help.
10-21-2003, 06:43 AM
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Re: Basics of a Cam So do you drive yours on a regular basis? I have an M6 also. Also how much power could you make with the 224 cam and a set of good heads?
Thanks.
Nick
Thanks.
Nick
10-21-2003, 03:55 PM
#17
Re: Basics of a Cam
So do you drive yours on a regular basis? I have an M6 also. Also how much power could you make with the 224 cam and a set of good heads?
Thanks.
Nick
Thanks.
Nick
with some ported heads and a 224 and other bolt ons your over 400rwhp.
10-21-2003, 04:03 PM
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Re: Basics of a Cam My friend (who installed his 224) and I (who's never installed anything more than a MAF), put my cam in a couple weekends ago. Everything went fine (following JMX's write up). Only thing that went wrong was that the ASP pulley started to creep forward after driving for a week. Had it redone at a shop. No probs now. This big cam rocks too by the way. Check out the sound clip in the multimedia forum.
Good luck. I learned about cams on this forum too.
Good luck. I learned about cams on this forum too.
10-22-2003, 01:16 PM
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Re: Basics of a Cam south fl. is yours a daily driver also? Your cam is a little bigger also. I want to go about as big as I can and still be able to drive it on the street. Like I said before, without looking like too much of a jackass.
Thanks for everyones help so far.
Nick
Thanks for everyones help so far.
Nick
10-23-2003, 08:37 AM
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Re: Basics of a Cam
south fl. is yours a daily driver also? Your cam is a little bigger also. I want to go about as big as I can and still be able to drive it on the street. Like I said before, without looking like too much of a jackass.
Thanks for everyones help so far.
Nick
Thanks for everyones help so far.
Nick
This cam lopes hard I tell ya, but it still drives well on the street.
I drove my friend's M6 Z28 with a 224/224 .588/.588 112, and it as an audible lope to it without attracting too much attention. The 224's are great all around cams.