Cams - what does it all mean?
Discussion
Pretty much certain that my CV8 will get the cam treatment from Monkfish next year along with a 3.91 diff. FI is too much of a stretch financially.
I hear people talk about wild cams, hot cams, mild cams, magic cams and use lots of numbers that look a bit like an IP address and I have no idea what it all means.
Can someone explain?
What gives a cam a particular characteristic that labels it as wild or mild?
What do emission have to do with the choice of cam?
Will the noise of the car change with a cam change and if so why?
Will a cam improve power or torque or both?
As you can see I know FA...
I hear people talk about wild cams, hot cams, mild cams, magic cams and use lots of numbers that look a bit like an IP address and I have no idea what it all means.
Can someone explain?
What gives a cam a particular characteristic that labels it as wild or mild?
What do emission have to do with the choice of cam?
Will the noise of the car change with a cam change and if so why?
Will a cam improve power or torque or both?
As you can see I know FA...
Decide what you want from the cam, does it have to be emissions compliant (adviseable!) do you want an idle that similar to standard or one that bounces all over the place and how much power do you want from the car.
Once you know ask one of the experts to pick a cam for you and get it fitted
I tried understanding it all and after nearly 2 weeks gave up lol
Once you know ask one of the experts to pick a cam for you and get it fitted
I tried understanding it all and after nearly 2 weeks gave up lol
after_shock said:
Decide what you want from the cam, does it have to be emissions compliant (adviseable!) do you want an idle that similar to standard or one that bounces all over the place and how much power do you want from the car.
Once you know ask one of the experts to pick a cam for you and get it fitted
I tried understanding it all and after nearly 2 weeks gave up lol
Once you know ask one of the experts to pick a cam for you and get it fitted
I tried understanding it all and after nearly 2 weeks gave up lol
I would like to cam ma car but iam lost when they start putting ratio`s up
I think i would like a cam that would give even power all the way up.
nosubstitute said:
Pretty much certain that my CV8 will get the cam treatment from Monkfish next year along with a 3.91 diff. FI is too much of a stretch financially.
I hear people talk about wild cams, hot cams, mild cams, magic cams and use lots of numbers that look a bit like an IP address and I have no idea what it all means.
Can someone explain?
What gives a cam a particular characteristic that labels it as wild or mild?
What do emission have to do with the choice of cam?
Will the noise of the car change with a cam change and if so why?
Will a cam improve power or torque or both?
As you can see I know FA...
Thank youI hear people talk about wild cams, hot cams, mild cams, magic cams and use lots of numbers that look a bit like an IP address and I have no idea what it all means.
Can someone explain?
What gives a cam a particular characteristic that labels it as wild or mild?
What do emission have to do with the choice of cam?
Will the noise of the car change with a cam change and if so why?
Will a cam improve power or torque or both?
As you can see I know FA...
You saved me asking 
If you want to understand the terminology a bit then read one of the article on the Internet. here's one - http://www.chevyhiperformance.com/techarticles/148...
If you just want to get a cam then consult an expert, have them quiz you and spec a cam.
If you just want to get a cam then consult an expert, have them quiz you and spec a cam.
Magic919 said:
If you want to understand the terminology a bit then read one of the article on the Internet. here's one - www.chevyhiperformance.com/techarticles/148_0405_camshaft_variables_basics/index.html
If you just want to get a cam then consult an expert, have them quiz you and spec a cam.
If you just want to get a cam then consult an expert, have them quiz you and spec a cam.
If your like me and dont really fully understand whats going on with a cam and know what your reading just rely on an expert, could go badly wrong!
It's not the best written scentence I've ever seen, but I understand his point. What don't you get Magic?
I've read that link and I'm sure it does explain things very fully, but it is very technical. Someone that knows alot about engines may read that a think yep, that's a pretty good explanation. I read that and I struggle to understand what it's saying. It would be nice for someone with a bit of knowledge to help explain things.
From what I gather, cams are valves that sit on the engine. On top of the valves are covers (or lobes) which are opened and closed by the cam shaft allowing air in. Depending on which cam you go for those lobes will even open wider, or for longer length of time. Depending on whether they open longer or wider you get different performance through the engine range.
So does that mean you need to get a cam based on where you want the performance i.e. if you're going for more low end grunt or top end speed?
Confused.com.
It would be nice if someone just came along and posted a decent response instead of the classic try google response.
I've read that link and I'm sure it does explain things very fully, but it is very technical. Someone that knows alot about engines may read that a think yep, that's a pretty good explanation. I read that and I struggle to understand what it's saying. It would be nice for someone with a bit of knowledge to help explain things.
From what I gather, cams are valves that sit on the engine. On top of the valves are covers (or lobes) which are opened and closed by the cam shaft allowing air in. Depending on which cam you go for those lobes will even open wider, or for longer length of time. Depending on whether they open longer or wider you get different performance through the engine range.
So does that mean you need to get a cam based on where you want the performance i.e. if you're going for more low end grunt or top end speed?
Confused.com.
It would be nice if someone just came along and posted a decent response instead of the classic try google response.
Tempy said:
From what I gather, cams are valves that sit on the engine. On top of the valves are covers (or lobes) which are opened and closed by the cam shaft allowing air in. Depending on which cam you go for those lobes will even open wider, or for longer length of time. Depending on whether they open longer or wider you get different performance through the engine range.
So does that mean you need to get a cam based on where you want the performance i.e. if you're going for more low end grunt or top end speed?
Cams can go above or below - the classic engine design has the cams mounted near the crank at the bottom and use solid metal shafts to actuate the valves. Modern engines generally have the cam shaft mounted on the cylinder head as this results is a lower mass meaning everything can be a bit lighter, more responsive and easier to reach higher RPM. On a lazy engine like the LSx series with a relatively low RPM limit its not a problem.
Anyway, I digress. There are three different aspects to a Cam
- when it opens
- how far it opens (AKA lift)
- and how long it opens (duration)
The intake and exhaust valves have their own pattern and can either share the same cam shaft or use their own.
For power you want to blur the intake opening and exhaust closing but this is not fuel efficient and increases emissions.
Converserly, for economy you almost want a definate "gap" between the operation of the exhaust and intake valves.
You're right in that if you want ultimate top end BHP performance with no variable valve technology then you do in general sacrifice low/mid range as the valve timing is way off the optimum. This is the classic lumpy idle mentioned above.
I've had road cars tuned to 130bhp/litre NA with no variable valve and below 3k rpm it was considerably slower than an identical standard car tuned to 70bhp/litre. However, once the air was flowing and the engine on the boil above 4k rpm it was simply stunning.
As with most things it's all about compromise... if you want to MOT friendly then you'll need to bear in mind really wild/hot cams can be difficult to get through and if you want a car that remains easy to drive around town then again you want to go for warm rather than hot cams.
after_shock said:
Magic919 said:
If you want to understand the terminology a bit then read one of the article on the Internet. here's one - http://www.chevyhiperformance.com/techarticles/148...
If you just want to get a cam then consult an expert, have them quiz you and spec a cam.
If your like me and dont really fully understand whats going on with a cam and know what your reading just rely on an expert, could go badly wrong!If you just want to get a cam then consult an expert, have them quiz you and spec a cam.
If your like me and dont really fully understand whats going on with a cam and dont know what your reading just rely on an expert. It could go badly wrong!
Its pretty complex and is very much based on wave tuning physics, delta air pressure, volumes, velocities, temperatures. You base on required use profile, rpm range, power requirements, driveability, durability etc.
As mentioned it is a compromise. However other than spring wear lift is always good as it can only help and doesnt often affect rpm range, use profile etc. Duration, overlap and valve timing determine most of the factors. The cam is selected based on the whole package from exhaust to intake filter. Though the cylinder head is a large determinant.
The valve is the MAIN impediment to power, nothing else has as much affect on engine power as the valves do. Hence why its so important, the cam operates the valve!
You can look at camquest from comp, its free software and enter all your engine details, it will give you a torque graph and suggested power range etc. Using that will automatically put you ahead of most internet armchair specialists. I dont know enough myself. But Im happy to spec my own cams these days. They might not be 100% optimal, but Ive always had the best dyno results of any NA setup on the forum, including the stock cam. But I always treat the engine exhaust to intake which not many do.
A stock LS1 cam is 15 year old technology. When looking for power Id look to that first. Why use ancient technology designed when computing power was a fraction of what it is now!? Comp LSR lobes are the latest technology and used by countless nascar teams etc. Though other cam companies arnt far behind. Pretty much any reasonable replacement will be a massive step forward. Bare minimum anyone should look at IMO is the 216/220 cam with a good high lift lobe and proper valve springs to handle it etc.
The Stock LS2 cam is something like a 202/211 IIRC. So its not that much larger. My current cam is a 230/238. I know the guys with lighter cars like Brummie and Tinker etc like stuff in the 24x range as they cam for higher rpm and have less weight to shift. Plus larger engines have more torque anyway, so you will retain plenty of torque for low rpm use in any case.
As mentioned it is a compromise. However other than spring wear lift is always good as it can only help and doesnt often affect rpm range, use profile etc. Duration, overlap and valve timing determine most of the factors. The cam is selected based on the whole package from exhaust to intake filter. Though the cylinder head is a large determinant.
The valve is the MAIN impediment to power, nothing else has as much affect on engine power as the valves do. Hence why its so important, the cam operates the valve!
You can look at camquest from comp, its free software and enter all your engine details, it will give you a torque graph and suggested power range etc. Using that will automatically put you ahead of most internet armchair specialists. I dont know enough myself. But Im happy to spec my own cams these days. They might not be 100% optimal, but Ive always had the best dyno results of any NA setup on the forum, including the stock cam. But I always treat the engine exhaust to intake which not many do.
A stock LS1 cam is 15 year old technology. When looking for power Id look to that first. Why use ancient technology designed when computing power was a fraction of what it is now!? Comp LSR lobes are the latest technology and used by countless nascar teams etc. Though other cam companies arnt far behind. Pretty much any reasonable replacement will be a massive step forward. Bare minimum anyone should look at IMO is the 216/220 cam with a good high lift lobe and proper valve springs to handle it etc.
The Stock LS2 cam is something like a 202/211 IIRC. So its not that much larger. My current cam is a 230/238. I know the guys with lighter cars like Brummie and Tinker etc like stuff in the 24x range as they cam for higher rpm and have less weight to shift. Plus larger engines have more torque anyway, so you will retain plenty of torque for low rpm use in any case.
right-o I'll have a go, too !
The single most important thing about a cam is that it defines the shape of the power curve - a "mild" cam will give you a flatter power curve, whilst a "wild" cam will give you a steeper power curve.
You should decide what shape curve you want and spec the cam to give you that shape.
As an example, if you're designing an engine for ma. and pa. to drive to the shops, a flat power curve is a good idea - it will be very easy to drive and return decent fuel economy.
if you already have an engine and want to raise the peak power, then you have to fit a cam with a more "mountainous" shape to the power curve. You can, however, go too far - it's relatively easy to choose your peak power to be right at the top of the speed range that the engine will operate at. (or even beyond)
the figures that come with a cam allow some sort of measure between mild and wild.
Now, of course that's a very simplified explanation, there are a myriad of variations to the shape and profile of the cam - these keep the entire industry in beans. To give you an idea, I once wrote a treaty on "Hertzian camshaft stress levels in the XXXX engine".
the easiest number to get a view from is the duration. It's not really important to understand what the numbers actually mean, but 260 to 270 degrees means it's "mild", 270 to 280 is starting to get more entertaining, 290 to 300 will be a very sporty drive and 300+ is race-car territory.
One other thing - "emissions compliant". For a camshaft that you'd buy over the counter, this means that "the camshaft will operate in a standard engine without compromising the factory exhaust emissions". This DOES NOT mean that it'll no longer pass the MOT. A full emissions test takes about three days, and must be done in a proper lab like MIRA or Millbrook on a machine that costs £5M or more - it is the qualification test for the new vehicle. Most cams that aren't hugely "wild" will continue to pass the MOT if installed correctly with the appropriate mapping adjustments.
The single most important thing about a cam is that it defines the shape of the power curve - a "mild" cam will give you a flatter power curve, whilst a "wild" cam will give you a steeper power curve.
You should decide what shape curve you want and spec the cam to give you that shape.
As an example, if you're designing an engine for ma. and pa. to drive to the shops, a flat power curve is a good idea - it will be very easy to drive and return decent fuel economy.
if you already have an engine and want to raise the peak power, then you have to fit a cam with a more "mountainous" shape to the power curve. You can, however, go too far - it's relatively easy to choose your peak power to be right at the top of the speed range that the engine will operate at. (or even beyond)
the figures that come with a cam allow some sort of measure between mild and wild.
Now, of course that's a very simplified explanation, there are a myriad of variations to the shape and profile of the cam - these keep the entire industry in beans. To give you an idea, I once wrote a treaty on "Hertzian camshaft stress levels in the XXXX engine".
the easiest number to get a view from is the duration. It's not really important to understand what the numbers actually mean, but 260 to 270 degrees means it's "mild", 270 to 280 is starting to get more entertaining, 290 to 300 will be a very sporty drive and 300+ is race-car territory.
One other thing - "emissions compliant". For a camshaft that you'd buy over the counter, this means that "the camshaft will operate in a standard engine without compromising the factory exhaust emissions". This DOES NOT mean that it'll no longer pass the MOT. A full emissions test takes about three days, and must be done in a proper lab like MIRA or Millbrook on a machine that costs £5M or more - it is the qualification test for the new vehicle. Most cams that aren't hugely "wild" will continue to pass the MOT if installed correctly with the appropriate mapping adjustments.
just found a 'Janet and John' moving digram in case it helps anybody which shows the basic principle.
http://www.ul.ie/~kirwanp/examplesofsystemsinuse.h...
http://www.ul.ie/~kirwanp/examplesofsystemsinuse.h...
ringram said:
You can look at camquest from comp, its free software and enter all your engine details,
Easier said than done !! You need to know a little bit more about your engine specs to get it to work !!Have I got a standard 2 valve wedge head ??!! Whats my compression ratio ? Whats my preferred lifter type and my weight ?
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