I've only owned my C5 for less than a year as of this posting. When talking to people about what I plan to do with the car, one of the first questions is will I install a cam?

So, why would I want to install a cam?
Will this lead to other performance up grades by necessity?
What would those other required upgrades be?

I am not an auto tech or a racer, though I plan to maybe do some autocross. I know guys with cams. You can always tell because the cars sounds like a very rough idle as if the car is about to stall. Is this always the case? Do cam'ed cars always have that rough idling?

 

Dropping a cam in is one of the easiest / cheapest ways to add a healthy dose of power, that's why so many do it, or recommend doing so. And most love that rough idle, some want a cam almost just for this reason.
No other upgrades are necessary, but supporting upgrades to assist breathing (intake and headers,
and you will need a tune) are really advantageous.
You can get a cam suited best to your mods however, and it need not have a rough idle (although iit likely will be a bit more rough than stock, even a stock Z has a bit of chunk).

 

For a car whose intent is autocross.... I think the early preferred mods would be: mgw shifter, tick master clutch cylinder, upgraded rotors/pads or even c6z brake swap, stickier tires, upgrade shocks (bilsteins are the best performance /$... I have coil overs and love them, but unnecessary expense... Just my preference), sway bars, end links, trans mount brace, ecs diff brace, slightly lower the car.

Just me, but.... Amsoil the rear and trans.

Later, when the clutch wears, replace with McLeod rsx (light pedal feel like factory, but massive grip) and some six shooters for the tube along with a Finanza lightweight flywheel.

My theory is that if you're trying to improve times.... Adding power is a quick fix, yes, but what good will it be if you can't already optimize the power you have now.

 

If the focus is biggest change for the buck for first mods?

Bilsteins, c5z sway bars, c5z springs, mgw shifter.

New or used, you're looking at less than a grand to radically change how your car handles, how you feel it respond to you, and how you can deliver input.

 

If you're planning on doing some autocross a cam is a really bad idea. First of all it bumps you into a class where you'd get killed by cars that were much better prepared and secondly it will generally make your car slower.

The reason is that most hotter cams are really designed for wide open throttle acceleration. Great for 1/4 mile times, but worthless on the track. For autocross you want linear throttle response. That is you need to be able so squeeze on the throttle and not get too much or to little power to the back wheels. Big cams come on abruptly and make big power, but are hard to modulate and WHEN the hit (and it is WHEN and not if) the back end of the car steps out and you are looking from whence you came...

I had a friend with a Mustang who had a bigger than stock cam and was trying to autocross the car and eventually took it out, every time the cam came in he was fighting for control.. If you're already near the limits of control, like you are everywhere in an autocross, the cam coming in is going to toss you over the edge.

If you go to the autocrossing and road racing page and do a search on cams you'll find that virtually nobody who is doing track days or autocross is using a big cam. The stock Z06 cam is about as big as you want to go for track days, simply because of reliability reasons. While on the street a bigger cam is reliable and fine because you really don't go into the high rpm range often or for very long. Even at the drags you're into the high rpm range for only 12 seconds. On a road course you're at high rpms for most of the time you're running. You're always going to be between 4500 and 6000 rpm for the entire 20 minute session, and you do that 3 times in a day. That's an hour of high rpm time, or the equivalent of 300 drag runs, and that's in only one track day.

If someone has 300 runs on his drag car and a valve spring breaks it's sorta like the price of doing business. If you break a valve spring a wreck an engine in one track day you wonder what was wrong with the parts.

Bottom line is that if you want to go faster on the street, you can get a cam and have some fun. If you want to go faster on the autocross course, work on the suspension and tires and leave the engine alone. The most aggressive I would do is upgrade to Z06 parts if you want some more poke and you'll still have something that is driveable and reliable.

 

That's a pretty harsh review of cams. Though I'm not saying it's inaccurate.

Cams do have an rpm at which they begin to make power, though it is not like a nitrous hit. If you know your car, you simply adjust which gear your hold for a corner. Changing cams to one with a broader power range may even yield the opportunity to hold a gear instead of shifting.

If a cam is selected properly as a matching piece to your overall engine combination, I don't see failure as an increased risk. But if you, say, kept everything else stock and went with a very aggressive ramp for the car lobe then you're asking for trouble. Either way, always warm the car up prior to an event. Especially with aftermarket Springs.

When I did autocross, I never felt it was too harsh... But that is based on how I drove. I focused on being smooth and consistent over slamming the drive train. Picture a Viper owner doing autocross. It is effective application of power, not slamming gears, which gets you to the end for a good time. If all that torque were being used aggressively, all the car would do is donuts. For me, when I hear comparison to drag racing.... Where you abusively shift (or power shift) the car and engine and drivetrain alike are being abused as harshly as possible.... I don't make the equation to a half hour of cross. Maybe it's just how I drive or conceptualize it in my head.

 

I was wondering that same as the OP. I thought that switching the cam alone wouldn't be that much of a difference until you do all the supporting mods: heads, headers, springs, cam, etc...) and by then it will probably end up costing $3000-5000 (with install cost and tune) or so. Wouldn't it make more sense at that point to just switch to a supercharger kit?

 

The parts tend to complement each other (cam, heads, intake, exhaust, and drive train).

Cam loping is a result of loss of low end performance (volumetritic efficiency actually) at idle in exchange for performance at higher RPM's. Long duration and narrow lobe separation angle cams generally lope.

It is possible to get more than one atmospheric pressure in the cylinder through scavenging. This is similar to boost but usually happens at a certain RPM. Cams with a narrow LSA will usually have more of a peak in the torque curve in a narrower RPM range. A wider LSA will generally have a more flat curve. Longer duration cams will tend to make power hat higher RPM's with a sacrifice in the lower RPM's.

There is a lot more to cams, like timing of these events and ramp speed, but I listed some basics.

With that said I would think that it would be undesirable to road race a car that only performs well above 4,000RPM (then a huge spike in power) like some drag cars.

I would rather have the power more spread out with good mid range for coming out of the apex.

 

Anyone who ask why do I need a cam has never had the pleasure of pulling into a car show with a healthy cam, headers and Borla Stingers.

 

This is why.

 

You are right. I have not. This C5 is my first Vette.

 

Not being a tech, I had not considered that approach.

 

The supercharger will work a lot better with A cam, heads and headers. It needs to breath too.

 

 

If chosen well I believe a cam change can benefit an autocross car, but also agree that the tires and suspension parts changes would give a better bang for the buck in autocrossing.

If you do change the cam in most cases you should also be changing the pushrods and valvesprings. Some would also say you should change the rocker arms, or at least do the trunion upgrade to the stock rocker arms. I've had good luck in my vette and truck with cam changes running non-modified stock rockers. A custom tune will be necessary or highly recommended in most cases as well.

As you have noted many vehicles with large cams have a rough idle. But, you don't have to go from one extreme to the other. The car companies know that for most people they will have a harder time selling cars if they don't idle well than if they idle very smoothly, so they generally make conservative cam choices. For me, a Z06 cam is too conservative but the cams I've put in my truck, although a bit more aggressive than a Z06, still idled very well, but a trained ear could easily note that it wasn't stock. For the vette, you can make out visually a bit of shaking in the car, and certainly feel it when sitting in it. The wife and I like it that way!

 

I have a pretty big cam in my car which is my DD and occasionally track time, this car will run low 10's in the quarter and behave on the streets. Here is a video clip of a larger cam at idle 900 rpm's - when in gear will idle smooth (to me) at 800 rpm's.

I thought most of the road course folks were getting away from the superchargers and going N/A. What do I know?

 

A lot of S/C and Turbo setups on the track have issues with heat, hence why a cam and N/A power is the choice for some setups. It really depends what you want. You don't have to go full out with a giant lope, you can get a mild setup that's fairly tame... But then you have to decide if you're cracking open the motor to do a cam swap, is that power really worth the time/money to do it? If you're looking to drag race, forced induction is your biggest bang for the buck. If you're autocrossing (like me), suspension and TIRES are your best performance bargain. Tires are HUGE for AutoX depending on your class. Right now my tires are my bottle neck for running in CAM-S as I can't push the car into faster times until I get a 200 tread rating tire.

My C5Z is a weekend car/autocross fun machine. I considered a cam, but I really don't wanna drop that much cash into it. It'll be fun on the street, but for my AutoX times it's not really going to help me a lot.

 

I bought the car last summer. This spring, I hope to attend my first Autocross meet. This is something that I have wanted to do for a very long time, but never had a car to do it with. Looking forward, I am asking about various performance directions, including adding a cam. I am hearing that surface grip mechanics (tires & suspension) should be paramount for Autocross. I certainly agree with that, and those are the kinds of upgrades I can do in my garage. But that is topic for a separate thread.

Note, this is first and foremost a summer daily driver that I hope to have fun with on weekends.

 

Comments like these are why I take the internet with a giant grain of salt.

Not all cams are the same.

And as a note, you can, and people do, use what is known as a Stealth Cam. When done with a custom grind, it can make significant increases in torque through out the powerband and is audibly undetectable.

Not all cams are just for high rpm power.

 

Wait, minus the cam!