MatthewMenze

Hello all,

I am sure this is a easy question, but I searched, and have not found a good answer for it.

What is the reason the most performance cams (it seems anything except the lowest 'stage' performance cam) require aftermarket valve springs? Is it because in order to see power from the cam, you need to spin the motor at an rpm that exceeds the stock springs ability to prevent valve float? Or is it because the cam has a more aggressive lift rate on its lobes causing greater stress on the springs that exceeds the strength of the stock springs?

If it is just because of valve float, assuming one was limited to stock valve springs, would there be any benefit in taking a more advanced cam that requires aftermarket springs, and installing it with a cam gear (SOHC motor) and adjusting the cam gear to move the cams power band down into the stock RPM range?

Basically, I have found cams for my stock D16Z6 engine that done not require high performance springs ("stage 1") and other cams that DO require stiffer springs ("stage 2"...ect). I do not want to buy springs and a cam (Mostly hesitant to pull and tear apart the entire head of my daily driver in winter, when I don't have my motorcycle as a back up), but do intend to someday get aftermarket springs (assuming I want to push the car beyond a peppy weekend tinker project). Could I for the mean time run a hotter cam ("stage 2"), and adjust the cam gear so it's power range was below my stock rpm?

If so, would the hotter cam have any benefit over the more mild cam ("stage 1"), other than being able to increase my RPMs later if I decided to keep going? I could just as easily install the 'stage 1' cam and be happy with it. I am doing it more for something fun to do over a weekend, then to get some super fast car road eating machine. I have a motorcycle for that. Just wanna mod my car.

Thanks for your time,
Matt

P.S. As a side note, do aftermarket cams for VTEC motors tend to have two cam profiles like the stock cam does? Or do they tend to forgo that aspect of VTEC? Just wondering.

EsotericImage

iTrader: (8)

im just besides myself that someone put their 1st post in the right catagory

EDIT: Search Summit Racings site for "selecting the right camshaft" theres 2 videos. that will explain everything you seek yung grasshoppa!

doood

iTrader: (1)

both

Skunk2Brian

OEM valvesprings can only open so far before the coils stack up on top of one another or "coil bind". One your chosen camshaft generates more lift than the OEM spring can travel you need an aftermarket spring which can be compressed further without binding.

Often times these aggressive camshafts also have steeper ramp rates to go along with the higher lift. This is one of the reasons a stiffer valvespring is required as it keeps the valvetrain stable at high rpm.

josephcmiller2

1. Why are you looking for a cam right now? Have you decided on your goal for the car? Is it to be a peppy daily driver or a track car?

2. If you have decided on the goal for your car, do you have a long-term plan to get there?

Swapping a cam doesn't automatically give you more power. You can make less power and lose drivability if you choose the wrong cam. Your questions about the cam are good questions that show you are doing the right research. But we should make sure you are going in the right direction first.

MatthewMenze

Sorry for the late reply, I'm finishing up this crazy internship and have been kinda held up with work and life...

In response to your questions:

1. I am looking to do a cam for the experience of doing it, I figure it would complement the other mods I plan to do with it, and be a fun weekend. (At the same time I am going to put on headers, performance intake manifold, and possibly a few other mods, and a tune at some point once I decided how I want to go about it). Yes, I want to make it faster, but more importantly, I just want to tinker with my car.

2. My 'dream' goal for the car is for it to be a peppy and fun daily driver. I am okay if I it becomes some what less friendly to drive from a daily driver standpoint (that's part of the fun), as long as it is within the realm of being able to get used to it. If your looking for a hp or something, I would like to hit around 160-170, with the understanding that a D16Z6 is in the realm of 130 stock. But I understand that is likely a bitch much to shoot for without a full build. Honestly, I just want to modify it a little at a time, I don't feel like something is really mine until I change it, even it it's not much better than it was stock.

Obviously I understand that a more efficient route to tuning a car would be to plan out a build, save the money and do it all at once...But I care more about just having fun and doing random little projects here and there, it just means more to me I guess. Even if my mods hurt the performance, I would still have fun and gain experience from attempting it, and then later trying to resolve it.

Thanks again folks for your help, it's really great hearing your insight.

spAdam

iTrader: (1)

There are two main reasons that you need stiffer valve springs with larger cams.

The first is the obvious one, in that most aftermarket cams raise the power band higher up into the rpm range. More rpm means that you are accelerating the valve at a higher rate, and so the spring must be stiffer in order to control this acceleration. the lack of spring force is what leads to the valve head leaving the rocker, aka valve float.

The second reason is a different component of the first. Since aftermarket cams almost always have more lift, the valve is displaced more and the motion requires a stiffer spring to be controlled. It's the same reason that you have to increase your spring rate when lowering your car, but a different application.