How to Destory a Thread ...was...The Truth About Valvesprings!

Over the last few months, there have been some discussions about valvesprings, much without data or hard information. So anyway, I thought I'd share and article and an offer to get the ball rolling here.

First some background. I'm a physicist, so I'll start from springs and masses. The point of a valve spring is to keep the valve following the cam profile throughout the RPM range of interest. Pretty simple, yes? So then why are springs rated at things like 80 lbs seat pressure closed, and 200+ lbs seat pressure open to just keep a little valve that weights at most a couple ounces where it's supposed to be? Don't those numbers sound excessive?

So, let's think about the valve train. There is a camshaft with it's lobes. There is some form of rocker that rides the lobes, pivots somewhere, and presses on the end of the valve. This is for overhead cams (standard V8s have lifters and pushrods, but the idea is the same). What pushes back on all this stuff to keep it from rattling is the valvespring. It sits on the top of the head, and is kept in place by the retainer and lock. So this spring has to be able to push all this hardware back against the cam lobe.

The real killer hear is that as things go fast, it's not the basic static weight of the parts that comes into play. The spring has to overcome the inertia of the valve, the retainer, the lock, the rocker, as well as the spring (or springs) themselves. At 7000+ RPM, this takes a lot more force than is needed to just hold the parts against the force of gravity. Thousands of times the force. It can get pretty staggaring.

So, what does all this matter? For our Tritec engines, the choices for valvesprings have, until recently, been pretty limited. Every head I've seen has used some form of convetional spring. No one was offering beehive geometry. Some used Ti retainers, some used the stock steel ones. Some used single springs, some double. Some of the springs needed pocket work cause they were too long, and some needed spacers cause they were too short. None of this is bad per se, but it's all the consiquence of using parts pretty much designed for other applications and used because they were "close enough".

So, what's different? Well, nothing really. The PAC Racing Springs in the NS Valvespring and Retainer kit aren't custom for the MINI. They are, in fact, "close enough" springs found in the PAC spring catalog. What is different with the set is that the retainers are custom to the MINI so that a spring that is a touch too long can be used without machining a deeper pocket. What is new is that this is the first spring set for the Tritec that uses ovate wire (oval spring wire) and beehive geometry. The result of this is a lower mass spring and retainer set that has reduced harmonics compared to conventional springs.

Now, in some of the PMs that I've gotten from people, some who were not really happy when about the debate about springs, there was one quote that stuck in my mind: "You know that no one can feel the difference between one valve spring and another." And to be honest, I think that if the springs are properly selected, that may even be true. But we have a group of people in MINIs who are pushing ever higher RPM, and using aftermarket cams with more lift and aggressive profiles (this is called "ramp" to the cam guys). The faster the ramp, the faster the acceleration of the parts. Agressive ramp is the key to the NS cams benefits with lower overall lift (but that's another story). Anyway, we're demanding more and more out of the valvespring and retainer. And some are doing this with stock, or stock equivalent springs (for example the Cosworth single spring setup was a stock-equivalent spring. Same strength as the stock, just more consitent in specifications.)

Think this is all just marketing BS? Well, this is why I love Hot Rod Magazine. Sure it caters to the V8 Big Block crowd and American chassis and the like, but engines are engines, and they do some really great tech articles. The November issue was no exception and they have this article All About Valvesprings. I scanned it for your reading pleasure. It's seven pages (a lot for a mag article) and the high points of it are:

• In the past, valve train performance was limited by spring technology.
• Times have changed, and new geometries and materials have come into play.
• One V8 engine had significant high RPM HP increases when going to a SOFTER beehive from a dual spring set up!

So read away, and learn from the experts......

I've also got an offer to those that are interested in our spring and retainer set. The set retails for $385 on our site here. I want to get some of these kits into the hands (and onto the engines) of those that think they can benefit from them. So for the first 5 kits that are ordered in this offer, I'll let them go for $335 a set. To get this price, you have to do PayPal to [email protected]. If you want to do a telephone credit card transaction, e-mail me at [email protected].

If you have a stock motor, no tune, no cam, no nothing, these aren't for you. If you have a raised red-line and/or aftermarket cam, these may be just the ticket for really getting all the HP your engine has to offer as you bang the rev limiter!

Matt

 

Because there are so few of these sets running out there...

I don't have good data sets of before and after. What I found so surprising in the article was going from a 523 lb open dual with damper to a 318 lb open beehive gave almost 40 HP to the engine at 6800 RPM. While it's 425 HP 406 CI small block chevy, that's still a heck of a lot of "found" hp for just going to lighter springs and retainers. And as a percentage of weight, it's even less when one considers that this has lifters and pushrods! Anyway, that was quite the eye opener for me.

I'm looking forward to installing these on my car. But every time I get ready to do it, I send a spring and retainer out so that vendors and head builders can check them out....

Anyway, if you're doing a head, talk to your head builder about these. If you build heads and want to use these, get in touch with me about using them for your builds.

Matt

 

No matter how you slice it....

lower mass valve springs and retainers can control valve motion to higher RPM because they weigh less. This means more of the spring derived force goes into moving the valve and valvetrain that just controlling the mass of the spring themselves. That's just fact.

What really is key here, and not really in play because no one has good data, is how do all the springs available work with the different cams, different valves (with different mass) and the like. I wish I had a Spintron machine to do it all and generate the data set.

I was surprised that no pissing contest had started up yesterday, but I see it wasn't a question of if, but when. Oh well.

Anyway, I hope those that were curious about valvespring technology learned something from the article I posted. There is also a perfect example there of springs that in a given app (that they are sold to) spin up to a given RPM but aren't really doing the job at that RPM that a better spring can do. What I found so interesting on that example was that the conventional dual spring was so strong that it was actually bending valvetrain components (more torque at low RPM), yet didn't have the strength to control the valves at the high RPM that the engine was designed for. No, that wasn't a Tritec, but it's a real example of how a lighter single beehive can do a better job than a heavier, stronger dual spring set up. This is a perfect example of how lighter valvespring/retainer combination can do more of what one wants from it while providing less stress and wear on a valvetrain.

Take from it what one wants.

Matt

 

WTF?

So, for those that don't know anything, or very little, about valvesprings you think an article about the technology that explains the pros and cons has no value? That's just silly. Best (and real) criticism is that while the examples are illistative, we don't know how much they bear on our engines.

Read the article. See how builders of engines use technology to create better motors for people. See how they have found different technology to provide real world gains. It's usefull. The article talks about beehive springs, oval wires, dual spring setups with and without dampers and triple spring set ups. The dangers of going to deeper pockets on heads to accomidate longer springs. Retainer to valve fit. Ti retainers. Exotic valve material. Valve locks. It illustrates these concepts with engines that are of interest to the market market of Hot Rod. (V8s, that's the only thing that has no direct bearing on MINIs.) It's a good article. Go ahead and read it and find what you think is useless and post it up. It's not going to be a very long post.

Matt

 

Jan, I totally understand what you are saying

but even you would grant that there is a HUGE performance envelope between running optimally and total failure. So, the very same "proof" you state (It's run at that RPM and hasn't failed) says nothing about if it's working perfectly at those RPM.

Matt