Hey guys/gals, I'm new to this forum but not NASA. I currently run in TT and instruct in the Midwest and Great Lakes regions. I'm currently building a 944 Spec car and with a lot of luck will be done late summer. Just in time to put it away for the winter. LOL

My proposal is to allow for different valve springs. Since these cars are known for their interference fit, it would be nice to run a stiffer spring to help with over-revving and missed shifts. We all know what happens if this occurs. Money and down time, and since I'm in the process of building mine, it would be nice just to install the springs once and be done with it. There would be no performance gains in the spring alone, just a more reliable motor, and isn't that the intent of the rules. To build a low cost racing platform that is reliable.

I am not much of a mechanic, but from what i have heard the turbo springs will add HP to the motor.
I went with standard springs to stay within the rules of NASA even though another club i run with does allow for the turbo springs.
if you are worried about the springs and rebuilding, just buy new (non turbo)ones instead of trying to reuse springs that are potentially up to 25 years old.

OK, Joe, another question for you to weigh in on. Do stiffer springs add HP?

My guess is no because of several issues.

1. Our intake system seems to be a real limiting factor.

2. Our engines make power in the 5,000 rpm range and are not good about 6,000 rpm anyway. I would think stiffer springs would allow for higher revs with less chance of damage but that won't help our engines make more power.

As with every issue, if a change can help prevent damage to our cars/engines and, therefore, result in lower cost racing and does NOT create a performance advantage, I am all for it.

Big Dog

The springs themsleves don't add HP, it's the cam. A higher lift/longer duration cam would need stiffer springs to close the valves on time and not let them float. That's what happens when you over-rev our engines. The valves start to float and WHAM!!! There goes the valve and possibily a piston. The stock ecu (which is the one we must run) will only allow it to rev to a certain RPM before it shuts off fuel and or spark or both. A stiffer spring would not allow the valve to float. On the down side if you use a spring to stif it will rob HP by adding to the frictional rotation of the motor and could possibily wear the cam lobes prematurly.

I want your avatar. It is disturbingly hot.

Big Dog

Firstly...
These cars don't float valves at 6500 RPM. The can in fact be run there all day with no float. Now if you are going for 5th and mess up and get 3rd you can be in trouble, but that is a driver induced problem and we can't prevent that. Well in fact we do allow something to minimize that which are the rules that allow for your make a more positive shift feel without changing the throw of the shifter.

So I don't buy the float argument one bit.

Now there was an argument for Turbo valve springs as related to them being cheaper than NA valve springs. The issue however comes to performance impact. If they make more hp then we have a problem. If not then their could be a reason to consider it.

I will say that I have no data either way that proves turbo valves springs do anything for hp. I do have information to show they are stiffer, but I am not sure how that will impact an NA motor that uses the same cam. Remember Turbo and NA cars use the same cam and the same head (turbo uses ceramic ports, but that is the only difference). I can only guess they made the spring stiffer to deal with a boosted cylinder. Since our motors run zero boost I am not certain they would be helpful especially with a stock cam and stock rev limit.

Even so with no hard data I am not inclinded to open a can of worms.