single or dual springs???
 

I'm about to return my accidentally bought 1.8 valves and springs to supertech from a hungover purchase and this time I'm going to get the oversized 1.6 valves and don't know if I should get single or dual valve springs. I'm not going solid lifter at this time and I have no idea which springs to get. After I get a new IM and cams this engine will most likely turn 7500+ if the turbo is till good for it which I think it should be. So back to the question, single or dual springs?

Considering the goals you have, I would go with single springs. 7500 is not much of an rpm increase, and it would not take much of a cam to get that kind of rpm.

If you go with a spring that is too stiff, it will take more horsepower to compress the valve, and you will ultimately hurt performance.

If you have a monster cam, then the power you get from the duration and lift, will offset the horsepower loss that would accompany a very stiff spring.

I spin over 8k with the singles no problem. The hydro lifters are a little noisy so I suspect the duals would be worse. Cams are 9m lift 264 duration.

Thanks guys. Once I hear back from supertech I'll tell them to send me the single springs. Hey alta racer do you have any videos of how the cams sound? I've tried searching but came up with nothing. I'm thinking about going with some 272s

I dont have any soundbites of the motor, but was planning to take the car out of mothballs this week or next, I will see if I can manage a clip then. With as big a cam as you are planning, I would really want to run mechanical lifters. I wish I had the cash to have done that, but I just went with new hydros. I have given some thought to putting in solid lifters on this cam, but it scares the heck out of me, as its hydro cams. Perhaps I will look into bigger solid cams in the future, but it takes a bucket full of cash to do it right.

You can convert any miata cam to solid lifters. Some will tell you otherwise, but I got my solid lifters and info on how to do it from Mazdamotorsports.