Big Boy

I am working on a 99 head right now. I haven't yet decided to do Camshafts at this moment but I will be in the future if not right now. What I want to know is has anyone had experience with different valve springs? I have looked at the FM ones but I would like to look into other possibilities. Does anyone have experience with dual spring, beehive, or elliptical springs? I don't know much about this topic. I am using this project as an opportunity to learn.

Hot_Wheels

iTrader: (12)

i sish i could find more people that have had experience with other parts too other then FM. let me know what parts you find

patsmx5

iTrader: (16)

FWIW my 99 head doesn't float valves at 7800. So unless you have done like 3K worth of porting to your 99 head, you won't need valve springs. Headwork should come before cams. If you want to reduce valve float AND simultaneously reduce the loads on the valvetrain then get lighter valves. But honestly they aren't needed.

Big Boy

Honestly I am looking to rev past 7800. I am looking at cams also in order to shift the powerband to higher RPM. I am not ripping on anyone or even FM, but the last thing I want is a cookie cut FM setup. Granted they do build build nice engines, but due to my personality, that just doesn't sound like fun to me. I applaud all of you who worked on the billet oil pump gears. I can't wait to get mine.

patsmx5

iTrader: (16)

Well what's being done the the head? Because stock it runs out of breathe around 5500 RPMs stock. By 6500 torque is fallling off badly. Nobody makes peak power after 7K.

A miata is not a good high rev engine by design as it's undersquare. You can't fix this. You can try to improve it, and you'll get some results. But I doubt you can keep 90% torque past 7K no matter what you do. The fundamental problem is the head is "small" for the displacement. That's cause the engine has more stroke than bore; not ideal. So when the valves open they are heavily shrouded. You put a cam in and they open a bit further, and they help some, but the real problem at hand still remains. Your best bet it to work, or have worked, the head to get it flowing better. Last thing you would do is put a cam in it.

Big Boy

I am planning on getting the head worked I just don't know quite when that will be. You are correct about it being undersquare. As you said though it can be improved so why not do some research and development throughout the process and see where it leads.

Big Boy

Maybe I should explain my reason for having rev room. The reason for having it able to rev this high is not to run it past the peak torque in a drag race. The reason is so that you can stay accelerating in a gear if you don't want to take the time to shift before a turn. That would mean 2 unnecessary shifts. Upshift...blurp a little power out of that gear...downshift back to square one...turn.