So I just recently finished my monster 302 build but my coil over springs are not looking too good. they are currently 425 spring rate. I was wondering what size I should go to maybe
504 at 9 k or higher. was looking at a f c o. thanks

 

We need to know your application. I know a few tracked v8 miatas that run 900-1000 lb springs in the front. and many run similar rates to those for purely street use. Let us know more about application and we can probably help.

 

I hope to get on the track a few times next year for some auto x and drift events and some street. This car is a weekend driver and would like a street/strip set up. not so much track that it beats me to death and not so much street that it will not handle on the track competitively.

 

I certainly wouldn't go to 1000 lb springs. I would stick with 500ish lb springs or less in the front.

I am running 550 lb/in springs in the front and on some particular roads, its tough to see the jolting they give the car.

 

will that be able to deal with the extra weight of the V8 motor. Right now I have 425 lb springs and they are getting squished in area's.

 

what are your rear rates? seems to me you are looking for something a bit more than just weekend warrior. you can probably do 650 (maybe even 700, if you don't care about comfort on the roads) lb springs front and 400 lb rears depending on your sway bar setup.

I don't really know a lot about suspension tuning for the v8s, but I imagine you will want a good bit of FRC bias to give you the extra traction in the rear.

 

I would go minimum 700 or 800 with an iron block 302 in that thing. Spec Miatas run 800 with a stock engine. You will want to invest in proper shocks to hold that much weight and spring in check. I'm running 2000 Miata "Hard" Bilsteins (factory option) with 450lb springs and don't think they would have any problem with a lot more. I really think I should have gone with stronger springs. Not all Bilsteins are valved the same though.

You will also want coilovers to adjust the height. There are some pictures and some discussions about making coilovers fit in a couple of suspension threads on here.

 

copy pasta from 949...

"For a mostly daily driver that only sees occasional autocross or track use, 550/350 if using really sticky street tires. For medium or small (205/50 on 15x7) street tires on a mostly street car, 450/300 rates. If running an LSx conversion, sames rates apply. If running a small block Ford conversion, add 100# front and 50# to each recommendation range. If you are still not sure, give us a call. We'll get the system matched exactly to your needs."

 

Give who a call? 949 racing?

 

Yeah, it looks like that was pasted from their website. 949Racing is a good company that knows their stuff.