I got the same impression from a group from Nissan running a B13. Of the two 7 hour races they've been to, the engine has let them down in some manor.

 

I think the issue is oil pressure and oil supply issues. There's some articles on motoiq on how to make internal engine mods to help.

An accusump might also help and it's only 10pts

 

I certainly appreciate the feedback so far.

Can anyone else confirm if I need upper spring centering units with the NA top hats?

Anyone else have an opinion on the length of springs (say 550/350) with 5" all star sleeves?

 

No centering needed. 6 inch is perfect. 7 inch is too long (I found out recently)

 

my heavy boat of a car needed at least 7" 300 lb springs in the rear, could have gone longer.

 

My suggestion (if you can spare the time), is go to a Chump Car race and see what the top Miata teams are doing for suspension. Bonus if one finishes in the top 5 and you can get a close look during impound while the wheels are off. I know the teams I work with used cut springs and stock sway bars on off the shelf KYB's for 2014. We haven't decided on our 2015 dampers. I will say that that a good car and driver combo can get you into the top 10, but strategy and luck get you to the top 5.

 

Thanks guys.

Braineack - How low do you have your car and which top hats are you running?

aidandj/aidandj - Which tops hats are you running? NA top hats obviously lose some travel: https://www.miataturbo.net/suspensio...op-hats-79066/

Regarding examining what the top teams do: In the race I participated in last year there weren't many Miata teams (although the one seemed to know what they were doing). Based on online comments, I'd say for 2014 they probably ran cut springs (say 30-50% rate increase) with KYB shocks. For 2015 it appears better shocks (eg. Bilstein HDs) can be adapted the car. My thinking (right or wrong) is this opens the opportunity for stiffer springs and lower ride heights.

 

I'm running ISC.

 

12.75-13" rear and NB tophats.

Even when I switched to Tien Flexes, I had to install longer springs in the rear than was supplied because they would bind.

 

i have seen the sr20s dominate on the west coast. until they got busted for cheating.

 

Back from the dead. I began the installation of an allstar coilover setup. Based on feedback from this thread I did not purchase the centering top. It looks to me like the 2.5" springs would slide around in the NA top hat.

Are you guys certain I do not need something to prevent the springs from sliding around? Do I need an allstar top? http://www.summitracing.com/int/parts/aaf-all64171