How long will springs last in this setup... tsp 231/237 112lsa + 918s or crain duels every thing else stock. Will I have to replace springs again after so many miles???

 

what is the lift on that cam? If it is right at .600 you might want to get some of the dual springs just for safety reasons. Most people say change your 918's around 9k to 10k max miles though but if you have a hight lift cam i.e. near .600 it would be wise to change them well before 9k IMO.

 

The lift is .598/.595. I ran mine for 3,000 miles on 918's with no problem, then upgraded to the patriot gold duals for piece of mind. I have ran those for 5,000 miles and last week when I swapped cams I took two of the valve springs off and brought them to patriot for Terry to test on his spring tester. They still fell within the factory specs after 5,000 miles.. so I reinstalled the same springs with my new cam.

 

it depends also how you plan to run the car, just around town daily driving the 918's should hold up fine. if you plan alot of high rpm stints at the track i'd invest in some crane duals.

and whey you say "everything else stock" are you refering to the rest of the vavle train or the rest of the car. if the car i think you'll be dissapointed in the lack of significant gains with that cam w/o the supporting bolt ons.