How long should my 918s last with my T1 cam before they need to be changed again? I've already got about 10k miles on them, and hearing some talk that valvesprings should be replaced every 17-20k miles with an aftermarket cam. I don't beat on the car much, and it gets maybe 15-20 passes a year.

Also, how would they fail? Is it more likely they would fatigue, giving less seat pressure and have valvefloat at the high rpms. Or would they just flat out fail catastrophically?

Thanks!

 

15-20 passes a year might be hard on the springs. I beleive the determining factor (slong with the lisft) is how often and how long the car sees red-line rmps.

 

I got 7K out of mine and Road Race, not drag race. The damn things broke while idling at a stop light. Only thing I can say is make sure the car is warm before beating on it. The tool steel they use in those springs is good but not at low temps.

 

So the heat cycle will make or break them huh? Good to know, thanks.

 

I have about 10000 miles on mine too with the T1 cam. So far, so good.

Les

 

Oh I definitely wait for the engine to come up to operating temp before beating on it. Also I heat cycled the springs 3 times when they were new before opening it up. Like I said, I put maybe 15-20 passes a year on it, but other than that it sees redline maybe once every 2 weeks or so, if that. Plus I'd say at least half, if not more of my milage is highway time cruising at 2000 rpms.

I had read suggested change intervals of like 17k miles with the bigger cams, like the X1, so I was hoping the T1, which is relatively tame in comparison to ramp rates and lift of the X1, could go a bit longer.

 

How do you heat cycle the springs.

 

I hate to get off topic, but what is the number 1 spring to chose today. I've run a T1 cam for about 2.5 years, with 941's at first, then I switched too K-Motion 750's.
I broke 2 of each within 12K miles! All were different springs, intake and exhaust, they are not prejudice!
I even installed a Oil Temp gauge to make sure the oil reach 180* before I take it over 2K rpms.

Is the 918 now the latest and greatest?????

 

I have used the 918s for about 4k miles now with no troubles.I am putting in a bigger cam and am looking at my options as there have been new springs coming out now.

 

Letting the car/springs get up to operating temps before beating on it is VITAL for spring life....

With a few heat cycles when new, and warm ups before you drive the car, the 918's should have no problems with a T1 for at least 15K or more. I have a buddy who ran 941's(known for breaking) and his T1 for 25K before changing them.

Josh