So, at a drag strip test and tune I performed the fabulous 3-2 up shift; the Modifry shift beeper indicated 10,300 rpm. About a month, and less than 1,000 miles, ago I had the valve spring retainers replaced with new AP1 parts; class rules don't allow part updates.

The engine runs and drives fine, with exemplar intake retainer pictures and leak down & compression test results below.

So, what should I do? Learn to drive, buy stiffer engine & transmission mounts, buy an automatic, just drive it a monitor the retainer condition, pull the head....

 

Class rules don't allow slightly better retainer that will potentially save you thousands in repairs? ...i say pretty stupid rules and competition if you ask me.

a) i would inspect them all (pic of the two you posted looks ok and not recessed like cracked ones would be)

b) replace intake side retainers with AP2 and not talk about it during inspections (good look dis-proving that your retainers arent AP1 as they look identical)

 

How would they even know?

 

At a glance you cant tell the difference between AP1 retainers and AP2 retainers. Someone who isnt familiar with the S2000 could hold the parts in their hands and couldnt tell what one was what generation. Put the AP2 retainers in, they will never know the difference.

 

If you hit 10,300 on ap1 retainers, then they are split guaranteed.