I posted in the "Under the Hood" section but would love input from the race crew on this too.

https://www.s2ki.com/forums/index.ph...&f=22&t=807109

Coles' Notes:
AP1, 2nd to 1st at speed. 9650 rpm for short period. Replace valve spring retainers only or more work needed?

Thanks!

 

bummer!

a compression or a leak down test will tell you what you want to know. i believe a leak down test would be a little more thorough in your particular situation. it would also be wise to remove the valve cover and inspect retainers.

good luck.

 

I went from redline in 3rd clean into to 2nd at the track on an ap1 I think thats much worse than 9650 sounded like at least 10,000 for a second on mine

I had the intake side retainers changed for AP2 ones and valve adjustment
Removed retainers and everything looked ok but better safe than sorry

 

I suspect this is what eventually caused the demise of our AP1 engine at Road America.

Sorry to hear it. Welcome to the club.

 

Corey, while I am no expert on S2000 valvetrain, I can speak to personal experience on this. I went to 1st from 2nd (trying to go to 3rd obviously) not once but TWICE in an autoX session last year. Specifically, at 9000rpm in 2nd gear I shifted to 1st instead of 3rd. It made the most insane, high pitched, scary over-rev sound that I have ever heard in succession with almost putting my head through the windshield. That was 10000 miles ago. My car has 80k miles now. I have no idea how high it over-revved, but I would not be surprised if it was north of 10000 rpm. I immediately went clutch-in almost simultaneously after the botched shifts were made, so I speculate the engine was there for at least a few tenths of a second during each botch. Since that day, I vowed never to attempt a 2-3 shift in the AP1 in autoX situation again. (Not that you really need to as the AP1 does like 70mph in 2nd gear with the 245's )

Anyway, the car runs mint, pulls like a raped ape up top, no smoke ever. If any damage was done, it's not noticeable at all. I have heard of fellas revving the F20 to 10K on stock springs without problems. But I have zero experience with that.

Good luck.

Nick

 

Corey - do a leakdown as already suggested, and pull the valve cover and check the retainers, you should be able to see if they are cracked. I did one of these at a track day a few years back, and as Nick mentions above from his experience, no ill issues since. I think I very slightly bent an intake valve on #4 (4% leak vs 1-2% in the other cylinders), but otherwise, the car still runs like a champ, 40K miles later.

 

Cool, thanks for the peace of mind guys. I'll do a compression and leakdown test to make sure the worst didn't happen, then I'll swap out the retainers and keepers to be absolutely sure. I don't trailer my car so a failure at an out of town event will cost way more than the new retainers will in towing costs alone.

Watching the video, one saving grace was that the shift to third was in a turn. The rear end stepped out from the engine braking, possibly limiting the top speed the engine hit. I could see this being even worse if it happened in a straight line!

Our course designer makes courses that are quite fast, going to 3rd isn't uncommon. We had a 5-cone slalom that I did at ~104 km/hr (64 mph) on my 2nd run. I think I could have gone a bit faster with smoother steering inputs, I was debating trying third for my 3rd and 4th laps to see if it was beneficial.

Video of my 2nd run (also FTD!), not the run with the over-rev: [media]http://www.youtube.com/watch?v=fKTqlZSeu9w [/media]

 

A bunch of years back I over-reved past 10k at Watkin's Glen. The engine stumbled and thought it was done, but afterwards all was good. Been working fine past few years, over 30k km, autocross seasons and 40+ track hours afterward.

 

I did a bit of reading on this when I did a 3 ---> 2 money shift. It's quite possible you cracked some retainers. From what I understand, it's difficult to spot a cracked retainer from just taking the valve cover off as the crack could be extremely small. These small cracks might not do any thing immediately, but from what I've read, they'll propagate over time and eventually you'd drop a valve. This could happen 20k+ miles from now, but apparently some blown motors have been traced back to this. Replacing the retainers is probably the safest bet, but if you can find a way to inspect them, maybe start with that? There was a guy named something like "BillMan" that seemed to have a lot of experience with this, it might be worth your while to search out some of his posts on the topic.

Good luck either way... I got off okay w/my AP2 money shift (apparently they bend valves before cracking retainers), but I bent 4 valves doing the same thing on a GS-R I used to own.

 

Timely & topical:

https://www.s2ki.com/forums/index.php?showtopic=805324