rocket71

I got into a discussion at the Nashville Road Tour about max speed in 2nd gear. I am able to get a Racekeeper/GPS verified 60.5mph out of second gear when hitting the rev limiter. I am tuned to 8500 rpm. Is that right? Another AP2 driver said he was at 62/63. He didn't say what he was tuned to but did elude to if you are willing to increase the rev limiter you could get more speed out of 2nd gear (well duh). Then went on to say maybe he is only getting 60 mph. Maybe it was just word games but what is everyone getting out of 2nd? Anyone got there rev limiter above 8500 (AP1 aside)?

Does anyone know if anyone has done an reliability testing above 8500 rpm on a AP2? I have read a bit about piston speed and am just curious what the limits would be. To further ramble on, I would not hesitate at a tour event to bump the limiter to 9k if it would make the difference for a win. (I am a ways from getting the whole driving part down though.)

takchi

Psychoazn did a UOA to determine whether an 8500rpm redline had more wear than an 8400rpm redline. His findings were summarized to:
At 8400rpms, there is no increased wear from the stock 8100-8200rpm redline.
At 8500rpms, there is increased wear compared to the 8400rpm redline.

In other words, if you're tracking, keep it under 8400rpm. If you're doing the occasional street pull, up to 8600rpm redline is fine.

TTMartin

According to Turn Zero max speed for an AP2 in second gear at 8500 rpms should be 60 mph.

psychoazn

One thing to note, is that I rode the rev limiter (at the appropriate turns/straights) for testing purposes, as opposed to my usual "get to the rev limiter, and hold the RPM" when I was testing.

rocket71

For AutoX purposes where you only bump the rev limiter at 8500 for at most 3-5 seconds (that is likely high) I do not think wear would be an issue. I am curious though as to what is the "safe" limit of using additional rpm to gain those extra mph. Could I feasibly take it to 9k? What speed would that be? I know I am inviting trouble but am curious how long a stock engine would last if it hit 9k over and over for very short bursts. Rough math, I would guess in a year about 200 hits at a 9k limiter lasting at most 3 seconds long.

Richard EVO

A little off topic, but my '92 NSX with U.S. gearing goes 82 mph at 8000 rpm in 2nd gear.

takchi

I thought I read somewhere a long time ago that GT Motoring supposedly went through a motor every 10 time attack days redlining between 8600-9000RPMs. I'm not certain but my assumption is that redlining anything higher than 8600RPMs for spirited purposes is not recommended if you want to keep your motor. I don't see what's wrong with keeping the redline at 8400RPMs.

@Richard: That's pretty cool. When does 1st end?

robinson

I spent most of last year with a 9K redline. With 245 Dunlops I was seeing 64-65 MPH at redline.

psychoazn

IIRC, I had 3 track days with the higher limit, and on the average lap, I spent less than 1 second per lap bouncing off of the limiter. Guesstimating 10 laps a session, and 4 sessions a day, that would give us about 2 minutes spent bouncing off of the limiter. In reality, I tend to do less laps per session, but these are conservative numbers.

Wear basically tripled with 100 extra RPM during that oil change interval.

All samples are with 300V 5W30. I would imagine my oil temps are higher on track than at a AutoX, but 300V takes high temps well.

UOAs available upon request; just send me a PM.

rocket71

How often were you hitting the 9k? How many miles are on your car?