S2000 Under The Hood S2000 Technical and Mechanical discussions.

New to S2k trying to understand over-rev

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Old Dec 9, 2006 | 08:48 PM
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Default New to S2k trying to understand over-rev

I've been reading ALOT on here and I have a few questions about over-reving. From what I've read the car has a rev limiter around 9200 rpms, but I've read alot about people down shifting leading to over-revs and then the valve guides fail. If the car has a rev limiter how can you over-rev? Also if you run the rpms too high the red part of the tach will start blinking right? Thanks
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Old Dec 9, 2006 | 09:00 PM
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The car does have a rev limiter. It works by cutting fuel at the programed high RPM. An over rev caused by a mis-shift causes RPMs to rise mechanically. Cutting fuel will have no effect in this case. As a result, a mis-shift can cause an over rev of your engine beyond the point where the rev limiter has cut fuel.
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Old Dec 9, 2006 | 09:19 PM
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That makes sense. Thanks
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Old Dec 9, 2006 | 09:36 PM
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Wait now I have a question . In my previous cars (Acura TSX 6spd, Subaru WRX STi) I always shifted at low rpms and the mpg difference was obvious. I drive this car the same way. Is it making a difference or no?
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Old Dec 9, 2006 | 10:01 PM
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mgp_2675: Yes, of course it is.
Using the car in the lower RPM range will, without a doubt, yield a higher mpg value than using the car in the higher RPM range.


To the OP: Here's a post of mine from a different thread
https://www.s2ki.com/forums/index.php?showt...0&#entry9077926
Quoting myself:
...The existence of a fuel cut off doesn't apply to a mechanical over-rev, if you did indeed engage the clutch fully after putting the shifter into 2nd when you were at the redline in 3rd, you were doing about 50-60kmh 'more than the engine can do when in 2nd gear', even if the fuel did cut off, which it probably did (a fuel cut-off does indeed exist), it doesn't matter at that point.

The car is moving at a given speed and the transmission is engaged...
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Old Dec 9, 2006 | 10:31 PM
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Thank you...glad to know I'm doing things right.
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Old Dec 9, 2006 | 10:40 PM
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Originally Posted by mgp 2675,Dec 9 2006, 11:31 PM
Thank you...glad to know I'm doing things right.
What's "right"? IMO,if you drive the S2000 around at 3000 rpm in order to save gas, it probably means you bought the wrong car.

But that's just my opinion.
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Old Dec 10, 2006 | 03:58 AM
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Originally Posted by UofA_S2000,Dec 10 2006, 12:48 AM
the valve guides fail.
It's not the guides. First thing to break is the intake retainers, and it won't show any symptoms.

At a higher over-rev, you'll bend the exhaust valves. Symptoms for sure
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Old Dec 10, 2006 | 05:44 AM
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Originally Posted by mikegarrison,Dec 9 2006, 11:40 PM
What's "right"? IMO,if you drive the S2000 around at 3000 rpm in order to save gas, it probably means you bought the wrong car.

But that's just my opinion.
What, do you shift around 5k every time? That's nuts. 3k is actually where you're supposed to be shifting. This is a high-revving car but when I'm not trying to have a lot of fun with it, it's time to save gas. That's right IMO.
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Old Dec 10, 2006 | 09:09 AM
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Originally Posted by mgp 2675,Dec 10 2006, 06:44 AM
What, do you shift around 5k every time? That's nuts. 3k is actually where you're supposed to be shifting. This is a high-revving car but when I'm not trying to have a lot of fun with it, it's time to save gas. That's right IMO.
"Supposed to be"? WTF decided what is "supposed to be"?

I upshift when I think it is time to upshift, and I downshift when I think it is time to downshift. Those upshifts might happen at 5K or they might happen at 8.9K or they might happen anywhere in between. They rarely happen less than 5K, but in the occasional highway cruising situation they might.

YMMV, but I don't see where you get off saying that everyone is "supposed to" drive the way you do.
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