Subaru Impreza GC8 & RS Forum & Community banner

1 - 11 of 11 Posts
H

·
Guest
Joined
·
0 Posts
Discussion Starter #1
OK this time it wasn't a simple cruising in 5th @ 80 downshift into 3rd, it was a bouncing-off-the-limiter in 3rd into 2nd mis-shift.

grr.

So what damage occurs when the engine spins to uh, say, 8000?
 

·
Premium Member
Two Mini Coopers!
Joined
·
10,629 Posts
If it's only for a few seconds - not much. However, if you hold it there and/or drive it like that often, you can expect to throw a rod, bent valves, or a variety of other internal nasties.

But once a year? Nah - they are designed for people who do much worse things than you just did! :lol:
 
H

·
Guest
Joined
·
0 Posts
Discussion Starter #3
Hmm. Maybe it's time to make a purdy gated shifter like a Ferrari.

Of course, then I'd lose stuff down in the gates. Like my packs of gum. Or change. Or my sunglasses. Or pens... anything that goes in that pocket.
 

·
Registered
02 RS, 97 brighton
Joined
·
105 Posts
You arnt the first. I missed shifted into second at about 70 and got the tach up around 7600 for a second, scared the shit out of me but I caught it before I let the clitch out all the way. They say the stock internalls are good for about 7200, so a second beyond couldnt do much harm:confused:
 

·
Registered
Joined
·
42 Posts
Somewhere I heard that an engine's functional maximum speed is can be limited by the rate of the valve springs. I'm trying to think things through and wonder if these springs would be the week link here ... whereby, the valves just have inadequate time to close between cycles. If this is the case, one can imagine the mayhem for gaseous forces as a result. Also may indicate a mod with faster acting springs, if this is case.

Anyone know what's going on inside our engines with this kind of over revving ??
 

·
The first ex-ex-moderator!
00 RS & GSX-R 750
Joined
·
1,446 Posts
If you rev to high you will float a valve and it will then get kicked in the face by the piston and then.........on my signal unleash hell. I would imagine the 7300 rpm handling point set by Cobb was limited the most by the stock springs. At any higher rpm's the springs can't decompess fast enough to get the valve back up before the piston hits TDC so the piston hits the valve.
 

·
Registered
2001 Silverthorn Coupe
Joined
·
144 Posts
Over reving by forcing the engin faster with a missed downshift is much easier on the engne than reving it that high with the accelerator. Its still not good though. I would like to know how far the engine is capable of over reving with the accelerator. The ECU has a rev limiter, so the engine is only able to accelerate the engine to the redline, and what ever left over energy before the revlimiter hits is all that is left to push it past the redline. So, by holding your foot on the accelerator, the initial trip up the rev range will be a hairy one, the suceeding bounces off of it will not be that bad. While it isn't a good thing to do, it is a design feature to protect itself and as someone said a once in a while accident isn't going to kill it.

I would like to know how much momentum the tach has on our cars, it doesn't always read correctly. The rev limiter, accoring to the tach, is lower in first gear. :rolleyes: So what you guys saw on your tachs is not correct, the needle may have been trying to catch up the the real RPM and overshot. It may not as bad as you think.

cheeRS,

Greg
 
H

·
Guest
Joined
·
0 Posts
Discussion Starter #9
I wasn't looking at the tach when I missed the shift.
I know that I was bouncing off the rev limiter in 3rd and I put it in second. IIRC there's a 1500 or so RPM difference between 2nd and 3rd, which would put it around 7750rpm.
 

·
Registered
Joined
·
89 Posts
the stock EJ valvetrain is good to 8000rpm, although i doubt that's sustained. ;) an occasional lapse of judgement like that won't kill your engine.
 

·
Registered
2.5 RS
Joined
·
169 Posts
I have had two instances where I missed my gear, one time I was coming off the highway from about 80 put my foot on the clutch and went from 5th to 4th and let it coast and then from 4h to 2nd. Needless to say my car literially cried when I did that and so did I. It felt like it just jumpped and stopped so I put my foot back on the clutch. The other time I went from 5th to 2nd, don't ask how I did that but I caught it quick. Think I have any damage?
 
1 - 11 of 11 Posts
Top