Rev Limiter
Thread Starter
Advanced
Joined: May 2001
Posts: 54
Likes: 0
From: London
Rev Limiter
Anyone ever caused any damage by hitting the rev limiter? A friend of mine drove my car yesterday, and hit the rev limiter in 3rd for about 2 seconds. I know it's there for a purpose (to prevent over-reving),so I would be very surprised if anyone has sustained damage???? How does it work (ie does it cut the ignition?)
many thanks
many thanks
RL Technical Advisor
Joined: May 2001
Posts: 11,870
Likes: 75
From: Portland Oregon
Hi Francesco:
Hitting the rev limiter, once in a great while, will not damage anything. Hitting it during track events and somewhat continuously is very hard on the rods and rod bolts, and NOT recommended.
The rev-limiting function on Motronic cars is controlled in software (chip controlled fuel cut-off) and should not be changed, much less exceeded, unless certain mechanical components of the engine are upgraded.
At a minimum, I would change the valve springs, valve spring retainers, and rod bolts, if operation at the rev limiter or higher is required.
Hitting the rev limiter, once in a great while, will not damage anything. Hitting it during track events and somewhat continuously is very hard on the rods and rod bolts, and NOT recommended.
The rev-limiting function on Motronic cars is controlled in software (chip controlled fuel cut-off) and should not be changed, much less exceeded, unless certain mechanical components of the engine are upgraded.
At a minimum, I would change the valve springs, valve spring retainers, and rod bolts, if operation at the rev limiter or higher is required.
Addict
Rennlist Member
Rennlist Member
Joined: Jul 2001
Posts: 982
Likes: 93
From: Atlanta
Francesco '97 993 S:
I had a '96 993 that I converted to a track car and ran for over 100 hours in 2 years in racing and/or race like conditions. I hit the rev limiter countless times with no ill effects. One caveat to that is that it depends how you hit the rev limiter. If you downshift from 3rd or 5th into 2nd, that would be a bad thing if you meant to select 4th or 6th. If you are not in gear and you just nail the accelerator pedal until the rev limiter kicks in, that would be a bad thing but not as bad as the aforementioned unintentional downshift. If, however, you just bounce of the rev limiter, forget about it. No damage has occurred. Like Steve suggests, I wouldn’t make a habit of it, but once or twice or even 20 times isn’t going to damage anything. I am sure that there is always some strange case where someone slightly over revs a motor with catastrophic results, but you would probably know that by now.
Just my experience,
Hank Cohn
I had a '96 993 that I converted to a track car and ran for over 100 hours in 2 years in racing and/or race like conditions. I hit the rev limiter countless times with no ill effects. One caveat to that is that it depends how you hit the rev limiter. If you downshift from 3rd or 5th into 2nd, that would be a bad thing if you meant to select 4th or 6th. If you are not in gear and you just nail the accelerator pedal until the rev limiter kicks in, that would be a bad thing but not as bad as the aforementioned unintentional downshift. If, however, you just bounce of the rev limiter, forget about it. No damage has occurred. Like Steve suggests, I wouldn’t make a habit of it, but once or twice or even 20 times isn’t going to damage anything. I am sure that there is always some strange case where someone slightly over revs a motor with catastrophic results, but you would probably know that by now.
Just my experience,
Hank Cohn
Instructor
Joined: May 2001
Posts: 156
Likes: 0
From: Scottsdale Arizona
The rev limiter is the signal to upshift. When racing, the optimum point to upshift in most Porsches is at redline. I try to shift just before the rev limiter engages but in some cases I reach the limiter and do not worry about it.
Regards,
George
In sunny Arizona
Regards,
George
In sunny Arizona
AutoX
Joined: Aug 2001
Posts: 13
Likes: 0
Francesco,
As my rennlist name suggests, I have very similar experiences as Hank. I run a '95 993 as a track only PCA racer and have logged over 3500 track miles in the last two years. I hit the rev limiter at least three or four times a day on the track, coming from acceleration NOT downshifting. The engine which is bone stock has not suffered any ill effects so far and I have run with many other 993s that encounter similar limiter conditions with no problems. Therefore, one brush with the rev limiter (hopefully the engine was warmed up and properly filled with oil) should be no problem whatsoever.
As my rennlist name suggests, I have very similar experiences as Hank. I run a '95 993 as a track only PCA racer and have logged over 3500 track miles in the last two years. I hit the rev limiter at least three or four times a day on the track, coming from acceleration NOT downshifting. The engine which is bone stock has not suffered any ill effects so far and I have run with many other 993s that encounter similar limiter conditions with no problems. Therefore, one brush with the rev limiter (hopefully the engine was warmed up and properly filled with oil) should be no problem whatsoever.
