how high can u rev???
09-06-2005, 03:30 AM
#1
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how high can u rev???
i was wondering if anyone knows of some spec on how high a stok 20v aan head can rev to...i've been to 7200 but i was wondering if 8000 is asking too much of it....also what are your opinions on what would fail first...springs, lifters, valves....etc
09-06-2005, 04:16 AM
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My assumption has always been... bad or not, it's red for a reason. But also ->
Having had the S4 on both road courses and the drag strip, I don't feel revving to 8000 would really do you much good in an otherwise stockish car anyways.
It starts to run out of power when you get up that high, the only real reason you even run it to 7000 is so that it's not bogged down in the next gear when you shift.
It starts to run out of power when you get up that high, the only real reason you even run it to 7000 is so that it's not bogged down in the next gear when you shift.
09-06-2005, 06:18 AM
#6
At some point above the 7200 RPM (ish) electronic rev limiter, I believe the first...
thing that would happen would be the valve springs would not be strong enough to retract the valves quick enough to get them out of the way of the pistons. The result would be bent valves.
BTDT on a semi-"built" VW engine that had no rev limiter of any sort. I autocrossed that car (1980 Jetta) and regularly saw 7K+ rpm with no problems. Then I drag raced somebody and missed a 1-2 shift (almost unheard of with a VAG trannie (NOT)) and over rev ved the engine. Ran fine that night but the next morning - no compression on a couple of cylinders - two bent valves. Relatively inexpensive and quick to fix on that engine. I would NOT want to experiment on the 20V head in the same manner.
Dave F
BTDT on a semi-"built" VW engine that had no rev limiter of any sort. I autocrossed that car (1980 Jetta) and regularly saw 7K+ rpm with no problems. Then I drag raced somebody and missed a 1-2 shift (almost unheard of with a VAG trannie (NOT)) and over rev ved the engine. Ran fine that night but the next morning - no compression on a couple of cylinders - two bent valves. Relatively inexpensive and quick to fix on that engine. I would NOT want to experiment on the 20V head in the same manner.
Dave F
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09-06-2005, 07:42 AM
#8
I have Bilstein valve lifters...
When Dave Jones rebuilt my engine 60,000 miles ago, he added these lifters. They allow me to use an 8,000 RPM rev limit since I have an adjustable ignition redline cut that I can move around. While I was still running Motronic, I had custom dyno tuned software. My electronic redline was at 8,000. My new AEM Engine Management System, allows me to set this redline wherever I want it. Assuming my self imposed 8,000 RPM limit I will set the AEM to about 8200. Although my horsepower is tapering off at that level, I do use it sparingly. The only reason AFAIK to go to such a high RPM is when setting the car up on the track to be in the right gear for a turn. Under other conditions, I use 7800 as my shifting point. Again, this limit is something that is easily adjusted using the AEM. HTH.
Hap, wit dakine adjustable functions from Evahboost
Hap, wit dakine adjustable functions from Evahboost