5AT Redline/Rev Limiter - What a beast

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Jun 2, 2006 | 07:20 PM
  #1  
So yesterday, my friends and I took the car out for some spirited driving.
Yes, we were doing this at a safe place so let's keep this thread informational.
Anyways, at 1,700 miles this was the first time I actually unleashed the beast.
(I followed recommended break-in procedure/changed oil at 1220 miles/have been filling nothing but Chevron 91)
I was going through all of the gears aggresively and about 4-5 times hit the rev limiter and held it there for about 3-4 seconds max.
I understand that the 6700 redline is the maximum rev's I can get on the VQ but what I don't get is the fact that the rev limiter does not have the same setpoint as the 6700 redline.
If it's there to protect the powertrain when one goes beyond redline, why does it kick in 500 revs above the "safe" point.
I was reasearching the posts conserning TechnoSquare tuning and obtained some information stating that their chip program bumps the redline to 7100.
This being said, VQ can safely rev up to that range and for how long can RPM's be kept before the thing blows.
I remember reading somewhere that the VQ was tested at 7500 rev's for 15 minutes?
Let's discuss...
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Jun 2, 2006 | 08:43 PM
  #2  
Quote: So yesterday, my friends and I took the car out for some spirited driving.
Yes, we were doing this at a safe place so let's keep this thread informational.
Anyways, at 1,700 miles this was the first time I actually unleashed the beast.
(I followed recommended break-in procedure/changed oil at 1220 miles/have been filling nothing but Chevron 91)
I was going through all of the gears aggresively and about 4-5 times hit the rev limiter and held it there for about 3-4 seconds max.
I understand that the 6700 redline is the maximum rev's I can get on the VQ but what I don't get is the fact that the rev limiter does not have the same setpoint as the 6700 redline.
If it's there to protect the powertrain when one goes beyond redline, why does it kick in 500 revs above the "safe" point.
I was reasearching the posts conserning TechnoSquare tuning and obtained some information stating that their chip program bumps the redline to 7100.
This being said, VQ can safely rev up to that range and for how long can RPM's be kept before the thing blows.
I remember reading somewhere that the VQ was tested at 7500 rev's for 15 minutes?
Let's discuss...
The rev limiter is truely set at 6700rpms. The reason it's not consistent is because the tach isn't terribly accurate, especially in gears that wind out quickly.

I wouldn't suggest riding the limiter like you're doing. The limiter is there for a reason and it's really not good to continue to bump it because it's pretty hard on the motor for more ways than one.

TS bumps the limiter to 7100rpms, but it serves no real advantage because the power peaks at ~6,200 and steadily falls after 6,400rpms. Winding out to 7,100rpms is not ideal for racing situations except under certain road course conditions. Also, the 03-06 5ATs and 03-04 6MTs VQ35s really aren't happy to rev above 7,000rpms due to weak connecting rod bolts and lack of breathing ability above 6,200rpms. The 05+ 6MTs actually have 7,100rpm limiters, but they have revised intake manifolds, cam timing, and cam profiles which make them more willing to rev and make more power above 6,200rpms.
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Jun 2, 2006 | 08:55 PM
  #3  
DaveB, thanks for the info.
I can't recall hitting 7,200 rev's even though other 5AT guys claim they've been there.
You stated that the rev limiter is truley set at 6700rpms which is quite true IMO because I recall the needle being somewhere in the 6800-6900 range.
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Jun 2, 2006 | 08:58 PM
  #4  
An interesting note on the tachs on these cars. I've mentioned in other posts the inaccuracy of my tach. A few weeks ago we had a techtom hooked up to cheryl's car, and it read low(as opposed to reading high in my car). It wasn't off too badly. Near redline it was only off by maybe 50-100 rpms.

Her speedo was 2.5mph high just like mine though.
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Jun 2, 2006 | 09:00 PM
  #5  
Yeah, I guess you're right.
Like David originally said:
"The reason it's not consistent is because the tach isn't terribly accurate, especially in gears that wind out quickly."
I reached the rev limiter on either 3rd or 4th gear (probably did both since I got up there about 4-5 times) and that's why I got the accurate reading of 6800-6900 rev's.
Could be wrong though...pushing 150MPH was good enough
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Jun 2, 2006 | 10:33 PM
  #6  
Quote: DaveB, thanks for the info.
I can't recall hitting 7,200 rev's even though other 5AT guys claim they've been there.
You stated that the rev limiter is truley set at 6700rpms which is quite true IMO because I recall the needle being somewhere in the 6800-6900 range.
When I'm at the track I manually shift the 2-3 at an indicated ~6,600rpms which executes the shift at ~6,800rpms. I hold 3rd through the traps and usually tap the limiter at 6800rpms shortly after the finish. I don't bother manually shifting the 1-2 because the tranny doesn't respond fast enough to my inputs and will usually hit the limiter.
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Jun 3, 2006 | 12:54 AM
  #7  
So technically speaking, the car will never go above 6700 rev's?
Although the tach might show anywhere above 6700 due to inaccuracy, the rev limiter has already kicked in at 6700rpm.
What's all the talk about 7200rpm's on other threads?
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Jun 3, 2006 | 09:53 AM
  #8  
Quote: When I'm at the track I manually shift the 2-3 at an indicated ~6,600rpms which executes the shift at ~6,800rpms. I hold 3rd through the traps and usually tap the limiter at 6800rpms shortly after the finish. I don't bother manually shifting the 1-2 because the tranny doesn't respond fast enough to my inputs and will usually hit the limiter.
This is because you don't manually shift a 2003.. you "allow" the automatic to go from 2-3 anytime it feels like it after you bump the display from 2 to 3. The manual mode in 2003's is a top-gear limiter for the tranny, not a gear selector. The newer ones work differently.
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Jun 3, 2006 | 10:22 AM
  #9  
Quote: This is because you don't manually shift a 2003.. you "allow" the automatic to go from 2-3 anytime it feels like it after you bump the display from 2 to 3. The manual mode in 2003's is a top-gear limiter for the tranny, not a gear selector. The newer ones work differently.
Huh? I manually select a gear and it shifts. My basically operates the same way my 04.5 and 05 loaners have worked. The only difference is that my 03 will not force me to row back through all the gears when I come to a stop. I have to manually select 1 if I want to go through the gears. This whole "top gear limiter" thing just doesn't make sense. I can hold 1st, 2nd, 3rd straight to the limiter if I wish. When when I manually shift up at anything other than WOT, the tranny responds extremely quickly. When the I'm at WOT in 1st, the tranny can't respond quick enough to my upshift input therefore if I upshift at 6300rpms, there is a chance the car will tap the limiter before shifting. The 04.5/05 loaners respond the same way on the 1st and 2nd upshifts. The only difference is the 04.5/05s have a more solid 1-2 shift. Downshifting isn't a problem either. The tranny responds the same way in the 03, 04.5, or 05. The 05 has the rev-match feature which is cool, but it's manual downshift response time is no different than my 03s.

People need to understand that these trannies are still automatics. They have torque converters and utilize line pressure for shifts. An automatic WILL NEVER match the shift speed of a clutch sequential shifter. Never.
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