How close to red-line? - Pontiac GTO Forum
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post #1 of 24 (permalink) Old 05-30-2006, 11:12 AM Thread Starter
 
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How close to red-line?

Newbie-type question here:

How close can you let the engine rev to the red-line while accelerating and still have it be safe?

Given that my only stick shift previously was a 4banger econocar, I've never revved a car very close to redline before. I've been letting the rpms get a bit higher on the Goat while accelerating, but I want to be careful.

Most stick-shift cars I've sat in have had the red area marked off, and they'll have an orange/yellow "caution" section on the tachometer. The GTO surprisingly does not have a caution area. I've heard rumors that may or may not be true that going to red or just before red is never safe, that you should not go above (500rpm below redline, 1000 rpm below redline--some numbers I don't remember). What would you say is safe, for a stock engine?

I tried searching and couldn't find the answer.

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post #2 of 24 (permalink) Old 05-30-2006, 11:56 AM
 
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As long as you aren't going past redline without any engine modifications to warrant it, I wouldn't worry... maybe I'm wrong though. :P If the engine could be easily damaged by going say 500rpm or even 1000rpm less than the redline, one would think they wouldn't set the redline so high... or a bunch of owners would come back complaining about blown engines.

If I'm going for the maximum possible speed, I shift right before the rev limiter cuts me off, just as the engine touches redline.
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post #3 of 24 (permalink) Old 05-30-2006, 01:40 PM
 
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I shift right at Redline for max speed. I've also have bounced off the rev limiter several times without any issues. 10,984 miles, and still going strong.
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post #4 of 24 (permalink) Old 05-30-2006, 01:42 PM Thread Starter
 
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Ok, thanks for the replies.

I had forgotten about the rev-limiter; that probably helps. Most of the 2nd and 3rd hand vague stuff I had heard was dealing with older cars (60s, 70s, and early 80s) and possibly rev limiters didn't exist then.

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post #5 of 24 (permalink) Old 05-30-2006, 05:51 PM
 
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Honestly, I don't know how much good it does acceleration-wise to wind your RPMs past the horsepower and torque peaks. The LS2's horsepower peak is at 5,200 RPMs, while torque peaks at 4,000. I'd venture to say that you're just wasting time letting the engine rev much past the horsepower peak.
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post #6 of 24 (permalink) Old 05-30-2006, 06:26 PM
 
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because

Quote:
Originally Posted by GM Kid
Honestly, I don't know how much good it does acceleration-wise to wind your RPMs past the horsepower and torque peaks. The LS2's horsepower peak is at 5,200 RPMs, while torque peaks at 4,000. I'd venture to say that you're just wasting time letting the engine rev much past the horsepower peak.
Correct!
You can feel where the power starts to fade, around 5400-5600, the car will feel like it's not pulling as hard as it did just a moment before. As far as I'm concerned, there's really no need to hit the rev limiter other than by accident during a burnout or something, you're just wasting power and gasoline by going that high.
With that said, if you make modifications to the car, such as a cam, your powerband will usually be moved up the RPM range, so you would want to shift a bit later...but it sounds like that's not an issue with your car yet, so if I were you, I'd probably shift by no later than 5800-5900 RPM.
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post #7 of 24 (permalink) Old 05-30-2006, 06:35 PM Thread Starter
 
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That is a good point about the power dropping off after a bit.

So far, I think I've taken the car just high of 4000 (maybe 4100 or so), but no higher. I figured I had room to go a bit more--and it was still definately pulling at 4k--but after remembering the vague horror stories from yon I figured I'd play it safe and ask first.

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post #8 of 24 (permalink) Old 05-30-2006, 06:41 PM
 
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I've bounced mine off the rev-limiter several times too, with no damage, and it's got 21k miles.
If you take it up to about 5400 and beyond, you will feel the power drop off. You're not going to break anything by taking it up toward the redline, these engines are designed to rev pretty high.
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post #9 of 24 (permalink) Old 05-30-2006, 08:24 PM
 
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Actually peak horsepower is at 6000 rpms and peak torque is at 4400 rpms. Your redline is at 6500 rpms and the rev limiter is somewhere between 6700 and 7000. To stay above the torque peak you need to shift close to redline, this will enable you to stay on the power curve. The LS2 is a deep breather with excellent high rpm response.

You more than likely won't damage the engine if you bounce it off the rev limiter a couple of times. More than that though is asking for trouble. Something else to remember is the tach is fairly slow compared to how fast the engine revs.

What I found from my drag racing experience is that winding 1st in a full on run it hits the rev limiter at around 6300 rpms on the tach. I found that 6100 in first is just about optimal as a shift point. In second the engine is not winding up as fast so the tach is not as far off and you need to shift at 6200-6300. 3rd is closer still and I'd pull when I thought I saw 6300.
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post #10 of 24 (permalink) Old 05-31-2006, 09:27 AM
 
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Quote:
Originally Posted by fergyflyer
Actually peak horsepower is at 6000 rpms and peak torque is at 4400 rpms.
I got my info from the Pontiac Web site, but what do they know?
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