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Rev Limiter Question

Freedom

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In the Mustang GT, the optimal shift point is at redline (which also happens to be approximately the fuel cutoff/rev limiter). In the EB, you'd shift earlier (I've done the calcs, but forget exactly what the number is, and for that car it does depend on gearing somewhat).

Running up to the rev limiter and bouncing off it momentarily should not cause any issues. The designers know this will happen and set those values in order to preserve some safety factor against damage.

Missing a shift and forcing the engine far beyond the rev limiter can definitely be a problem, and should be avoided.

If you have an automatic, it will prevent you from downshifting to a gear that would force the engine past the rev limiter. Basically if the automatic lets you do it, you should be fine.

Just don't try to put the car in park while it is still moving.

-T
there was this dude who had a fusion and shoved it into park while driving. Nothing happened at all and it kept it in gear, but ofc dont try it yourself.
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TomcatDriver

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there was this dude who had a fusion and shoved it into park while driving. Nothing happened at all and it kept it in gear, but ofc dont try it yourself.
Most (virtually all) modern automatics are electronically controlled and will not shift into park or R at 60mph, but they might suddenly at 3mph as you slow down, and that isn't too good for the tranny either.
 

Trackaholic

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Good point. Electronic transmission controls would probably prevent that as well.

I always think of the scene from the original Terminator where Sarah Connor shoves the truck into park and it comes skidding to a halt just in time to avoid crashing.

-T
 

Abb0nz

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You're misinformed...

Also Redline and rev limiter are different. Shifting at the Redline is the optimal shift point for maximum performance (generally speaking). If you've only done this 6 times...you're missing out.
I think you're the one misinformed. The optimal shift point is at (maybe just past) max HP. The redline is seldom, if ever, at that point.
 

Gurjit

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I think you're the one misinformed. The optimal shift point is at (maybe just past) max HP. The redline is seldom, if ever, at that point.
Incorrect
Watch this video
Gear ratio advantage outweighs your peak hp rpm

 

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Grintch

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Incorrect
Watch this video
Gear ratio advantage outweighs your peak hp rpm

Right you want the most area under the curve, with consideration for the gear ratio. Shifting at peak power is virtually never the best plan.

My calculations put the optimum shift point at around 7300 rpm (varies a bit by gear).
 

Abb0nz

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Incorrect
Watch this video
Gear ratio advantage outweighs your peak hp rpm

Good point, I stand corrected. Call it a brain fart or old age, I did know this but the brain must have been asleep when i replied...
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jasonstang

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Ford uses a soft cut meaning it simply reduce throttle opening instead of the more harsh spark/fuel cut type that would bounce off the rpm.
When I had stock exhausts I would not knowing I already hit redline in 2nd gear.
 

millhouse

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Ford uses a soft cut meaning it simply reduce throttle opening instead of the more harsh spark/fuel cut type that would bounce off the rpm.
When I had stock exhausts I would not knowing I already hit redline in 2nd gear.
No, they use a hard fuel cut like every other manufacturer. It's not hard on the engine at all...no fuel=no combustion.
 

DickR

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No, they use a hard fuel cut like every other manufacturer. It's not hard on the engine at all...no fuel=no combustion.
See post 14 in this thread. Soft cut starting at 6850 followed by hard fuel cut at 7000 if necessary. I've hit and "held" the soft cut many times in autocrosses in second gear with no apparent hard cut. May have hit hard cut in first but when I hit the limiter in first I shift immediately.
 

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millhouse

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See post 14 in this thread. Soft cut starting at 6850 followed by hard fuel cut at 7000 if necessary. I've hit and "held" the soft cut many times in autocrosses in second gear with no apparent hard cut. May have hit hard cut in first but when I hit the limiter in first I shift immediately.
The only cut I have ever hit is the hard fuel cut. I'm assuming the only way to hit the soft cut is when you are holding high RPMs?
 

jasonstang

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The only cut I have ever hit is the hard fuel cut. I'm assuming the only way to hit the soft cut is when you are holding high RPMs?
How do you hit hard cut? I have never had the rev bounce off the redline.
It just stops and holds there.
 

millhouse

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How do you hit hard cut? I have never had the rev bounce off the redline.
It just stops and holds there.
It doesn't bounce....the engine just falls flat on it's face once the fuel is cut. There is no holding, it feels like the engine shuts off.
 

jasonstang

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It doesn't bounce....the engine just falls flat on it's face once the fuel is cut. There is no holding, it feels like the engine shuts off.
That is called a soft cut or throttle cut.
A hard cut is when the rpm bounce back and forth because ignition cut.
 

millhouse

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That is called a soft cut or throttle cut.
A hard cut is when the rpm bounce back and forth because ignition cut.
Were arguing semantics here, but soft cut limiters are typically refereed to as soft not because they are easy on the engine, but because they allow you to maintain or slow the engines RPM. A hard cut limiter is just that, a limiter that kills the engine temporarily.
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