Reaching redline.

[erom]

Hey,

I looked around a bit but looking for something more direct...(in terms of answers)

I hit redline a few times in the car and would like to have a better grasp of what happens at that moment.

I know that I can get into the car and test it out firsthand but I think it's a bit safer for now to have some knowledge beforehand.

I'm interested to hear a bit more about the limiter, 'bouncing', and possible hazards of hitting the red zone.

Thanks in advance.

- erom

PS. 6 MT FR-S (raven)

[atledreier]

You are at the point of the powercurve where the car pulls best, and then suddenly it doeasn't. It will feel like hitting a wall, but it's really just the car that stops accelerating. It's not the healthiest you can do to your engine, but it shouldn't hurt it unless you really ride the limiter constantly.

[arghx7]

It's probably cutting fuel.

[breezy]

The redline is there because that's the highest RPM that Subaru is promising safe operation without engine failure. Above that, things may start to happen (valve float, lubrication issues, etc.) that might compromise your engine. So a limiter is programmed into the ECU to cut spark once you reach the redline RPM.

Bouncing off the limiter occurs when you keep your foot on the throttle even when you've reached redline. The ECU cuts spark, there is no power stroke, so the engine will begin slowing down. At an RPM lower than redline, the ECU will once again allow spark plugs to fire and resume normal operation. Then you reach redline again and the ECU cuts spark and the cycle continues, as long as you're on the pedal.

Possible hazards? If you stay near redline for very long, the lubrication system might not be able to keep up (depending on how Subaru designed it), then you will lose bearings and everything else that happens after that...

[d1ck]

Originally Posted by breezy

The redline is there because that's the highest RPM that Subaru is promising safe operation without engine failure. Above that, things may start to happen (valve float, lubrication issues, etc.) that might compromise your engine. So a limiter is programmed into the ECU to cut spark once you reach the redline RPM.

Bouncing off the limiter occurs when you keep your foot on the throttle even when you've reached redline. The ECU cuts spark, there is no power stroke, so the engine will begin slowing down. At an RPM lower than redline, the ECU will once again allow spark plugs to fire and resume normal operation. Then you reach redline again and the ECU cuts spark and the cycle continues, as long as you're on the pedal.

Possible hazards? If you stay near redline for very long, the lubrication system might not be able to keep up (depending on how Subaru designed it), then you will lose bearings and everything else that happens after that...

Although I can't say with 100% certainty, I'm confident that the rev limiter would be a fuel cut, and not spark. I don't know of any factory vehicles which use a spark limiter. With a spark limiter you can get combustion in the exhaust which has the potential of damaging your exhaust valves or the catalyst.

[#87]

I hit the redline accidentally, it just cuts power and you go o shit and shift gear. It doesn't "bounce"

[inz]

The rev limiter is there to protect the engine from over revving.

It is not a spark cut, unless you run a missfire system... Which you're not. Because you're missing a TARBO.

The car doesn't pull the hardest near redline. That is stupid. Cars aren't built from factory with peak torque at 8000RPM. After all - these are street cars. Cars travel FASTER at 8000 rpm than they would at say, 6000rpm. But power is not torque. And torque is what puts you back in your seat.

The only difference between 4000rpm and 8000rpm is about 4000rpm. The engine does all the same things. Rev limit protects the head from things like valve float.

Also, of you look carefully, there is a light on the dashboard that flashes when you make a "perfect shift" and you will get a little boost in acceleration...

[Subie]

Is the rev limiter right at the redline in this car? I've never before owned a car that didn't have a small range in the red zone above the redline but before the rev limiter.

[Draco-REX]

You're fine hitting redline once in a while It's there to protect the engine.

As for high RPM oiling, don't worry about that either. Subaru oil pumps move a LOT of volume. IT's one reason why Subaru oil filters are preferred. They have much higher bypass valve pressure.

[Coheed]

Originally Posted by d1ck

Although I can't say with 100% certainty, I'm confident that the rev limiter would be a fuel cut, and not spark. I don't know of any factory vehicles which use a spark limiter. With a spark limiter you can get combustion in the exhaust which has the potential of damaging your exhaust valves or the catalyst.

You would be correct, most limiters are fuel-cut. Most newer cars offer both as part of the factory programming. the newer Evos are a good example. they cut fuel, then spark around the same time.

[Snoopyalien24]

You can set your redline limiter on the car. I just don't remember the thread that shows you how to do it. If you're scared it might cause damage, just set the limiter to a few hundred before the limit

It should be in the DIY section

[xpicer]

Rev limiter always kills injector pulse, other ways you would 1 flood engine , maybe hydrolock ( if pulse is wide enough) , depending kn engine conditions, pre combustion.

[Coheed]

Originally Posted by Snoopyalien24

You can set your redline limiter on the car. I just don't remember the thread that shows you how to do it. If you're scared it might cause damage, just set the limiter to a few hundred before the limit

It should be in the DIY section

that would be the shift light. Not the limiter.

[Snoopyalien24]

Originally Posted by Coheed

that would be the shift light. Not the limiter.

Oh yeah, my fault. But still, that could help ?