"The most antiquated and still very effective way of limiting engine speed is stopping Ignition spark to the cylinders immediately which in turn halts the engine acceleration, it feels like fuel is being taken from the engine so hotrodders coined the phrase "Fuel Cut"."

"Our cars have a "Soft" limiter which first retards timing a little, then more then cuts the ignition power (within a few milliseconds) this causes more of a surging feeling rather than a series of whiplash inducing jolts."

"Still another method used is the Throttle control method. Cars with Electronic throttles (in some cases) use the computer to close the throttle when it reaches its Rev Limit and this in turn creates another type of soft revlimiter."

Why do I post this?
I have a 2006 5AT Sedan and never experienced the "pegging" phenomenon.
Note, I've kept it at the rev limiter for about 3-4 seconds at 6800 RPM.

Someone on the forums originally stated that:
"These are drive by wire cars, when limiter is hit, it simply shuts down the throttle. i.e. no different than you taking your foot off the gas."

Has Infiniti done some changes?

 

I have a 2004.5 5AT coupe. When I have hit the rev limiter, it definitely gives a jolt! Not a pleasant feeling at all!

 

So fuel is not being cut and thus, we are not running insanely lean.
My car did not jerk itself, the tachometer was not "pegging" redline, but I did feel a sudden surge which went away after I upshifted the vehicle.

I really want to research this topic because the major consensus on the forums is that reaching the rev limiter will not cause damage yet TS claims that "Hitting the rev limiter too often, could actually damage the engine since it is achieved by cutting fuel."

I was reading an F1 forum and they stated that most cars were "inevitably hitting the "hard" limiter at the end of most straight aways causing internal damage to the parts as well as killing speed." Now, they're using a "soft" limiter built into the engine management system, electronically cutting spark when a certain revs are hit.
Drive-by-wire anyone?

 

Street cars:
Fuel is cut (when i say cut i dont mean completely taken out)..

Timing is Retarded

Throttle (by wire in our case) is ECU controlled

Race Cars
Fuel is not cut.. (fuel cut = boom for most race cars at high rpm)

Ingition maybe cut (some cars spit out enough fuel to hydro lock a motor if there isnt any spark)

but what im trying to say is.. cause we're a street car our fuel will be cut a little.. why? because the government does NOT want us to release raw fuel into the atmosphere through our exhaust

 

So with the "newer" system we are not running too lean (technically fuel is not being cut) and thus eliminate the chances of pre-ignition or detonation (which is due to the "pegging" as the car jerks itself in regards to fuel starvation).
With the "soft" limiter in tact, there is a very slight chance of engine damage, even if you hold it there.
Kind of makes sense for Infiniti to bump up their standards because I think they have done it with the newer models.

 

I know that with the VQ30s, both spark and fuel is cut to cylinders 1 and 6. The rev-limiter on my old VQ30 was far softer than the one on my G35. I think it has everything to do with the throttle-by-wire. I really think that all Nissan did was cut the voltage to the throttle-by-wire to close throttle at the limiter. What you end up getting is a throttle opening and closing rapidly which results in an almost violent rev limiter. I don't think the limiter is going to cause damage, but as with any engine, I wouldn't recommend riding the limiter for any extended period (more than 1 second).

 

I notice with my Stillen SC that if I hit rev limiter my peak boost is 0.2-0.4psi higher than ever before.

 

I'd be interested to find out what happens during rev-limiting too. I've noticed the rev limiter on the 05-6MT is very generous...running hard in first you rev to 7200+ and then shift. In second you can still hit 7200 and then shift. 3rd revvs slower and won't get much past 7050 before having to shift. But I've just learned by reading some posts here that revving that far doesn't have any advantage. Where should we be shifting to achieve the best performance, around 6800-6900 perhaps?

 

Around 6400 I believe. That's where you're getting the most power but your best bet is to dyno the car and see where you peak.
I think Infiniti has bumped up their standards on the newer models, not only is the rev limiter a lot more generous but it's safer as well IMO.

 

In my 2004.5 it feels like throttle is cut, not fuel. You can hear it. It feels exactly like pumping the pedal at high revs in any given gear.

Maybe the newer models don't open and close the throttle, but just find the right position to maintain rpms - resulting in a much gentler rev limiter.

I don't think either way is any "safer" per se (if that's the mechanism used).

 

what ever is happening we are being limited, now the question how do we become liberated?

 

It's all dependant on power peak and gear ratio. Generally for most cars you want to shift 300-500rpms past power peak in 1st and 2nd gear. In 3rd and 4th, you'll be okay with shifting at peak or shortly there after. With the Rev-up, peak power occurs at around 6400-6600rpms. So, I'd say:

1-2 7200
2-3 7100
3-4 6900

 

Newer vehicles limit RPM by closing the electronic throttle control and only use the harsher fuel cut if that fails.

Fuel cut rev limiters are actually the best method. They do not cause an engine to run 'lean', for the very definition of 'lean' is insufficient fuel, not non-existent fuel. Bear in mind: what do we typically fear from a lean condition? Detonation! But detonation still requires fuel...take away the fuel altogether, and you also take away any possibility of detonation. Air alone will not detonate!

Why is the fuel cut rev limit preferred? Well, once we understand the above, we can consider what 'interrupting' the spark (the other method of rev control) does to the engine. As we take away interspersed ignition pulses, we cause a very unstable condition to a very smooth-revving engine. The cylinder fires, then it doesn't, then it does, then it doesn't...mechanical parts are being jacked around, unevenly unloaded, then instantly reloaded...unburned/partially burned fuel causes all kinds of instabilities in the cylinder, as well as intake and exhaust systems...oddball pressure waves are caused in the manifolding...backfires often occur. Use your imagination and think about what's going on in there as the spark turns on/off repeatedly. It's just wrong on so many levels, and your engine HATES it, especilly when it's at its most tender condition...maximum RPM!

This is why manufacturers have moved to the fast acting and highly accurate electronic throttle as the primary method to control engine torque (and hence RPM). If you ever see an LS2 V8 hit the RPM limit you'll be quite surprised how civilized it all is, compared to the bucking fuel cut.

'Soft' rev-limiting method, rather than just hitting a certain RPM point where the engine suddenly begins to 'miss' to control revs, the rev limit actually sounds like one is modulating the throttle to 'hold' a particular RPM. Then, several tenths of a second later, the more aggressive 'limiter' engages, sounding much more like a conventional rev limit.