Clutchless

In the Paul Walker case a contributing factor was that at least two of the tires that failed were over 9 years old, plus excessive speed for conditions. I doubt a stability nanny would have saved them.
http://articles.latimes.com/2014/mar/26/local/la-me-ln-paul-walker-porsche-outdated-tires-crash-20140326

Finally, the first of several lawsuits against Porsche was dismissed.

A federal judge has ruled that Porsche bears no responsibility for the crash that killed movie star Paul Walker and his friend Roger Rodas in 2013, the Associated Press reports.

Walker and Rodas were killed when a modified Porsche Carrera GT, driven by Rodas with Walker as a passenger, careened off a Los Angeles road, struck a pole, and caught fire. Both men were pronounced dead at the crash scene.

The suit, filed by Rodas's wife, alleged that Porsche was at fault for the fatal accident due to a lack of numerous safety features in the Porsche Carrera GT that the men were driving in. U.S. District Judge Philip S. Gutierrez ruled that the suit "has provided no competent evidence that Rodas' death occurred as a result of any wrongdoing on the part of defendant." Rodas's lawsuit claimed that the Carrera GT's lack of a roll cage, fuel cell, and stability control made the crash fatal, and that the car's suspension failed in the moments leading up to the crash, allegations the judge refuted.

Immediately after the crash, L.A. investigators determined that the Porsche was traveling between 80 and 93 mph at the time of impact; that both Rodas and Walker were wearing seatbelts, and neither was under the influence of drugs or alcohol; that both occupants' air bags deployed; and that no mechanical failures contributed to the accident. The Porsche was found to be riding on tires that were more than nine years old at the time of the crash. Engineers from Porsche and Michelin, the maker of the tires, cooperated in the investigation.

The lawsuit brought by Rodas's wife is just the first to be decided. Paul Walker's daughterand father have both brought similar lawsuits against Porsche, alleging that design flaws in the Carrera GT caused the fatal crash.

vlad_a

There was no price difference between H and V-rated 19" Michelin Premier LTX tires I put on our RX.
I also found out installers will go down 1 speed rating, but not two. So, H is still suitable for the RX.
I do operate T-rated (118MPH) winter tires, but I got them as a stand-alone set from TireRack.

ColAngus

^No.
Do any cars work this way?! It's always fuel cut, isn't it?

^Yes.

SteveCraig

I'm not an engineer but still have to disagree. The Honda 3.0 V6 will spin up to about 6200 RPM before the limiter cuts the fuel. This much is true.
Picture spinning at that point, constantly hitting the limiter in 6th gear. Not sure how fast the car is travelling but it's well beyond any street legal limit.
Some reason.......could be an obstacle, a set of red & blues, anything to make the inexperienced driver bring it back to Earth in a real hurry.
Downshift intended as from 6th to 5th ends up really a 6th to 3rd ! Revs climb in a very quick hurry & the limiter instantly cuts the fuel.
Momentum of the car's mass against a dry clutch still pushes the engine North of 10K RPM,however, for a short time only.
This is the instant before locking up the front two, again very short time. Rubber looses traction & regains as the car slows down. It's all over by then.

slawless

Just a comment further. Most modern cars have a speed limiter and an RPM (rev) limiter. As far as I know they are independent. Both are in software and can be changed or removed with the proper software. Both my BMWs have had the speed limiter removed. I have no intention of ever going any where near 155. but the fact it was there just bothered me. As to the rev limiter, manufactures have different ways of handling the situation when you reach red line. Both of my BMWs work differently. Both are manual trans so I can easily take them to red line. The 2003 will cut the fuel at red line. The engine just dies. The 2008 has a little more finesse. It just stops at the red line and doesn't go any further. I have never had the RX at redline. As stevecraig mentioned you can over REV an engine with a manual transmission. I knew a guy (not me) who was doing 125 in an E46 M3. He tried to do a 6-5 shift and did a 6-3 shift instead. It was towed to BMW. BMW said It stopped recording at 9000 rpm. YOU over reved the engine. That is not covered by the warranty. A new engine is $18000 and it may take up to a year to get one. On BMWs your top speed, top RPM and number of redlines are permanently recorded. This can be accessed but not changed with the proper software. Modern ECUs are amazing at what they know. Sorry for blabbing about BMWs, I just know more about how they work than my Lexus, but a lot of the same applies.

cc16ue

iTrader: (1)

I can't imagine how bad of a jerk it would of been when the driver went from 6th to 3rd at over 100mph!!

On a side note, each manufactory is programmed differently with their speed/rev limiter. On a ford, the car just refuses to go any faster than the limiter no matter what gear you are in even if you down shift, whereas a Chevy just cuts the engine so you can't do anything on the accelerator until the speed is dropped down way below the limiter until you have power again. This is definitely not for everyone to try but good to know for personal reference.

ColAngus

But, the fuel has still been cut in your Honda. You're just mechanically forcing it to temporarily rev higher with the tranny. When you say "fooling it" you're making it sound like you can downshift to make to car go faster than the rev limiter will allow and that's not the case. Obviously, we agree that it will temporarily make the rpm go beyond its designed range, but the car is not going to go faster - actually, it will decelerate.

vlad_a

It is fair to say there is confusion between rev limiter and speed governor. Both are not the one and the same. While rev-limiter may act as a speed governor when vehicle reaches max RPMs in top gear, speed governor will not allow the vehicle to accelerate past a pre-set speed.
Both may cut fuel or may simply override the pedal input, as everything is drive-by-wire nowadays.
It makes no difference whether a vehicle is auto or manual. As stated above, one may damage an engine in a manual car by over-revving it, but it has little to do with this particular topic.

MellonC00

I can confirm that on Audi's and Lambo's they don't cut the fuel off all together. It reduces the fuel until the rev comes down from the redline, then, if you have the foot on the floor, it goes right back up there. At a recent exotic car event, an owner of his Diablo was demonstrating this. It was loud and, well, interesting almost like music. It goes, broommm, then, purrrr, kapap, pap pap pap pap then, broommmm again. it's like he was modulating the throttle but really it was the computer doing that all along....

vlad_a

In a gas engine, fuel has to be cut - it can't be reduced. If less gas makes its way into cylinders, it will create what is called a lean condition. Lean burning of fuel results in very high exhaust temperatures and will damage the engine.
What you may be experiencing is cylinder injection being cut off in a sequence. In other words, a V8 may effectively become a V3, depending on the amount of intervention needed.
You are correct in a sense that the fuel is reduced, but the reduction is in its overall flow by a series of cutting its supply to specific cylinders.
And that would explain why the exhaust note changes dramatically.

Some traction control systems are setup to function this way. I actually have RaceLogic unit laying around that I never got a chance to put into my old IS300.

SteveCraig

You are correct.
My earlier wording leads the reader to believe you can intentionally over rev the engine.
In most cases, if not all, the over revs was purely unintentional.