HyperX

Nope. the rev limiter will not protect you if you miss shift. It will be in mechanical override at that time. This has been covered on this forum.

LS9Drew

I thought that was the whole point was in case you missed going 2 to 3 or 1 to 2. That you didn't over rev, well that sucks guess I need to be extra careful then only missed like 4times but I don't sit at the limiter I let off real fast

160KTS

Let's say you're on the track, a nice cool evening running in the 1/4. You get off the line really well, let's say a 1.8 60" and you shift into second no problem... now you're approaching the top of third and go to do another seemingly perfect shift at 7k rpm and you accidently shift into first gear again, causing an overrev. The computer can't fix that because it's a manual and you did it. The car may blow, it may not... depends on how quickily you react...
Ouch.

HyperX

Hey I just noticed the slam on the corvette club thing.

Try this experiment. Call them (pick a random club) and ask if anyone heard of ls7 engines blowing up. I challenge you to do it. I can guarantee you the answer will be no. Then ask them if they know about the roof issue, or even the 2006 rear ends. I can almost gurantee you that everyone will know about the flying roof. Some will know about the bad rear ends (not as many).

So its not even if people have this experience, but if they actually heard of it. Keep in mind, these clubs have their little meetings, etc, and they hear and talk about things. The ls7 blowing up doesnt come up.

ZO ZICK

I believ all of them have the issue if you drive them hard stock

lt1z

Simple solution is to practice driving the car hard. Accidental downshifts at redline are pure driver error and no amount of safeties built into the ECM can save you from yourself if you do stupid things. People who have a problem with this frequently should go ahead and trade the car in for an automatic GS.

OnPoint

Rev limiter helps you avoid over revving the engine with the throttle. I.e. you get in, start up the car, stand on the throttle, it will rev up to the limiter and it will keep it from going any farther.

If you're accelerating in a gear and not paying any attention to your rpms - the rev limiter will keep you from over-revving the engine.

But - if you down shift into a lower gear, thinking you're upshifting into the next gear (i.e. in 3rd, think you're shifting to 4th, but hit 2nd instead), you can mechanically over-rev the engine and do some major damage.

The rev limiter is fuel/spark control - it can't stop a mechanical over-rev.

Prime Target

Here we go again.....

PHXAZ06

I simply took Jason at Katech's word for it. Zero LS3 valve problems.

You ask for the impossible, as I stated. Not even GM has the data, and without the data, well, it's conjecture.

Every other thread in this forum is about a blown motor - a new one every week.

Don't worry, yours won't blow....

Jawnathin

It is all mechanical forces a rev limiter cannot prevent. The transmission will turn the motor over, and if its a downshift, revs will go up.

At 30mph, that about 2300rpm in 2nd.
At 60mph, you're doing nearly 4750rpm.
At 120mph, its 9.5k~ rpm.
At 180mph its 13k~+ rpm.

If you're at 120mph in 3rd and attempting to shift to 4th but throw it into 2nd instead, you're looking at around 9.5~k rpm. BOOM!

Rev limiters are just cutoff fuel which prevents the motor from revving on its own further. It won't save the transmission from turning the engine over on a botched downshift.

LS9Drew

Oh ok misunderstanding, I was gonna say what is the point of it then. Luckily I'm not that retarded to go 3 to 2 at WOT lol. I didn't even think that's a common thing lol

FrankTank

Every other thread in this forum is not about a blown motor...most of them are the same ol threads dreged up so folks can keep arguing... or a person asking about a blown motor, or what year had a problem because they've bought into the fact these motors are flawed.

You know what I think is impossible?? People who mod the car and take it outside of what it was designed to do, and then fault it when it goes kaboom. Like I said, all the modded blown motors..you don't think a single one was due to a mis-shift, faulty aftermarket part, issue with a tune or install? I also don't trust that some folks are providing the whole story here on some of these motors..but again as you stated , it is impossible to know that.

Yes, there are 2 new ones this week...both MODDED and one that saw 24k track miles...so Yea I tend to agree with you... I am not the least bit concerned mine will blow up.

GM would have never kept producing them all these years if there truly was an issue, nor would they have bothered to put the motor in the 427 Vert Edition that is coming out.

Jawnathin

This doesn't necessarily reflect my stance on whether or not this is an issue, but in my mind the challenge with calling the local Corvette Club is that very few of the members drive their car hard or do much if any power mods.

As far as I can tell, they're mostly full of waxers who put minimal miles on their car and sometimes they have the occasional hot shoe and heavy modder here and there. Given we think this issue occurs with aggressive power mods (cams) and hard driving, its not unreasonable to think that most Corvette Club members won't know of the problem.

The de-laminating roof is a bit more widely known because it affected every car (within that year), GM had a public TSB on it, and it doesn't matter how hard the car is driven, it just happened, even to waxers.

So in short, I agree that if you call up your local Corvette club, you're unlikely to hear about any reported problems, but I do not feel they're the best source of input based their driving style and how we think the problem is generated.

If it means anything, I took my other car out to a local track day event and when speaking to a Viper owner about Z06s, he even specifically mentioned dropped valves in Z06s. My friend who has zero affiliation/background with Corvettes but is considering a Z06, mentioned he heard of 'engine problems' in these cars when he was asking his car's forum about them. So word has certainly gotten around.

Jawnathin

LOL. Unfortunately it does happen. The gates between 2nd and 4th are less than an inch away. Its not far fetched to think its possible to mess up a shift in a WOT run and accidentally throw it in the wrong gear.

This type of mis-shift is commonly known as the 'money shift'. You can probably guess why

Random84

Many posters here cross-post in other enthusiast forums - very much like the Ferrari or even Camaro forums. A lot of cross-talk, so yes: on the internet, word travels fast.

But that doesn't mean that it's a wide-spread problem, in that Joe Public is going to be asking his local dealer about the issue.

FrankTank

as someone posted the other day.... things are just made more public now because of the internet

people have been blowing modded motors they raced since hot rodding has been around... you just hear more about it now becaues of the internet.

LS9Drew

Lol money shift. Ya Corvette clubs aren't the best place to ask I've never seen a guy in one floor their car lol. Best bet is to go the track or street races and ask or check on here those are mainly the people who actually push their car.

Jawnathin

Im not suggesting this is a problem or whether it is wide spread or isolated, I am just simply stating that 'word has gotten around'.

This was on a Honda forum by the way

Frans96ss

We try to prevent the problem before it happens. Whenever i sell a cam package to someone i always STRONGLY recommend them getting the exh valves replaces. I would say i have seen it happen to 10-15 personally and NUMEROUS others on the forum.

I couldnt even begin to estimate how many LS7's ive worked on. 100's

LS9Drew

Thanks, out of those 10-15 did they have a cam without doing heads or exhaust valves like you recommend? I figured you'd have some insight since you seem to work on a ton of LSx cars