lancelot1

Is it feasible to make an estimate of the number of wot pulls an LT1 can experience before valve train components or the piston/ rod assembly will fatigue and fail? An estimate of a 7-9 pound boosted LT1 would be of particular interest. Assume a nominal build with proper operating parameters and maintenance.

k24556

The engine will have life-cycle fatigue predictions for all components subject to cyclical loading. That's how the designers determine how to design something so the individual parts and the assembly will have the design basis projected life. This will be a closely held secret so that competitors don't know how they did it, and then there is the distant nuisance of a pissed-off customer. The last thing they want us to know is how long THEY expect something to live.

The valve springs are going to be the first to fail in fatigue. How many millions of cycles to failure? a few million. WOT to redline 6500rpm, so you can do the math, but the answer would be regular replacement of the springs if you are going to bang the crap out of the engine. Most other parts in an engine usually fail by some wear mechanism. Then sometimes overheating can cause an interference; sumpin' gets tight and blam all goes before the predicted end of useful life. Overheating also screws up lubrication and then accelerated wear happens.

I would worry most about the exh valves. If the cam is anything like the LS cams, then during the exhaust stroke the PTV clearance is close. Anything that causes an exh valve to stay down a bit longer sends the conn rod out the side of the block the next stroke

weakend valve spring, overheating causes interference between valve stem and valve guide, loss of lubrication causing abrasive or adhesive wear, etc.

rrsperry

What's the point of your question?

Anyway, the mean time between failure probably is going to be longer than the time you own the car and then decide that you want more power and rebuild the engine.

k24556

Maybe, depends on the model inputs the designer makes. Lots of assumptions about frequency, stresses, and metal surface condition, which plays a role in fatigue life projections. The lawyers and bean counters also input, because if you turned engineers loose, the general public could not afford to buy the PERFECT lasts-forever Corvette. For example, if you could make the valve spring 4 inches long, they would last a pretty long time and surface condition would not be as important. BUT, now there has to be tall valve covers, longer valve stems, and two FUGLY bumps in the hood for the valve covers.

Another example, remember the LS6 vellow vs blue valve spring problem? That was a fatigue problem, and it was related to the metallurgy of the spring AND the surface condition. Quite a few broken springs that if they broke at high RPM caused other damage. Some C5Z06 owners caught it in the driveway, others not so lucky. That problem was not predicted, I'll bet.

So did we answer the OP's question? probably not. There is no equation out there that will tell you precisely when failure is imminent so you can go in and change the offending component. Statistics is used with probability assessments to HOPE to predict the end game, but like the probability of rolling seven, it's still a crap shoot to some extent. There is some limited validation testing, and some life-cycle testing, but this too, is an expense that adds cost to the product. So you are left with deciding how likely end of life is then take a conservative stand and either fix the issue or sell it to someone else to solve.

smajicek

OP, you opened up a can of worms and you will not get a clear answer. Not every C7 is alike, you can buy 2 corvettes at 1 time, drive them equally and 1 blows the motor and the other does not. why is that? **** happens in life. People die unexpectedly every day who are healthy, followed good lifestyle and then the heart stops, the coroner will state died of natural causes. **** happens, I have added a blower on my 2014 LT1 last march, done many wots and no issues. I see new buyers buy new corvettes and 2 weeks later stock motor blows. **** happens. bottom line here is your **** happens. Sorry for not giving a better explanation. I wrote this to get subscribed and watch everyone's opinions.

k24556

You are 100% correct. In the end it is 100% about the money. Even the cost of the liability of loss of life.

Think about the Takata airbag issue. Which statistician predicted that one? Had they done so every car so so equipped would have been 2X the original cost. Or the Toyota sticking gas pedal? The cemetaries and junk yards are testament to miscalculation.