70 mph in 2nd gear

**westernb4** · 06-14-2011, 07:18

Listening to Car Talk the other day. A young woman calls in, asking whether
driving a short distance at 70 mph in 2nd gear could have blown her father's Volvo's engine.
Apparently she did this shortly after a long overdue muffler repair.
Tom and Ray say no, 70 mph/2nd gear didn't do it; happened as result of valves overheating from lack of backpressure from absent muffler.
Not sure about the backpressure issue, but I think that the 70mph/2nd gear certainly could have wrecked the engine.
Agree/disagree?

**nsxtasy** · 06-14-2011, 09:47

Originally Posted by westernb4

I think that the 70mph/2nd gear certainly could have wrecked the engine.
Agree/disagree?

Yes, if that speed exceeded the engine's redline.

**heySkippy** · 06-14-2011, 10:39

Originally Posted by westernb4

I think that the 70mph/2nd gear certainly could have wrecked the engine.
Agree/disagree?

Not enough info. If it's a 6 speed manual, almost certainly yes. If it's a 3 speed automatic, probably not.

**westernb4** · 06-14-2011, 11:00

It was a manual.

Story was that after she got the muffler repaired, she lost the loud exhaust note cue to shift, and left it in 2nd gear until she hit 70 mph.

**jond** · 06-14-2011, 11:51

I think it's safe to debunk the second explanation. Running w/o a muffler is not going to kill your engine. At least not quickly, maybe over a few years.

**Miner** · 06-14-2011, 12:13

Originally Posted by jond

I think it's safe to debunk the second explanation. Running w/o a muffler is not going to kill your engine. At least not quickly, maybe over a few years.

Tom and Ray know a bit about cars, I would call baloney if it were anybody else.

Miner

**broinkrist** · 06-14-2011, 12:18

yep, not going to happen.

even if she did take it to the redline, i would think that the volvo would have a software rev limiter in there so she couldn't rev past the indicated redline. now if she took it all the way to redline in 2nd and then shifted into first quickly, then that's a different story...

**jond** · 06-15-2011, 04:26

From my understanding, burnt valves are caused by the car running lean. Low backpressure can cause that in older cars, but in newer cars the computer should adjust.

**nsxtasy** · 06-15-2011, 07:38

Originally Posted by broinkrist

yep, not going to happen.

even if she did take it to the redline, i would think that the volvo would have a software rev limiter in there so she couldn't rev past the indicated redline. now if she took it all the way to redline in 2nd and then shifted into first quickly, then that's a different story...

Yup. And that would be my bet as to what actually happened, regardless of whether or not she realizes it. There's a reason why they call a mis-shift - accidentally downshifting from redline instead of upshifting - a "money shift".

**nsxtcy85** · 06-15-2011, 08:37

Originally Posted by jond

I think it's safe to debunk the second explanation. Running w/o a muffler is not going to kill your engine. At least not quickly, maybe over a few years.

Your on the right track, except running without a muffler will never kill your engine. Unless your a dumb chick who doesn't know when to shift.

**SilverStone05** · 06-15-2011, 11:13

Pish posh. Shitty Volvo.

The vette will do 90 in 2nd.

**Hapa88** · 06-15-2011, 17:06

Originally Posted by SilverStone05

Pish posh. Shitty Volvo.

The vette will do 90 in 2nd.

1991-1994 NSX does 81 in 2nd!

That being said, most cars are geared to hit 60mph in 2nd gear at redline. Therefore I think driving 70mph in 2nd would probably be excessively high RPMs for a Volvo.

**NSX UNITED** · 06-16-2011, 16:25

Originally Posted by nsxtasy

Yup. And that would be my bet as to what actually happened, regardless of whether or not she realizes it. There's a reason why they call a mis-shift - accidentally downshifting from redline instead of upshifting - a "money shift".

Don't think it's a money shift.

I bet the lady is just a lazy shifter, I mean c'mon, even without the sound of a muffler, any driver who knows how to drive a stick knows when to shift. She's just making excuses.

Plus the story didn't mention anything about shifting gears other than staying in 2nd.

My conclusion is that it's just bad luck for her. A Volvo which had a long overdue muffler repair sounds like a pretty beat-up old car. The same could've happened to anyone in her shoes.

**nsxtasy** · 06-17-2011, 15:35

Well-maintained engines don't just blow up. There has to be a cause. In the absence of any other explanation (e.g. no oil put back in during an oil change), and especially since there are indications of a shifting issue here, the cause is almost certainly a money shift.