Hey everyone,
A lot of my co-workers seem to slam on the gas as soon as they get into their cars at 5PM. I almost cringe every time I see someone turn the key and pedal to the metal.
I'm always the one babying the powertrain for the first 6 miles of driving. I stay below 3K RPM and use the throttle gingerly, basically I just drive nice and easy so the car can warm up.
Besides increased wear, what does this kind of hard acceleration do to modern cars? I'm curious if the damage is really that bad, after all cars are becoming more and more idiot proof.
-Thanks
Effects of hard acceleration on a cold engine
- Thread starter Swift101
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I am not a hard driver so on any other vehicle it's really no different than I would normally drive.
My focus refuses to cold idle at anything below 2500RPM when it's moving so I just let the clutch out in 1st gear, then shift to 2nd, let the clutch out, etc and next thing I know I'm going 55 with no gas pedal ... then the cat lights off and I have to push the pedal.
I don't have an answer for you, but I've wondered about that too.
On some car shows, when they start up the car (sometimes after appearing to have sat for a long time, barn finds), they'll get it running then rev it up quite a bit. Not quite the same as a hard acceleration, but still. I thought that it was better to let everything come up to temp before revving it up.
The cars are usually flipped anyway, so longevity may not be a concern for them.
Originally Posted By: Miller88
I am not a hard driver so on any other vehicle it's really no different than I would normally drive.
My focus refuses to cold idle at anything below 2500RPM when it's moving so I just let the clutch out in 1st gear, then shift to 2nd, let the clutch out, etc and next thing I know I'm going 55 with no gas pedal ... then the cat lights off and I have to push the pedal.
Originally Posted By: Swift101
Besides increased wear, what does this kind of hard acceleration do to modern cars? I'm curious if the damage is really that bad, after all cars are becoming more and more idiot proof.
I wait the ten seconds it takes for my idle to drop from the high of about 1,700 to just below 1,000. I don't have any particular reason other than being accustomed to the drivetrain
"clunking" hard when shifting into reverse at high RPM. That is not an issue with this car, but habits die hard.
We have a parking garage at the office and many will spend three times as long parking so the can be "head out" in the space. I guess they are in that much of a rush to leave at the end of the day, or their backing skills are poor. Never have quite understood the appeal since it seems to take more time to back into the space in the morning than it does to back out at the end of the day.
from an engine wear standpoint, it's better not to let your car warm up gradually (better to get the engine hot faster). But... aluminum head, steel bolts... difference in expansion coefficients... head gasket would be the concern.
Obviously it's not conducive to long engine life.
The good news is that most North Americans are now running 20 grade or a light 5W-30 so it is hard to actually break an engine
using very high rev's even at freezing temp's.
Do it with a straight 40 or 50 grade oil and you could seize the
engine as some idiot friends of mine have done in my youth.
Originally Posted By: Swift101
Hey everyone,
A lot of my co-workers seem to slam on the gas as soon as they get into their cars at 5PM. I almost cringe every time I see someone turn the key and pedal to the metal.
I'm always the one babying the powertrain for the first 6 miles of driving. I stay below 3K RPM and use the throttle gingerly, basically I just drive nice and easy so the car can warm up.
Besides increased wear, what does this kind of hard acceleration do to modern cars? I'm curious if the damage is really that bad, after all cars are becoming more and more idiot proof.
-Thanks
I'm not sure how hard or easy it is on the engine(s) but the knock sensor on my Regal is programmed to start listening at a ECT of 140 F.
I presume that other manufactures have something similar so that is a safeguard that is disabled for a short time. And of course not every engine has used knock sensors....
I always let my engine idle between 30 seconds and a couple of minutes depending on the coolant gauge and how long it was sitting for. Cold start from sitting over night it idles around 1400 for a brief second then drops to 1200 for a minute or two then 1000. Usually once I see 1000 rpms or less I put it in gear. FWIW.
Edit: I forgot to add that there is a spark modifier table that adds timing based on airflow and ECT. Why GM does this with knock sensors deactivated I will not know. (I have zero'ed out a lot of these tables out that make no sense with my laptop.)
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And by high rev's I'm talking in excess of 4,500 rpm. Taking the engine to 2,500 rpm shortly after starting when first driving off is no problem even in the dead of winter.
Originally Posted By: DBMaster
We have a parking garage at the office and many will spend three times as long parking so the can be "head out" in the space. I guess they are in that much of a rush to leave at the end of the day, or their backing skills are poor. Never have quite understood the appeal since it seems to take more time to back into the space in the morning than it does to back out at the end of the day.
It may or may not significantly affect the life of most engines, but my vote for the engine component that suffers most from high power at low temperatures is the piston/cylinder interface. At least that's the top issue than snapping an oil pump drive shaft, or ballooning a spin-on oil filter or blowing it right off the block from excessive pressure.
When the engine's cold, the pistons are loose in the bores and rock side-to-side during operation more than when they warm up a few minutes. This dimension changes more from cold engine to warm engine than any other clearance in the engine. That's what causes "piston slap" in engines that are prone to it. The fact that slap is audible doesn't mean that excessive wear is happening versus a quiet engine- but the fact that it quiets as the engine warms up tells you that more wear is happening there cold than hot. Even an engine with no audible piston slap still has more piston movement in the bore when its cold than when fully warmed up, and therefore more wear.
Also, the piston skirt strikes the wall of the cylinder harder when the piston/wall clearance is large, so you're more likely to crack a piston skirt when you're demanding a lot of power from a cold engine.
My wife does it every morning when leaving the house, regardless if summer or dead of winter. I've given up on trying to school her - it's not worth the aggravation. She always has a million other things on her mind so taking it easy on the engine just does not register in her brain. I think I'd rather pay for a new car than argue with her over this.
But as much as I cringe when she does this, I'm pretty sure the engine will still last longer than we care to keep the car. The UOAs certainly haven't shown anything alarming.
Originally Posted By: itguy08
Where I work they demand that company cars are parked "head out" and we are encouraged to do that as well with our personal cars. They explained it to us as safety. When you pull forward and then reverse you know the space behind you is clear and when you pull out of the spot there is less of a chance to hit someone by not being able to see them back there. Makes sense since we are a utility and some of those vehicles can have huge blind backsides. Even in today's cars, visibility in the rear can be an issue.
I would "think" that in the summer with temps in the 80's/ 90's that not to big of a deal, especially with todays thinner oils. But winter--Seems to me that even with 0/xx oils it just isn't going to get to everywhere it should for at least a minute or so, (possible exageration) not to mention that the clearances of everything are larger than a fully warm engine. I guess I am just old school, but I still like to take it "easy' until at least there is heat from the heater. And yes I know the engine etc. are far from fully warmed at that point, but at least it seems to be better than 5000 rpm on a fully cold engine. I believe the last new car i had said to drive "moderately" for the first few miles. I do pick up speed faster now than in the old days when I was driving cars made in the 50's 60's and 70's and 80"s
I used to design and build generator sets for extreme cold weather. In our testing the most wear was experienced not at start up but between start up and normal operating temps. Some emergency generator sets were required to be able to accept full load at 3600 RPM, 60 seconds after start. These engines hit fill oil pressure in 3 seconds from starting based on mechanical instrumentation at the opposite end of the engine block. We used a thermos to save hot coolant and inject it back into the engine at start up kind of like a modern day Prius. In some cases oil was kept warm with a heater, all the time the gen set was off. There was always a big effort to reduce the warm up time. Nothing was ever don't to the actual start up like those oil boosting systems for start up because in our testing they were not effective in reducing wear.
Based on my experience I would say that once an auto engine is started it should be gently driven right away and gradually brought up to speed. Idling to warm up is running an engine in it's highest wear state. Today most people don't keep their cars very long and with the quality of oil maybe it makes no difference. You're not going to wear the engine out, just the rest of the car. It may go out of style, too.
Since most modern automatic cars will accelerate quite briskly only requiring shifts at 3500 RPM or so, there is really no worry about the extra wear. Sure, it may look like these guys/gals are flooring the go pedal, but in reality the tranny shifts at reasonably low RPM.
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Pretty sure the second oil pressure is obtained, the car is ready.
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