Thanks for the info ekpolk. Goes to show if cold-starts weren't a concern, Toyota wouldn't have added those subsystems and the associated costs.
Interesting. I know an engineer who liked to tinker. 20 years ago he modified his car by putting a small hot water heater in the trunk, with a pump connected into the cooling system. He never had to plug his car in even during cold weather. He just turned the pump on, waited a few minutes and started up the car. We thought he was nuts!quote:
Originally posted by ekpolk:
The current generation Prius (MY 2004-now) has built-in block heating AND a form of pre-lube system. Upon shutdown, the car pumps 3L of hot coolant into a thermal bottle that's capable of keeping it at or near op temp for three days (I assume that time drops with ambient temps, to some extent). As soon as you turn the drive system on, it immediately heats itself by quick-pumping that coolant back into the block and head of the gas engine (keep in mind that generally, the gas engine won't fire up until this is done; your're on electrics until then).
Try answering my post again, pointing out in a rational and understandably way how my math is incorrect and my definition of start up wear is incorrect. And please stick strictly to what I said.quote:
Originally posted by 427Z06:
Well...math isn't your strong point I presume?quote:
Originally posted by jmacmaster:
Lets take the mid-point of that 200-1,000 miles of wear per start up, which is 600 miles, and assume that you get the "wear-equivalent" of driving 600 miles with each cold start.
Then lets assume two cold starts per day (which I think is conservative for the average driver) over the period of a year, which equals 730 cold starts for the year.
Then multiply the 730 cold starts by 600 miles of wear. You get 438,000 miles. So the cold starts for that year caused as much engine wear as driving the car for 438,000 miles would have caused. So any new car's engine would be worn out long before the end of its first year.
This is patently absurd. I think that the amount of engine wear caused by cold starts is vastly overestimated.
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AND EXACTLY WHICH OF MY MATHEMATICAL CALCULATIONS IS INCORRECT? IF YOU'RE GOING TO INSULT MY MATH ABILITY, THE LEAST YOU CAN DO IS POINT OUT THE ERROR(S) IN MY MATH.
Seriously, you make the mistake of equating start-up wear miles as defined above with actual miles on a typical vehicle.
Recall that startup-wear miles are normalized to the wear rate with fresh oil at steady highway speeds.
YOU ARE THE ONE THAT QUOTED A STUDY THAT SAID THAT START UP WEAR MILES WERE "NORMALIZED TO THE WEAR RATE WITH FRESH OIL AT STEADY HIGHWAY SPEEDS". I TAKE THAT STATEMENT TO EQUATE START UP WEAR MILES TO MILES DRIVEN DOWN THE ROAD, SO THAT A START UP WEAR MILE EQUALS A MILE DURING WHICH THE CAR IS DRIVEN DOWN THE ROAD. THIS DEFINITION/EQUATION IS FINE WITH ME. ITS WHAT I USED IN MY POST. I SEE NO MISTAKE IN WHAT I SAID.
This means that the average engine, with average maintenance, in the average climate starts out with approximately 2 millions miles of life. Toyotas probably start off with 3-4 million miles.
WHAT THE HECK DOES THAT MEAN? I HAVEN'T THE SLIGHTEST IDEA WHAT YOU ARE SAYING HERE. ARE YOU PERHAPS TRYING TO SAY THAT THE AVERAGE NEW ENGINE WOULD GO 2 MILLION MILES IF IT WERE NOT SUBJECTED TO STARTUP WEAR? IF SO, YOUR FIGURE IS APPARENTLY BASED ON YOUR BELIEF AS TO WHAT PERCENTAGE OF ENGINE WEAR IS CAUSED BY START UPS. A BELIEF THAT SOME OF US THINK IS INCORRECT. IF THAT BELIEF IS INCORRECT, THEN SO IS YOUR 2 MILLION MILE FIGURE.
Also, one has to define what worn out means. A worn out engine may still run, but one or more of the engine specifications are out of spec. This could be one or more of the following: bearing clearances, piston/ring clearances, bore taper, leakdown rate, chain stretch, etc, etc.
Your example above still gives you 5 years of starting a cold engine and running it up to temperature twice a day, everyday, before something is out of spec. And if you drove for 10 miles each start, 36,500 miles would be on the odometer.
I DON'T UNDERSTAND YOUR REASONING IN YOUR LAST PARAGRAPH. I DOUBT THAT ANY OF US DO.
I would say that average BITOGER is in the 200 miles of wear per start up range. And many are probably closer to the 100 miles of wear per start up range.
this was my understanding, but i cannot find any data to back it upquote:
Originally posted by Pacecar:
The PAPER AIR FILTER, replacing the old oil bath air cleaner, is the most significant factor for increasing engine overhaul periods.
When CHINA imported the 2.2 Chrysler engine assembly line, they experienced lots of cylinder bore wear and short overhaul periods. But they were still using the oil bath air cleaner. When they switched to paper air filters, the problem completely disappeared.
I'm still not buying this one. I've seen the fuel wetting that goes on in the combustion chambers of modern fuel injection engines. These were especially equipped test engines with view ports to allow high speed video. No doubt it helps, but it's not the single biggest contributor. Reliable, high power ignition systems that virtually eliminate random misfires may even trump it.quote:
Originally posted by carock:
Here are a few factoids for this thread:
1. Fuel injection is the single biggest reason for improved engine wear we have seen today. It has been proved that most engine wear is caused by carbon particles formed from blow-by. Eliminating these particles can improve valvetrain life by a factor of five, engine bearings by a similar factor, and piston ring life is improved. The fuel injection system running a constant stoichiometric air/fuel ratio significantly reduces blow-by and the carbon particles.
The main advantage of EFI isn't it's (necessarily) precision in fuel metering. It's its precision over the life of the vehicle. Carbs were complex and not nearly as reliable.quote:
Originally posted by Master ACiD:
i dont know if fuel injection plays as big of a role as some of you guys would like to believe. if you take 2 identical cars with the sole exception being fuel injection and carb, they both reach a good long service life.
lets take ford festiva for example. they all had the same engine, yet certain models had carbs, some had fuel injection, they ALL would last over 200,000 miles, carbed or not.