Calculating overall Car life

[Zephyroth]

By now, the lifetime of the engine is calculated in MRev's, which is perfectly ok for engine design. But for a given engine, the overall car lifetime (= the predicted mileage) is needed.

Now I created a quite simple model, which fits quite good, when I use real world data. I made an example with the 2012er Honda Accord 2.4i with 6-speed manual:



You can see the gears (1st to 6th) and their weigthing (in this case percent).
Out of this I calculated an average gear ratio. Combined with the final drive, the engine life and the wheel circumference I calculate the predicted car life. I was very surprised, that the result fits perfectly into the real world, where the typical car life of a passenger car is between 150.000-200.000mi.

I calculated this with an Excel spreadsheet, so if anyone wants to have it to play with weighting, gear ratios etc., I can send it...

Greetz,
Zeph

[Daffyflyer]

Looks like an interesting start at the very least, if you could send the spreadsheet to contact@camshaftsoftware.com that'd be cool

[Zephyroth]

I've sent it. It's really a good point to start. But it doesn't consider the engine load. That doesn't matter either, as long as there are speed limits. Germany for example is a very special case.

Greetz,
Zeph

[flyingtaco]

Wouldn't you also have to consider things like suspension failures? My Dad's most recent car failed at 160k miles because one of his suspension arms snapped in half, but the engine was still fine.

[Zephyroth]

Yes, of course you have to consider all parts. Maybe the name of the topic is misleading. It's just meant for calculating engine life in a reasonable unit.

Greetz,
Zeph

[Zephyroth]

Hi, there!

Just found the function to attach files

Please find my lifetime calculator attached in the Zip-File.

Greetz,
Zeph

[masteroferdinger]

Hey everybody, this will be my first post in this forum.
At first, thank you dear devs for this amaizing (even if it's beta) game (or simulation ; ))! I had such an idea 6 years ago and I didn't think it would become "reality" some day.

Now back to topic:
I'm from Germany and I think the engine load doesn't affect the lifetime this much. Even if we have open (unlimited) Autobahn-sections not everybody drives like a lunatic.
I think in other countries there are the same sort of people who accelerate at full throttle just to reach the speed limit as fast as they can. Therefore we should calculate the minimum lifetime with max engine load and with average load and use these two numbers to decide when a car will reach the end of its lifetime.
We can assume that the majority would't drive like hobby racedrivers but like people that are threathend by high fuel costs. (maybe consider a variation over time)
I hope I was able to give an understandable explanation of my idea; if not feel free to ask

Erdi

[Lastgameking]

He Zephyroth,

Your calculate looks nice.

But how do calculate the car life?

Is it a sum of Mref and average speed range?

L

[T16]

He takes the average gearing times wheel circumference (that will give you the distance per revolution of the engine) times MRev = distance.

Of course that's is a bit of a oversimplification and Automation will (hopefully) take of variable into consideration.

[Zephyroth]

He takes the average gearing times wheel circumference (that will give you the distance per revolution of the engine) times MRev = distance.

Of course that's is a bit of a oversimplification and Automation will (hopefully) take of variable into consideration.

Exactly that's what I do. It's just a starting point for further developments, of course every beginning is simple. The challenge is not in the simplicity of the model, it's more finding a useful gear weighting for different countries. I tested the model with different cars, the achieveable mileage is very close to the real world examples.

Of course for a model in Automation more variables have to be taken into account:

+ Load of the engine at average speed (especially for Germany)
+ Temperatureprofiles (for very warm countries)
+ driving cycles (means cold starts)

etc... Many room for ideas (which are very welcome, let us develop a useful model)

Greetz,
Zeph

[Lastgameking]

Oke the distance per revolution of the engine. It is really complicated to calculate the real mileage.

But what does rev mean? The mileage of the engine, distance in no load?

[Zephyroth]

When you design an engine, the engine designer calculates the engine lifetime in Million Revolutions (MRev) of the crankshaft. I don't know the algorithm behind it, but it depends on many things (materials used, flywheel weight, air intake, cam profiles, max. revs etc.).

What I've created is a very simple way to get a rough estimation, which mileage your drivetrain (engine, gearbox, differential) can reach.

Greetz,
Zeph

[masteroferdinger]

Maybe the character of of the countryside should be considered, too. Mountains (e.g. Switzerland, Austria) and dust (Africa?) will definitley shorten the livetime of several parts.
For Example, we could develop a table with values that reduce lifetime for every country (or region)
Flat, dry but dustfree (only as reference) would be 0
Mountains, wet (with salt in the wintermonths), dustfree could be 0.8
Flat, dry, dusty cpuld be 0.9
and so on.
These values are completely random, but I think it shows what I'm trying to do.

E

[Lastgameking]

Oke that's complicated. But thanks for your information, Zephyroth!

L

[Daffyflyer]

Good thoughts everyone, keep at it and we'll be refering back to this thread when we do more design work on car life