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visits member for 2 years, 1 month
seen Aug 25 at 4:45

Recently entered the world of IT, I'm now learning to develop databases and build iOS apps.


Jul
6
comment Does “slogging” an engine (open throttle at very low RPM) increase mechanical wear?
Ah I didn't see that question, don't think it came up in the Related questions list. Should I delete this, or leave it as is to serve as a link redirection?
Jun
27
comment How does cold, dry weather affect horsepower?
Interesting point. Though I think humidity is a different case, as it's in gaseous form then, not droplets of liquid.
Jun
25
comment How does cold, dry weather affect horsepower?
Great, so it looks like I indeed have a free cold air intake! Would be fascinating to see if super cold temps, like -40C, continue to make a big performance improvement. I'll have to take my car to Antarctica to find out...
Jun
25
comment BMW 530xd e60 2008 diesel engine turns but won't start
Was there any resolution to this? Or is the car still not starting?
Jun
3
comment Do fast cars need to occasionally be driven fast?
True, ideally the engine should just be pushing out CO2 rather than soot. Might not always be the case with some engines, and those might benefit from a fiery soot-cleaning, but that then changes this question to "Do fast, poorly tuned cars need a good fanging?". Thanks for all the info!
Jun
3
comment Do fast cars need to occasionally be driven fast?
Ah fascinating. Ok so it makes sense that an engine running at operating temperature is a happy engine - no need to fang it. Last point - how about the exhaust? Some cars have monstrous exhaust pipes (GT-R) to handle the exhaust from a 600 BHP+ engine, and my understanding of back pressure says that you'd get carbon buildup from driving well below the max power output. Would this be the one case where an Italian Tuneup is helpful?
Jun
2
comment Do fast cars need to occasionally be driven fast?
Ah right, so would that mean that harder driving doesn't require the radiator (fan) to work significantly harder?
Jun
2
comment Do fast cars need to occasionally be driven fast?
Interesting, nice to have an anecdote. And yes, I'm realising that there isn't substantial objective knowledge about this. That forum unsurprisingly includes people advocating spirited driving for engine maintenance, but again, the bias is heavy! I'll let this question hang for a bit longer to see if we get some more objective responses.
Jun
2
comment Do fast cars need to occasionally be driven fast?
Good answer. I guess the uncertainty lies around the "operating temperature". Yes you have the cooling system temp, though for a given cooling system temp my understanding is that you could have a significant range of temps of the engine internals. I think it's possible that the engineers could design an engine for which the proper operating temperature, for internal carbon buildup prevention, is actually quite hot due to "spirited driving". I'm still learning about mechanics, but would that be reasonable?
Dec
10
comment Engine power specification at different rpm?
Great explanation. Do you prefer the peaky curve even just for street driving, or is it mainly because you track your car?
Dec
4
comment Assuming identical and sufficient ABS, and ignoring aerodynamics, are tires the only factor for braking distance?
@BobCross Yep I hope I portrayed that by showing that µ isn't constant. Ok to try make it really clear, I mean a braking system which is overpowered. The pads and pistons and all that have more than sufficient force to slow down the wheels as much as they want - so much so that they could lock the wheels, but due to the use of ABS they don't lock the wheels, they instead grip at the threshold. I don't get why you're saying the cornering grip and braking grip is completely unrelated - didn't you read the "Traction Budget" from The Physics of Racing?
Dec
4
comment Assuming identical and sufficient ABS, and ignoring aerodynamics, are tires the only factor for braking distance?
@mac Exactly, that's what I wanted the answer to contain. Check out the answer I wrote up, do you think it's reasonable?
Dec
4
comment Assuming identical and sufficient ABS, and ignoring aerodynamics, are tires the only factor for braking distance?
@BobCross Not a problem if you don't agree with the edits, I'll just draft up something myself.
Dec
4
comment Assuming identical and sufficient ABS, and ignoring aerodynamics, are tires the only factor for braking distance?
@BobCross I did some more research, and Wikipedia (en.wikipedia.org/wiki/Tyre_load_sensitivity) and other sites (technicalf1explained.blogspot.com.au/2012/10/…) explain that the coefficient of friction decreases slightly as load increases. This explains everything in my mind - your experience of higher mass resulting in slightly worse braking, and even the nose dipping doing likewise. I'm going to draft some edits on your answer incorporation this, hopefully we can come to an agreement.
Dec
3
comment When is EBD (Electronic Brakeforce Distribution) beneficial?
So how come my car claims to have ABS but not EBD?
Dec
3
comment Assuming identical and sufficient ABS, and ignoring aerodynamics, are tires the only factor for braking distance?
@BobCross Definitely, more weight is going to increase the rate of brake fade. However my premise is a one-off stop, so I'd build the experiment around that. This question may be left open for a while until I can actually test this. Also need to make sure I have cash to replace the brakes if need be - this doesn't sound like a healthy test for my brake pads!
Dec
2
comment Assuming identical and sufficient ABS, and ignoring aerodynamics, are tires the only factor for braking distance?
@BobCross My biggest gripe with your answer is the assumption that the braking force will be the same as the mass of the car increases, even if the tires can still lock up. I also don't get why you recommend a set of articles and then disagree with it. Anyway it looks like we're in a bit of a stalemate until we have some numerical data. I would love to carry out that experiment, I'd have to think where and when I could do it. I'd change it so that weight is alternated each run, current experiment setup will make progressive brake fade skew the results.
Dec
2
comment Assuming identical and sufficient ABS, and ignoring aerodynamics, are tires the only factor for braking distance?
Your core point is very true - there's a lot of factors that I'm now just realising that go beyond simple block physics. I've had a bit of a read through The Physics of Racing and it's quite interesting. He does say that "If a tyre can take one g before sliding, it can take it on a lightweight car as well as on a heavy car", which is in line with what I've been saying about mass, not what you've said above. However he does explain the challenge of keeping the tires in contact and under static not dynamic friction. If you change the bit about mass, I'll accept your answer.
Dec
2
comment How can I repair cracks in leather seat?
Wow those guys even have my obscure BMW leather colour "Indigo BMW228" - that's the first I've seen of it online. You're a hero, I may actually tackle this project some time and fix my driver's seat.
Dec
2
comment Assuming identical and sufficient ABS, and ignoring aerodynamics, are tires the only factor for braking distance?
Ok also 3. Can a very skilled driver brake better without ABS than they would with ABS? I gave more detail to the scenario in my question.