Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

How a Car Engine Works

jacoboneal.com

Post reply on HN
Print view View original

101–110 of 172 posts

Re: How a Car Engine Works

#101

Post by Thrymr »

gxs wrote: post #97
peterwwillis wrote: post #92

Earlier quoted context omitted.

Isn't that how medicine works?

I agree. When I first started looking into medications like Aderall, it was surprising to find how little we actually know about how medicine works. Take the above example - we really don't know how it works. We measure the amount of dopamine/serotonin in the spine before and after you take it so we assume it increases the presence of those chemicals in the brain, but it's not really mapped out. A lot of people have…

We even have a Ministry of Medical Magic in the US now: http://nccam.nih.gov

Re: How a Car Engine Works

#102

Post by smacktoward »

gxs wrote: post #97
peterwwillis wrote: post #92

Earlier quoted context omitted.

Isn't that how medicine works?

I agree. When I first started looking into medications like Aderall, it was surprising to find how little we actually know about how medicine works. Take the above example - we really don't know how it works. We measure the amount of dopamine/serotonin in the spine before and after you take it so we assume it increases the presence of those chemicals in the brain, but it's not really mapped out. A lot of people have…

The brain (and how it works) specifically is an area that modern medicine really hasn't figured out yet. I learned this when my father had a stroke. Talking to the doctors I learned that, unlike the rest of the body, our understanding of the brain is still sufficiently primitive that it's treated as sort of a black box.

Re: How a Car Engine Works

#103

Post by grecy »

nexox wrote: post #100
grecy wrote: post #94

Earlier quoted context omitted.

> a dual clutch is not much faster than a properly-operated manually-clutched gearbox That's not correct. When the GT-R first came out I read a great article about why it was so damn quick down the 1/4 compared to super cars that are 2-6x more expensive. The reasons were: 1. Most of them dyno at around 480hp AT THE WHEELS. So it's making more power than Nissan claims. 2. It's the first car to get all the electronics…

You seem to have ignored my "All other things the same" qualifier - that means you have to assume that power, weight (except for the difference between the gearboxes,) suspension, environment, tires, and everything else, is identical for the quoted part of my sentence to apply. I don't see how your first two points are relevant to what I said, or your original post. You can love the GTR all you want, I don't mind, an…

> I don't see how your first two points are relevant to what I said

They're not, I just wanted to include them for the curious.

> You can love the GTR all you want, I don't mind, and I never claimed that there was anything wrong with it.

It's an amazing car, but it's not like I have one or even want one.

>As for point 3, if you were to compare to a theoretical manual transmission GTR, that half a second of extra power would still only net you a couple tenths advantage, since acceleration and aerodynamic drag are nonlinear. And I stand by my claim that a couple tenths on a 12 second quarter mile is 'not much faster.'

You've never tried to build a 12 second car have you? A couple of tens is HUGE for a well behaved road car with a sound system, air conditioning and creature comforts. You could easily spend tens of thousands on a drag car in an attempt to get that. (I just looked it up, Motor Trend ran an 11.6, which is F-A-S-T)

Re: How a Car Engine Works

#104

Post by T-hawk »

smandou wrote: post #29

Water boil at exactly 100 degrees Celsius... not the conversion of 212 degrees Fahrenheit. Americans. ;-) Nice job still.

Those are exactly the same, it's not an approximation. (212 - 32) / 9 * 5 = 100 exactly. Water boils at exactly 212 Fahrenheit under 1 atm pressure.

Re: How a Car Engine Works

#105

Post by alirov »

nicholassmith wrote: post #33

This is pretty cool. When I was younger I built a mini engine (from a kit[1], I wasn't fabbing components) which gave me a nice intro to the basics of how a car engine operates, but whilst parts of it are pretty simple to get it's helpful to see the process. Even if it's a monolithic gif that annoys web developers. Or if it only shows one kind of engine design. [1] http://www.scientificsonline.com/smithsonian-gas-eng…

I had that same engine you link to as a kid except mine was orange instead of blue. It's definitely one of my more memorable childhood toys and even though a fairly basic representation of an engine, I agree that it was a great intro. On a side note, I remember the screwdriver that kit came with was ridiculously bad. It made stripping the included screws really easy and made putting together the model more of a chore than it should've been.

Re: How a Car Engine Works

#107

Post by nfailor »

negativity wrote: post #99
umsm wrote: post #74

Earlier quoted context omitted.

A professor in college once told me that if you can't explain a technology, you might as well assume it's magic.

Cue the Arthur C. Clark quote: “Any sufficiently advanced technology is indistinguishable from magic.”

I'm a Sagittarius and we're skeptical.

Re: How a Car Engine Works

#108

Post by pdonis »

plorkyeran wrote: post #56
freehunter wrote: post #53

Earlier quoted context omitted.

Yeah, I put in 93 once and had a small but noticeable increase in power. From my understanding, this only really happens if your knock sensor is retarding your timing with 87 octane and 93 lets it advance the timing further. It's 87 minimum, 91 recommended with my engine. Since I secretly wish my car was a small diesel, the slight lack of power with 87 doesn't bother me too much :)

Now that the price difference between 87 and 93 is typically under 10%, using 93 may actually improve your gas mileage enough to make up for the difference in price. If your drive enough that fuel expenses are meaningful, it may be worth testing if this is the case for your car.

This will only work if your engine can achieve high enough compression to take advantage of the higher octane number. Many engines can't.

Re: How a Car Engine Works

#109

Post by sitharus »

techdmn wrote: post #45
sitharus wrote: post #36

Earlier quoted context omitted.

I just took a close look at it, and I think you're right. It's not the easiest thing to see due to the wireframe, but with a second look it does appear that the injectors are just behind the valve. So yes, it's multi-point injection, rather than direct injection which is the new hotness for gasoline. Formula 1 will allow it from next year with the new V6 formula!

V6 formula!?!? Validating my decision several years ago to quit following F1. ;-)

V6 turbo with energy recovery on the turbo itself. They're also allowed to use that energy to re-spool the turbo to eliminate lag. They've also hugely bumped the KERS and built it in to the throttle map - no more button for it.

I can't remember the exact figures, but it means that they have so much torque when they go full throttle it'll spin the wheels at almost any speed.

I'm looking forward to them slipping around the corners again. Also to engines blowing up, since that doesn't happen much due to 5 year old engine designs.

Re: How a Car Engine Works

#110

Post by freehunter »

pdonis wrote: post #108
plorkyeran wrote: post #56

Earlier quoted context omitted.

Now that the price difference between 87 and 93 is typically under 10%, using 93 may actually improve your gas mileage enough to make up for the difference in price. If your drive enough that fuel expenses are meaningful, it may be worth testing if this is the case for your car.

This will only work if your engine can achieve high enough compression to take advantage of the higher octane number. Many engines can't.

But if the engine is running on lower power because of the knock sensor, higher octane should be called for, right?
Post reply on HN