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Internal Combustion Engine

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Re: Internal Combustion Engine

#191

Post by mysterydip »

Syonyk wrote: post #36
kingsuper20 wrote: post #10

It's a lot scarier when you see things going under load at speed. Lots of wiggling, twisty magic, waves. Smokey Yunick (blessed be his name) used to make see-through timing covers, oil pans, valve covers + strobe light + some sort of oscilloscope setup to watch the craziness. I think I remember seeing the results for small block Chevrolet timing gears on sprint car engines as the teeth wiggled more and more with rpm.…

> Smokey Yunick Oh, man. I'm not a huge NASCAR fan, but that guy. That guy. He was an absolute master of "But the rules didn't say I couldn't..." and probably is responsible for half the thickness of the modern rulebook on his own! "What? The fuel tank capacity can't have an inflated basketball in it that springs a leak during the race, leaving us with more fuel capacity?" "What? The fuel lines have to be a short pat…

He also had an infamous Fiero with a "hot vapor engine" that was claimed 50+ mpg and 250hp (when the stock 4cyl made ~90hp, it was the 80s after all): https://www.legendarycollectorcars.com/featured-vehicles/oth...

Re: Internal Combustion Engine

#192

Post by frosted-flakes »

mrfusion wrote: post #189

Isn’t it risky for the timing to rely on a rubber belt? Does it never slip? Even a mm of slippage seems like it would make the valve timing stop matching the pistons?

Timing belts are toothed, and if installed correctly they will never slip. Modern kevlar timing belts are near-indestructible under normal use. The real problem is the pulleys—once those bearings wear out, they can seize, causing the belt to slip or even break.

Re: Internal Combustion Engine

#193

Post by twicetwice »

rsj_hn wrote: post #178
outworlder wrote: post #108

Earlier quoted context omitted.

> by making it light If there's one thing that EVs are not, is "light". Model S ranges from 4,561 to 4,941 lbs. A model 3, 3,648 to 4,250 lbs. A Nissan Leaf - 3,538 to 3,946 lbs. In comparison, a Honda Civic weights 2,771 to 3,012 lbs. Regenerative breaking is nice but it's very dependent on the particular drive and terrain. Heaters are power hungry as there is very little waste heat that can be used (again, due to t…

> If there's one thing that EVs are not, is "light". sigh Obviously we are not comparing about the weight of an EV compared to an apple or vehicle that doesn't require a battery. We are talking about extreme measures taken to make the car lighter so it can improve range. Replacing cheaper steel with more expensive aluminum, reducing even surface area of plastics, reducing wires. Truly amazing steps were taken to redu…

You're comparing mass to volume in that last paragraph there. Based on a quick google search, that 1 kilogram of hydrogen is going to take up 3.4 gallons as a cryogenic liquid—so even more as a compressed gas.

Source: http://www.uigi.com/h2_conv.html

Re: Internal Combustion Engine

#194

Post by Alupis »

elihu wrote: post #183
Alupis wrote: post #154

Earlier quoted context omitted.

> A cheap generic cat might have the bare minimum amount of catalyst, and might not do a very good job It depends on the car/engine. My old Mazda RX-8 had a huge cat - longer than the muffler and cost me $2,000 to replace (including labor) back in the late 2000's. The rotary engine in that vehicle had a terribly difficult time passing California's emission laws even when it was brand new off the lot - which led to st…

It's funny you mention the RX-8, since I'm in the (slow) process of converting one to electric. That weird cat blower was one of the many parts I removed while thinking "I'm glad I don't have to understand or care about why this car needed something like that in the first place".

Just talking about the RX-8 brings back great memories - what a strange, yet beautiful car!

The cat blower, and the subtle whining sound it made when you started up cold was one of the ways every RX-8 owner was hazed into the fold... after calling the dealer or posting on a forum and finding out it's entirely normal!

Other oddities included how it deliberately burned oil (scaring new owners into thinking they had a serious engine problem), and how you were required to drive it hard to clear out its engine ports (multiple Mazda mechanics confirmed this factoid) - driving it like a normal car would literally clog up the exhaust ports and cause a loss of power (something to do with the lack of moving valves). If memory serves right, it had only 3 (!!!) moving parts in the engine, and was perfectly content to hang out at 9,000 RPM all day - that's incredible.

But, it seems the issues Mazda had maintaining it's emission certifications, and warranty issues with those apex seals (mine had 3 engine replacements over it's lifetime) eventually caused it to be retired. I was sad back then, and still sad we don't have a new improved version - there's really nothing else quite like it out there, not even the RX-7. It really was/is an enthusiast's car.

Good luck on your project - sounds like a fun one!

Re: Internal Combustion Engine

#195

Post by pjc50 »

mrfusion wrote: post #189

Isn’t it risky for the timing to rely on a rubber belt? Does it never slip? Even a mm of slippage seems like it would make the valve timing stop matching the pistons?

Timing belts have teeth.

Occasionally chains are used instead; more expensive and heavier, but more durable. You do need to maintain the timing either way it it will destroy the valves.

Re: Internal Combustion Engine

#196

Post by blamazon »

mrfusion wrote: post #189

Isn’t it risky for the timing to rely on a rubber belt? Does it never slip? Even a mm of slippage seems like it would make the valve timing stop matching the pistons?

In addition to what frosted-flakes said, many engines are “non interference” design so that if the belt snaps or jumps a tooth the engine won’t be destroyed, and the belt will just need to be replaced. However, non interference engines are not as compact as interference engines.

Many engines also use a timing chain instead of a timing belt, but this carries extra weight and requires lubrication.

It’s all about tradeoffs!

Re: Internal Combustion Engine

#197

Post by lubesGordi »

mrfusion wrote: post #189

Isn’t it risky for the timing to rely on a rubber belt? Does it never slip? Even a mm of slippage seems like it would make the valve timing stop matching the pistons?

It is risky and they do slip or even break from time to time. They are generally a 100k maintenance item. The alternative is a chain, which can also fail (or other related components), but is generally not considered a maintenance item.

Re: Internal Combustion Engine

#198

Post by mxxx »

mrfusion wrote: post #189

Isn’t it risky for the timing to rely on a rubber belt? Does it never slip? Even a mm of slippage seems like it would make the valve timing stop matching the pistons?

Yeah it’s one of those things that you just have to replace every X miles just to be safe. I got one replaced a couple of days ago because the service history was missing and I couldn’t tell whether it had ever been done. If your timing belt goes you’re in all sorts of trouble.

Re: Internal Combustion Engine

#199

Post by cesarb »

londons_explore wrote: post #45
kingsuper20 wrote: post #31

Earlier quoted context omitted.

>So one would think that when EVs reach the same scale they will be significantly cheaper than ICE vehicles. I expect that batteries are the only hangup, there's probably not that much magic left in an electric motor. Additional cost for regen brakes of course. I agree on the amazing cheapness of it all if you stick with the common stuff. That, along with the low cost of flat panel TVs is a miracle of the modern age.

> Additional cost for regen brakes of course. Regen braking has no physical cost associated - it's pure software/firmware. The exact same hardware that is used to power the car forwards can be used for regen braking. It can be as simple as a single negative sign in the code to cause the phase to be 180 degrees out, current to flow backwards, torque to go the other way, and the battery to be charged instead of dischar…

> One day regen braking will take over hydraulic brakes, and another big cost/complexity of a car will be eliminated.

I have read somewhere that the regenerative braking is much less effective when the car is going really slow, so you still need the hydraulic brakes to come to a complete stop.

Re: Internal Combustion Engine

#200

Post by Wxc2jjJmST9XWWL »

TwoBit wrote: post #169
Syonyk wrote: post #140

Earlier quoted context omitted.

I would assume that by some point, if one of his cars won, the officials just took the whole thing apart to find out what sort of bizarre loophole he'd found that met the letter of the requirements while totally violating the spirit. His antics weren't secret, even at the time he was working. He was just really good at it.

And nobody considers that dishonest? It's cheating in the spirit of the rules if not the letter of the rules.

Nope ; Motorsport is always drivers' skills coupled with engineering ingenuity. It's always about "what can I come up with, which gives me an edge, and still somehow is within the rules?" I don't know anything about Nascar, but the history of Formula 1 is full of such little tricks as well. It's just easier to regulate "other sports" than it is to regulate sports that come coupled with a lot of technological involvement.

If sth gives you an edge for half a season until rules are adjusted, that might be enough to win a championship. It's a cat-and-mouse game, but it's also exciting, and important for the whole thrill of it.

Decades past Gordon Murray designed a fan quite literally sucking cars to the ground, which somehow was within regulations, because no one even considered something like that https://www.youtube.com/watch?v=Hb6DAmm7sZg In rally driving, they would sometimes come up with fake reasons for a start to be delayed, so they wouldn't have to drive in the front car's dust all the time. Audi entering with their 4-wheel car back in the days was only possible, because they pushed for a rule change and no one else really knew what was coming. Sometimes manufacturers straight up "cheated" (almost, sometimes for real) https://www.youtube.com/watch?v=6lo4dGTrzr8 ; it's a thin line, but also what makes it exciting.

I would say that it's the hacker's / engineering ethos almost. What can I do within the framework? Whether it's building a bridge (to make it more stable while still following this brash design), a road car (how can I create something fun, with torque, sound, emotion, down force, power, but a nice shape, and still get a road legal car within environmental regulations), computer games (consider https://www.youtube.com/watch?v=izxXGuVL21o ; computer games are full of hacks to get the most out of the hardware), even legal (how can we pay almost no taxes, while not being busted for tax avoidance?) ; not every ingenuity is necessarily good, but it will always be cat-and-mouse, that's the point of living.

This got meta quick ... and quite a more detailed answer than I anticipated. Sorry for that, hope I gave you a different perspective though.

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