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Dumb questions someone else might answer


#61

Center of mass is what I was thinking of I guess


#62


#63

…Was what I said really that stupid?


#64

The center of mass of most humans is around their hip, which in most carts is around 2 inches from the ground, meaning that only half you weight will raise the CG of the cart, and even then because of how you sit in karts, the CG of your torso will be MAYBE 1 foot off the ground. And that’s only your torso, which is only a small part of the weight of your typical loaded rental kart.

Because the typical 9hp rental kart isn’t that light. They are designed to stand years of abuse and being crashed by idiots who ignore the “do not bump” rule. They can easily weight 150+kg empty.

The only way to flip those karts is to do something really retarded, especially considering that a 9hp kart isn’t that fast. Both tracks I went to you topped out at 60-65kph.


#65

I raced them competitively for a couple years (in ones that had anywhere from 15-20 hp that could do 60 in a straight line, it was a fairly long track, and I had plenty of experience at this point), and even in the fast ones, you’d have to completely upset the weight balance to tip those over. Especially if you were taking a decent line, and weren’t dumb enough to crash into anything (they had officials all over the place ready to drop the black flag of shame on you if you tried any funny business).


#66

Yeah can attest to the utter stability of a kart. You can scream into a bad camber corner three abreast way too hot and have a pile up and nobody will flip. Back before I knew how to drive smoothly, I threw the kart around in the most heinous ways I could and all I managed was bald tyres and a very pissed off proprietor :joy:

However that doesnt stop you from having horrible death by go-kart. Go karting got shut down in HK for a bit because one young lady was wearing a scarf (or maybe a hijab) and it got caught in the wheels… Needless to say the outcome was… Bad. In Australia the last venue I went karting, that year somebody died after a frontal collision with a wall and apparently the trauma of the harness precipitated a heart attack. The latter shouldn’t be a problem if you’re fit and well and young, though.


#67

I remember drifting in a 13hp Honda kart with overly-worn tires. So much fun. I still managed 4th place. I guess people were too scared to pass me. The two in front had significantly faster acceleration for some reason, and one I just couldn’t pass because drift 'yo. Never in my life did I think drifting would be so easy in a go-kart.

Dumb questions… hmm…
I’ve always been perplexed by the lack of tire on race cars of the 30’s. They were already pushing over 100hp, but had bicycle wheels. I understand that tire technology hadn’t progressed enough to allow wider tires… so why didn’t they just add more wheels like trucks did?


#68

They did to the cars that needed it most. Auto Union V16 was one of those cars that required it most


#69

Ah, so they did do it. Cool; I wasn’t aware of that specific Auto Union.


#70

Dumb question here…
Why euro-spec cars have more power than the versions sold in the US? I don’t know if that is still the norm, but while doing some research for my companies that seemed to be the case in the 70s.


#71

Because the USA actually has stricter emissions standards than Europe (at least if you live in a state that does emissions, especially if they use California standards). Why do you think we don’t get very many diesels beyond 3/4 ton trucks and heavier?


#72

Particularly in the 1970s, American emissions regulations got very strict, very fast, and today, the US has some of the strictest emissions regulations in the world, getting tighter quicker than the technology of the combustion engine can match. (Which has caused several companies to cheat the system, Volkswagen, Audi, Fiat are just to name a few.) Emissions regulations strangled performance, even on domestic cars. So naturally most companies need to strip away power to compensate for the lowered emissions. Plus, some things just aren’t legal in some countries that are legal in others… Porsche 911R has a plexiglass rear window on the euro spec, legal in Europe, illegal in the US.

TL;DR, The US usually has stricter emissions regulations and that robs a lot of power, and US cars need to be cheaper to satisfy our tastes.

My turn. Why do different engine configurations produce different sounds? ignoring exhaust packaging.


#73

Firing order is the biggest determining factor concerning what an engine sounds like.


#74

That and header design.


#75

I always saw europe more eco-friendly than america :stuck_out_tongue:

@DoctorNarfy This might be interesting -->

I did an audio experiment, and I must said the explanation sort of fits… I will upload my experiment later.


#76

There are a few things to take into account.

Bank Angle: Degrees between cylinders on the same crank journal
Manifold Configuration: Equal Length, Un-Equal length, Tuned

Lets start with Bank Angle, this effects the time between BANG on cylinders on a common journal. The wider the angle, the more spaced out the bang will be. Keep in mind you can have cylinders on a common journal fire on the same stroke, or opposing strokes with the bank angle further effecting how far out the cylinders are from one another.

I will be using two cylinder engines to example what is happening.
Example:
Inline Twin: With a Common crank angle you will have two modes of firing: 360° or 0° (pop-360-pop-360-pop-360-pop, or POWx2-360-missx2-360-POWx2-360-missx2)
V-Twin 90°: With a Common crank angle you can have a firing 360°(270) or 0°(90) (pop-270-pop-90-miss-270-miss-90-pop, or pop-90-pop-270-miss-90-miss-270-pop

That effects sound substantially.

Next is Manifold construction.
Un-Equal: Lets pretend we have an Inline-2 firing at 0° with a common crank angle. If you make one cylinders manifold twice the length of the other, it would sound like an engine firing at 360° at the tailpipe.

With Equal length you will always hear the exhaust pulses matching with the degree of difference to the cylinders.

Tuned: This is where un-equal length meets science. Cylinders which are 180° from one other are mated, so the exhaust pulse from one cylinder will pass the union right as the exhaust valve from another cylinder is opening. Promoting the scavenging effect to help make a more efficient fresh air charge.
A Tuned manifold can make a Subie sound like a Honda, or make a X-plane V8 sound like a FPV8 it is entirely up to the man man who makes the manifolds. A 4 could sound like a twin, or a 8 could sound like a 4.

Last is Crank angle, this makes things even more confusing, but to keep it short, if you made a cross plane i4, you could make it sound similar to a V8, or with a tuned header, make it sound like a normal i4.

Hope this was helpful.


#77

It’s not stricter, it’s different.


http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=URISERV:l28186
There’s a lot of text if you wish to read it all

The real reason, actually it’s because USA has worse quality fuel than Europe, so most of the cars are de-tuned along with the extra emission bull installed.

Because your fuel is cheaper than bottled water in Europe so you don’t really care about fuel economy?


#78

Actually, as a european, I don’t really care about fuel economy. As long as you’re not driving hundreds of kilometers every day it’s only a minor part to the upkeep of a car.

Which leads to the next question … why does it seem so stupid expensive to own a car in Europe compared to countries like the US?


#79

Fuel is expensive, taxes in most countries, also the insurance


#80

Listen to a Triumph(parallel twin) or a BMW R engine(boxer).
The pistons move exactly the same, away from the TDC towards BDC at the same time, 360 deg firing order.
But they sound different. I REALLY would find an answer to that one.
VW Beetle 4cyl Boxer, Subaru 4cyl boxer, pistons move the same as nearly every I4 on the market,
yet sound VERY different.