Auto repair myths

[RGUN]

Originally posted by: MercenaryForHire

Originally posted by: BoomerD
Running premium in my Honda really improves the performance...

1. S2000
2. CBR

😛

- M4H

Its not going to help your CBR

 

[Rubycon]

Originally posted by: Pacfanweb
Ha, nitrogen in tires.

What a complete load of B.S. that is. Does absolutely nothing but inflate the tire.

Well when one considers the air we breath is almost three quarters nitrogen.

I believe the aeroplanes use it for the gear wheels - pure, dry nitrogen so in case there is a fire in the well and the tire blows up it doesn't provide an oxidizer. At cruising altitude most fires won't burn due to lack of sufficient oxygen.

 

[RGUN]

Originally posted by: junkiefp

Originally posted by: Pacemaker

Originally posted by: Vic
AWD/4WD helps you brake in slippery conditions.

I have never heard anyone say that, but it's really stupid. Just goes to show that people don't know what the acronyms mean.

Hate to explain it to idiots but it does when you downshift...

He said brake, not downshift. Therefore they are correct, but Ill forgive you since you were so polite to them.

 

[RGUN]

Originally posted by: shortylickens

Originally posted by: junkiefp

Originally posted by: Pacemaker

Originally posted by: Vic
AWD/4WD helps you brake in slippery conditions.

I have never heard anyone say that, but it's really stupid. Just goes to show that people don't know what the acronyms mean.

Hate to explain it to idiots but it does when you downshift...

FTW!

Downshifting and/or engine braking in slippery conditions is much better than using the brake pedal.
And better control means less of a need to brake in the first place.
But the original point still holds true: Vehicles have 4 wheel brakes regardless of drive.

As for the halogen/blue lights I wish more people would get a clue. Those things dont help you see shiate.
I helped a guy change his headlights one night. We went driving around town and he was like: "Dude, these things suck!"
They look really cool and annoy the crap out of the other drivers. Give them up.
Spend the money on something that will help you, like a garfield toy with suction cup hands.

WHAT?? So you're driving along an icy road and you need to slow down, apply brakes and use all the wheels and the ABS safety net OR downshift to a lower gear therefore making power application much less smooth and risk locking the wheels? yeah thats intelligent alright.

 

[RGUN]

Originally posted by: broon
Tailgate down gives you better gas mileage.

Tailgate down would reduce the drag obviously (unless you had a cap or something). Reduced drag = decreased power required --> less power required means less fuel consumption. See where Im going here?

 

[mugs]

Originally posted by: RGUN

Originally posted by: broon
Tailgate down gives you better gas mileage.

Tailgate down would reduce the drag obviously (unless you had a cap or something). Reduced drag = decreased power required --> less power required means less fuel consumption. See where Im going here?

Except you're wrong. 😉 Tailgate down doesn't decrease drag, it increases drag. I'm not a scientist so excuse my non-scientific language, but the air swirling around in the bed of the truck basically creates a "bubble" that the air going over the truck flows over.

 

[jemcam]

Originally posted by: mugs

Originally posted by: RGUN

Originally posted by: broon
Tailgate down gives you better gas mileage.

Tailgate down would reduce the drag obviously (unless you had a cap or something). Reduced drag = decreased power required --> less power required means less fuel consumption. See where Im going here?

Except you're wrong. 😉 Tailgate down doesn't decrease drag, it increases drag. I'm not a scientist so excuse my non-scientific language, but the air swirling around in the bed of the truck basically creates a "bubble" that the air going over the truck flows over.

QFT, Mythbusters proved this.

 

[Pacfanweb]

Originally posted by: MS Dawn

Originally posted by: Pacfanweb
Ha, nitrogen in tires.

What a complete load of B.S. that is. Does absolutely nothing but inflate the tire.

Well when one considers the air we breath is almost three quarters nitrogen.

I believe the aeroplanes use it for the gear wheels - pure, dry nitrogen so in case there is a fire in the well and the tire blows up it doesn't provide an oxidizer. At cruising altitude most fires won't burn due to lack of sufficient oxygen.

Also so the water in the air won't freeze at 30+ thousand feet. I told some guys at a dealership who mentioned that they used nitrogen in airplane tires that next time I decided to drive my car at 30,000 feet, I'd be sure to stop by and fill up with nitrogen.

 

[Pacfanweb]

Originally posted by: mugs

Originally posted by: RGUN

Originally posted by: broon
Tailgate down gives you better gas mileage.

Tailgate down would reduce the drag obviously (unless you had a cap or something). Reduced drag = decreased power required --> less power required means less fuel consumption. See where Im going here?

Except you're wrong. 😉 Tailgate down doesn't decrease drag, it increases drag. I'm not a scientist so excuse my non-scientific language, but the air swirling around in the bed of the truck basically creates a "bubble" that the air going over the truck flows over.

I can attest to the fact that tailgate down doesn't help.....I have a full size Chevy drag truck. I tried it multiple times at the 1/4 mile track...tailgate up and down. Made absolutely no difference in ET or MPH. So it stands to reason that it wouldn't help mileage.

 

[WhoBeDaPlaya]

Originally posted by: Pacfanweb
Also so the water in the air won't freeze at 30+ thousand feet. I told some guys at a dealership who mentioned that they used nitrogen in airplane tires that next time I decided to drive my car at 30,000 feet, I'd be sure to stop by and fill up with nitrogen.

Don't you own a certain DeLorean equipped with a Mr. Fusion? 😉

 

[DarkKnight69]

I ran 2 tanks of premium in my excel (1.5l, 93hp). No performance difference...However, there was a noticble difference in how easy it is to start in cold weather running 91 to 87...

 

[Pacfanweb]

Originally posted by: DarkKnight69
I ran 2 tanks of premium in my excel (1.5l, 93hp). No performance difference...However, there was a noticble difference in how easy it is to start in cold weather running 91 to 87...

So the 87 was easier to start, right? The premium should be harder to start in cold weather.

 

[spidey07]

Originally posted by: RGUN
WHAT?? So you're driving along an icy road and you need to slow down, apply brakes and use all the wheels and the ABS safety net OR downshift to a lower gear therefore making power application much less smooth and risk locking the wheels? yeah thats intelligent alright.

True. Downshifting is not a good idea and could lead to a loss of control of ALL 4 WHEELS instead of just two.

I hate trying to explain this to idiots that don't know how it works.

 

[RGUN]

Originally posted by: Pacfanweb

Originally posted by: mugs

Originally posted by: RGUN

Originally posted by: broon
Tailgate down gives you better gas mileage.

Tailgate down would reduce the drag obviously (unless you had a cap or something). Reduced drag = decreased power required --> less power required means less fuel consumption. See where Im going here?

Except you're wrong. 😉 Tailgate down doesn't decrease drag, it increases drag. I'm not a scientist so excuse my non-scientific language, but the air swirling around in the bed of the truck basically creates a "bubble" that the air going over the truck flows over.

I can attest to the fact that tailgate down doesn't help.....I have a full size Chevy drag truck. I tried it multiple times at the 1/4 mile track...tailgate up and down. Made absolutely no difference in ET or MPH. So it stands to reason that it wouldn't help mileage.

I stand correct, perhaps if you put a spoiler on the back of the cab (a la Subaru WRX) it would direct some air downward and develope Laminar flow out the back of the bed?

 

[WhoBeDaPlaya]

Originally posted by: foghorn67
Simply start the car, and drive it gently until it warms up.

That's what I've been doing, since I have to pass through residential and school zones anyway. How cold is extreme cold though? 0F? -20F?

 

[mugs]

Originally posted by: RGUN

Originally posted by: Pacfanweb

Originally posted by: mugs

Originally posted by: RGUN

Originally posted by: broon
Tailgate down gives you better gas mileage.

Tailgate down would reduce the drag obviously (unless you had a cap or something). Reduced drag = decreased power required --> less power required means less fuel consumption. See where Im going here?

Except you're wrong. 😉 Tailgate down doesn't decrease drag, it increases drag. I'm not a scientist so excuse my non-scientific language, but the air swirling around in the bed of the truck basically creates a "bubble" that the air going over the truck flows over.

I can attest to the fact that tailgate down doesn't help.....I have a full size Chevy drag truck. I tried it multiple times at the 1/4 mile track...tailgate up and down. Made absolutely no difference in ET or MPH. So it stands to reason that it wouldn't help mileage.

I stand correct, perhaps if you put a spoiler on the back of the cab (a la Subaru WRX) it would direct some air downward and develope Laminar flow out the back of the bed?

I have no idea, but a tonneau cover is supposed to be the most aerodynamic.

 

[91TTZ]

Originally posted by: mugs

Originally posted by: Zenmervolt
You're both right.

At a constant speed, especially higher speeds, A/C is typically more efficient. When speed varries, A/C is less efficient. The A/C compressor carries a healthy amount of inertia and when a car is accelerating/decelerating often it is felt much more than when the car is at a constant speed.

To wetcat, remember that drag increases with the square of speed, double your speed and you quadruple your drag. All else being equal, you need 8 times the power to double your speed (4x power to overcome extra drag multiplied by 2x more power to double your speed). A slight increase in drag at 30 mph can have a huge impact at highway speeds.

ZV

Pretty sure that's some screwy math there...

That math sounds right to me.

The power needed to push an object through a fluid increases as the cube of the velocity.

 

[Pacfanweb]

Originally posted by: 91TTZ

Originally posted by: mugs

Originally posted by: Zenmervolt
You're both right.

At a constant speed, especially higher speeds, A/C is typically more efficient. When speed varries, A/C is less efficient. The A/C compressor carries a healthy amount of inertia and when a car is accelerating/decelerating often it is felt much more than when the car is at a constant speed.

To wetcat, remember that drag increases with the square of speed, double your speed and you quadruple your drag. All else being equal, you need 8 times the power to double your speed (4x power to overcome extra drag multiplied by 2x more power to double your speed). A slight increase in drag at 30 mph can have a huge impact at highway speeds.

ZV

Pretty sure that's some screwy math there...

That math sounds right to me.

The power needed to push an object through a fluid increases as the cube of the velocity.

You also have to figure another reason that A/C works better at highway speeds: Cooling. There is more air moving across the condenser, so the refrigerant is cooler and is therefore more efficient at removing heat from the passenger compartment air.
Plus, if you drive a long distance, a good A/C system will get the air regulated so well that it won't have to run anywhere near as much as it would sitting in traffic.
edit: which is essentially what ZV was saying.

 

[mugs]

Originally posted by: 91TTZ

Originally posted by: mugs

Originally posted by: Zenmervolt
You're both right.

At a constant speed, especially higher speeds, A/C is typically more efficient. When speed varries, A/C is less efficient. The A/C compressor carries a healthy amount of inertia and when a car is accelerating/decelerating often it is felt much more than when the car is at a constant speed.

To wetcat, remember that drag increases with the square of speed, double your speed and you quadruple your drag. All else being equal, you need 8 times the power to double your speed (4x power to overcome extra drag multiplied by 2x more power to double your speed). A slight increase in drag at 30 mph can have a huge impact at highway speeds.

ZV

Pretty sure that's some screwy math there...

That math sounds right to me.

The power needed to push an object through a fluid increases as the cube of the velocity.

Sure enough. My bad. 🙂

Edit: I see why I was wrong. You use 8 times the power, but you do twice as much work. I was thinking in terms of energy efficiency.

 

[IronWing]

Originally posted by: Pacfanweb

Don't forget your muffler bearings!

My muffler does have bearings. 😛

Okay, it is the exhaust pipe and it has a ball joint in the middle but it is the same idea.

 

[Rubycon]

Originally posted by: Pacfanweb
You also have to figure another reason that A/C works better at highway speeds: Cooling. There is more air moving across the condenser, so the refrigerant is cooler and is therefore more efficient at removing heat from the passenger compartment air.
Plus, if you drive a long distance, a good A/C system will get the air regulated so well that it won't have to run anywhere near as much as it would sitting in traffic.
edit: which is essentially what ZV was saying.

Cooler condenser = lower head pressure = less power requirement on compressor. Auto compressors are interesting in themselves. 🙂

 

[npoe1]

4) If you have keyless entry and you lock your keys in the car, you can call a friend on your cell and have them use the spare remote to unlock your car if they point the remote at their phone and if you put your cell phone near the car.

WTF! 😕

 

[mugs]

Originally posted by: npoe1

4) If you have keyless entry and you lock your keys in the car, you can call a friend on your cell and have them use the spare remote to unlock your car if they point the remote at their phone and if you put your cell phone near the car.

WTF! 😕

It's a hoax that was passed around in e-mail forwards.

 

[npoe1]

Originally posted by: waggy
red makes the car faster!

My blue motorcycle is faster than your red motorcycle.

 

[foghorn67]

Originally posted by: WhoBeDaPlaya

Originally posted by: foghorn67
Simply start the car, and drive it gently until it warms up.

That's what I've been doing, since I have to pass through residential and school zones anyway. How cold is extreme cold though? 0F? -20F?

The expception for cold weather starts doesn't really have to do with the oil. I think it has something to do with the different types of metals expanding at different rates when warming up to abruptly. Causing valve malfunctions and engine seize.
For example my forged pistons have the familar 'piston slap' noise until warmed up.