Automotive Stuff Trivia #2!

[pigeon]

If you're interested in the first one, see this thread:

http://www.wihandyman.com/forum/showthread.php?t=11905&highlight=automotive+trivia

And here goes round 2!

1. When installing fasteners of any kind, it is always important that they are tightened the correct amount. An extremely stressed fastener in combustion engines are connecting rod bolts. The MOST correct way to tighten a rod bolt is:

A - with a torque wrench
B - with a bolt stretch gauge
C - applying a small amount of ATF on the threads of the bolt to help lubricate the threads, allowing a more accurate reading off of the torque wrench
D - torque with a torque wrench, loosening a 1/4 turn, and then re-torque
E - hand tighten, and then 3/4 turn with a ratchet/wrench

2. If the percent water content of brake fluid increases, its boiling point:

A - increases
B - decreases
C - remains unaffected due to brake fluid being silicon based

3. DOT 5 brake fluid is silicon based.

True or False

4. The stoichiometric air/fuel ratio for an unmodified 4 stroke combustion engine is:

A - 16.3:1
B - 13.6:1
C - none of the above

5. Which of the following 4 scenario's could potentially induce detonation?

A - a clogged air filter
B - retarded timing
C - a warped flywheel
D - an EGR valve that is stuck shut

6. What would be MOST indicative of a lean running engine?

A - high exhaust gas temperatures
B - 12:1 air fuel ratio reading
C - low compression
D - inaccurate TPS sensor

**BONUS**
7. Who has a faster car:

Me or you?

[charles]

I didn't see the original, looks like an interesting read.


1) dunno
2) B - decreases
3) true
4) C - none of the above
5) dunno
6) A - high exhaust temperatures
7) As of right now, I think it's me.

[lscrx]

1:B
2:B
3:True
4:C
5:D
6:A
7: Me!

[JGSlayer]

1. A
2. B
3. true
4. C
5. B
6. A
7. the faster driver

[pigeon]

anyone wanna try before i post the answers?

[charles]

Well, for #7, don't you have a WS6 or something?

[JesseSays]

B
B
True
C, 14.7:1 by weight
D, sorta
A
yes

[BPower]

1) A
2) A
3) True
4) C
5) B
6) A
7) Yes

[lscrx]

What are the answers?

[goldstar]

1.?
2. B
3. True
4. C
5. D
6. A
7. Me

[pigeon]

Answers!

Alrighty guys,

1. When installing fasteners of any kind, it is always important that they are tightened the correct amount. An extremely stressed fastener in combustion engines are connecting rod bolts. The MOST correct way to tighten a rod bolt is:
B - a bolt stretch gauge

The way these work is its a little dial that resembles a caliper (as in venier caliper or micrometer, not brake caliper) and it actually measures the length of a connecting rod bolt

When you tighten a bolt down tight, it actually has a small amount of 'give' or stretch…
The bolt is strongest when its tightened right below its elastic limit

Now connecting rods are probably the most stressful on its bolts out of all the bolts in the engine... if a bolt is tightened too tight, it will eventually break when enough stress is placed on it

if a bolt is too loose, it will stretch that 0.001 inch on every time the piston changes direction... and eventually the bolt will snap (similar to taking a paperclip and bending it back and fourth and back and fourth)<-- that spot gets weak

You could use a torque wrench under ideal conditions, however the problem is that if there is crud in the hole, or the friction from the different types of metals and all that stuff will affect your torque wrench readings

you COULD use a tq wrench when doing rod bolts, however there is a special lubricant you're supposed to use to try to get the most consistent readings. The question asked for the most correct answer however, and the MOST correct answer is B - the bolt stretch gauge!

Ideally it would be best to use this technique on all bolts, however on something like say... lug nuts, you dont have access to the otherside of the stud.. so your only option is a torque wrench or torque stick

2. If the percent water content of brake fluid increases, its boiling point: B - Decreases

Most if not all got this one right, one of brake fluids purposes is to be hygroscopic (absorb water vapour)
The more water that is absorbed in it, the lower the boiling point (the easier it is to get a soft pedal induced by boiled fluid)
Thats why its important to do flushes, as well as to prevent brake system corrosion.

3. DOT 5 brake fluid is silicon based. The answer is TRUE

DOT5 fluid is silicon based (as opposed to ether based like DOT3 and DOT4)
Which means it is NON-hygroscopic (it does not absorb moisture)
The moisture pools in the brake lines and calipers
The good thing about DOT5 is that it doesent eat the **** out of your paint if its spilled!

4. The stoichiometric air/fuel ratio for an unmodified 4 stroke combustion engine is: The correct answer is C

14.7 parts air to every 1 part fuel... you all got it right

5. Which of the following 4 scenario's could potentially induce detonation? The correct answer is D

Some of you said retarded timing, but that actually does the opposite!
Advanced timing would induce cause preignition (which is similar enough to detonation)
None the less, the EGR valves main purpose is to lower combustion chamber temperatures. It does that by introducing small amounts of already burnt exhaust gases. Now everyones first instincts are to say "how does it LOWER temperature by putting HOT gas into the combustion chamber?"

The exhaust gas is "hot"...
However we know that oxygen, when burnt in the combustion chamber is HOTTER.
(if anyone ever used an oxy-aceytelyne (sp?) torch, you remember that the oxygen is what really heats things up)
What the exhaust gas does is it takes up room in the combustion chamber.. so there isnt much room for the oxygen. It displaces the oxygen. So in reality, the exhaust gas actually lowers temps by just sitting there being a useless tit, instead of letting oxygen in to burn and make more power!
If its stuck shut, the oxygen is coming in just like usual... and since the vehicle was designed with fuel/timing parameters that thinks the EGR is gonna lower the temps, it just keeps going as normal... and you get pinging (a.k.a. slight detonation)
Cars designed without EGR's deal with this situation by either retarding the timing or enrichening the mixture temporarily.
EGR reduces noxious emissions as well... incase you gave a ****.

6. What would be MOST indicative of a lean running engine? The answer is A!

Lots of forced induction people put EGT gauges as opposed to those silly air fuel gauges, because the EGT will give a combined reading of all 4 cylinders temperatures. And temps could be directly related a/f mixtures. The a/f gauges are good for indicating trouble, but are useless in tuning. A EGT gauge can be used to do both. They're not as fun looking, but they serve more of a purpose.

7. BONUS.

Incase you don’t know my vehicular situation, I have a Z5 running on 3 cylinders… I guess it should be called a Z3.75
I was hoping someone with an automatic would reply to this so I could pretend im fast… but I guess the world doesn’t revolve around me… it should though.
So yes, you're all faster than me... at the moment. But dont be too flattered, because a pregnant midget old lady with one leg crawling on her hands uphill in a snowstorm after having nothing to eat all day... with a geo tied to her back, would be faster than me.

Anyways, wasn’t this fun!!?

Oh ya and:

LSCRX: 7/7 = 100%
GOLDSTAR: 6/7 = 86%
JESSESAYS: 6/7 = 86%
CHARLES: 5/7 = 71%
JGSLAYER: 5/7 = 71%
BPOWER: 4/7 = 57%

[lscrx]

w00t w00t!!! why am I even in college?

[goldstar]

Congratulations lscrx and thanks pigeon for an interesting and informative quiz.

02 DX Millenium Red

[pigeon]

anytime!

[BPower]

Hay, My car is up on jackstands with no front tires. I hope yours is at least a little faster than mine