THSCC Forums

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Has no responsibility whatsoever.

Where is the point in taking the test if you can't protest the one you miss. In fact you can't determine which one they "think" you miss. I want a rematch, dang it! They could be mistaken

Charlie G

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1998 BMW Z3
1987 BMW 325is
2000 BMW
1996 F250 Turbo Diesel

There is magnifying glass icon that will let you see where you messed up.
I got a 94 and was displeased. I made a stupid mistake on one, clicked the wrong button or scrolled it.
Just looked at one of the gear questions without calcing it in my head, stupid mistake.
I still question the venturi answer. By their "correct" answer a carb would not work.

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RedLanternRacing, builders of the fastest cars in last place.
Success is not an option.
1981 Scirocco, "Vera"

I got the following ones wrong... a,b,c,d matching gear, the venturi one the fan vs. fan one and the intake cycle one. I think the fan vs. fan one is poorly worded and I stick with my answer, but I know why they said the one they said is correct. I also think that the intake question had two valid answers of which I didn't pick the one they wanted.

So it scored me as a 92%. I think it should have been a 96%

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Richard Casto
1972 Porsche 914
2013 Honda Fit Sport
2015 Honda Fit EX
http://motorsport.zyyz.com
Money can't buy happiness, but somehow it's more comfortable to cry in a Porsche than a Kia.

If you haven't taken the test yet and want to do so, stop reading. Spoilers in posts below...


I answered it incorrectly, but after seeing the answer, I agree theirs is right. As the water flows through the narrow part, it's speed increases. The pressure is reduced and the pressure differential causes the water in that column to be lower.

The carb example is air flowing through the venturi. It lowers the pressure and the pressure differential pushes the fuel in.

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Richard Casto
1972 Porsche 914
2013 Honda Fit Sport
2015 Honda Fit EX
http://motorsport.zyyz.com
Money can't buy happiness, but somehow it's more comfortable to cry in a Porsche than a Kia.

ok, now to bitch about my "wrong" answers...

Fan question...

Their "correct" answer says "The working fan will cause the other fan to rotate in the same direction".

I said it would rotate in the opposite direction. However that is based upon the fact that they have the fans face to face. From the motor perspective they rotate in the opposite direction. But I think they are viewing the rotation along the same axis (regardless of location of motor or point of reference). To avoid confusion, they could have had both fans pointing in the same direction. Either way, the powered fan blades moves the unpowered fan blades and both would rotate the same using the same point of reference.

The intake question...

Their "correct" answer says "from atmospheric pressure pushing it in".

My "wrong" answer was "from suction caused by the piston going down".

Both are right. I understand why they said theirs was the more correct one. They wanted to make the point about atmosphric pressure is pushing the air into the cylinder that has a lower pressure. But from my perspective, it has a lower pressure, because the piston moved and increased the volume for given mass of gas. No piston moving, no pressure differential, nowhere for the atmoshere to push into.

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Richard Casto
1972 Porsche 914
2013 Honda Fit Sport
2015 Honda Fit EX
http://motorsport.zyyz.com
Money can't buy happiness, but somehow it's more comfortable to cry in a Porsche than a Kia.

98%

Grr the point of reference on the stupid fan question tricked me up. The poor wording of the 4-stroke motor question was sort of lame too but I guessed right on their intent (assume perfection of a 4-stroke with instant valve openings, if everything was perfect there would be a vacuum in the cylinder at BDC. Silly).

--Kevin H.

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2003 WRX (again!)

shocker...i failed...i got almost all of the electrical questions wrong...i hate that stuff.

<-chief of tech

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05 MCS

I passed by their standards, but didn't do well. 84%. My biggest screwup was in the pullies. I got the common one's wrong too, including the water through the tube and the fan direction.

Overall, I was pleased that I didn't "fail" - AB

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'14 Toyota Sequoia Platinum 4WD
Super Westerfield Bros - '93 Integra - LeChump Du Jour
STX 93 - Scion FR-S

I got tricked by the fan wording too, missed the oil and water, and miss judged the surface area of the canisters. Scored 94%

Bet I get 100% next time. HA HA

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George Bright Member # 141
One of the youngest of the old farts.
Yes I voted against you joining the club.

I got 100%. So what!!!! I'm retired and don't want to be a ford mech

I still disagree. I even have a gadget in myshop that will draw fluid using the venturi principle.

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RedLanternRacing, builders of the fastest cars in last place.
Success is not an option.
1981 Scirocco, "Vera"

Actually it "is" drawing fluid.

Look at it this way. If the water is not flowing the level will be the same in both A and B. As the water starts to flow, the venturi effect causes the lower pressure in B and "pulls" fluid down the column. Or another way of looking at it, the pressure is lower in the venturi so the atmosphere pushes the water down.

If you reversed the fluids (air in the venturi of a carb) and fuel on the outside of the second pipe (in the bowl in a carb), the lower air pressure in the venturi would allow the atmosphere pressure to push fuel into the venturi.

http://en.wikipedia.org/wiki/Venturi_effect

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Richard Casto
1972 Porsche 914
2013 Honda Fit Sport
2015 Honda Fit EX
http://motorsport.zyyz.com
Money can't buy happiness, but somehow it's more comfortable to cry in a Porsche than a Kia.

Whether or not a venturi will draw fluid into the venturi is a function of the velocity increase /pressure drop of the propeling medium. If the pressure drop is high enough the venturi will suck or draw fluid, if the pressure drop is lessened to the point of no longer causing atmospheric pressure to overcome the pressure in the venturi then the level in the venturi tube will drop below the level of the fluid in the tube before the the venturi. In either case the level of the fluid in the venturi will be lower than the level before the venturi. The only time this is not true is when there is no flow in the venturi then the level in the two tubes will be the same.

I have always know I am a parts changer, not a mechanic. I have actually been going to go to Barnes & Noble and look for Electrical/Mechinical Concepts for Dummies. Anybody know of anything like that.

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2002 MCS, 2003 MCS Track Rat, 2003 Generic White Yukon, 2003 BMWk1200rs, 1973 CB350F, 02 996. 08 Cayenne Turbo
http://www.clinehallagency.com