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Old 2nd June 2010, 22:00   #31
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@Garipagol & @XH_vee - RKS is a banned member; he doesn't belong to TBHP community anymore & this, probably could be the post for which he was being banned. However both of your comments are valid.
Oh... I am still a newbie and did not notice his status. Anyway hope he reads those comments as a guest nonetheless - better still others notice those as well.
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Old 4th June 2010, 13:12   #32
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1.Another thing I remember my instructor saying to us:
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It is to imagine a lane dividing the road into "our side" and "opponent side."

He would yell at us if we took the car into the "opponent side" during a RH or LH turn.

2. Our instructor also taught us and made us imbibe this - The right foot comes near the brake(one does not have to press the brake but just to be prepared..) whenever the right foot is taken off the throttle. This was useful to deal with two wheelers in general(especially cyclists) and unexpected opponent-entry-into-our lane during RH/LH turns.
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Old 4th June 2010, 14:26   #33
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Originally Posted by ashwanth View Post
1.Another thing I remember my instructor saying to us:
Attachment 361105

It is to imagine a lane dividing the road into "our side" and "opponent side."

He would yell at us if we took the car into the "opponent side" during a RH or LH turn.

2. Our instructor also taught us and made us imbibe this - The right foot comes near the brake(one does not have to press the brake but just to be prepared..) whenever the right foot is taken off the throttle. This was useful to deal with two wheelers in general(especially cyclists) and unexpected opponent-entry-into-our lane during RH/LH turns.
The red line is the typical Indian way of taking a turn. Drivers just invade the opposite lane unnecessarily. This is absolutely not required. Just drive in your lane and turn sharper at the corner rather than invading opposite lane while turning. The downside of sticking to your own lane while turning is that some fools will try to overtake you through the red line (in the figure) if you are going through the green line!

Last edited by clevermax : 4th June 2010 at 14:28.
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Old 4th June 2010, 15:58   #34
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Guys I have a doubt. I know its not placed in the right thread .
But why do some sports cars and supercars rev a lot upon startup and then come to an idle ?
Can you please direct me to the right thread.
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Old 4th June 2010, 16:26   #35
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Quote:
Originally Posted by ashwanth View Post
1.Another thing I remember my instructor saying to us:
Attachment 361105

It is to imagine a lane dividing the road into "our side" and "opponent side."

He would yell at us if we took the car into the "opponent side" during a RH or LH turn.

2. Our instructor also taught us and made us imbibe this - The right foot comes near the brake(one does not have to press the brake but just to be prepared..) whenever the right foot is taken off the throttle. This was useful to deal with two wheelers in general(especially cyclists) and unexpected opponent-entry-into-our lane during RH/LH turns.
Your instructor is right. You are lucky to have got a good instructor. Most driving schools are mostly interested in collecting fees and getting the D/L issued. They are not as much interested in teaching the proper techniques. You are fortunate to have found a guy who is different from the regular breed.
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Old 4th June 2010, 18:04   #36
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Wow, in all this, ashwanth, I really appreciate your instructor. Pretty hard to come across a guy like that in this day and age. Seems like he has taught you the right way to drive - with all proper inputs thrown in. I was looking at your last diagram and I thought - "my instructor would actually shout at us if we did not drive in the middle of the road!"
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Old 4th June 2010, 18:22   #37
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Originally Posted by arjunrudra View Post
.
But why do some sports cars and supercars rev a lot upon startup and then come to an idle ?
I've a feeling that is just to give some drama at the start. I could be wrong though..
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Old 4th June 2010, 21:57   #38
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I've a feeling that is just to give some drama at the start. I could be wrong though..
Probably to improve the short term fuel trim values in the ECU to enable a powerful start?
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Old 5th June 2010, 11:57   #39
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But why do some sports cars and supercars rev a lot upon startup and then come to an idle ?
Almost all engines do that to a certain extent. Its more evident on the ones that have a loud exhaust note.

When my OHC had the stock exhaust, i could barely hear it start, but now that i've got a performance exhaust, it starts with a powerful growl and then settles down.

And if its a cold start it stays at 1200rpm for a few secs and then comes down to 800rpm.

Watch this bone stock Civic. The revs rise to 1500rpm and then come down to 1000rpm, but bcoz it's exhaust sound is muffled, you can barely hear it.



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Last edited by Shan2nu : 5th June 2010 at 11:58.
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Old 5th June 2010, 12:16   #40
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The car runs rich for a few seconds upon startup to bring up the engine temperature quickly. Nothing to do with helping startup as there are seperate compensation tables for startup depending on the engine temperature.
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Old 5th June 2010, 23:49   #41
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Quote:
Originally Posted by ashwanth View Post
1.Another thing I remember my instructor saying to us:
Attachment 361105

It is to imagine a lane dividing the road into "our side" and "opponent side."

He would yell at us if we took the car into the "opponent side" during a RH or LH turn.

2. Our instructor also taught us and made us imbibe this - The right foot comes near the brake(one does not have to press the brake but just to be prepared..) whenever the right foot is taken off the throttle. This was useful to deal with two wheelers in general(especially cyclists) and unexpected opponent-entry-into-our lane during RH/LH turns.

The red line is close to the racing line on a track. It reduces the radius of curvature and is the quickest way around a corner. But that is not how one is supposed to drive on the road where the other lane is for the oncoming vehicle. Again brings out the glaring differences between race tracks and roads.

Very good point... I agree most driving instructors would not dwell upon these very important subtleties.
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Old 6th June 2010, 00:06   #42
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Originally Posted by arjunrudra View Post
Guys I have a doubt. I know its not placed in the right thread .
But why do some sports cars and supercars rev a lot upon startup and then come to an idle ?
Can you please direct me to the right thread.
When the engine is cold, the cylinder is small and pistons run with minimal clearance. Thus the friction is higher. That is why the coolant also bypasses the radiator till the engine working temperature is reached. The working temperature of the engine is roughly the middle of the design temperature range. In other words Tworking= Tmax - Tcold / 2

Most conventional cars have EGRs and also their working temperatures are quite low since their Tmax is low. They also have cold start fuel enrichment and that is sufficient to run the pistons at the low clearence.

Race cars have the Tmax quite higher than the conventional cars. Also there are seldom any EGRs and exhaust backpressure is minimal as they use free-flow exhausts. The pistons are almost siezed at ambient temperatures (Tcold). Even to crank the engine at these temperatures you need lot of power. And if you see the engine power to engine speed (rpm) curves - power rises with engine speed. So at higher engine speed, you have more power available. Also revving them starts building temperature towards Tworking faster.
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