Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 12th February 2005, 16:51   #46
Senior - BHPian
 
Deeps's Avatar
 
Join Date: May 2004
Location: Delhi/Noida
Posts: 1,090
Thanked: 67 Times
Default

Wooh,, we are very much Off Topic. But doesn't matter!! Shan2nu, can u explain wht u mean by blipping the throttle while downshifting? There is a jerk when u downshift from 3rd to 2nd even at 2000RPM. However, if u release the clutch gently, its hardly felt. So can u explain the concept of blipping the throttle and how to do it properly?
Deeps is offline   Reply With Quote
Old 12th February 2005, 17:32   #47
BHPian
 
Vulken Auto's Avatar
 
Join Date: Jan 2005
Location: Hyderabad
Posts: 418
Thanked: 54 Times
Red face

Dont use the clutch, it is for changing gears not savin fuel

Respect your RIDE!!!!!
Vulken Auto is offline   Reply With Quote
Old 12th February 2005, 17:48   #48
Senior - BHPian
 
Shan2nu's Avatar
 
Join Date: Feb 2004
Location: Hubli - Karnata
Posts: 5,525
Thanked: 86 Times
Default

Quote:
Shan2nu, can u explain wht u mean by blipping the throttle while downshifting? There is a jerk when u downshift from 3rd to 2nd even at 2000RPM.
Yup, there is a jerk at even low rpms and that is the very reason why blipping the throttle is important. To give you a jerk free shift and maintain your overall momentum.

It also makes sense using it on a race track, when you need to post a fast lap time.

But, this is not used by all drivers. I have this video of Peter Solberg driving a stock Subaru and the foot cam clearly shows that he doesn't blip the throttle while down shifting.

Basically, the idea is to match the engine speed to your vehicle speed .wr.t the selected gear.

Lets say you're travelling at 80kmph in 5th gear at 2300 rpm and you suddenly need to accelerate, hitting the gas pedal in 5th ain't gonna work. You know you need to shift into 2nd gear. But at 80kmph your rpm in 2nd has to be around 5650rpm, 3350rpm more than you are doing right now.

Just shifting into 2nd will surely create massive engine braking, slowing the car down and you don't want that to happen. So what do you do?

Shift into 2nd and while you do that, press your gas pedal until the revvs reach near the 5650 mark and then leave the clutch. If this is done perfectly, you won't lose speed, your shift will be jerk free and you will be able to accelerate instantly.

On a road car, this technique helps prevent premature wearing out of the clutch. In a race car, it's more to do with speed and lap times.

Shan2nu

Last edited by Shan2nu : 12th February 2005 at 17:52.
Shan2nu is offline   Reply With Quote
Old 13th February 2005, 00:21   #49
Senior - BHPian
 
Deeps's Avatar
 
Join Date: May 2004
Location: Delhi/Noida
Posts: 1,090
Thanked: 67 Times
Default

Yes, i understand it better now. but how do u blip the throttle while downshifting and how quick is the whole process?
Deeps is offline   Reply With Quote
Old 13th February 2005, 00:50   #50
Senior - BHPian
 
Shan2nu's Avatar
 
Join Date: Feb 2004
Location: Hubli - Karnata
Posts: 5,525
Thanked: 86 Times
Default

I think this webpage should give you enuf info on what toe heel braking is.

Toe heel braking...........

Shan2nu
Shan2nu is offline   Reply With Quote
Old 14th February 2005, 17:15   #51
BHPian
 
Join Date: Jan 2005
Location: Bangalore
Posts: 615
Thanked: 11 Times
Red face

Quote:
Originally Posted by muni
i know for sure that engine braking is achieved by applying brake followed by changing to a lesser gear and releasing the clutch..that allows the vehicle to come to the speed based on the rpm reading ( shan2nu's speed formula..)

Is there any difference in the braking distance b/w engine braking and just plain braking?
Muni,

Nobody could have explained engine braking better that what Shan2nu has done.. You don't need to apply brakes at all for engine braking. Its just that you need to match the revvs for a particular speed while downshifting gears.

Its basically a reverse process of moving from the 1st gear to the 5th gear, but needs some skill..

Lets take an example, Say you are travelling at 80 kmpl in the 5th gear and you need to slow down over a distance, You need to press the clutch and downshift to the 4th gear, Now you need to revv up the engine a bit and release the clutch and accelerator so that your vehicle does not create a jerk.. You've got to release the accelerator gradually so that the vehicle slows down by means of the gear-box. Repeat the same process till you are in the 2nd gear..

I think engine braking is definitely better than normal braking, since it avoids wear and tear of your brakes. Also since you are using the clutch properly, it should not result in wear and tear of your clutch plates either. Braking hard from 80 kmpl using normal brakes is detrimental to your brake-pads. Whereas braking hard from 80 kmpl using Engine braking is bad for your gearbox if you don't do it properly..

Regards,
Manish
man23ish is offline   Reply With Quote
Old 14th February 2005, 21:28   #52
BHPian
 
Join Date: Jan 2005
Location: Bangalore
Posts: 615
Thanked: 11 Times
Default

By the way, i think we have drifted from the main topic.. I am aware of engine braking.. My question was a bit different. Consider the scenario, where i am driving at a speed of 80 kmph and I need to stop suddenly at a traffic light, i apply brakes and downshift to lower gears. In such a scenario, is it better to

1> Shift in the reverse sequence after stopping say 5-4-3-2-N

Or

2> Can i apply brakes and stop the car in the 5th gear and then down shift directly to the 2nd gear 5-N-2 ??

Which is the correct technique and would minimise the wear and tear of the vehicle??
man23ish is offline   Reply With Quote
Old 14th February 2005, 21:35   #53
Senior - BHPian
 
Shan2nu's Avatar
 
Join Date: Feb 2004
Location: Hubli - Karnata
Posts: 5,525
Thanked: 86 Times
Default

Quote:
By the way, i think we have drifted from the main topic.. I am aware of engine braking.. My question was a bit different. Consider the scenario, where i am driving at a speed of 80 kmph and I need to stop suddenly at a traffic light, i apply brakes and downshift to lower gears. In such a scenario, is it better to

1> Shift in the reverse sequence after stopping say 5-4-3-2-N

Or

2> Can i apply brakes and stop the car in the 5th gear and then down shift directly to the 2nd gear 5-N-2 ??

Which is the correct technique and would minimise the wear and tear of the vehicle??
if you have enuf time to do all that you can, but in most cases it's not possible to follow the downshift pattern in emergency situations.

I usually press the brakes and keep pressing them as long as they don't lock up. If they do lock up, i just come off the brakes slightly and maintain that rythm.

Pressing the clutch is only necessary if the revvs drop too low or if you need to downshift, if you're gonna brake from 150 to 100, you wont need the clutch as the 5th gear can pretty well manage 100kmph.

Shan2nu
Shan2nu is offline   Reply With Quote
Old 15th February 2005, 12:53   #54
BHPian
 
Join Date: Jan 2005
Location: Bangalore
Posts: 615
Thanked: 11 Times
Default

Shan2nu,

Let me try to understand here.. You saying that either of the techniques is fine so long as the car thing stops right?? Yeah i understand that and agree with you.. My question is which one would cause less wear and tear Option 1 or Option 2 ??

Manish.
man23ish is offline   Reply With Quote
Old 15th February 2005, 13:22   #55
Senior - BHPian
 
Shan2nu's Avatar
 
Join Date: Feb 2004
Location: Hubli - Karnata
Posts: 5,525
Thanked: 86 Times
Default

Quote:
My question is which one would cause less wear and tear Option 1 or Option 2 ??
In an emergency, option 1 will cause less wear bcoz you'd be using only the brakes. In option 2 you'd be using the clutch to downshift for engine braking which if not done right, will wear out your clutch, strain your drivetrain and still add to brake wear.

Shan2nu

Last edited by Shan2nu : 15th February 2005 at 14:15.
Shan2nu is offline   Reply With Quote
Old 15th February 2005, 14:06   #56
Newbie
 
Join Date: Feb 2005
Location: Hyderabad
Posts: 17
Thanked: 0 Times
Default

Shan2nu, I'd like to thank you for that insightful information about changing gears while accelerating and braking. I never knew there was that much to driving!
riffst3r is offline   Reply With Quote
Old 15th February 2005, 14:17   #57
Senior - BHPian
 
Shan2nu's Avatar
 
Join Date: Feb 2004
Location: Hubli - Karnata
Posts: 5,525
Thanked: 86 Times
Default

Quote:
I never knew there was that much to driving
There's a lot more to driving than just this. There must be so many things which i don't kow but i do make it a point ot read stuff, as much as i can.

Shan2nu
Shan2nu is offline   Reply With Quote
Old 16th February 2005, 12:26   #58
BHPian
 
Join Date: Jan 2005
Location: Bangalore
Posts: 567
Thanked: 22 Times
Default

nice work shant2nu and co. .appreciate ur efforts..we r always part of the learning/sharing curve.
muni is offline   Reply With Quote
Old 19th February 2005, 17:11   #59
Senior - BHPian
 
Deeps's Avatar
 
Join Date: May 2004
Location: Delhi/Noida
Posts: 1,090
Thanked: 67 Times
Default

Quote:
Originally Posted by riffst3r
Shan2nu, I'd like to thank you for that insightful information about changing gears while accelerating and braking. I never knew there was that much to driving!

True that tthere's so much more to driving than just accelerator, brake, clutch and steering. I wish they taught all this in high school or at least driving school. Then we'd have guys like Shan2nu becoming teachers.
Deeps is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
First Gear : A Book for first-time Car Buyers in India (Download link Inside) GTO The Indian Car Scene 24 5th August 2013 15:58
My First New Car; My First Diesel; My Second Ford..The Figo! vij4all Test-Drives & Initial Ownership Reports 27 7th August 2011 05:39
i10 gear stuck in reverse gear drkunaldas Technical Stuff 33 23rd November 2009 02:21
Swift 2nd Gear Problem EDIT: Now first gear problem BUSA Technical Stuff 85 2nd September 2009 18:47
Top Gear in 'Top Gear' (3 veyrons offered for shoot) SumitB Shifting gears 8 4th August 2008 13:22


All times are GMT +5.5. The time now is 06:52.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks