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


Closed Thread
 
Thread Tools Search this Thread
Old 11th September 2007, 11:58   #46
Senior - BHPian
 
srishiva's Avatar
 
Join Date: Nov 2006
Location: Bengaluru
Posts: 3,572
Thanked: 814 Times
Default Engine heaters

Engine block heaters are already used to ease cold startup here in the U.S. Wouldn't it be helpful ? It runs on AC power though.
srishiva is offline  
Old 11th September 2007, 16:57   #47
BHPian
 
sathya_nars's Avatar
 
Join Date: May 2007
Location: Bangalore
Posts: 642
Thanked: 52 Times
Default

Quote:
Originally Posted by supremeBaleno View Post
sathya_nars, I would suggest you dont bother looking at the rpm meter. Instead, listen to the engine, as if it were a living being. It will tell you when you should upshift/downshift etc. If it sounds strained, you are not doing it right. I am sure, you will get the hang of it after some time.

Ofcourse, if you are one of those that love to hear the engine growl, this is not going to help you with FE.
Yup I could feel it nowadays and raising/reducing gears based on it. But in 5th gear beyond 60 or more, I couldn't feel much may be due to racing sound of engine, that's why I had to ask this question !!

Quote:
Originally Posted by mclaren1885 View Post
Varies from engine to engine. Basic factor being the torque curve and where the peak torque is produced.
Oops! I heard it somewhere as well (outside of TBHP) and I didn't believe due to this reason: my car SX4's peak torque is at 4200 RPM and in 5th gear I would be beyond 110 kmph or so at this rpm (because, 80 kmph is around 2500 RPM), does it give best FE at this speed? It's hard for me to believe because, in 2 long drives, I got best mileage (16 kmpl) when I stayed within 80 kmph (whereas got 14.75 kmpl when I crossed 100 many times).

I am missing to understand something here, please help me understand.
sathya_nars is offline  
Old 11th September 2007, 17:50   #48
Senior - BHPian
 
Join Date: Sep 2007
Location: New Delhi
Posts: 3,083
Thanked: 252 Times
Default

Sathya, your observation is correct - stay below 80 kmph and you will get the best FE.
Other things like gradual acceleration, gentle braking (wherever possible, and using gears to decelerate), optimal gear, etc. have already been covered.
And no you're not 'missing to understand' anything.

Last edited by anupmathur : 11th September 2007 at 18:08.
anupmathur is offline  
Old 11th September 2007, 18:05   #49
BHPian
 
sreenivass's Avatar
 
Join Date: Oct 2006
Location: Bangalore India
Posts: 872
Thanked: 6 Times
Default w.r.t staying in the torque band

Quote:
Originally Posted by sathya_nars View Post
Yup I could feel it nowadays and raising/reducing gears based on it. But in 5th gear beyond 60 or more, I couldn't feel much may be due to racing sound of engine, that's why I had to ask this question !!



Oops! I heard it somewhere as well (outside of TBHP) and I didn't believe due to this reason: my car SX4's peak torque is at 4200 RPM and in 5th gear I would be beyond 110 kmph or so at this rpm (because, 80 kmph is around 2500 RPM), does it give best FE at this speed? It's hard for me to believe because, in 2 long drives, I got best mileage (16 kmpl) when I stayed within 80 kmph (whereas got 14.75 kmpl when I crossed 100 many times).

I am missing to understand something here, please help me understand.
I do not think it should be peak torque, it would rather be in the right torque band. Typical example may be on a slope you could stay in gear 3 straining the engine but still pulling or stay in gear 3 with less pressure on gas. You may want to consider this scenario with various loads: only driver in the vehicle you can shift pretty early say 10, 20, 35, 45 and 50+ KMPH. On a fully loaded one you may want to shift a little late to get enough pull (torque) say: 15, 25, 40, 60 and 80 KMPH. These are not absolute figures, it depends on where you feel enough pull for given load and gear and shift at the right point. Its to get minimum required work done by the engine for a given load.

Gurus, please feel free to correct if my fundas seem wrong, do not flame me though
sreenivass is offline  
Old 11th September 2007, 18:22   #50
Senior - BHPian
 
Join Date: Sep 2007
Location: New Delhi
Posts: 3,083
Thanked: 252 Times
Default

Driving with window/s rolled down induces drag on the car - leading to poor FE.
Under-inflated tyres are no help either.
Has anyone got any figures for a) windows down, no AC and b) windows rolled up, AC on? Which would give better FE?
(Turbosam,? please)
anupmathur is offline  
Old 12th September 2007, 11:54   #51
BHPian
 
Join Date: Jul 2006
Location: pune
Posts: 241
Thanked: Once
Default

at max torque the engine is most efficient as heat exchanger as well as pump. ull be getting max performance in minimum fuel consumed.
kmpl efficiency on the other hand , wil be achived at much lower rpm/speed. ull be getting better kmpl figures @ 60-90kmph of steady driving in top gear with minimum input from accelerator input-just barely to maintain the momentum(even though the engine is less efficient at that rpm )
if u have an engine who has massive flat torque from as low as 1000-1500 rpm to @4000-5000 rpm then ur sitting in a gold mine ull get a road muncher at a fraction of a liter examples --most of the maserati 's especially bora,khamsin ,ghibli engines-4.9l redline at 5500 power rated 320 bhp torque 481.4 Nm, POWER BAND 800-5500 RPM..but then
maserati is maserati...

[quote=sathya_nars;560460]Oops! I heard it somewhere as well (outside of TBHP) and I didn't believe due to this reason: my car SX4's peak torque is at 4200 RPM and in 5th gear I would be beyond 110 kmph or so at this rpm (because, 80 kmph is around 2500 RPM), does it give best FE at this speed? It's hard for me to believe because, in 2 long drives, I got best mileage (16 kmpl) when I stayed within 80 kmph (whereas got 14.75 kmpl when I crossed 100 many timees)
TURBOSAM is offline  
Old 12th September 2007, 12:00   #52
Senior - BHPian
 
srishiva's Avatar
 
Join Date: Nov 2006
Location: Bengaluru
Posts: 3,572
Thanked: 814 Times
Default

Quote:
Originally Posted by anupmathur View Post
Driving with window/s rolled down induces drag on the car - leading to poor FE.
Under-inflated tyres are no help either.
Has anyone got any figures for a) windows down, no AC and b) windows rolled up, AC on? Which would give better FE?
(Turbosam,? please)
Windows rolled down with no AC is better than AC with windows up. AAA in U.S recommends this and its tried and tested.
srishiva is offline  
Old 12th September 2007, 12:23   #53
BHPian
 
Join Date: Jul 2006
Location: pune
Posts: 241
Thanked: Once
Default hi

yes , any thing which adds drag will hamper fuel efficiency too.
all ground effect spoilers, gurney flaps, wings ,wide tyres, big exposed wheel arches,plow like design of rear bumper<unfortunarely on all indian cars>roof mounted racks all add to drag .. drag means more poerr to overcome resictence means more fuel (in an extreme case top f1 cars has down force is of @ 3 tons at 330kmph that means equivalent of moving 3 tons more at that speed)
fuel consumption in a/c depends upon ur car interior material, compressor size, its gear ratio to engine ,desired temp setting ,sunshades fitted,cabin volume,car colour.....
u can save some fuel by switching the a/c on only while coasting and breaking once the comfortable temp is achived . it also adds the life to a/c clutch which otherwise keeps engaging and disengaging continously and suddenly at high rpm which saps compressor life too

Quote:
Originally Posted by anupmathur View Post
Driving with window/s rolled down induces drag on the car - leading to poor FE.
Under-inflated tyres are no help either.
Has anyone got any figures for a) windows down, no AC and b) windows rolled up, AC on? Which would give better FE?
(Turbosam,? please)
TURBOSAM is offline  
Old 12th September 2007, 13:08   #54
Senior - BHPian
 
Join Date: Sep 2007
Location: New Delhi
Posts: 3,083
Thanked: 252 Times
Default

Thanks Turbosam. Awesome.
Another query: If handling and 'grip' are not important, would it be advisable to slightly over-inflate tyres for better FE?
anupmathur is offline  
Old 14th September 2007, 18:46   #55
BHPian
 
Join Date: Jul 2006
Location: pune
Posts: 241
Thanked: Once
Default hello!

if handlng and grip is not imp plus if u are ready to accept a bit noisey and a bit of harsher ride then, tyres inflated to the max- 1 to-2 psi recomanded by the tyre manufacturer will give you @ 5-15% more distance per lit . apard from lesser rolling resiestence, the tyre will deflect lesser so EFFECTIVE rolling radious will be more by @ 5-7% this difference will NOT show on the guage as number of revolutions will be translated in kms covered but when meter says 100 kms actually u have travelled 105 +kms as with larger radius, u will be needing lesser revolutions to cover the same distence .
its as god as fitting taller tyres ..


Quote:
Originally Posted by anupmathur View Post
Thanks Turbosam. Awesome.
Another query: If handling and 'grip' are not important, would it be advisable to slightly over-inflate tyres for better FE?
TURBOSAM is offline  
Old 14th September 2007, 19:11   #56
Senior - BHPian
 
Ricky_63's Avatar
 
Join Date: Dec 2006
Location: Gurgaon
Posts: 3,845
Thanked: 375 Times
Default

@ TURBOSAM..

It has been a pleasure to read your posts, as they come from an "unassuming" & knowledgeable person (as is evident from all the above posts) - rather than from those of us who think "they are the most knowledgeable" or from those whose each sentence is full of spite & sarcasm.

I hope that more people such as yourself would come forward with "knowledgeable answers" to address queries of members who are keen to know things but don't know whom to ask.

Kudos to you. No offense meant to any fellow member

Cheers

Last edited by Ricky_63 : 14th September 2007 at 19:13.
Ricky_63 is offline  
Old 14th September 2007, 19:14   #57
Senior - BHPian
 
Join Date: Sep 2007
Location: New Delhi
Posts: 3,083
Thanked: 252 Times
Default

Makes perfect sense! Thanks. I presume the effects described are mainly for tubeless.
anupmathur is offline  
Old 15th September 2007, 11:29   #58
BHPian
 
Join Date: Jul 2006
Location: pune
Posts: 241
Thanked: Once
Default thanks man!

it hsa boosted my moral even higher . thanks
Quote:
Originally Posted by Ricky_63 View Post
@ TURBOSAM..

It has been a pleasure to read your posts, as they come from an "unassuming" & knowledgeable person (as is evident from all the above posts) - rather than from those of us who think "they are the most knowledgeable" or from those whose each sentence is full of spite & sarcasm.

I hope that more people such as yourself would come forward with "knowledgeable answers" to address queries of members who are keen to know things but don't know whom to ask.

Kudos to you. No offense meant to any fellow member

Cheers
TURBOSAM is offline  
Old 15th September 2007, 11:36   #59
BHPian
 
Join Date: Jul 2006
Location: pune
Posts: 241
Thanked: Once
Default thanks

those effects are for both tubeless as well as tube types as long as they are radial types .
in bias ply tyres the tyre will be ovel or round if over inflated as there is no mechanism to maintain the near-flat contact patch .
it will reap even better milage benifits in bias ply tyres, but the contact patch will be too small to safely stop the car .plus it will over agriviate the tyre centre line wear.

Quote:
Originally Posted by anupmathur View Post
Makes perfect sense! Thanks. I presume the effects described are mainly for tubeless.
TURBOSAM is offline  
Old 15th September 2007, 14:01   #60
BHPian
 
Join Date: Mar 2006
Location: Mumbai
Posts: 393
Thanked: 9 Times
Default

Hi TURBOSAM,

I agree with Ricky_63 about pleasure in reading your post.I do feel that it comes from direct experience and sharing without any expectation.I too felt many times the depth of the subject presented in a very simple way.I appreciate your effort.
finetuning is offline  
Closed Thread


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Autocar India & Ford Fiesta achieve 33 kpl? windsurfer The Indian Car Scene 58 22nd August 2011 20:44
Tata Indica e-xeta petrol with 17.1 kmpl and e-xeta LPG sidindica The Indian Car Scene 7 9th July 2011 12:39
Unable to achieve engine braking robinson.s 4x4 Technical 192 11th July 2010 16:33
How to achieve Max FE in an Opel Corsa? raj_7703 Technical Stuff 22 2nd July 2010 01:17
How to achieve better engine sound? raj_7703 Modifications & Accessories 7 6th November 2009 19:10


All times are GMT +5.5. The time now is 16:10.

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