Throttle Position During Acceleration and its effect on FE - Page 2 - Fuelly Forums

Click here to see important news regarding the aCar App

Go Back   Fuelly Forums > Fuel Talk > General Fuel Topics
Today's Posts Search Click Here to Login
 
 
Thread Tools Display Modes
 
Prev Previous Post   Next Post Next
Old 09-05-2005, 08:50 AM   #1
*shrug*
 
Join Date: Sep 2005
Posts: 6,195
Throttle Position During Acceleration and its effect on FE

Quote:
<p><small><font face="Verdana,Arial">You'll get the best efficiency
around town by accelerating with full throttle, and shifting up to
the next gear quickly, before engine RPMs rise too high.</font></small></p>
<p><font size="2" face="verdana,arial">There are
two reason why this works. One is that the higher the gear, the lower
the frictional losses. By getting to 5th quickly, the total number
of engine revolutions is reduced, with a corresponding reduction in
frictional losses. The second reason is pumping losses. This is the
work done to force air past a partially closed throttle plate. The
more closed the throttle is, the higher the losses. Accelerating quickly
reduces throttle losses, because the throttle is open. In addition,
engine speed is lower in fifth, so to generate the same amount of
power, you have a larger throttle opening (and hence lower throttle
losses) - this is another reason to get to higher gears as quickly
as possible.</font></p>
<p><font size="2" face="verdana,arial">The best fuel economy is gained
by a combination of the gas petal to the floor with shifts at as low
an rpm as possible to sustain your desired acceleration. This ensures
a fully open throttle during the entire acceleration event and gets
you out of the lower gears as quickly as possible, for lower frictional
losses. It also gives you even more electric motor assist, as the
acceleration takes longer. There is only one problem with this technique
- its virtually impossible to do. You have to shift like a race car
driver, except that the shifts are at low rpm instead of high rpm.
You wind up going through gears like a maniac. It can be a lot of
fun, but you have to be really involved with driving (no cell phones)
and the technique is extremely counterintuitive. The combination of
mashing the accelerator and shifting at 2500 or 3000 rpm just doesn't
feel right. However, if someone is willing to practice this, they
can get a nice boost in FE around town.</font></p>
<p><small><font face="Verdana,Arial">After accelerating this way in
1st &amp; 2nd gears, you'll often be up to your desired cruising speeds.
Now it is time to switch modes, using as little energy as possible
to maintain this speed. Typically you'll now want to be in fifth gear.
The <strong>1-2-5 shift pattern</strong> (or 1-2-4 as the case may
be) may seem strange at first. After all, why are those other gears
there if you shouldn't use them? The answer is to think of them as
passing gears or cruising at slower speed gears. In most cases, this
is the way I use the five gears:</font></small></p>
<blockquote>
<p><small><font face="Verdana,Arial"><strong>1:</strong> Accelerating
gear<br />
<strong>2:</strong> Accelerating gear<br />
<strong>3:</strong> Even slower cruising / quick passing gear<br />
<strong>4:</strong> Slow cruising / slower passing gear<br />
<strong>5:</strong> Cruising gear</font></small></p>
</blockquote>
<p><small><font face="Verdana,Arial">Once you're up to speed, in addition
to quickly getting into your cruising gear, you'll also want to begin
feathering the throttle. Since you should have done all your acceleration
before going into cruising gear, you now want to use as light a throttle
as possible that will still maintain your current speed. If you find
that you want to accelerate further, you may be better to downshift
for a quick blip of acceleration, and then shift back into your cruising
gear.
</font></small></p><p>&nbsp;</p><p>&nbsp;Does this sound right? Am I crazy? Slam it to 50 mpg in second then shift into 5th? Huh? What? It is from insightcentral so they know their stuff, but really? <br /></p>
SVOboy is offline   Reply With Quote
 


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Fuelly iOS Apps
Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 02:30 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.