Ethanol injection for knock control - Fuelly Forums

Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

Reply
 
Thread Tools Display Modes
 
Old 06-01-2009, 06:21 PM   #1
Registered Member
 
theholycow's Avatar
 
Join Date: Apr 2008
Posts: 6,624
Country: United States
Send a message via ICQ to theholycow Send a message via AIM to theholycow Send a message via MSN to theholycow Send a message via Yahoo to theholycow
Lightbulb Ethanol injection for knock control

http://www.newscientist.com/article/...efriendly.html

Quote:
[...]So says the Ford Motor Company, which on 19 May revealed test results on a novel ethanol-assisted engine. Called a direct-injection ethanol engine, the unit runs primarily on petrol. When it needs to deliver maximum power - to climb a hill or overtake, for example - the engine management computer adds a little ethanol to the fuel injected into the combustion chambers.

This arrangement allows the engine to operate at a much higher compression ratio - a measure of the amount by which the fuel-air mixture is compressed before being ignited - than normal. As a result, an average car engine can be "downsized" to one that should have around 23 per cent better fuel efficiency, Ford says.[...]
Nothing particularly new to us here, but a different combination of things we often talk about.
__________________

__________________
This sig may return, some day.
theholycow is offline   Reply With Quote
Old 06-02-2009, 03:29 AM   #2
Registered Member
 
Join Date: Mar 2009
Posts: 1,139
Country: United States
They mention that they want to make sure the engine doesn't become unusable if you run out of ethanol. Seems like in that case, you could limit maximum power to prevent knocking. Not exactly ideal, but you could still limp along.
__________________

__________________


Main Entry: co de pen dence - see codependency
co de pen den cy
Pronunciation: \kō-di-ˈpen-dən(t)-sē\
Function: noun
Date: 1979

: a psychological condition or a relationship in which a person is controlled or manipulated by another who is affected with a pathological condition (as an addiction to alcohol or heroin) ; broadly : dependence on the needs of or control by another
GasSavers_maximilian is offline   Reply With Quote
Old 06-02-2009, 09:00 PM   #3
Registered Member
 
GasSavers_Erik's Avatar
 
Join Date: Nov 2006
Posts: 1,027
Country: United States
Is the compression ratio adjustable on this engine? That seems like the only logical explanation for why it doesn't detonate without the ethanol- perhaps it is a turbo and when the raise the boost pressure way up, they start injecting more ethanol.
GasSavers_Erik is offline   Reply With Quote
Old 06-03-2009, 03:59 AM   #4
Registered Member
 
Join Date: Mar 2009
Posts: 1,139
Country: United States
If it were variable compression they wouldn't need ethanol for knock control. They're worried that it will knock without ethanol. Knock usually is much more of a problem at higher throttle settings.
__________________


Main Entry: co de pen dence - see codependency
co de pen den cy
Pronunciation: \kō-di-ˈpen-dən(t)-sē\
Function: noun
Date: 1979

: a psychological condition or a relationship in which a person is controlled or manipulated by another who is affected with a pathological condition (as an addiction to alcohol or heroin) ; broadly : dependence on the needs of or control by another
GasSavers_maximilian is offline   Reply With Quote
Old 06-03-2009, 06:47 AM   #5
Registered Member
 
GasSavers_Erik's Avatar
 
Join Date: Nov 2006
Posts: 1,027
Country: United States
I see- so it is simply a high compression engine that adds ethanol only under high throttle conditions (that normally would result in knocking).

This would make fillups interesting- have two gas gauges, tanks, filler caps, etc.
GasSavers_Erik is offline   Reply With Quote
Old 06-03-2009, 02:45 PM   #6
Registered Member
 
Join Date: Oct 2005
Posts: 21
Country: United States
WOW! How about stepping back to the thirties?

IF an auto manufacturer were attempting to create an economy engine via high compression, seems like the most logical thing to do would be to properly design a combustion chamber that would withstand 12-13:1 static compression on pump fuel alone, it is a fact that as static CR #'s increase, maximum cylinder pressures greatly increase. Over the long run this is probably not desirable.

For starters, ethanol has a low calorific value - the stoichiometry is 9:1, so obviously not the most potent fuel for extracting mechanical energy. The only thing beneficial to ethanol as a fuel supplement is its high latent heat absorbs massive amounts of heat before the intake valve closing resulting in a higher volumetric efficiency, (more power). However, this may only be true to an extent, under certain conditions and there is a point of diminishing returns. The slight gain in thermal efficiency is likely at best, negligible for this company's approach.

Reducing flame temps increases thermal efficiency. This has been commonly accomplished by operating at leaner than stoichiometric ratios with a super homogeneous intake charge. There is a catch though, flame speed decreases and more ignition timing is required, ultimately defeating the purpose. The static CR could be increased to offset the difference, I find it a curiosity as to why this hasn't been done. The civic VX is likely operating in that sweet spot somewhere between 16-17:1. Nearly every mass produced powerplant after that engine which attempted to achieve ultra high economy is severely lacking.
greasemonkee is offline   Reply With Quote
Old 06-03-2009, 03:30 PM   #7
Registered Member
 
theholycow's Avatar
 
Join Date: Apr 2008
Posts: 6,624
Country: United States
Send a message via ICQ to theholycow Send a message via AIM to theholycow Send a message via MSN to theholycow Send a message via Yahoo to theholycow
Quote:
Originally Posted by greasemonkee View Post
For starters, ethanol has a low calorific value - the stoichiometry is 11:1, so obviously not the most potent fuel for extracting mechanical energy. The only thing beneficial to methanol as a fuel supplement is its high latent heat absorbs massive amounts of heat before the intake valve closing resulting in a higher volumetric efficiency, (more power).
Were you talking about ethanol, or methanol?
__________________
This sig may return, some day.
theholycow is offline   Reply With Quote
Old 06-03-2009, 10:03 PM   #8
Registered Member
 
Join Date: Oct 2005
Posts: 21
Country: United States
Ethanol. Must have been thinking one thing and typing another. Stoichiometry of methanol is 6.4, ethanol is 9.0

Went back and edited my #'s, haste = errors. My apologies
greasemonkee is offline   Reply With Quote
Old 06-05-2009, 05:01 PM   #9
Registered Member
 
imzjustplayin's Avatar
 
Join Date: Dec 2011
Posts: 720
Country: United States
Quote:
Originally Posted by theholycow View Post
Were you talking about ethanol, or methanol?
lawl, you're funny, you found the methanol problem in my thread and then in this thread... I wonder how many times this happens on this forum.
__________________

imzjustplayin is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
New graphic idea MatrixDom Fuelly Web Support and Community News 2 03-11-2012 01:17 PM
Average fuel mileage line in the history graph? BDC Fuelly Web Support and Community News 1 05-06-2009 01:07 AM
Florida announces first commercial cellulosic ethanol plant theholycow Automotive News, Articles and Products 3 03-01-2009 02:01 PM
searching? blind monkey General Discussion (Off-Topic) 7 01-09-2009 07:16 PM
91 CRX DX 5 Speed Head Gasket Confusion UfoTofU General Maintenance and Repair 2 04-26-2008 11:09 AM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 05:06 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.