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Octain Rating is not energy content in auto fuel - Its BTU (

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pcondon(at)mitre.org
Guest

Posted: Thu Jun 01, 2006 6:23 am Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

Octain boosters will allow higher compression engines to extract a

little bit more energy from the combustion cycle by virtue of enabling

higher compression piston/cylinders by delaying the combustion point

and allowing a smoother flame front upon actual ignition not

preignition(compressive heating causing premature combustion). BTU is

one measure of the potential energy of the fuel we ignite. Kerosene or

diesel has the highest potential energy, then gas and finally

alcohol(in this limited fuel discussion). Adding alcohol, which has

much less BTU potential to gas makes the new mixture less BTU capable

per unit volume (gallon of fuel). Alcohol mixed gas has roughly 17%

less energy per unit volume(as currently mixed and sold I the US). Less

energy to extract, less miles per gallon, less manifold pressure, less

work. Adding octane boosters has little to nothing to this energy

conversion equation. There is simply less BTU (energy) in this new

liquid we can burn.

noelloveys(at)yahoo.ca
Guest

Posted: Thu Jun 01, 2006 2:12 pm Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

The question of octane boosters came from the fact you can wash the ethanol

out of your gasoline but as you do that you will reduce the octane rating of

the gas about 4 or 5 points.  I was wondering what is readily available to

add to the fuel to get those few octane points back.  From the sound of it

kero or diesel in small quantities might, and I stress might, work.  I

understand from another list racers used to add a bit of kero to smooth out

their high compression engines.  I'm not sure I would want to try that in

the plane.



Noel



[quote] --

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Thu Jun 01, 2006 7:11 pm Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

I don't think adding diesel or kerosene not increase the octane  

rating of gasoline since both of these fuels by themselves have a  

much lower octane rating than gasoline. To increase the octane rating  

of gasoline you need to add a compound composed of lighter short  

chain molecules with lots of branching such as benzene or toluene.

On Jun 1, 2006, at 6:10 PM, Noel Loveys wrote:



 	  Quote: 	
		   



 The question of octane boosters came from the fact you can wash the  

 ethanol

 out of your gasoline but as you do that you will reduce the octane  

 rating of

 the gas about 4 or 5 points.  I was wondering what is readily  

 available to

 add to the fuel to get those few octane points back.  From the  

 sound of it

 kero or diesel in small quantities might, and I stress might, work.  I

 understand from another list racers used to add a bit of kero to  

 smooth out

 their high compression engines.  I'm not sure I would want to try  

 that in

 the plane.



 Noel


	


-- 

Bryan Martin

N61BM, CH 601 XL, Stratus Subaru.

do not archive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

Crvsecretary(at)aol.com
Guest

Posted: Fri Jun 02, 2006 2:58 am Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

Exactly what IS the octane rating of diesel and kerosene?  I  understood 

diesel to have a CETANE rating which measures the AFFINITY of fuel to  ignite 

spontaneously under extreme heat and pressure - exactly the opposite of  octane.

 

 

Tracy  Smith

Naugatuck, CT

601xl N458XL (reserved)

do not  archive



 

In a message dated 6/1/2006 11:12:28 PM Eastern Standard Time,  

bryanmmartin(at)comcast.net writes:






I don't think adding diesel or  kerosene not increase the octane  

rating of gasoline since both of  these fuels by themselves have a  

much lower octane rating than  gasoline. To increase the octane rating  

of gasoline you need to add  a compound composed of lighter short  

chain molecules with lots of  branching such as benzene or toluene.

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Fri Jun 02, 2006 5:43 am Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

From What I've read, kerosene and diesel have octane ratings in the  

15 to 25 range. I don't believe adding them to gasoline will raise  

its octane rating.

On Jun 2, 2006, at 6:56 AM, Crvsecretary(at)aol.com wrote:



 	  Quote: 	
		   

 Exactly what IS the octane rating of diesel and kerosene?  I   

 understood

 diesel to have a CETANE rating which measures the AFFINITY of fuel  

 to  ignite

 spontaneously under extreme heat and pressure - exactly the  

 opposite of  octane.


	




-- 

Bryan Martin

N61BM, CH 601 XL, Stratus Subaru.

do not archive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

Michael Valentine

Joined: 09 Jan 2006
Posts: 108

Posted: Fri Jun 02, 2006 6:34 am Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

Do not archive.



Sorry, but could someone explain the signficance of the octane discussion.

I understand that alcohol has less energy.  What significance does the

octane rating have.  Plus, if I have 93 octane mogas and add alcohol, how

does that affect the rating.  Then, if I remove said alcohol, why does that

then affect the rating?



Thanks, Michael

(Planning on using a Corvair, which is likely to be fed some mogas.)

moorecomp(at)yahoo.com
Guest

Posted: Fri Jun 02, 2006 7:44 am Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

Tracy,



Here is a very informative article about octane and

cetane ratings.



http://www.prime-mover.org/Engines/GArticles/octane.html



Best regards,



Craig Moore A&P

701 builder wannabe



--- Crvsecretary(at)aol.com wrote:



 	  Quote: 	
		   

 Crvsecretary(at)aol.com

 

  

 Exactly what IS the octane rating of diesel and

 kerosene?  I  understood 

 diesel to have a CETANE rating which measures the

 AFFINITY of fuel to  ignite 

 spontaneously under extreme heat and pressure -

 exactly the opposite of  octane.

  

  

 Tracy  Smith

 Naugatuck, CT

 601xl N458XL (reserved)

 do not  archive

 

  

 In a message dated 6/1/2006 11:12:28 PM Eastern

 Standard Time,  

 bryanmmartin(at)comcast.net writes:

 

 

 <bryanmmartin(at)comcast.net>

 

 I don't think adding diesel or  kerosene not

 increase the octane  

 rating of gasoline since both of  these fuels by

 themselves have a  

 much lower octane rating than  gasoline. To increase

 the octane rating  

 of gasoline you need to add  a compound composed of

 lighter short  

 chain molecules with lots of  branching such as

 benzene or toluene.

 

 

 

 

 

 

 

 

 

 



 browse

 Subscriptions page,

 FAQ,

 http://www.matronics.com/Navigator?Zenith-List

 Admin.



 

 

 

  

  

  

 

 

 

 


	




__________________________________________________

noelloveys(at)yahoo.ca
Guest

Posted: Fri Jun 02, 2006 9:11 am Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

Michael:



If you have 93 octane gas and add 10% ethanol the resulting octane rating

will be around 98.  Ergo if you have 98 octane gasahol and remove the "ahol"

part you are back to 93 octane.  Many aircraft engines need high octane fuel

so the question arises as to how to boost the 93 octane "clean" gas back to

something we can use.  



The other method to use would be to find a way to remove most/all the lead

form 100 LL although the lead it self helps to raise the octane level. This

is mostly an issue with the high revving two stroke crowd.  Although the

lead certainly has a big effect on certified engines.

Any way you want to cut the mustard ethanol and aviation should not mix!



Noel



[quote] --

frank.hinde(at)hp.com
Guest

Posted: Fri Jun 02, 2006 9:52 am Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

Any way you want to cut the mustard ethanol and aviation should not mix!

Not sure I agree with that satetment at all..i think there has simply

been very little resarch done on the matter, more like that is the

established wisdom but it has not been proven that there is a real

issue. Certainly in the altitudes that Zodiacs fly at I believe is is a

non issue (400 hours would prove it my case). As I said at length in a

previous note, Superior said they tested 10% ethanol on a Lycoming clone

and it caused vapor lock and was therfore a no-no...When I pressed them

it turns out they were not talking about vapor lock at all, but boiling

within the injector lines, which may or may not turn out to be no more

than a nusance, until it is TESTED though I don't think we can take this

as truth.



"Many aircraft engines need high octane fuel"...



Once again, this highly conjectural (is that a word?). All of the

naturally aspirated Lycomings will run quite happily on 92 octane

mogas...In fact Superior found it very difficult to make an IO360

detonate on the test stand running unleaded (92 octane) fuels.



About the only flat engine that will detonate without 100ll is the

turbocharged 350HP IO540...Not "many" of those around and a totally

different (fire breathing) animal than most of the

Lycoming/continentals. 



Frank 



 



--

Clmelenyzeriv(at)cs.com
Guest

Posted: Tue Jun 06, 2006 7:04 am Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

FYI there is a flying team, 4 or 5 aircraft, all RVs that fly out of Tea, South Dakota which is just south of Sioux Falls.  This team is sponsored by the Ethanol lobby and they are using E85.  I do not know what engines they are using or what modifications were required.  I have not talked to any of the pilots, but have heard from others at the airport that the engines are "tricky" to start.

 

 C. L. 

 601XL 20%

 

 "Do not archive"

frank.hinde(at)hp.com
Guest

Posted: Tue Jun 06, 2006 7:39 am Post subject: Octain Rating is not energy content in auto fuel - Its BTU (

Yes they will be, at least when trying tostart a hot  engine. this is because they have 1/8th Stainless injector lines that sit on top  of the engine. As the only restriction is the injector restrictors (which is  basically an open pipe onto the back of the inlet valve), when the engine stops  the injector line fuel boils off and you have to wait till the mechanical pump  refills the pretty long lines...Hence the cranking and  cranking.

  

 With my Lycoming I have electric pumps only so I'm hoping a  lot of this issue will not happen with my setup.

  

 The E85 engines MAY have larger nozzles to get more fuel in  there. As the mixture is set by the pilot this is no big  deal.

  

 Make me less worried about finding alcohol in my Lycoming  though.

  

 Frank

  

 Do not archive



   From: owner-zenith-list-server(at)matronics.com  [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of  Clmelenyzeriv(at)cs.com

Sent: Tuesday, June 06, 2006 8:04  AM

To: zenith-list(at)matronics.com

Subject: Re: Zenith-List:  Octain Rating is not energy content in auto fuel - Its BTU  (...

 

FYI there is a flying team, 4 or 5 aircraft, all  RVs that fly out of Tea, South Dakota which is just south of Sioux Falls.   This team is sponsored by the Ethanol lobby and they are using E85.  I do  not know what engines they are using or what modifications were required.   I have not talked to any of the pilots, but have heard from others at the  airport that the engines are "tricky" to start.



C. L. 

601XL  20%



"Do not archive"

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