Go Back  Offshoreonly.com > General Discussion > General Boating Discussion
Can you achieve greater speed / horsepower with real gas? >

Can you achieve greater speed / horsepower with real gas?

Notices

Can you achieve greater speed / horsepower with real gas?

Old 09-28-2011, 03:59 PM
  #21  
Registered
 
Join Date: Jun 2009
Posts: 310
Likes: 0
Received 0 Likes on 0 Posts
Default

I think part of the problem is confusion between potential energy per unit volume and octane.

The two are not the same thing. Potential energy in the case of gasoline is measure of how much work can be done, or how much power can be made. Where octane is a measure of how much the air/fuel mixture can be compressed without detonating.
fireguy is offline  
Old 09-28-2011, 04:12 PM
  #22  
Registered
iTrader: (5)
 
Join Date: Mar 2008
Location: Traverse City MI
Posts: 3,577
Received 260 Likes on 92 Posts
Default

Originally Posted by fireguy
I think part of the problem is confusion between potential energy per unit volume and octane.

The two are not the same thing. Potential energy in the case of gasoline is measure of how much work can be done, or how much power can be made. Where octane is a measure of how much the air/fuel mixture can be compressed without detonating.
Thanks for clearing up for us. I agree with you.

But which is better for our boats? Not sure I want to give up octane for potential energy....
offshorexcursion is offline  
Old 09-28-2011, 04:22 PM
  #23  
Platinum Member
Platinum Member
 
CigDaze's Avatar
 
Join Date: Jun 2001
Posts: 21,346
Likes: 0
Received 8 Likes on 8 Posts
Default

Originally Posted by offshorexcursion
Thanks for clearing up for us. I agree with you.

But which is better for our boats? Not sure I want to give up octane for potential energy....
Generally speaking, you should run the lowest octane possible that your engine can handle. If your engine manufacturer recommends 87, then run 87.

Octane is a measure of a fuel's stability, not energy. Higher octane gasoline actually has lower energy. All a higher octane gas provides is that it will resist premature detonation up to a higher compression ratio (that's the stability part). By doing so, it makes it possible to build an engine with higher compression and thus the potential for more power.

Last edited by CigDaze; 09-28-2011 at 04:26 PM.
CigDaze is offline  
Old 09-28-2011, 04:24 PM
  #24  
Platinum Member
Platinum Member
 
CigDaze's Avatar
 
Join Date: Jun 2001
Posts: 21,346
Likes: 0
Received 8 Likes on 8 Posts
Default

Originally Posted by C_Spray
I'm no fan of it as a substitute for gas. It has some nasty emissions side effects, too. From Wikipedia:

"Ethanol combustion in an internal combustion engine yields many of the products of incomplete combustion produced by gasoline and significantly larger amounts of formaldehyde and related species such as acetaldehyde. This leads to a significantly larger photochemical reactivity that generates much more ground level ozone. These data have been assembled into The Clean Fuels Report comparison of fuel emissions and show that ethanol exhaust generates 2.14 times as much ozone as does gasoline exhaust. When this is added into the custom Localised Pollution Index (LPI) of The Clean Fuels Report the local pollution (pollution that contributes to smog) is 1.7 on a scale where gasoline is 1.0 and higher numbers signify greater pollution. The California Air Resources Board formalized this issue in 2008 by recognizing control standards for formaldehydes as an emissions control group, much like the conventional NOx and Reactive Organic Gases (ROGs)."
Agreed. Frankly, I see no reason nor benefit for mandating ethanol use for the mass public. Not only is it worse environmentally, but more energy and money go into making it, than will ever be output from it.

Last edited by CigDaze; 09-28-2011 at 04:26 PM.
CigDaze is offline  
Old 09-28-2011, 04:30 PM
  #25  
Registered
 
Join Date: Dec 2005
Location: Florida
Posts: 2,796
Received 11 Likes on 9 Posts
Default

I can't find ANYPLACE with out this ethanel chit...
I use octane boosters as much as I can. Luckly I have SST tanks. I mix fuel when I can and avarage 89 octanes. If I can get 89 great, if not I use half 87 and half or so 91 or 93.
Didn't notice much difference however, due to this crazy Merc computer stuff.
PARADOX is offline  
Old 09-28-2011, 06:58 PM
  #26  
Registered
iTrader: (1)
 
Join Date: Sep 2008
Posts: 1,016
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by PARADOX
I can't find ANYPLACE with out this ethanel chit...
I use octane boosters as much as I can. Luckly I have SST tanks. I mix fuel when I can and avarage 89 octanes. If I can get 89 great, if not I use half 87 and half or so 91 or 93.
Didn't notice much difference however, due to this crazy Merc computer stuff.


Peter

The gas station on the North west side of the Port Richey bridge has non-ethanol 91 octane.
Steve
smiklos@sunprint is offline  
Old 09-28-2011, 07:15 PM
  #27  
Registered
 
waybomb's Avatar
 
Join Date: Jan 2004
Location: South of the North Pole
Posts: 611
Received 23 Likes on 15 Posts
Default

Here - find non e gas near you:
http://pure-gas.org/index.jsp?stateprov=FL
waybomb is offline  
Old 09-28-2011, 07:59 PM
  #28  
Registered
 
Join Date: Jan 2004
Location: Jacksonville FL
Posts: 1,847
Received 6 Likes on 4 Posts
Default

Originally Posted by CigDaze
Generally speaking, you should run the lowest octane possible that your engine can handle. If your engine manufacturer recommends 87, then run 87.

Octane is a measure of a fuel's stability, not energy. Higher octane gasoline actually has lower energy. All a higher octane gas provides is that it will resist premature detonation up to a higher compression ratio (that's the stability part). By doing so, it makes it possible to build an engine with higher compression and thus the potential for more power.
thats where my question comes in,

if the manufacturer recommends 93 oct, are you better off with 89 non eth, or 93 eth?
Boomer35 is offline  
Old 09-29-2011, 02:15 AM
  #29  
Charter Member # 55
Charter Member
 
Griff's Avatar
 
Join Date: Oct 2000
Location: Omaha/LOTO
Posts: 19,516
Received 1,782 Likes on 884 Posts
Default

Originally Posted by SWW17
I dont think the two equate eg., 93 with ethanol vs. 89 real gas. Some motors like a 496 HO or 525 are happiest with the lower 89 octane.

My question stems around whether there are any notable horsepower / top speed differences with an apple to apple comparison whether it be 89 with E to 89 without E, or 93eth. to 93 octane real gas.

There seems to be a consenses building that the fuel burn actual volume is potentially 20% more with ethanol (seems kind of big if it is really that much!)

But if you can only flow X = max. amount of fuel at WOT. Would'nt the boat perform substancially better if real gas can provide that much mor energy to burn?

Just trying quantify and decide if it is worth the extra effort for the pure gas search.

Thanks
E10 has about 4% less BTU's. The HP made will thus loose about the same 4%. A 502mpi making 415hp will probably only make about 400hp on E10. That translates into about 1mph.

Originally Posted by Boomer35
thats where my question comes in,

if the manufacturer recommends 93 oct, are you better off with 89 non eth, or 93 eth?
You must run the 93 octane E10 fuel or the engine will detonate.
Griff is offline  
Old 09-29-2011, 06:46 AM
  #30  
Platinum Member
Platinum Member
 
CigDaze's Avatar
 
Join Date: Jun 2001
Posts: 21,346
Likes: 0
Received 8 Likes on 8 Posts
Default

Originally Posted by Boomer35
thats where my question comes in,

if the manufacturer recommends 93 oct, are you better off with 89 non eth, or 93 eth?
Like Griff said, if you're engine mfg specs 93 then you must run 93 or higher - pure gas or ethanol blend, makes no difference. In your example, 93 ethanol blend is WAY better than 89 pure gas because you're engine will survive the 93 ethanol blend fuel, but probably won't run very long with the lower octane pure gasoline.

Everything you ever wanted to know about octane ratings:
http://en.wikipedia.org/wiki/Octane_rating
CigDaze is offline  

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.