[TR] U.S. EPA Finalizes Rulemaking to Permit Year-Round Sales of E15 Gasoline

DAVID MASSEY dave1massey at cs.com
Thu Jun 6 19:15:10 MDT 2019


 I would have thought you can get +\- 5% changes just in the adjustments available.
The other consideration is what does the alcohol do the the rubber parts in the fuel system.  Here in the Midwest we have had 5% alcohol in our gas for decades.  Both my cars suffered fuel pump failures when the pump diaphragm  went all stiff and cardboardy on me.  I fitted an electric pump to the TR6 and a rebuild kit in the TR3 is still working just fine.  Replacing all the fuel hoses is a good idea, too.
 
Dave 

 
 
-----Original Message-----
From: Michael Porter <mdporter at dfn.com>
To: Randall <TR3driver at ca.rr.com>; 'Greg Lemon' <grglmn at gmail.com>
Cc: triumphs <triumphs at autox.team.net>; 'Pete Arakelian' <Arakelianp at mossmotors.com>
Sent: Thu, Jun 6, 2019 4:59 pm
Subject: Re: [TR] U.S. EPA Finalizes Rulemaking to Permit Year-Round Sales of E15 Gasoline

On 6/6/2019 2:57 PM, Randall wrote:
>
> Those brass needles are really soft; I would suggest a fine tooth file and a
> light touch rather than a Dremel.  I haven't worked out how big the flat
> should be, but it won't take much.  You're only looking for something like
> 5% more fuel (or maybe 6%, depending on whose numbers you believe).
>
> Again assuming you want to run E15 in the first place.
>
The calculation is .85 x 115.5 + .15 x 76.0/115.5 = 0.94874, nominally - 
5.125%.  But, there are other considerations.  The latent heat of 
evaporation of alcohol is pretty high, so the flame front will propagate 
a bit more slowly, which means the advance can be raised slightly.  And, 
since the octane rating for ethanol is 110, the compression ratio can be 
raised slightly with no ill effect.  Both of those effects translate to 
slightly better mileage, or at least mitigate the loss in fuel value.  
The octane increase is not insubstantial.  If the gasoline in the blend 
is 87 octane, the total blend with 15% ethanol is 90.5.

Anyone operating at altitudes well above sea level will probably see a 
slight improvement in performance, because of an oxygen atom in the 
alcohol molecule, presuming that all else is right with the engine 
(i.e., mixture correct and timing adjusted for altitude).

The bugaboo, I suppose, is that some people may still have rubber hoses 
installed that aren't alcohol-proof, and that's something that would 
have to be corrected.  Buna-n (nitrile) will work, but with shorter 
life, but neoprene or SBR (styrene-butadiene rubber) would have good 
resistance to alcohol and are readily available. Anyone contemplating 
replacement of rubber hoses with braided stainless steel w/Teflon liners 
should avoid that.  Nylon or XLPE liners are fine.

But, in general, go easy on needle mods.  For SUs and Strombergs, simple 
mixture enrichment and a little fiddling with the advance may get one 
most of the way there.  Plug cuts will tell the tale.


Cheers.

-- 


Michael Porter
Roswell, NM


Never let anyone drive you crazy when you know it's within walking distance....



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