[Healeys] Test--is the list down?
Bob Spidell
bspidell at comcast.net
Thu Sep 12 22:10:51 MDT 2024
"... as long as the octane rating is high enough for the effective
compression ratio of the engine in which it is being used higher octane
rated fuel is of no benefit ..."
That's what I've always believed to be true and, as far as preventing
detonation that is true. However, according to the video--and the guy
knows his stuff and shows data--the /additive package/ can make a
difference in engine /wear/ over time. According to the testing he cited
ZDDP gets diluted and consumed in the combustion chamber (ZDDP, of
course, is the stuff we rely on to protect our flat cam/lifter engines).
In Europe, apparently, you can choose fuels with the same octane rating
but better/higher additive packages (presumably, the latter costs
more--can any European listers verify this? Kees?). In the US, again
apparently, you will only get the better additive package in 'premium'
higher-octane fuel; Shell even claims as much (all fuel sold in the US
and, presumably, Canada, has to have a minimum level of detergents, to
prevent greater emissions from 'dirty' engines). This is all news to me;
now he needs to do an analysis on the various additive packages to see
who has the best additive package (some Mustang owners swear by Shell).
Historically, the gas companies have always bragged-on the detergent
qualities of their fuels, there may be even more to it if they have
'friction modifiers' that can reduce wear.
The required octane rating gets muddied in modern, VVT engines. The Gen
3 Coyote engine in my Mustang is rated at 475HP with 91-octane fuel, and
480HP with 93-octane. I mixed-in some 100-octane racing gas to achieve
93-octane, but you can't really feel 5HP with your butt dyno. This
engine will run, albeit poorly I suspect, on regular by changing valve
timing to dynamically reduce its nominal 12:1 compression. The Coyote
has both direct and sequential port injection, I suspect their mapping
can be changed to accommodate differing fuels as well. OTOH, a friend of
mine had one of the original Ford Taurus SHOs with the Yamaha V-6. It
was designed for regular (87-octane) fuel and could develop problems if
you ran higher octane fuel in it. Lower octane fuel is more 'explosive'
than higher octane, which deflagrates--i.e. burns--more slowly (still
pretty fast though). The SHOs could suffer deposit issues due to the
slower-burning premium fuels.
So, technically, if this guy's claims are true, the statement is
incorrect, at least WRT engine wear properties. As for detonation
resistance, performance, mileage and emissions the statement /is/ true.
As for aircraft engines, you can't really have too high an octane rating
as, if fueled or operated incorrectly detonation can be severe and
destroy an engine in just a few seconds and, if the destruction is
violent enough it can shake the engine off its mounts and/or detach the
prop (no fun). The highest-octane aircraft fuel I've ever heard of, but
not seen, is 110 (I think 120 existed at one time). It's loaded with
TEL, and will quickly foul the plugs in lower compression engines. The
search is on for a lead-free fuel for aircraft engines--it would have to
be 95-octane or better--but, so far, no one's willing to fly behind it
(the AOPA does have a twin running the lead-free in one engine, and it
appears to work OK, but the engine manufacturers--Continental and
Lycoming--threaten to void the warranties if it's used in their engines).
On 9/12/2024 4:57 PM, Michael Salter wrote:
> Question for Bob. Through my aircraft engines training and experience
> and many years in the automotive industry I have learned that "octane"
> is only one of many properties of gasoline which have affects on
> engine performance. Octane is a measure of fuel's resistance to pre
> ignition and has been grossly over sold to the unknowing public as
> "the" measure of the quality of fuel. There are many other properties
> of gasoline which can profoundly affect the performance of gasoline
> but these are seldom mentioned.
> As I understand it as long as the octane rating is high enough for the
> effective compression ratio of the engine in which it is being used
> higher octane rated fuel is of no benefit. Is that a correct statement?
>
> On Thu., Sep. 12, 2024, 7:36 p.m. Michael Oritt,
> <michael.oritt at gmail.com> wrote:
>
> Bob--
>
> I live in MD where both 93 octane gasohol and alcohol-free fuels
> are available. Aside from some gasoline-powered garden tools for
> which I bought the long-lasting stuff they sell by the gallon I
> have always used pump gas.
> My 2007 Tundra was great in that it would run on 87 whereas
> my Audi A4 requires 92--which works out to 93.
> As for the Healey I always use 93 gasohol though I think I am
> wasting money and could probably get by with 91.
> As for my Ginetta G4 (Ford Kent precrossflow) and Elva MK IV
> (Coventry Climax FWB) race cars I buy unleaded high octane (110)
> at the track and pay whatever I must in order to play..
>
> Best--Michael Oritt
>
> On Thu, Sep 12, 2024 at 12:16 PM Bob Spidell via Healeys
> <healeys at autox.team.net> wrote:
>
> OK, I'll get the ball rolling.
>
> I have a background in chemistry, and have always been
> interested in stuff chemical, including motor oil and fuel.
> This is, to me, an interesting take I hadn't given a thought
> to before. I've always run premium in my Healeys, Lincoln
> (required) and Mustangs (of course) and my two-strokes*
> (chainsaws, blower, trimmers), but have made do with
> regular--mostly Costco--in my other equipment (Ranger,
> tractors, mower, edger, quad, squirrel gasser, Gator). My
> engine builder told me the engines he sees in the best shape
> have been run exclusively on Chevron premium, so the Mustang
> and Healeys get that whenever possible, the Lincoln and
> two-strokes get Costco 91; everything else gets Costco 87
> (note Costco gas claims to be 'Top Tier').
>
> * My Stihl 4-stroke string trimmer specs 89-octane, but Costco
> only has 87/91 so the 2-stroke mix gets 91.
>
> https://www.youtube.com/watch?v=DAmEGI7xvBw
>
>
> On 9/12/2024 7:27 AM, Steven Kingsbury via Healeys wrote:
>> It's just been very quiet on the list lately. Seems to be
>> less busy, I guess everyone's cars are all running just fine! Ha!
>> Cheers!
>> Steven Kingsbury
>> BN1
>>
>>> On Sep 12, 2024, at 12:15 AM, Alan Seigrist
>>> <healey.nut at gmail.com> <mailto:healey.nut at gmail.com> wrote:
>>>
>>>
>>> Hi Bruce - I see you. did you check your junk folder?
>>>
>>> Alan
>>>
>>> On Thu, Sep 12, 2024 at 12:13 PM healeybruce--- via Healeys
>>> <healeys at autox.team.net> wrote:
>>>
>>> I’ve not been receiving emails for several weeks.
>>>
>>>
>>> Bruce Steele
>>>
>>> 1960 BN7
>>>
>>>
>>>
> _______________________________________________
> Support Team.Net http://www.team.net/donate.html
> Suggested annual donation $12.75
>
> Archive: http://www.team.net/pipermail/healeys
> http://autox.team.net/archive/healeys
>
> Healeys at autox.team.net
> http://autox.team.net/mailman/listinfo/healeys
>
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/healeys/michael.oritt@gmail.com
>
> _______________________________________________
> Support Team.Net http://www.team.net/donate.html
> Suggested annual donation $12.75
>
> Archive: http://www.team.net/pipermail/healeys
> http://autox.team.net/archive/healeys
>
> Healeys at autox.team.net
> http://autox.team.net/mailman/listinfo/healeys
>
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/healeys/michaelsalter@gmail.com
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20240912/a5e0d02b/attachment.htm>
More information about the Healeys
mailing list