[E-Type] Grade of gas for E Type?

In reply to a message from Wiggles sent Wed 4 May 2011:

Paul,

Also interesting that the ‘‘modern’’ pent roof, four valve engine
(1912) pre dates the hemi, but it got a back seat until the sixties
because of alcohol fuels and supercharging. This quote does not
mention the offset spark plug, which makes the ‘‘orange peel’’
chamber even worse for detonation. You can find many quotes that
the hemi’s central spark plug prevents detonation, but most of them
have offset plugs to fit the largest possible valves. Twin
plugging a hemi is a solution that goes back to the 30’s. On the
Porsche 911 engine, a wide VIA hemi like the XK, it lowers the
octane requirement several points and drops the ideal spark timing
from 35 to 25 BTDC. Jaguar made a few twin plug heads for the D
Type, but claimed they were of little benefit. Probably because
the focus was LeMans and finishing, they kept the compression low
because of fuel quality and the real issue of fuel ‘‘sabotage’’.
Heynes states in his paper they kept the C Type to 8:1 because the
bad gas at Lemans caused piston crown burning at WOT. The
definitive ‘‘hemi vs pent roof’’ study was done by Honda in the 60’s
and makes a good read. It is the inspiration and reason for the
pent roof revival by Ferrari, Coventry Climax, Westlake and
Cosworth in the late 60’s. A lot of data, but it concludes that
the four valve pent roof’s real benefit is lighter valves with a
higher mean effective valve area allowing higher rpm and output.
They tested engines out to 24,000 rpm and, interestingly,
detonation is no longer an issue above 15,000 rpm…

Paul–
The original message included these comments:

In reply to a message from PS sent Wed 4 May 2011:
I thought this passage to be very interesting, and relevant.
''One of the characteristic chambers that people are familiar with
is the Chrysler Hemi. The engine had a chamber that was like a half
of a baseball. Hemispherical in nature and in nomenclature, too.
The two valves were on either side of the chamber with the spark
plug at the very top. The charge burned downward across the
chamber. That approach worked fairly well in passenger car engines
but racing versions of the Hemi had problems. Because the chamber
was so big and the bores were so large, the chamber volume also was
large; it was difficult to get the compression ratio high. Racers


PS
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In reply to a message from PS sent Wed 4 May 2011:

Suppose one does lower the C:R to 8:1. What is the required
octane rating?–
Eric
Republic of Texas, United States
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In reply to a message from 64etype sent Wed 4 May 2011:

Eric,

All I could say is less. On paper, the factory dropped the spec
from 98 RON to 95 RON for 8:1 engines. 95 RON is around 90-91 CLC
(US) octane, but the fuel is not comparable. At this age, every
engine is different and air temp, coolant temp and oil dilution
make it hard to generalize.

Paul–
The original message included these comments:

In reply to a message from PS sent Wed 4 May 2011:
Suppose one does lower the C:R to 8:1. What is the required
octane rating?
Eric


PS
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In reply to a message from PS sent Wed 4 May 2011:

In the ‘‘six degrees of separation’’ game, it almost all goes back to
Sir Harry Ricardo, doesn’t it? Also, Dr. Moss’ experiments with
turbosupercharging up Pike’s Peak, not to mention the entire
Offenhauser team of geniuses were so key to ‘‘modern’’ designs as we
see today.

There were reports of detontation actually being beneficial, in
regards to the 1.5 liter Coventry Climax V8s: they were able to
turn in excess of 10,000 rpm and at that speed the flame front
speed of detonation doesn’t ‘smack’ the piston hard enough to
damage it, but actually seemed to act as a type of beneficial
BMEP ‘‘increaser.’’–
The original message included these comments:

Also interesting that the ‘‘modern’’ pent roof, four valve engine
(1912) pre dates the hemi, but it got a back seat until the sixties
because of alcohol fuels and supercharging. This quote does not
mention the offset spark plug, which makes the ‘‘orange peel’’
chamber even worse for detonation. You can find many quotes that
the hemi’s central spark plug prevents detonation, but most of them
have offset plugs to fit the largest possible valves. Twin
plugging a hemi is a solution that goes back to the 30’s. On the
Porsche 911 engine, a wide VIA hemi like the XK, it lowers the
octane requirement several points and drops the ideal spark timing
from 35 to 25 BTDC. Jaguar made a few twin plug heads for the D


Paul Wigton, steward to a '60 DKW 1000 SP, Tweety, '63 FHC!
Keenesburg, CO, United States
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In reply to a message from Mal9 sent Wed 4 May 2011:

FWIW, AKI (Anti-Knock Index) is the same as CLC (Cost of Living
Council, US). The congress started requiring octane to be posted
on pumps, regulated by the CLC, and the oil lobbyists made sure
that a number lower than the then-standard Research Octane Number
(RON) would be used, to fool people into getting more expensive
gasoline. AKI/CLC is the average of the RON octane and the Motor
Octane Number (MON) which is a lot lower – RON + MON / 2. Only
trouble is that older cars only show RON octane recommendations.
Big oil succeeds in pulling the wool over our eyes!

In general the RON number is about 5 numbers higher than the AKI
number, so US 91 AKI is RON 95-96. It does vary, but I have been
able to find the specs on some gasolines online, ant both the RON
and AKI numbers are listed. California pump gasoline 91 octane
works fine in a clean 9:1 E Type engine for hard driving, FWIW.

Seems that AKI has superceded the CLC tag, so I’ll try to forget it!

Jerry–
The original message included these comments:

Europe etc. uses RON octane rating, US AKI.


Jerry Mouton '64 FHC 889791 ‘MIK Jaguar’
Palo Alto, California, United States
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In reply to a message from Wiggles sent Wed 4 May 2011:

Paul,

Most of it pre date Ricardo and he dismisses the DOHC pent roof in
his 1923 book. He did however design the only DOHC four valve
engine that also had rocker arms, pushrods and three spark plugs.
Never made the grid of a GP and he never designed a winning GP
engine. Ernest Henry is the man responsible for combining most the
XK engine’s features for the first time.

Moss, on the other hand, after a few drinks, wrote the number
41,000 on a napkin when he bet how high the first turbocharged
Liberty V-12 biplane could climb. Macready made it to 40,800 ft.
Good at math. The Liberty was based on the same type MB 1914 GP
engine that WO Bentley ‘‘borrowed’’ for Roll Royce to copy.

Nice video of one of the last Offenhauser/Goossen ‘‘hemis’’, In 1963
the Novi was making 742 hp, the equivalent of a +1100 hp 4.2. 8:1
compression and 35 lbs boost, 50 BTDC timing, no detonation on 80%
methyl alcohol.

Paul–
The original message included these comments:

In the ‘‘six degrees of separation’’ game, it almost all goes back to
Sir Harry Ricardo, doesn’t it? Also, Dr. Moss’ experiments with
turbosupercharging up Pike’s Peak, not to mention the entire
Offenhauser team of geniuses were so key to ‘‘modern’’ designs as we
see today.


PS
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In reply to a message from PS sent Wed 4 May 2011:

My compression is on spec as is my static timing and vacuum
advance. I used to run the highest octane available around here;
93. I’ve tried 91 and the car runs fine on it.

YMMV–
John Walker, 1969 E-type 2+2 - ‘Lola’
La Porte, Tex, United States
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In reply to a message from PS sent Wed 4 May 2011:

And THAT’S why I said ‘‘almost.’’

:wink:

Ricardo’s stuff was pivotal inasmuch as it was some of the first
widely-accepted ‘science’ on engine design, not that he was that
visionary.

I forgot to mention Henry, since I have great respect for his
efforts, which brought to life the domineering 1914 Peugeot GP
engines which of course, led to Miller/Goosen/Offenhauser et al,
running with those designs.

Ever visit the Museum of American Speed, in Lincoln? I near fell
over at the sight of that many Miller Engines! Heck, before that,
I’d never even seen a SINGLE real one!

http://www.museumofamericanspeed.com/Default.dlp

One of my fave designs of the multitude of OHV designs for the
Ford T and A engines (Carl, you’d LOVE these displays!) was the
curved, ball bearing ‘‘pushrods.’’

!!!

BTW: About a week ago, I saw a flatbed OTR semi with a load of
larrge radial engines on it and nestled amongst them was a Curtiss
OX-5 engine! 'Bout drove off the side of the road!

http://en.wikipedia.org/wiki/Curtiss_OX-5--
The original message included these comments:

Most of it pre date Ricardo and he dismisses the DOHC pent roof in
his 1923 book. He did however design the only DOHC four valve
engine. Ernest Henry is the man responsible for combining most the
XK engine’s features for the first time.
Moss, on the other hand, after a few drinks, wrote the number
41,000 on a napkin when he bet how high the first turbocharged
Liberty V-12 biplane could climb. Macready made it to 40,800 ft.


Paul Wigton, steward to a '60 DKW 1000 SP, Tweety, '63 FHC!
Keenesburg, CO, United States
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In reply to a message from Wiggles sent Wed 4 May 2011:

Wow, thanks for all the replies: overwhelming. My only
remaining question is: who is this guy RON you all talk about?–
Julian, '69 2+2 www.xkedata.com/cars/detail/?car=1R41300
Pasadena, United States
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In reply to a message from 1952gmc sent Tue 3 May 2011:

I’m really sorry but you couldn’t be more wrong…
High octane does not mean more power… nor will it make the car
happier or you better looking…
Now First please understand the octane required in your owners
manual is based on the old way of measuring Octane… The currant
method yields a lower number but it’s not a poorer grade of
gasolene…
Look up motor method (MM) and research method (RM) of grading
gas. (if you doubt me)
You have a hemi headed engine with an aluminum head… What that
means is that the octane requirement is not as high as less
efficent combustion chamber designs with cast iron heads… You have
a 9.0-1 compression ratio. Normally that wouldn’t require any more
than 87 octane MMxRM divided by 2
There can be flaws in your engine due to poor repairs or timing
errors… (advance retard mechanism in your distributor could be
off. (very likely based on the great preponderance of flawed
distributors I find when I put them on my distributor machine)
Why is it so darn hard to put a couple of drops of oil in the
distributor like the owners manual says you should? I digress.
At some point your head may have been milled and a sharp edge left
or milled so much compression has increased.
You may have carbon build up or the wrong heat range spark plug…
Your valves may be cut too much leaving a sharp edge to
preignite.
ETC… Higher octane may mask those flaws but won’t make more
power…–
The original message included these comments:

Get the highest octane at the pump you can get!
Regardless of the current engine compression, all of our gas
now tends to have a lower octane than these cars were built
possible for these cars. IMHO.
I believe that 91 is pretty standard here in California.


MGuar
Wayzata Minnesota, United States
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In reply to a message from jjbunn sent Wed 4 May 2011:

RON = Research Octane Number.–
The original message included these comments:

Wow, thanks for all the replies: overwhelming. My only
remaining question is: who is this guy RON you all talk about?


Paul Wigton, steward to a '60 DKW 1000 SP, Tweety, '63 FHC!
Keenesburg, CO, United States
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In reply to a message from MGuar sent Wed 4 May 2011:

True for old cars like the E Type, but for most modern cars higher
octane can in fact mean more power. That’s because the knock
sensing electronics adjusts timing to adapt to lower octane. The
owners’ manual will give you a recommended octane and a minimum
octane. Going higher than recommended won’t help, but up to that
point the car’s performance will improve.

Funny how old rules of thumb have a tendency to change like that.

Jerry–
The original message included these comments:

High octane does not mean more power… nor will it make the car
happier or you better looking…


Jerry Mouton '64 FHC 889791 ‘MIK Jaguar’
Palo Alto, California, United States
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In reply to a message from mouton sent Wed 4 May 2011:

Jerry
You are correct, modern cars do learn…
UGH!!!
Luddites of the world unite…–
The original message included these comments:

True for old cars like the E Type, but for most modern cars higher
octane can in fact mean more power. That’s because the knock
sensing electronics adjusts timing to adapt to lower octane. The
owners’ manual will give you a recommended octane and a minimum
octane. Going higher than recommended won’t help, but up to that
point the car’s performance will improve.


MGuar
Wayzata Minnesota, United States
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Good point, Jerry. Changing octane requires a change in the timing.
LLoyd

If, by sorcery, any citizen, of whatever rank or station, shall find him, her, or itself in the body, form, or husk of another already bound to these Rules, the Rules governing the actual body, form, or husk inhabited by soul or spirit shall prevail and be binding.
The Book of Rules, II, 412-9-11(d)----- Original Message -----
From: “mouton” jerry@moutons.org
To: e-type@jag-lovers.org
Sent: Wednesday, May 4, 2011 11:16:37 PM
Subject: Re: [E-Type] Grade of gas for E Type?

In reply to a message from MGuar sent Wed 4 May 2011:

True for old cars like the E Type, but for most modern cars higher
octane can in fact mean more power. That’s because the knock
sensing electronics adjusts timing to adapt to lower octane. The
owners’ manual will give you a recommended octane and a minimum
octane. Going higher than recommended won’t help, but up to that
point the car’s performance will improve.

Funny how old rules of thumb have a tendency to change like that.

Jerry


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In reply to a message from soothsayer1@comcast.net sent Thu 5 May 2011:

But… but… the car was in time when it left the factory…?>;-P

The original message included these comments:

Good point, Jerry. Changing octane requires a change in the timing.


Paul Wigton, steward to a '60 DKW 1000 SP, Tweety, '63 FHC!
Keenesburg, CO, United States
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…implying you were there, and you checked your watch when it rolled out of the factory door? Can you tell the jury…
Good grief, I’ve been on jury duty the past couple weeks and it is getting to me…
LLoyd

If, by sorcery, any citizen, of whatever rank or station, shall find him, her, or itself in the body, form, or husk of another already bound to these Rules, the Rules governing the actual body, form, or husk inhabited by soul or spirit shall prevail and be binding.
The Book of Rules, II, 412-9-11(d)----- Original Message -----
From: “Wiggles” vrooomie@gmail.com
To: e-type@jag-lovers.org
Sent: Thursday, May 5, 2011 9:27:26 AM
Subject: Re: [E-Type] Grade of gas for E Type?

In reply to a message from @soothsayer1 sent Thu 5 May 2011:

But… but… the car was in time when it left the factory…?

:stuck_out_tongue_winking_eye:

The original message included these comments:
Good point, Jerry. Changing octane requires a change in the timing.


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…implying you were there, and you checked your watch when it rolled out of the factory door? Can you tell the jury…
Good grief, I’ve been on jury duty the past couple weeks and it is getting to me…

Ah yes, also “assuming” the factory workers were diligent and it wasn’t
Monday or Friday or just after tea time at the local Pub!

Jury duty can be an exercise in seeing the worst in people. Not only
the accused but some of the jurors. Jury of my peers my behind!

Hope I never have to rely on a jury to decide my fate. I was called for
duty recently but got excused when they selected enough before calling
me. :slight_smile:

George Cohn
'70 OTSOn 5/5/2011 9:39 AM, soothsayer1@comcast.net wrote:


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In reply to a message from soothsayer1@comcast.net sent Thu 5 May 2011:

Excellent points, Schmeds.

Points. Get it?? Arf arf.

LOL!!!–
The original message included these comments:

…implying you were there, and you checked your watch when it rolled out of the factory door? Can you tell the jury…
But… but… the car was in time when it left the factory…?


Paul Wigton, steward to a '60 DKW 1000 SP, Tweety, '63 FHC!
Keenesburg, CO, United States
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In reply to a message from George Cohn sent Thu 5 May 2011:

Heh…I’ve often thought the same.

‘‘A jury trial? By peers of MINE? I am so fu***d.’’>;-P

The original message included these comments:

the accused but some of the jurors. Jury of my peers my behind!
Hope I never have to rely on a jury to decide my fate. I was called for


Paul Wigton, steward to a '60 DKW 1000 SP, Tweety, '63 FHC!
Keenesburg, CO, United States
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'Ya know, George, I just got a chance to interact with an “average American”. John and Jane Doe are just plain ignorant. Uneducated, uninteresting, and worst of all, uninterested. How in Gods name did this great country get such a huge number of uneducated, uncaring people? It actually scares me.
LLoyd

If, by sorcery, any citizen, of whatever rank or station, shall find him, her, or itself in the body, form, or husk of another already bound to these Rules, the Rules governing the actual body, form, or husk inhabited by soul or spirit shall prevail and be binding.
The Book of Rules, II, 412-9-11(d)----- Original Message -----
From: “George Cohn” gwcohn@simplybits.net
To: e-type@jag-lovers.org
Sent: Thursday, May 5, 2011 9:48:03 AM
Subject: Re: [E-Type] Grade of gas for E Type?

Jury duty can be an exercise in seeing the worst in people. Not only
the accused but some of the jurors. Jury of my peers my behind!

Hope I never have to rely on a jury to decide my fate. I was called for
duty recently but got excused when they selected enough before calling
me. :slight_smile:

George Cohn
'70 OTS


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