Re: [Chrysler300] Can't Get Good Gas Anymore?
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Re: [Chrysler300] Can't Get Good Gas Anymore?
- From: lettercars@xxxxxxx
- Date: Sat, 30 Jul 2011 11:52:41 -0400 (EDT)
Hi All:
The hemispherical (more properly---I guess---spherical segment) combustion
chamber engine is more---perhaps much more---tolerant of lower octane
fuel. The main reason is that the fuel air mixture is compressed much more
evenly than in the wedge chamber engine where there are uneven, tight "squish"
areas to cause premature heating and resulting pre-ignition. My personal
experience with this characteristic involved running my 300C on Sunoco 190
in the '60's with no trouble at all--even with 10:1 compression ratio
resulting from a .040" head shave. Car ran good, too. Lots of full throttle
runs, pushing the "2" button when the speedo said 60 mph. Of course the ole
torqueflite wasn't quite as happy about that as the engine was. Ah, those
were the days!
300ly, Gil Cunningham
In a message dated 7/29/2011 7:53:57 P.M. Eastern Daylight Time,
chesnutt@xxxxxxxxxxxx writes:
Hi George and Tony,
Re: 1957 300C
Fuel economy at 4,000 feet could be improved by using the Chryslers
Altitude Package which contains one size leaner metering rods Cater No. 75-1180
as per a letter I have from E.P. Carr, Car Engineering, Chrysler
Corporation. Our 300C has these rods since 1958. I have 10 1/2 compression and no
problems.
John Chesnutt, Portland, OR
-----Original Message-----
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of George McKovich
Sent: Friday, July 29, 2011 6:30 AM
To: Tony Rinaldi
Cc: Chrysler 300 Club
Subject: Re: [Chrysler300] Can't Get Good Gas Anymore?
Tony
This is a very interesting analysis. Do you have anything to add when one
considers altitude? I live and much of my driving is at or about 4,000 feet
elevation.
Thanks
George
Sent from my iPhone 4
On Jul 28, 2011, at 7:49 PM, Tony Rinaldi <awrdoc@xxxxxxxxx> wrote:
> Hi To All,
>
> Leaded High Octane Fuel is no longer readily available.
>
> {Before you delete this message, here is the bottom line: use colder
spark Hi George,
> plugs with today's bad gas}
>
> Gone are the days of the 99 octane or better gas.
>
> Newer unleaded fuels burns hotter. Add ethanol and the fuels burn even
> hotter.
>
> What do we do with our high compression, high performance engines? They
> burned hot with the gas they were designed to run on. They burn even
hotter
> with today's pump gas.
>
> Short of using racing gas and octane additives, we use 93 octane, if we
can
> get it. And we retard the spark. This eliminates detonation, associated
with
> lower octane, that is destructive to the engine internal parts.
>
> But when we retard the spark to avoid pre-ignition, we further increase
the
> heat in the engine especially in the exhaust manifolds. The retarded
timing
> will allow the majority of the heat (Flame) to blow out of the exhaust
> instead of keeping it in the cylinder to produce power.
>
> Too hot of a heat range of the plugs, usually recommended for our
engines,
> indirectly leads to a runaway pre-ignition condition that can increase
> engine temperature. We then have to retard the spark even further
creating
> more heat in the exhaust manifolds.
>
> Heat from the combustion chamber escapes through the exhaust gases and
the
> side walls of the cylinders.
>
> Ever wonder why we repeatedly have exhaust manifold leaks or we have
boiling
> gas in the bottom of our exhaust heated crossram carbs on really hot
days?
>
> We are generally limited in the availability and selection of spark
plugs.
> This means that we are using plugs with heat ranges that were good for
> 1960's gas not today's gas.
>
> Not sure how well this subject has been covered in the past, but my race
> mechanic shared some of the work around techniques that the NASCAR people
> are using to deal with the elimination of leaded fuels in recent years.
>
> In hotter heat range plugs, the tips remain hotter between firings and
start
> acting as glow plugs. The cylinder mixture will tend to prematurely
ignite.
>
> The use of newer spark plugs with colder heat ranges is a good option to
> help relieve low octane detonation. These plugs fire with the same
intensity
> but have more insulation. This dissipates the heat from the tips quicker
> thus eliminating pre-ignition.
>
> A heat range refers to how much heat a spark plug is capable of removing
> from the combustion chamber.
>
> NASCAR is so big, spark plug manufacturers listen to them and are
> manufacturing colder heat ranges.
>
> The more internal modifications that are done to make our engines more
> powerful, the more heat the engines generate.
>
> Domestic plug manufacturers use designations where the higher numbers are
> hotter heat ranges and the lower numbers are cooler.
>
> NGK numbers are the opposite. 2 is the hottest and 12 is coldest heat
range.
>
> The NGK R5670-6 V-Power Plugs (NGK Stock #2746) for Big Block
413-426-440
> (Raised Deck) with iron heads or Standard NGK Plugs XR5 (#3339) are
close to
> the heat range of an Autolite 85 which is the replacement plug for the
> original A32 for wedge crossram engines. There are no heat range choices
for
> the Standard NGK XR5 plugs. The R5670 V-Power series of racing plugs do
have
> colder ranges however.
>
> The rule of thumb is to use the coldest heat range plug that you can run
> without fouling. NGK V-Power plugs are known for not Fouling readily
> especially with the projected tips on the R5670s. Reference the following
> quotes below about NGK V-Power plugs:
>
> "These NGK V-Power spark plugs offer economical performance for nearly
any
> automotive application, and are the only plugs with NGK's V-Groove
> technology. They enhance ignitability, lower the voltage requirement of
> ignition systems, and have strong anti-fouling characteristics, while
> improving fuel mileage and acceleration performance. The V-Power plugs
also
> are highly durable against electrical and chemical wear, making them a
> long-life replacement plug. Because of the V-Groove, the spark occurs at
the
> edge of the center electrode. So heat is not absorbed by the electrode
> itself. This allows the flame kernel to expand quickly and efficiently
for a
> complete burn and great performance." strokerengine.com
>
> "NGK's V-grooved center electrode moves the spark to the outer edge of
the
> electrode for improved ignitability in all combustion chamber conditions.
> This configuration is especially helpful for throttle responsiveness,
> quicker corner exits, and more power on the bottom end in a drag race
> engine. The high-purity alumina silicates used in the insulators of NGK
> Spark Plugs helps keep the spark plug tip warm enough to burn off
deposits
> at low-speed, yet still be able to transfer enough heat during high-speed
> operation to prevent detonation and pre-ignition.: NGK
>
> "I have two cars with 440 engines and one car with a 360. Both 440
engines
> were rebuilt and placed into service with Champion plugs in them. Both
> engines fouled atleast one plug before they even had a hundred miles on
> them. At the advice of a friend that owns a parts store, I went to NGK
> V-Power plugs. No more fouled plugs. And my 360 that I rebuilt 6000 miles
> ago also has the NGK V-Power plugs and hasn't fouled any." Mopar
Enthusiast
>
> Check your exhaust manifold temperature before with your existing plugs
once
> the engine is at operating temperature after a good run. You may want to
> check and record other areas of the engine as well as take note of the
> temperature gauge.
>
> Harbor Freight sells a laser heat gun for about $20.
>
> A good plug to consider starting with is one that is 2 heat ranges colder
> than you are running now. NGK R5670-8 (#3354) V-Power plugs should do it.
> About $20 for 8. They come in packs of 4. Then advance the timing.
>
> If your engine has been rebuilt with lower compression, consider trying
the
> NGK R5670-7 (#2891) (one heat range cooler) to make up for the lower
octane
> unleaded fuel. Then advance the timing.
>
> If you only can get fuel that is lower than 93 octane, add one more heat
> range cooler than recommended above.
>
> After you have installed your cooler plugs and advanced the timing
> appropriately, check the exhaust manifold temperature in the same spot,
as
> well as your other reference points, once the engine is at operating
> temperature after a good run.
>
> The temperatures should be less and the drivability of your car should be
> better.
>
> My engine was built with larger cubic inches. I went to a NGK R5670-9
> (#3913).
>
> Do you expect a different result by doing the same thing over and over
> again?
>
> Been there done that!
>
> Did something different this time. It worked.
>
> Tony Rinaldi
> 300-F Conv't
>
>
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