WORKHORSE - If you need a vehicle for all seasons, this might be a good contender, if not for the climate unfriendly fuel consumption.

One problem with the Jeep Cherokee, is the poor fuel economy. John Storm, being a conservationist, was none too happy about that. Because of his sustainability beliefs and knowledge of renewables, he decided it would be interesting to convert his tough terrain buggy to run on methanol.

Classic Jeeps like the Cherokee are some of the few older vehicles still in high demand today. A quick scan of used Cherokees will show that for a vehicle built in the 1990’s, these Jeeps are still worth a hefty chunk of change. This is for many reasons. First, its early popularity made these Jeeps cheap and easy to work on. Second, styling of the Cherokee has held up over time. Third, they’re safe and comfy vehicles perfect for household projects or first cars. But the final, and most important reason that these jeeps are so coveted, is the 4.0L in-line “straight six” AMC engine.

CHRYSLER'S 4.0L STRAIGHT SIX ENGINE

The 4.0L AMC inline six is known as one of Chrysler’s best engines. Dating back to 1986, its torquey 190 hp engine would commonly chug along for upwards of 300,000 miles. Over the course of nearly 20 years this engine was refined and tweaked before being phased out in 2006. The inline six has powered Cherokees, Grand Cherokees, Wagoneers, Wranglers, and even Comanches. We think its best known for its time with the Cherokee, but it remains a major selling point no matter what it’s been dropped in.

Unfortunately, the AMC 4.0L inline six was replaced by the 3.8 OHV V6, which originated in Chrysler minivans. We think we’re not alone in saying that a minivan engine doesn’t belong in a Wrangler. The Inline six survived until 2006, and it will go down in history as one of, if not the most legendary workhorse engine Chrysler has ever made. 

The 4.0 L is one of AMC's best-known engines. It was one of four AMC engines kept in production when Chrysler bought AMC in 1987. Chrysler engineers continued to refine the engine to reduce noise, vibration, and harshness. The last in the line of the AMC inline sixes, the 4.0 L is regarded as one of the best Chrysler 4x4 off-road engines. A Motor Trend long-term test of a 1997 Cherokee XJ noted "this long-lived OHV powerplant has a reputation for getting people where they need to go" as well as "much love expressed by owners for the torquey 4.0-liter/190-horsepower inline six." The engine is known for longevity, and can sometimes go more than 300,000 miles (482,803 km) without rebuilding. Also, the vibration dampener (harmonic balancer) usually gives out after 300,000 miles, where it is common for the rubber insulation to deteriorate where a service replacement is warranted. Described "as reliable as a block of wood" by Popular Mechanics and ranked first among "the ten best car engines they stopped making in the past 20 years," the 4.0 L should run 200,000 miles before a rebuild is even expected and it is also able to "suffer running conditions that'd kill most motors."

In 1991, a Chrysler multi-port fuel injection system replaced the RENIX system, and the intake ports were raised approximately 1⁄8 in (3.2 mm) for a better entry radius. Chrysler also enlarged the throttle body and redesigned the intake and exhaust manifolds for more efficiency, and the fuel injectors were replaced with higher flow units. The camshaft timing was also changed. The net result was an engine that made 190 hp (142 kW; 193 PS) and 225 lb⋅ft (305 N⋅m). Badging on most Jeeps equipped with this engine reads "4.0 Litre HIGH OUTPUT." The new cam profile combined with altered computer programming eliminated the need for an EGR valve and knock sensor, but made the engine more sensitive to alterations, especially where emissions are concerned. The OEM fuel injectors used with the Mopar MPI system (manufactured by Siemens) have been known to leak fuel especially with OBD-II where plugged catalytic converters are common which usually throws a P0420 code. 

METHANOL AS A FUEL FOR INTERNAL COMBUSTION ENGINES

Transportation of people and goods largely relies on the use of fossil hydrocarbons, contributing to global warming and problems with local air quality. There are a number of alternatives to fossil fuels that can avoid a net carbon emission and can also decrease pollutant emissions. However, many have significant difficulty in competing with fossil fuels due to either limited availability, limited energy density, high cost, or a combination of these.

Methanol (CH3OH) is one of these alternatives, which was demonstrated in large fleet trials during the 1980s and 1990s, and is currently again being introduced in various places and applications. It can be produced from fossil fuels, but also from biomass and from renewable energy sources in carbon capture and utilization schemes. It can be used in pure form or as a blend component, in internal combustion engines (ICEs) or in direct methanol fuel cells (DMFCs).

These features added to the fact it is a liquid fuel, making it an efficient way of storing and distributing energy, make it stand out as one of the most attractive scalable alternatives.

Methanol was traditionally made from wood, hence one of its common names, ‘wood alcohol’ (ethanol has similarly historically been termed ‘corn alcohol’).

For those applications where fuels synthesized from renewable sources make sense, methanol is more attractive versus for instance synthetic gasoline from a production efficiency point of view (well-to-tank).

MARINE FUEL

There is currently a growing interest in methanol as an alternative fuel, in the marine sector. The main reason for this is tightening emissions legislation.

For ocean-going vessels, the International Maritime Organization (IMO) has introduced Tier 3 NOX emission regulations, applicable in the so-called Emission Control Areas (ECAs), e.g. densely populated coastal areas. The allowable sulphur content of marine fuels is also coming down. This has led to a number of technologies being introduced to meet the more stringent regulations. Next to technologies that allow the continued use of heavy fuel oils (HFO) such as after-treatment systems, alternative fuels are also gaining traction. Initially, the focus was mostly on liquified natural gas (LNG). However, making provisions for a liquified gas storage system has substantial effects on ship design or retrofits.

For many applications, methanol is an easier fuel to handle as it is liquid at atmospheric conditions. It can also be made from the natural gas. A recent technical report from the EU’s Joint Research Centre concluded that LNG and methanol seem to be the most promising alternative fuels for shipping at the moment. This is partly based on methanol’s availability in most large ports.

Methanol’s suitability as a marine fuel is linked to its safety characteristics, excellent emissions compared to the bunker fuel or heavy fuel oils that large ships currently generally use and the fact that it is infinitely miscible in water, meaning that the double hulls of existing vessels can be modified to suit its storage. Double hulls are a necessity for ships carrying hydrocarbons since these fuels will not mix with water; the infinite miscibility of methanol instead means that these voids can be used to store the alcohol because with a tank breach the fuel will just dissolve.

Generally large marine engines are dual fuel diesel engines, directly comparable to liquified natural gas (LNG) dual fuel marine engines. Such engines have been developed for example for LNG tankers. However, methanol is much safer in use than LNG because it is a liquid, and although the (net) volumetric LHV is approximately 23% lower (15.9 vs. 20.5 MJ/l) methanol is more easily stored aboard a vessel without the attendant storage complications arising from cryogenic storage of a gas. A very important safety consideration is that the flash point of methanol is much lower than that of LNG; the flammability index of methanol is in fact much closer to that of diesel, and in the instance of a pool fire methanol is vastly more safe than either gases or liquid hydrocarbons.

The best results are obtained in dedicated methanol engines. Even the first generation of M85 engines featured considerable advances in power and efficiency, mainly thanks to the increased knock resistance of methanol. This resistance enabled them to reach MBT spark timing (Minimum spark advance for Best Torque) over a wide range of operation points and allowed the compression ratio to be raised to 12:1 and above. For example, the 1981 M85 Ford Escort produced 20% more power while being 15% more efficient relative to
its gasoline equivalent.

VEHICLE HISTORY (FICTIONAL)

John set about restoring the truck. This soon led to improvements, such as a composite roof with solar panels, to generate power for his equipment, and keep the batteries charged when not in use for long periods. Then John added electric drive, using fuel cells to convert hydrogen. The vehicle thus became a zero emission hybrid experiment.

The Jeep Cherokee is a compact SUV that was first introduced in 1984 as a revolutionary vehicle with a unibody construction and an all-wheel drive system [1]. Some of the best features of the Jeep Cherokee SUV all wheel drive classic vehicle are:

- It offers unrivalled on-road performance while maintaining most of the off-road ability for which Jeep is famous [1].

- It comes with a Selec-Terrain switch that has up to five settings to adjust the all-wheel drive system according to different terrain conditions [2].

- It has a spacious and comfortable interior with a high level of standard equipment, such as power steering, alloy wheels, anti-lock brakes, remote central locking, air conditioning, cruise control and an automatic gearbox [1].

- It has a distinctive and rugged design with a wide D-pillar and a long fixed rear side window with an optional flip-out section [3].

The Cherokee ‘XJ’ was a radically new vehicle for Jeep in 1984. Developed under AMC with Renault, the compact SUV had revolutionary design features for a car of this class.

While other American manufacturers were rushing out rebodied pickups, AMC’s Jeep introduced the Cherokee XJ with a unibody construction and well-damped suspension that offered unrivalled on-road performance while maintaining most of the off-road ability for which the company was famous.

The Jeep XJ utilizes front and rear beam axle components (live axles) as opposed to an independent suspension. The live axle configuration offers advantages in off-road capability and performance at the expense of some on-road comfort and driveability.

ANTHROPOLOGIST - John Storm is near obsessed with the development of homo sapiens from the australopithecines, necessitating several Safari missions in Tanzania, South Africa. His trusty Jeep Cherokee is ideal transport where the going is rough. 

These were always highly equipped vehicles, especially in the UK where the value prospect was a big part of their market entry strategy. The 1993 UK-spec Cherokee Limited undercut rivals like the Isuzu Trooper and the Land Rover Discovery, while offering greater levels of standard equipment. You got power steering, alloy wheels, anti-lock brakes, remote central locking, six speakers, air conditioning, cruise control and an automatic gearbox all for free.

Electric everything of course: all four windows, the door mirrors, the front seats, and naturally the aerial for that impressive stereo. Metallic paint was a cheap option, and even leather seats were a very reasonable £1000.

The Jeep Cherokee SUV all wheel drive classic vehicle was a great choice for anyone looking for a versatile, reliable and stylish vehicle that can handle any road challenge, between the 1980s and 1990s. But is now very rare indeed.

The later iteration of the 4-litre petrol unit featured Chrysler fuel injection and is generally referred to as the high-output engine, because of its hike in power from around 175bhp to 190bhp. Torque remained roughly the same at 225lb.ft but at a significantly higher peak. This engine saw service from 1991 and proved to be exceptionally reliable, while its revised electronics were easier to diagnose when issues did crop up.

One of the best places to buy a quality classic Jeep Cherokee, is near Rome in Italy. Another is California, USA. Where they are very popular with the trendy elite.

[1] https://www.classic-trader.com/uk/cars/search/jeep
[2] https://classicsworld.co.uk/guides/jeep-cherokee-buyers-guide/
[3] https://www.autoevolution.com/news/jeep-s-awd-and-4wd-systems-explained-106633.html
[4] https://en.wikipedia.org/wiki/Jeep_Cherokee
[5] https://en.wikipedia.org/wiki/Jeep_Cherokee_(XJ)

[1] https://www.classic-trader.com/uk/cars/search/jeep
[2] https://classicsworld.co.uk/guides/jeep-cherokee-buyers-guide/
[3] https://www.autoevolution.com/news/jeep-s-awd-and-4wd-systems-explained-106633.html
[4] https://en.wikipedia.org/wiki/Jeep_Cherokee
[5] https://en.wikipedia.org/wiki/Jeep_Cherokee_(XJ)

ABOUT JOHN STORM'S JEEP

JEEPY - The Jeep Cherokee that Professor Douglas Storm gave to John - in need of much work. Previously used in connection with an ocean research project, this vehicle was fully loaded with leather seats and metallic paint job. The Professor did a lot of miles in this Safari wagon.

The straight-6 engine offers the smoothest way to deliver plenty of bottom-end torque. That's why BMW has stuck with the straight-6 for so long in its luxury sports sedans and coupes.

The roots of Jeep's inline 6-cylinder lump that powered the Cherokee and Comanche in the late 1980s, and then the Wrangler and Grand Cherokee in the early 90s, goes all the way back to 1964 and the American Motor Company (AMC). Jeep's engine was more powerful than its Japanese V6 contemporaries. It was also relentlessly durable while featuring plenty of torque low down in the RPM range, making it perfect for off-road workhorses. When it was laid to rest in 2006, output had reached 190 horsepower and 235 lb-ft of torque.