By J. Gathmann. Used by permission.
An often neglected aspect to the history of the Chrysler 3.3L V6 engine is its brief use in racing with the Shelby Dodge Can Am circuit.
In 1989, Shelby tried to bring back the Can-Am series, using the 3.3L V6 (not yet offered to the general public) in a special racing configuration making 255 HP — this was the same year that the Viper concept was showed to the public.
Originally the plan was to produce two versions of this car, a 255 hp version and a 500 hp model, the 255 hp version being the entry circuit. The cars were designed to be a cheap way for more people to enter auto racing. Since all the cars were identical, the winners were to be the people with the best talent, not the team with the biggest pockets. The engines had Shelby seals on them and could only be repaired by Shelby's shop, ensuring that all the engines stayed mechanically identical.
Allpar note: former Shelby employee Joel Jackson wrote about problems which prevented the circuit’s success. Some SCCA people objected to the idea of SCCA selling cars; and, Jackson wrote in his book, Fast Days, the Chrysler people altered the body and made it less attractive and increased drag, while Shelby used designs which had already been improved or substandard parts. The result was a car slower and less durable than the original prototype, though still impressive.
Only 100 of these 3.3s were ever built. Of these 100, 76 were put into Shelby Can-Am cars (the only 76 that were ever sold). No significant amount of spare parts were produced, and the unsold engines were used for parts/spares. Shelby specific parts, such as the upper intake manifold, were never made available to the general public.
According to a small article in the USA Today (in 1989), these cars were making 250 hp [stock 3.3 engines versions introduced in 1990 produced 150 hp] and hitting 160 mph on the track. Devan Standish said the engines, when modified, can produce over 340 hp at the flywheel, and many have been bored to 3.5 or even 3.8 liters; stock, Bob Johnston has seen them dyno-tested at 300 hp at the flywheel.
The circuit did not catch on for a combination of reasons. First, the car arrived in pieces, for about US$35,000, and had to be put together and kept up, which was cost prohibitive for a lot of people due to the amount of man-hours involved (the engines also had to be serviced by Shelby). Cost alone did not doom the Can-Ams, though. Lack of a fan base or sponsors, lack of media coverage, and having only 76 cars in the circuit, all hurt the circuit's ability to thrive. Since the circuit did not do well enough, the 500hp version of the circuit never came to exist.
Now as to how the engine is similar (and different) to a stock Mopar 3.3:
The engine itself was not that far from a standard-production 3.3. It had a special upper intake manifold, a throttle body with twin intakes (pictured), and a different version of the Mopar 3.3 PCM which had this engine redlining at 6800 rpm.
Some aspects of the Shelby engine were later used in standard-production 3.3s. The complex distributorless ignition system was later toned down for use in normal 3.3s. The Shelby DIS, like the current Chrysler version, uses three timing signals, one for each pair of cylinders. Unlike a normal 3.3, however, this computer system could fine tune the timing retard for each pair of cylinders individually. Thus a Shelby 3.3 could retard the timing for one pair of cylinders and not the others, where as a normal 3.3 will use the knock detector to change all three timing signals at the same time.
Internally, the engine uses forged pushrods, J&E Mayle pistons (which make 11:1 compression ratio), a forged crank, and a slightly different cam. The valves were slightly bigger, and the heads were ported and tuned by Shelby's shop. The exhaust system is pretty much just high diameter, low restriction tubing with larger exhaust valves. Fuel used is 100 octane (unleaded), however I have been told that some of these engines did run higher octane fuel at the track.
The engine was mated to a 4 speed manual transmission and the complete car (chassis, engine, trans, body) weighed about 1,820 lbs.
After the circuit dried up in the mid to late 1990s, 29 of these cars (complete) and much of the few remaining spare parts went down to South Africa to start a circuit down there - Vodacom Sports Prototypes (VSPs). This circuit more recently stripped these cars of their body and engines, and now uses a new South African-made body and a Nissan V6 engine.
A couple of years ago, a guy emailed me saying he had about 20 complete unrestored (used) Can-Am Shelby-Dodge 3.3 engines for sale, some various Can-Am body and brake parts, etc. I was not sure if it was legitimate (it sounded almost too good) so I passed up the offer. After finding out that the circuit no longer uses the Dodge engines (which are over a decade old by now and starting to get tired from racing use) I believe the guy was for real. He did email me a picture (below) of a room full of his engines for sale. This suggests that the engines are around.
The number of surviving Shelby Dodge Can-Am race cars left intact (with the original Mopar engines) appears to be down to 49, assuming all the ones which stayed in the US are still intact. Sadly, they are becoming fewer and fewer. It would be especially nice but extremely unlikely, if Chrysler started selling some of the Shelby 3.3 parts like the upper intake manifold.
Here are some various links about these cars for anyone seeking further information.
If anyone has further information, especially on the mechanical aspect of these engines - please distribute that information to Allpar.
Allpar’s main racing page / 3.3 liter engines page
All Mopar Car and Truck News