Mexican Engine Heads

Whoa, a lot of messages in a short period of time. I’ll try to respond all of them one at a time.

The most powerful VAM 282?

That depends on what you base your judgment on.

The most powerful factory VAM 282 engine was the 1979-1981 4.6 / X unit. It had an output of 172 net horsepower at 4,200 RPM and a net torque of 222 lbs foot at 2,200 RPM. Compression ratio was 8.5:1. This means a 40 net horsepower increase over the standard version.

This engine was installed in the 1979 American 06/S and 1980-1981 Rally GT models, both as limited editions.

The American 06/S in a few words was a base model two-door Concord sedan with the accessories and treatment of the 1978 Concord AMX. It is in fact the closest Mexican equivalent to the AMC Hornet SC/360 model. Only 499 units were produced.

The Rally GT can be described as a top-end performance version of the AMC Spirit GT coupe. 500 units of this model were produced per year. I own a 1981 unit. Unfortunately, the original engine was long-gone but slowly I have been able to get it back to its former glory.

Despite these two models being the only products of the company with this engine installed from the factory, some VAM dealerships did offer it as an optional package. A friend of mine from Veracruz has a four-speed 1981 Rally AMX (Spirit GT, regular version) with the 4.6 / X installed from the dealership that originally sold it.

Still in regards to factory-installed engines, the second most powerful VAM 282 was the 4.6 / SX unit. This engine was installed in the 1979 VAM Pacer X. This model was not a cosmetic optional package but a limited edition with a serious performance focus. Only 250 units were produced. Unfortunately, VAM did not make any engine output tests of this version, either due to the low volume of only 250 engines (no other VAM car ever incorporated it) and also due to shortage of time since the company had to focus on tests of regular production high volume models.

VAM engineers reported this engine had an estimated 150 net horsepower at 4,000 RPM. It can be described as a lesser version of the 4.6 / X. The only real difference between both engines was the camshaft. The 4.6 / X version had the performance 302 degree camshaft while the 4.6 / SX version had the regular production 266 degree unit.

The third most powerful version of the 282 would be the regular-production first-generation of the line. It was produced from 1971 through 1973, installed in the 1971-1973 Javelin and 1972-1973 Classic (Matador) models. Its main feature was a high compression ratio of 9.5:1. The advertised horsepower was a gross rating figure (200 hp). VAM engineers have reported the engine output in net rating in an estimated 145 net horsepower at 4,400 RPM. The only drawback of this engine was that the 1971 and 1972 units still had the 232/252 engine head with small valves.

However, there might be another 282 engine version that could be more powerful than the 1979-1981 4.6 / X units.

That would be the 1971-1973 Go Pack 282. In a few words this was the ORIGINAL 4.6 / X version, which was later updated and adapted to the environmental and legal conditions of the la 70s and early 80s.

The core of both Go Pack and 4.6 / X engines was the 302 degree camshaft. Their differences were four: 9.5:1 compression ratio for the Go Pack 282 against 8.5:1 of the 4.6 / X, ported head on the Go Pack 282 instead of the semi-ported unit of the 4.6 / X (both having large diameter valves), four-barrel carburetor in the Go Pack 282 versus the two-barrel of the 4.6 / X and finally top-end power headers (5,000 RPM) on the Go Pack 282 while mid-range power headers (3,500 RPM) were used in the 4.6 / X.

The Go Pack 282 was never installed from the factory in any VAM car, which is the main reason why no official performance or output tests were ever conducted. At all times it was available as a dealership option. However, VAM engineers did report numbers. The estimated output of the Go Pack 282 was 185 net horsepower against the 145 units of the stock 1971-1973 9.5:1 compression ratio 282. The estimated gross horsepower figure for the Go Pack 282 is 260 horses.

I am not entirely sure if this would be the most powerful VAM 282 engine ever, since a VAM mechanic I know who has prepared several VAM engines for performance insisted that the 4.6 / X would be the most powerful unit ever, mainly due to the improved machining and construction of VAM engines in the late 70s. The 4.6 / X did have some advantages in the form of a high-acceleration modified electronic ignition instead of the points and fan clutch (which means a better cooling system).

If the 185 net hp figure is correct, it means 13 horses of the Go Pack 282 over the 4.6 / X.

I will respond the remaining messages as soon as I have the time.

In the meantime, stay tuned.