Pity the poor American inline six. It just never got any real love or attention, unlike the sexier V8s, which were such a cheap way to get a shove in the back. It was perpetually relegated to powering the cheap strippers that thrifty old folks bought because they were done with the cheap thrills, or never wanted any. Or young families who truly couldn’t afford otherwise. Or taxis and fleets. The six had no sex, with only a couple of exceptions.
This blue Aspen wagon has one of them, the 225 Super (slant) Six. Of course, by the late seventies, it wasn’t exactly all that super, due to smog controls. But in its day, it was the only American six that even tried, as all the rest had succumbed to the torpor of the times. And for that, it deserves some love; maybe just the platonic kind, though.
The only American manufacturer that took sixes somewhat seriously in the 50s was AMC. Their compact Rambler was all about economy, and even after their new V8 arrived in 1957, sixes powered the overwhelming majority of them. In addition to the 125 hp base version of their 196.6 CID six, there was also a “power pack” version with a two barrel car packing a mighty 135 hp (gross, in both cases). It was still no hot rod, which would have been totally out of character for a Rambler six. A Rambler six with “scat-back getaway”? Fat chance of that.
After AMC’s excellent new 232 six appeared, it too got a two-barrel version for a few years, through 1967. Power was 155 gross hp, a ten hp bump from the one barrel version. This one got a bit closer to “scat-back getaway”.
(update: AMC went on to develop this six into the most powerful OHV American six, the Jeep 4.0, with up to 190 (net) hp in the HO version (1991 – 2006)).
But Rambler’s two-barrel sixes couldn’t hope to catch this scalding slant six. Chrysler’s new 1960 slant six was decidedly peppier than average, in both the 170 and 225 cubic inch versions, thanks to good breathing from a full 12 port head and long intake runners. They were rated at 101 and 145 hp (gross) respectively.
But Chrysler’s engineers knew the slant six had lots more performance potential than that, and they developed the 170 Hyperpak kit for the 170 inch LG (low block), that included a Carter four barrel carb on an aluminum intake manifold with even longer runners, and a split exhaust manifold. The Hyperpak was only sold as a $400 (expensive) dealer-installed kit, as there were no further internal changes to the little leaning tower of power, which was more than up to a 50% bump in power.
The 170 Hyperpak was rated at 148 (gross) hp, and was specifically designed to make the Valiant unbeatable in NASCAR’s new compact class. It’s generally accepted that it produced somewhat more than that on race day, considering the 130 mph top speed that the Valiants pulled, running at some 6600 rpm. They utterly dominated the series, leaving the Falcons, Larks and Corvairs in their snarling inline six exhaust chorus. (Full story here).
The Hyperpak was designed for racing, the slant six equivalent of Chrysler’s hemi for the big NASCAR cars, although it was quite tractable on the street, and some folks got a kick out of walking away from V8s at street-light drag races with their Valiants.
In 1964, Chevrolet made a very brief, and somewhat odd and half-hearted effort to inject a bit of zip into its 230 cubic inch Turbo Thrift six. Optional in the Chevy II and Chevelle, it was more about the visual, what with its chrome valve cover and air cleaner, than any serious grunt. It got a slightly more aggressive cam, but still kept the one barrel carb and attendant manifolding, the result being a bump from 140 to 155 (gross) hp. Given that the 283 V8 was also available on the Chevy II that year, the timing was odd. Where was this in 1962? By 1965, it was gone again, undoubtedly for lack of interest. More info here.
Pontiac’s SOHC six, based on the Chevrolet 230 and 250 cubic inch engines, was of course the great exception to Detroit’s dismissive attitude to sixes. This was classic John DeLorean, who was perpetually trying to inject genuine Euro-tech into his Pontiacs, like the rear transaxle and independent rear suspension on the 1961-1963 Tempest. His next act in that vein was the 1966 Sprint six, which in four-barrel form packed 207, 215, and ultimately 230 (gross) hp.
His timing was off, as during the mid sixties all anyone seemed to care about was big V8s. They all grabbed the real GTO, not GeeTO, Jr. After three years, the OHC six saga was over, but not before showing those Americans not completely besotted with big inch V8s what a sweet engine a properly set-up inline six could be. And of course, just as Pontiac ditched their OHC six, BMW brought out theirs. In the 80s, Pontiac tried to re-invent themselves as the Walmart BMW, but by then the six cylinder gravy train was long gone.
The inline six seemed destined to wheeze along into the seventies, losing what little power it had to ever more restrictive emission regulations. But Chrysler, that bastion of creative engineering, decided to fight the forces of EPA-entropy, and that the solution was to give the 225 slant six a mild hot-rod going-over.
The result was the 1976 Super Six, with a new intake manifold crowned by a Carter BBD two-barrel carb, a slightly less restrictive exhaust, some careful ignition timing calibration, and a less-restrictive air cleaner. Not exactly heady stuff, but enough to bump rated power from 100 to 110 net hp, and a similar increase in torque from 170 to 180 ft.lb.
Doesn’t sound like much, but an extra ten genuine real net hp in that time of strangled engines was a bit of sunshine, especially for slant six aficionados.
Needless to say, every junked Aspen or Volare with the Super Six long ago gave up its manifolds and carb to every slant six lover looking for an easy bolt on power increase. It’s a well engineered package, and the obvious easy and first step to take in making any slant six livelier.
Ideally, the Super Six would have a proper manual transmission backing it up, like a well-spaced four speed; better yet a fiver. But that was not to be the case; the Super Six, at least in 1979, was only available with the Torqueflite automatic. The one-barrel 225 could also be had with either a floor shifted three speed or four-speed, whose fourth gear was an overdrive. There is no joy in Mudville, which is an apt name for Eugene this wet winter.
I spoke to this car’s elderly owner when I shot it two years ago, and I’m struggling to remember the details. he’s had for some time, and was a long-time charter member of the slant-six fan club. He favors thrifty, long-live transportation, and this wagon has provided him with many years worth of that.
But now it’s been sitting on the front corner of this large gas station, for a couple of weeks now. I’m guessing it’s changed owners, and the new one likely works here. Well, odds are it will give him some more years of service too. I rather doubt he or she knows that under the hood is the last American inline six that had some aspiration to performance. Super Six? 110 hp? Well, it was the late seventies, and everything is relative.