We’ve bestowed a lot of love on the slant six hereabouts, especially the legendary Hyper-Pak version. It’s been portrayed as a V8 killer and able to leap tall buildings. But we’ve never had a proper vintage test. Just how fast was it, in stock form, rated at a lofty 196 hp for the 225 cubic inch version? And to top it off, the 225 cubic inch (3.7 L) engine used for this test had the fairly rare aluminum block, making it 50lbs lighter than the smaller iron 170 inch (2.8 L) version.
Did it live up to its much-hyped reputation?
Before we dive in, lets refresh our memory banks about the origins of the Hyper-Pak: In 1960, NASCAR launched a new series for compacts. All three of the Big 3 prepared entrants, but the Plymouth Valiant simply walked away from the Corvair and Falcon, thanks to a special high-output version of its 170 cubic inch slant six, which was inherently more powerful than the rather weak-chested Falcon 144 six and the Corvair’s initial 140 inch flat six.
The modifications for racing were quite extensive, with higher compression, a racing cam, improved valve train, and a really wild ram intake with a Carter AFB four barrel carb. The racing versions also had steel tube headers and of course a large diameter open exhaust. That all explains its ability to turn some 6600 rpm and hit 130 mph.
Since the Hyper-Pak kit was a package of bolt-on parts available over the counter, it did not have the internal changes as the racers did. The cam was not as wild, compression stayed stock, and the exhaust was a split cast iron manifold exiting through a single exhaust with a high flow muffler. It was rated at 148 hp on the 170 engine (101 hp stock) and 196 on the 225 (145 hp stock). That put the 225 squarely in V8 territory, but of course it was lighter, especially so with the optional aluminum block.
Update: there’s some question as to whether that 196 hp rating for the 225 Hyper-Pak applies to the version as used here, which has stock compression. Some sources suggest that it was rated at 196 hp with the high-compression pistons that were originally part of the 1960 170 Hyper-Pak. There’s some pretty good evidence that the 1960 H-P included the pistons, but clearly the 1961 kit didn’t. So it is possible that the 225 H-P as tested here would have had a somewhat lower output.
Among other things, what makes this test interesting and a bit different is that the car, a Lancer station wagon with the optional TF automatic transmission was not changed, only the engine was. This gave a much more direct comparison of the three engines, and was quite unlike any other test I’ve seen like that.
As to the Lancer, it was of course a mildly modified Valiant that arrived in 1961 to give the poor Dodge dealers who had lost the Plymouth franchise the ability to sell a compact. Its styling was toned down some from the Valiant, which was generally seen as a good thing. The Lancer wagon was praised for its good interior room despite its compact external dimension, good handling, a comfortable seating position, and…well not much else was said actually, as the test really focused on the engines and their performance.
Not surprisingly, the 170 cubic inch version was the laggard of the three. Only a year earlier, it had been widely praised for its superior power and acceleration, but once the 225 was made available in 1961, everything is relative. The 170 had to be pushed hard, which drove up fuel consumption. The testers recommended a three-speed manual and a higher numerical 3.55 rear axle if one wanted the 170.
The regular 225 was of course significantly livelier, and yet its fuel consumption was roughly the same as the 170’s. The 50lbs of weight reduction on the front end reduced understeer. It went about its business with less strain, noise and effort. A decidedly better choice.
The Hyper-Pak yielded on average two mpg less, but its performance was “almost as effective as installing a big V-8 under the hood”. Top end speed in the quarter mile was improved by a sold seven mph to 74 mph. the ET in the 1/4 mile dropped from 19.8 to 18.5 seconds. The 0-60 time dropped from 15.9 to 11.8 seconds. All very significant improvements, and the text suggests that the 1/4 mile time might have been bettered some by holding the automatic’s shift points to 6000 rpm.
Here’s all the stats. I was curious as to how the Hyper-Pak stacked up against some other cars of the early ’60s, with hotter sixes or a small V8.
I guess I was expecting a wee bit more from the Hyper-Pak, but it acquits itself quite well against these and others. I was a bit surprised that it wasn’t faster than the ’62 Corvair Spyder, with its much smaller 150 hp engine. Yes, the automatic probably sucked a few of the slant six’ ponies, but then the Torqueflite was generally was considered to not be a handicap, even against 4-speeds. That might have been a bit more the case with the big V8s; I suspect a 4-speed behind the H-P would have done somewhat better.
Of course the H-P slant six still had a significant amount of potential left. M/T had a ’62 Valiant project car a few years back (2016) that was optimized for drag racing and it clicked of mid-14 second ETs.
Related CC reading:
Automotive History: When The New 1960 Compacts Went Racing – The 130 MPH Valiants Cream The Corvairs And Falcons
Curbside Classic: 1961 Dodge Lancer & 1962 Dodge Lancer GT – How Are We Gonna Make You A Little Less Weird?
The Hyperpak “kit” from the dealer did have the internal parts. The kit had high compression pistons, plus a different clutch, along with the parts you mention in the write-up.
PS: back in 1976, my 65 Valiant NHRA stock eliminator car (Z/SA) with a 170 would run mid 16 sec 1/4 mile times
Yes and no. I’ve done a fair bit of looking into this issue and here’s what I’ve come up with. The Hyperpak was of course originally a racing-oriented package for the 170 in 1960. Those engines did have high compression pistons (Jahns, I believe) and some internal valve train parts. To the extent the Hyperpak was sold to the public in 1960 (which was probably very limited) it did presumably come with the HC pistons.
But it apparently changed for 1961, as the Hyperpak became more widely available also for the 225 and more street-friendly. The cam was not as wild, allowing it to be used with the automatic. And no pistons or other internal engine parts were included. That’s not to say that folks couldn’t choose to add them on their own.
It does raise the question of the hp ratings for the 225. I’ve seen that number (196hp) correlated with the HC pistons; others not. It’s possible that the actual number would have been lower with the stock pistons, as in this test. That would help explain why it wasn’t quite as quick as I might have expected.
The reality is that like many things from that long ago, some details are now shrouded in mystery. But it’s pretty clearly established the 1961 Hyperpak package as sold over the counters was all bolt-on and did not include pistons.
I just took my ’62 Valiant wagon on a 250 mile fall drive yesterday into the forests and mountains of PA.
I do not have the hyperpak on it, but it was sure fun.
I always wondered if there is any current history on the Nascar Valiants? I would sure like to find one if it was salvageable and or had any nascar parts left on it.
In your comparison table at the end, I am also a little skeptical of the test results on the Pontiacs. Test vehicles provided by Pontiac in those years were often tuned in mysterious ways by Royal Pontiac before the magazines got them. For example, I wonder about whether the 4 speed alone should have been enough to overcome the Lancer’s 30 horsepower advantage over the 4 cylinder Tempest. The lightest Tempest would also have outweighed the Lancer wagon by no less than 100 pounds.
Facelift-type designs often don’t come off as well as the originals, but I have always liked the looks of the Lancer quite a lot.
Autocar in the UK tested a Valiant 170 in 1960. It had an automatic and a test weight of 3,157 pounds, yet it reached 60 from a rest in 17.7 seconds. I’m not sure that the numbers from this test are good for much more than comparing these three engines to one another.
https://www.flickr.com/photos/triggerscarstuff/12369372393/in/album-72157640642145295
Can’t help but think the Dodge wagon tested here had a 170 that was a bit off, because the UK test car would’ve been using what I gather was not much better than slightly flammable drain water – in the form of the standard petrol they filled it with – in the Britain of 1960.
The numbers for the 170 do seem a bit low. A ML road test of a ’60 Valiant with the 3-speed manual yielded a 0-60 time of 16.7.
In Argentina this car was called Valiant 2. One of the first Chryslers here.
I wonder how the Hyper-Pak version would have done against Chrysler’s Australian Hemi 6 of 245ci? I think the 265ci version might be the winner.
Standard 245 was 167 HP, so no. But standard 265 was 205 hp, so maybe yes.
Definitely yes would be the the real hyper pack 265 with triple Webers and extractors (and other bits) at 302 hp, which was a factory option, but keep in mind those engines are more than half a liter up on a 225.
The Australian “hemi” six was a more modern engine with a better-breathing head.
Outstanding powertrain packaging, and choices. Too bad, about the polarizing styling. Borderline, dumpy. I personally find the styling too gimmicky (and faddish then), to want to own one.
Today when someone says a car is ugly they are mostly just looking at the front. Think current BMW and Lexus These Valiants are ugly front, back and side. Maybe that makes them good like a B-movie, but still.
My aunt bought a Valiant in 1960 and loved it. The car was tight, well-built and for her it had adequate power. As for the aluminum block, as I learned from a service representative when working at Chrysler in the 1970’s, the aluminum block slant sixes were produced to a total of 6000 units. They either failed or soldiered on. No one at Chrysler could figure out why, but the decision was made not to continue production because the company anticipated many problems due to this mystery. I have driven several slant sixes including a 1978 “Super Six.” Let’s not get excited about performance of these power plants but when it comes to reliability, they are wonderful. Since I was not going to fuss about drag-racing with every car at every red light, the Slant Six was fine for me. Remember: place car into gear (automatic transmission) and then wait for the engine to react. Do not yawn during this interval because Slant Sixes are easily insulted.
My understanding of not continuing the aluminum engine was cost, as it always is with a car sold at a low price point. Time is the main advantage, material cost the disadvantage. Iron castings take a lot more time, the main one being cool down before the block can be cleaned and machined. Buick/Olds aluminum V-8 engines were going in premium priced compact cars, not low end ones, so cost was much less an issue, still, iron won out in the end. Corvair was stuck with an air cooled horizontally opposed configuration that used iron cylinders anyway.
Before the Viper helped wake up Chrysler’s generally staid ’80’s reputation of K-Cars and minivans, bringing back the ‘Hyper-pak’ brand in some marketing capacity, would have been interesting. It’s a great catchy term, that aged well. ‘Hyper’ as a catch phrase, being big then. Would have went over well, in the right application during the ’80s, and Direct Connection era.
This would have been a great cult tune, to use in accompanying commercials.
Curious about the weight difference between a 225 iron six and 273 V-8 which essentially replaced the Hyper-Pac.
Slant six (iron block): 475 lbs.
273 LA V8: 525 lbs.
The 273 didn’t exactly replace the Hyper-Pak, which was strictly a kit of parts one had to install, and was sold in very small numbers. One couldn’t just option a new car with it. Initially the 273 was a low-output V8 with very tame manners.
This sent me rabbiting down internet holes.
I always thought the aluminium job was a brief experiment: in fact, they sold 45,000+ from ’61 to ’63. I found out it was originally intended to be the main engine of the new compact Val, with the iron one a stop-gap measure to have available while any high-pressure die-casting manufacturing issues were settled: the iron one was supposed to be gone by about ’61. As to cost, Chrysler figured that the higher cost of the block and tooling was amortized by the much easier life the machining tools would have, as well as the much less machining die-cast things need.
It didn’t work out that way, as they had high discard rates with the new tech, and in service, it took a punctilious owner to keep up regular (6 monthly) flushes AND corrosion inhibitor. (Second-hand neglect means that most of the blocks were probably done in within 10 or so years, accounting for the rarity today). They also had a slightly odd iron-sleeve installation, which relied entirely on a new-tech head gasket to seal everything up: any sort of neglect, and it failed. Thus, exit the alloy block, but it left an important legacy – the more stable, tougher nature of iron meant that the 12.5 million iron jobs made were over-built because they were designed to be made near-identically in alloy, a factor in their deserved reputation as unkillable. It’s got to be true: for starters, as in this test, how many 4-bearing straight sixes of 3.7 litres crank length length could endure 6,000 rpm on a standard bottom end?
So where did you read about this, the aluminum block being intended to be the original/main Valiant engine? Everything I’ve ever read suggest a somewhat different picture, and of course the 170 never got an aluminum block; only the 225, which was not originally even offered in the Valiant/Lancer.
My general take is that there was an interest in aluminum blocks throughout the industry, and that everyone felt the need to make them out so as to not be potentially left behind. Hence the Buick V8, and Rambler and Chrysler making aluminum block versions of their sixes.
But the notion that the slant six was to only have the aluminum block is new to me, and speculation that the slant six block (its “legacy”) was somehow more robust due to it being intended to be aluminum is not only totally new, but sounds highly speculative and without merit. I’ve never heard anything like this nor does it make any sense, actually. I’m aware of a number of cast iron engines being cast in aluminum but there was never a suggestion that the aluminum version needed to be beefed up as a consequence. It seems the two metals are roughly equally rigid for the application.
I have plenty of admiration for the slant six, but I also refuse to elevate its pedestal higher than it actually deserves. As to it being “unkillable” I will say from a completely unbiased perspective of a combination of direct experience (taxi companies), having owned one (that was very tired and on its last legs (yes, they do wear out) and many other sources over the last some 60 years that there’s no valid reason to suggest that it was any more durable than the Chevy or Ford sixes. All were used in huge fleets of taxis and trucks, and all gave roughly comparable service. And they all wore out and needed rebuilding, at between 150-200k miles, generally speaking (if not sooner). Mine was burning oil like made at 130k miles.
I realize that we all like to anoint winners and losers, but when it comes to the Big 3 sixes, I simply can’t pick one. Frankly, they were all tough work horses, and all had the potential to be hopped up to make remarkable power.
If you found a credible source that supports a different take on the subject, about the slant six being intended as only aluminum and such, I would be eager to read it.
This, plus an article i can’t currently find which I realized was largely Daniel Stern’s!
https://www.motortrend.com/how-to/mopp-0303-chrysler-slant-six/
Thanks. Here’s the key issue that I was trying to respond to from your previous comment:
Thus, exit the alloy block, but it left an important legacy – the more stable, tougher nature of iron meant that the 12.5 million iron jobs made were over-built because they were designed to be made near-identically in alloy, a factor in their deserved reputation as unkillable.
If you look at the pictures of the two blocks side by side, it’s quite obvious that they are very much different. The aluminum block is an open deck design, and otherwise different due to the ability to cast the aluminum with ribs and less material and such. But that all has no bearing on the iron block which except for its key dimensions (where needed) is otherwise quite different, and very conventional. Not so “near-identical”.
Maybe I’m missing something?
Found the Dan Stern piece. It appears to me in the pics there from end-on that it IS essentially the same casting, with the obvious difference of the open-deck liners. Hot Rod comment in a photo in their piece that the iron casting is thick where it doesn’t need to be due to the nature of iron casting, and that the crankcase design is nearly identical. It’s Hot Rod’s comment about the rugged alloy block becoming even more so when “rendered into more stable iron”.
https://www.slantsix.org/articles/dutra-blocks/alm-block-sl6.htm
I think something’s getting lost in translation. If you look at these three pictures below, which show both the iron and aluminum block, to my eyes it is very obvious that they are not “essentially the same casting”. Sure, the end effect, of where the various components and bearings and all (the architecture) is the same, but the actual castings are quite different. The iron one is clearly thicker and “cruder”, not surprising given the state of iron foundry technology at the time.
If I stumbled into these two blocks laying at a junkyard, I would assume they were from two different engines. Only a closer look would tell otherwise. The blocks are quite different, externally.
As to Hot Rod’s comment, that’s an opinion. I’m not saying it’s wrong, the cast iron block might well be (probably was) “more rugged” but it also has a considerable amount more metal in it. The casting is crude; the walls are thicker. But there was no choice.
Picture #2
Picture #3
The bottom reality is that while Chrysler may have had hopes of making the slant six block out of aluminum from the get-go, they didn’t. And they clearly designed a cast iron block also from the get go. And that there are clearly differences between them, due to the casting processes and the metals involved. The key part of the story I don’t buy is that this was essentially an aluminum block engine that was “converted” to an iron block. The iron block was there all along, and in fact it wasn’t until 1961 that they figured out the die casting for the aluminum. It was undoubtedly different than the early sand casting aluminum blocks, which were almost certainly much cruder than the die cast ones.
Not to belabor the point, but the end-on photos in the Dan Stern piece look the same (the Hot Rod one is rather corroded, I think), and the Hot Rod photos of the crankcase do look the same. But the truth is, I don’t know nearly enough about casting to really know, and Hot Rod’s comment may well be no more than an opinion, albeit an opinion with an instinctive appeal to it (which such instincts so often turn out to be wrong by objective measures!)
Fellow Mopar enthusiasts may I tend this Australian ‘Wheels’ road test data of a 1971 Valiant Ranger with the standard 245 cid Hemi 6 1BBL @ 165 hp. It’s fitted with a 3-speed column change and 2.92 final drive.
This is the new Australian ‘VH series’ which debuted the new ‘fuselage’ body. With this generation, Ranger became effectively the base model Valiant and the above-spec 245 Hemi was the standard engine of the VH range.
Below Ranger, a very rare & bare fleet-order variant was nominally available with a 215 cid Hemi 1BBL @ 140 hp, although this smaller engine was reportedly fitted to only 3% of all VH Valiants.
Introduced in 1970, the locally manufactured Hemi weighed 40 lbs less than the venerable (iron) 225 Slant Six, with Chrysler-AU claiming their new engine delivered 16% more power and 20% greater fuel economy – these figures being validated in many contemporary road tests.
Btw in Australia a 2BBL 160 hp variant of the Slant Six became available in 1967 Valiants, similar to your later US ‘Super Six’, and continued until 1970.
Personally I think VH was the most handsome Valiant sedan since Exner’s passionately individualistic and imho very attractive 1962 Plymouth Valiant, a style alas unloved in the US.
To my eyes, VH also predates the frontal styling theme of Austin’s 1973 Allegro, and far more successfully due to its much wider dimensions.
Of note compared to US-market Valiants, the front track of VH was increased by about a half inch, while the rear was widened an impressive 2.5 inches, meaning the rear track now became wider than the front. This change delivered the happy result of increased stability, and eliminating the notoriously twitchy ‘Valiant Tail’ of previous models.
I’ve owned 17 Vals, including numerous of these later ‘fuselage’ models (which have quite a solid feel) and always considered the latter to be a quite forgiving chassis yet great fun to drive, particularly when the always eager-to-rev Hemi was combined with a manual gearbox!
Love the fusey Vals, though the public didn’t, sadly. Too big, they said, without knowing that these were just 5mm wider than an HQ (and me neither, till recently!) They had faults: no flow-through vents, the steering was never too flash, for instance, but performance AND economy were much better than the competition. Best seats of the locals, too. Unfortunately (and subjectively) they were the worst rusters of the lot.
My sister had a VJ manual 215, and it (subjectively) felt a lot stronger than my brother’s HQ 202 manual. I had no idea it was so rare. Shoulda kept it, mate, as they say (only it wouldn’t have lasted too long with the driving, er, manners of my dear sis).