I recently posted a story about seeing a Ford Ranchero at the Bristol County Rod Show, but there was a hot rod there that was quite unusual. It was a Ford Model T hot rod with an unusual hot rod engine – a Chrysler Slant Six engine. This car is shown below.
Ford Model T Hot Rod With A Chrysler Slant Six Engine
The Chrysler Slant Six engine is more known as the engine that your Grandmother would choose. It also has a reputation of being a very reliable engine. In fact, if I was to nominate an American engine most likely to go 300,000 miles, then I would choose the Chrysler Slant Six engine. It is not the type of engine that you would normally associate with a hot rod.
The Surprising Engine In A Hot Rod
The Slant Six’s characteristic 30° inclination of cylinder block gives it a lower height overall engine package. This enabled vehicle stylists to lower hoodlines, and also made room for the water pump to be mounted with a lateral offset, significantly shortening the engine’s overall length. The slanted cylinder block also provides space in the vehicle’s engine bay for intake and exhaust manifolds with runners of longer and more nearly equal length compared to the rake- or log-style manifolds typical of other inline engines. The long Slant Six manifold configuration gives relatively even distribution of fuel mixture to all cylinders, and presents less flow restriction. This, in turn, provides for relatively good airflow through the engine despite the intake and exhaust ports being on the same side of the head rather than in a crossflow arrangement.
The Slant Six Engine
The Slant Six engine was introduced in 1960 in two displacement sizes – the 170-cubic-inch version in the Valiant that produced 101 horsepower and the 225-cubic-inch version in full size Plymouth and Dodge Dart models that produced 145 horsepower. The larger Slant Six was more well-known and eventually became more common. My guess, and it is only a guess, is that the engine in this hot rod is the 225 cubic inch version.
This Slant Six Has A Four-Barrel Carburetor And A Custom Exhaust
From 1960-62, Chrysler also offered a Hyper-Pak package, which included a four-barrel carburetor and numerous performance upgrades. On the 170 cubic inch Slant Six the Hyper-Pak took the horsepower from 101 to 148 horsepower. With the 225 cubic inch Slant Six, the horsepower was increased from 145 to 195 horsepower with the Hyper-Pak.
The 170 Cubic Inch Slant Six Engine With The Hyper-Pak Performance Package
The engine in this hot rod has all of the obvious Hyper-Pak modifications plus the valve cover says “Offenhauser”. I have no idea if this car really has a cylinder head upgraded by Offenhauser or perhaps it just has a Offenhauser valve cover.
This Slant Six Might Also Have An Offenhauser-Modified Cylinder Head
With the release of a number of compact cars in 1960, NASCAR sanctioned a special race for the new six-cylinder compact car class, which would involve all three major automakers. NASCAR’s Bill France saw that the new American compact cars- the Ford Falcon, Chevy Corvair, and Plymouth Valiant- were getting a lot of attention in the marketplace, so he created the Compact Series, which ran during 1960 and 1961. Some big names participated, including Curtis Turner, Richard Petty, and Fireball Roberts, and even a few Volvos even got into the act. With NASCAR putting out word of the series, the Chrysler engineers went to work on improving the 170 cubic inch Slant Six in the Valiant.
Race-Modified 170 Cubic Inch Engine For The NASCAR Race
Seven Slant Six Valiants entered the new NASCAR series; when the first race ended, not only had all seven Hyper-Paks finished, proving their reliability and durability, but they won the first seven places!
Marvin Panch’s Valiant Racer In The Compact Car Series
CBS television aired the compact sedan races as well as the qualifying for the Daytona 500 race in a live TV special for their “sports spectacular;” it was estimated that 17 million people were watching. The compact sedan race quickly turned into a dull affair as lap after lap the Valiants with the Hyper-Pak dominated the race.
Slant-Six Valiants Qualified At The Front
By the end of the 1961 season NASCAR quietly discontinued the Compact Series. Chrysler never really used the results of the series in their advertising and for the most part the whole Compact Series seems to have faded from history. The Slant-Six engine then simply became an engine that your Grandmother would use, not an engine that you would see in a Ford Model T hot rod. Chrysler then focused their performance interest on their V8 engines.
If you have any comments or questions about this post, then please leave a comment below or you can send me a private email message at the following address: shanna12 at comcast dot net
stevemckelvie.wordpress.com 
There is a video on the web of a slant 6 equipped valiant humbling a current Charger HellCat at the drag strip.. Granted highly modified vs stock but yes a slant six can be the leaning tower of power.
Great post, was just reading an article on the Slant Six in a recent issue of Hemmings https://www.hemmings.com/magazine/hcc/2017/12/Tilted-Perspective/3751312.html
I don’t have a good listing of the details of the Dodge and Plymouth cars. I found a good deal of information about the availability of the Hyper-Pak on the 170 cubic inch engine, but I don’t have a listing on the models in which the 225 cubic inch Slant Six was available with the Hyper-Pak. Any information on this would be appreciated.
Steve McKelvie
Check the reference section on the slant6 forum
The Hyper Pak was never a factory-installed thing. In order for the equipment to qualify as “stock” in terms of the requirements for the NASCAR compact car races of 1960 and 1961 (good details and footage at http://www.curbsideclassic.com/automotive-histories/when-the-new-1960-compacts-went-racing-the-130-mph-valiants-cream-the-corvairs-and-falcons/ ), the Hyper Pak kit, part № 2205573, was made publicly available for purchase at dealer parts counters, and dealer service departments could install it. A memo sent out to dealers read, in part, “Don’t Try To Sell the Hyper-Pak to just anybody! The Hyper-Pak was designed for performance. It’s not designed to idle smoothly or run quietly, and it certainly does not improve fuel economy. Mr. Average Motorist
won’t be interested. On the other hand, for the guy who wants his Valiant to outperform every other compact on the road and most of the standard cars, too, this Valiant Hyper-Pak is right down his
alley. Every prospect who’s interested in performance should be told about it. There is nothing like the Valiant Hyper-Pak on the market.”
Formal availability ran from ’60-’61; the Hyper Pak Valiants so completely trounced all other cars in the NASCAR compact races that GM and Ford pulled their sponsorship and the series was not continued past 1961. After that availability was limited to whatever kits remained on shelves. Most of the kits were installed in 1960 and ’61 Valiants and Lancers; modification and adaptation are required to install the Hyper Pak in even the very similar ’62 Valiant/Lancer. The kit, which cost $403.30 in 1961 ($3,359.71 in 2017 dollars!) officially comprised:
Camshaft № 2205620, 1ea
Valve spring & damper № 1944554, 12ea
Pushrod № 2129619, 12ea
Intake manifold № 2129898, 1ea
Exhaust manifold, front № 2129899
Exhaust manifold, rear № 2129900
Support, front, intake & exhaust manifold № 2205833, 1ea
Support, rear, intake & exhaust manifold № 2205834, 1ea
Spacer, intake to exhaust manifold № 2202567, 1ea
Carburetor assembly № 2129881
Air cleaner assembly № 2129992
Clutch cover & pressure plate assembly № 2201223
Clutch driving disc assembly № 2201219
This list does not tell the whole story, however. The pushrods, for example, are different lengths for the 170 vs. 225 engine. The part number in this list is probably for the 170 pushrod. And there was a fairly extensive list of other parts offered: three different manual-choke control assemblies with knob, bracketry, and bezel to suit (and match the rest of the controls in) ’60 Valiant, ’61 Valiant, and ’61 Lancer, large-diameter/dual-inlet exhaust pipe assembly and larger (Imperial) muffler sold together as part № 2298350, and a matching large-diameter tailpipe. There were high-compression pistons (10.5:1), at least one alternate camshaft, etc. This, and the rather well-known open secret at the time that Chrysler tended to understate their engines’ output ratings, make it difficult to know what configuration the officially-stated 148hp (170 engine) and 196hp (225 engine) figures apply to.
There were also upgrades done elsewhere on the NASCAR Valiants—brakes, suspension, etc—that were likewise available over the parts counter if you could dig up the part numbers (which was, seemingly intentionally, made rather difficult: “Gee, NASCAR, we made ’em publicly available just like you require…not our fault if almost nobody ordered ’em, whaddya gonna do?”).
In the late 1980s the long-runner Hyper Pak intake manifold was painstakingly reproduced by Doug Dutra, probably the world’s foremost Slant-6 expert. He made a variety of versions with different runner sizes and carburetor pads, etc, before selling the tooling and rights to Clifford, at which point price went up and quality went down. There have been rumblings recently of interest in reproducing the front-3/rear-3 cast iron exhaust headers, and it’s interesting to note that Chrysler Argentina used a conceptually similar front-3 cast iron exhaust header as part of their Valiant GT package. Not the same as the Hyper Pak front-3 exhaust; the Argentinian item (№ 3724807) was configured to leave space for the likes of an air conditioning compressor and power steering pump.
…also: No, this engine does not have an Offenhauser-made or -modified head; there’s no such thing for the Slant-6. It has an Offy aluminum rocker cover, that’s all, first offered in the early ’60s and still orderable.
And it’s an RG engine (a 198 or 225), not an LG (170). Giveaways are the block casting number visible enough above the left engine mount, as well as the length of the coolant bypass hose between the water pump and the cylinder head. Odds are it’s a 225, but only the crankshaft and connecting rods differ between that and the 198.
And if you want a quick additional 100hp or so, you can purchase a supercharger kit!
See the following link:
http://www.hotrod.com/articles/new-product-spotlight-torqstorms-supercharger-kit-chrysler-slant-six/