Road Test Comments on the McCulloch Supercharger

This section provides extracts from various road tests, and magazine articles, of McCulloch supercharged cars, and were extracted from articles that were originally featured in the motoring press during the fifties. I’ve provided them for a number of reasons: firstly they place the McCulloch supercharger in a historical perspective, they provide useful information on how a car performs with the supercharger installed, they provide comparative information between different installations, and are also very interesting to read, particularly the Hot Rod magazine articles. I’ve tried to keep the comments in the correct context, without reproducing too much of the non-supercharger related elements of the article.

Motor Trend, October 1953 – Supercharging made easy

McCulloch supplied Motor trend Research with three test cars; a ’52 mercury four door sedan with Merc-O-Matic, a ’51 Ford convertible with overdrive, and a ’53 Nash Ambassador hardtop with Hydra-matic.

All the cars started easily, idled smoothly, and ran the entire rpm range with just the slightest whisper of what was under the hood.

Throughout the entire speed range, the cars had a feeling of “go,” proving McCulloch’s claim of constant performance regardless of their stock characteristics. If the cars had any tendency to “flatten out” around the 70 mph mark, the supercharger went to work and eliminated it.

We carried out our most comprehensive tests on the Mercury, but the Ford and Nash supplied corresponding positive results with the McCulloch supercharger.

Its developers have installed the supercharger on practically every make of car with excellent results. If McCulloch can meet the target price of under $175, it will probably be the most successful performance accessory that anyone has put on the market for years.

Motor Trend, April 1954 -  Supercharged Kaiser Manhattan

The McCulloch-blown engine starts instantly by turning the ignition key to the far right. Kaiser and McCulloch engineers have worked closely together to keep down the noise level of the supercharger for this stock car installation. They have succeeded so well that you may feel a little cheated after payimg for this conversation piece that is so unobtrusive your passengers may never notice it; there’s no outward indication of this underhood surprise package either.

Performance-wise, though, they will know that there’s something very unusual about your new Kaiser. This years supercharged Manhattan with Hydra-Matic has at least 25 per cent better acceleration from a standing start than last year’s unblown version with same transmission. Improvement in the more important passing range is even better. Last year’s car took over a half-minute to get from 50 to 80 mph. Now it can be done in slightly under 20 seconds; this makes the Kaiser a much safer highway car for today’s traffic conditions. Another important safety consideration which only a supercharger can provide is that performance will hold up at altitude. Other ,more powerful cars, will be hard pressed to match the Kaiser’s ability in the second half of a long mountain climb (like Pikes Peak) because they do not have forced air induction.

Motor Trend, April 1954 -  Supercharged Kaiser Darrin

When we request a road test or impression test car, we ask for a production model and that means not specially tuned. Despite this rule, though, we couldn’t get very upset when we found the only Darrin available to drive was an experimental job powered by a McCulloch-supercharged Willys F-Head.

On the road, we soon became aware of the McCulloch blower. Loafing along at 60 mph in overdrive (2500 rpm on the tach), we tromped down into direct which also kicks in the supercharger. The tach jumped to 3800 almost immediately and acceleration was only slightly less dramatic. The little Willys F-head was throatily at home in the unfamiliar region (for it) of 4500-plus rpm. In the background was the whine of the blower.

The 4.55 rear-axle ratio combined with overdrive and supercharger is tricky. Full throttle standing starts in low spin the wheels on any pavement, and when you do get going, you’re soon at rpms which aren’t healthy for a borrowed Willys engine. A normal shift to direct second is fairly fast, and you can stay floorboarded to about 50 mph before dropping down to direct high. This technique, if it can be called that, will consistently give 0-60 times in the neighborhood of 10 seconds. Considerably better results can be obtained if you want to risk speed shifting with a somewhat inadequate change lever.

A high gear downshift at 30 mph will bring you up to 60 in about 10 seconds, and we trimmed two seconds off this by using second overdrive, even though the supercharger is not fully operating under these conditions. Fifty to 80 mph in direct high is an easy 12 seconds.

If Kaiser-Willys engineers and sales people decide to produce this car in supercharged form it will be very competitive to the Corvette in performance.

Motor Trend, September 1954 – ’54 Kaiser Manhattan

Ever since the day when Henry J. Kaiser jumped plumb into the automobile business with both feet, his products have been full of surprises. His merger with Willys slowed down both cars ’54 model announcements, but lots of people knew that the new Kaiser Manhattan, when it finally showed up, would have a supercharger - the first, incidentally, on a U.S. stock car since the Cord-like Graham departed this life back before World War II.

So, a far more eager crew descended upon our test Kaiser than usually greets a routine road-test car.

At the same time, Editor Walt Woron and Detroit Editor Don MacDonald were getting acquainted with another Manhattan in Toledo. The two cars made an interesting comparison, for they were equipped very differently. The California car had Hydra-Matic and power steering; the Ohio car, overdrive, standard steering, and tubeless tires.

First supercharged stock car engine since Cord-like Graham left scene, Kaiser’s. McCulloch-equipped engine has small (226 displacement, puts out 140 bhp.

Far and away the most interesting piece of equipment on both cars was the McCulloch supercharger. It is attached to an engine which is a lot like those on Motor-Trends ’53 Kaiser Manhattan and the ’54 Kaiser Special. Changes include prudent beefing-up of the main bearings, larger valves with rotating tappets, a cleaned-up manifold, and a new dual throat carburetor.

The closest approach to a whine we could get from this compact booster was a soft hum when we floored the throttle at around 40 mph, and that quickly died away. This discreet auditory response is no indication whatsoever of what is going on inside. One hundred and forty horsepower may no longer be an electrifying figure, but it’s an impressive one from an engine that has less displacement than any other engine in it’s price class or in the one below it, and is even smaller than a Chevrolet or a Ford V8.

What difference does the blower make to the guy behind the wheel? Much more at certain points than at others. From a standstill you can accelerate to a true 60 mph in 15.4 seconds with Hydra-Matic and 15.0 seconds with overdrive. At cruising speeds, the shift down to third gear in Hydra-Matic or overdrive, plus the stepped-up action of the blower, will take you safely out of harms way. Skipping from 50 to 80 in just 20 seconds, the new car will leave a ’53 (34.1 seconds) in the dust. That isn’t up there with Hamtramck hot rods like the Buick Century, but it’s not bad by any rating.

Kaiser makes the point that a supercharger just loafs along when you don’t need it (a solenoid on the throttle downshifts it, as it were, when you hit it hard). But even with the blower just along for the ride, as it was on our steady speed fuel checks at 30, 45, and 60 mph, the ’54 car didn’t begin to approach the miserliness of it’s ’53 counterpart. It registered anywhere from 2.2 to 6.7 mpg less, the larger difference being at the lower speeds.

Auto-Age, February 1955 – Supercharged Kaiser Manhattan

Not since the days of the lamented Duesenberg and Auburn has America had a production passenger car with a supercharger. There have been a number of good reasons for this. Superchargers, or “blowers” as they are sometimes called, are relatively expensive, they cut down on gas mileage and in some instances, especially if they are in constant operation in a car, they tend to reduce engine life. Besides, most of our cars have engines so large that supercharging is just not necessary for ordinary highway driving. McCulloch Motor Corp., in Los Angeles, Calif., has come up with a new supercharger that solves most of these problems and Kaiser is taking full advantage of it, getting a jump on the industry, so to speak.

Neat six-cylinder, L-head engine will get better than 20 miles to the gallon.Supercharger ups the horsepower from 118 to a rousing 140.

The new Kaiser Manhattan incorporates the McCulloch unit to raise its horsepower from 118 to a respectable 140. But gasoline mileage is still relatively unchanged; here’s why. The McCulloch blower has a “variable-speed drive” that allows it to mark time until you open the throttle all the way. This is operated by engine manifold pressure and thus gives you maximum power only when you need it for passing or hill-climbing. Most of the time the engine acts just the same as it would without the supercharger. In other words, the Kaiser Manhattan has a dual purpose engine; in normal operation it is an efficient and economical six-cylinder flathead, but when you really step on the gas it gives you all the jump of a large V-8 overhead-valve job. This, combined with optional Hydramatic drive or three-speed manual with or without overdrive, makes the Manhattan a right smooth and fast buggy.

It was on one of Ohio’s fine straight highways that I was able to clock the top speed of the supercharged Manhattan at 93 mph. At this time, too, I found useful passing acceleration by means of stepping down hard on the throttle (which throws the four speed Hydramatic into third speed). This moved the car from 50 to 80 mph (true speeds) in 14 seconds flat.

The McCulloch supercharger greatly increases this new Kaisers performance; it’s effect is felt immediately when you mash the throttle at any speed. Of course the supercharger (belt driven) does cut into the fuel mileage a bit at higher speeds, but even with Hydramatic our over-all mileage during tests was a reasonable 16.9 miles per gallon.

Motor Life, August 1955 – Supercharged Speedster

Earlier driver’s reports in Motor Life provided evidence that Studebaker’s Speedster lives up to it’s name as an outstanding performer. However, the recent installation of a McCulloch supercharger on a conventional-shift model by John McKusick, of STU-V, in Los Angeles, suggested such interesting possibilities that arrangements were made to take the car out onto the road for a check of the results.

Using only a stop watch and the Speedster’s own tachometer and speedometer (which previous tests have shown to be exceptionally accurate), some acceleration times were recorded.

The first effort was aimed at 30 mph from a standing start. The instant the clutch was released and the throttle depressed, however, the speedometer gave a flash reading of more than 30 mph, due to the rear tires breaking loose from the enormous thrust. We also were wary of fish-tailing from dead-stop in a full-on try. So, after three attempts which were brutal on the rear tires, it was decided to shoot at a 0-45 mph time.

Taking it a bit easier on the throttle and clutch, wheel bite was preserved and the Speedster soared to the higher mark in 3.5 seconds flat!

In comparison with the previous report on a non-supercharged Speedster, which recorded a time of 3.65 seconds 0-30 mph, this was one-tenth of a second less to go 15 mph faster. Other comparisons: 0-60 mph with the stock Speedster was 11.5 seconds, while the supercharged Speedster registered 7.7 seconds; standing quarter mile stock was 20 seconds to 80 mph, supercharger did it in 16.4 to 86 mph, 50-80 mph, stock 12.6 seconds, blown 7.0 flat (in second gear OD).

An experiment to see how the supercharged Stude Speedster operated without bucking or lurching was next. In top gear the car moved along smoothly at eight mph – the quality unchanged from that of the stocker. In all tests, the electric tach indicated the most effective range for the supercharged engine was from 1500 to 5200 rpm; above this point a minor case of valve float set in.

Arrows point out special modifications to handle blower under Speedster’s low hood: from left, new oil filler neck, bracket for blower, and right, new water hose to radiator.

Engine compartment of the ’55 Studebaker is compact, and addition of the blower required the engineering of a special kit by STU-V (price $390), which includes brackets allowing for clearance around power steering and other linkages. Installation instructions are provided for the advanced layman mechanics, although shop facilities are necessary to set up the arrangement.

Motor Life, September 1955 – Two Supercharged T-Birds

Two of the most persistent rumors from Detroit concern the 1956 Ford Thunderbird; one says it will appear with fuel injection, the other maintains the McCulloch supercharger will be optional equipment. Either, or both these reports may or may not be true. However, quite a number of Thunderbird owners are having the blowers installed on the 1955 models with performance results that are exceptionally interesting.

In view of all this, and invitation of Paxton Industries (the sales division of McCulloch Motors) to test drive a compressor equipped T-Bird was accepted. Whilst the investigation did not assume the proportions of a comprehensive road test, a fifth wheel, and Weston electric speedo was used to ensure accuracy.

Two Thunderbirds were taken out on a straight stretch of pavement for acceleration tests. One had a Fordomatic transmission, the other carried the overdrive unit. Speedometer corrections were made first, and disclosed the following: at indicated 30 mph, 45 mph and 60 mph, the respective actual speeds were 26 mph, 38 mph and 50 mph. Each of the cars, incidentally, were well broken in by thousands of road miles.

It required some experimenting with the supercharged versions to obtain the maximum benefits in acceleration without having the rear wheels spin. The experienced installers at Paxton’s (who say 50 per cent of the blowers are currently going on T-birds) advised making the gear changes from low to drive with the Fordomatic, at 4700 rpm on the tachometer.

Slightly better times were recorded with the overdrive arrangement, except on the 0-45 mph times where time required for engaging the clutch and shifting gears reduced whatever benefits the system provided mechanically. The following are the best times in seconds obtained with each car:

Supercharged Fordomatic

0-30 mph – 3 seconds, 0-45 mph – 5 seconds, 0-60 mph – 8 seconds

Supercharged Overdrive

0-30 mph – 2.2 seconds, 0-45 mph – 5 seconds, 0-60 mph – 6.8 seconds

Comparison of these times with figures from three previously published reports on Thunderbird performance (all involving Fordomatic transmissions) provides interesting material for speculation:


Test #1 -  0-30 mph – 4 seconds, 0-60 mph -  11 seconds

Test #2 -  0-30 mph – 3.7 seconds, 0-60 mph -  9.5 seconds

Test #3 -  0-30 mph – 4.3 seconds, 0-60 mph -  10.75 seconds

Motor Trend, April 1956 – Supercharged ’56 Plymouth

With performance to surpass that of Plymouth’s own Fury and a sound to match that of a screaming banshee, this blown Plymouth supplied to me recently by McCulloch Motors is an impressive package indeed. It smashed acceleration times set by the 4-barrel-carbureted ’56 Plymouth as easily as a mallet splatters an egg. Take a look at the comparative figures:

Speed/Distance                 200-hp ’56 Plymouth             McC. Supercharged Plymouth

0-60mph                                 11.9                                        8.2

¼ mile                                     18.9 (76 mph)                       16.7 (89.8 mph)

30-50 mph                             4.4                                           2.8

50-80 mph                             13.4                                        8.9

These figures put the blown Plymouth in the hopped-up Corvette and T-Bird class. And by “hopped-up” I mean one such as the ’54 Corvette with ’54 Caddy engine that I drove back in’54. The 0-60 runs were made using LOW range of PowerFlite only, while the ¼ mile runs were made using LOW, and shifting to DRIVE at around 60. The 30-50 runs were all made in LOW, while the 50-80 ones were a combination of the 2 gears. Any time you downshift below 60 mph with this setup, you get not only a surge when the transmission drops down a gear, but another one when the blower cuts in. The blower takes hold between 3000-3500 rpm.

Plymouth McCulloch Installation

If you feel that the ’56 Plymouth is dead on it’s feet (which I don’t), you can really get it up on its tiptoes with this blower. If you’re going to use the added power much, tho, the best place for it is the dragstrip or to compensate for the power loss you mountain dwellers experience with your cars.

Motor Life, December 1956

With engines getting bigger all the time, it’s news when a manufacturer introduces a car with less displacement than it had the year before. When displacement is reduced from 354 to 289 cubic inches without a corresponding cut in performance, it’s really news – and that’s exactly what Studebaker has done with it’s Golden Hawk!

There’s a gimmick, of course. In this case it’s spelled s-u-p-e-r-c-h-a-r-g-e-r! That’s right; the Golden Hawk is the second U.S. car of the post war era to offer a blower as standard equipment. Studebaker is using its 289 cubic inch V8 with a centrifugal supercharger in ’57 Golden Hawks instead of the 354 cubic inch Packard Clipper V8 which powered these cars in 1956.

How does the engine change affect performance? For the better, if anything, I would say.

I ran acceleration checks at Studebaker’s proving grounds on a Golden Hawk with Flightomatic and came up with 0 to 60 times ranging from 9.3 to 9.8 seconds (9.5 was the average) and 50 to 80 mph runs averaging 9.3 seconds. This was almost exactly the same as the Ultramatic equipped ’56 model I tested last year.

One difference I noted between the two cars was that the ’57 had a flat spot right above 100 mph. It would hit that spot, then level out there for a while before the speedo needle started climbing again. This hesitation wasn’t there in the ’56; it kept accelerating well beyond that.

That doesn’t sound like the newer Hawk is the better performer, but let me explain: First, engineers requested I hold the rev limit to 4000 rpm in low and intermediate ranges if I hand shifted the transmission – and the runs I made convinced me that winding higher would cut the times quoted.

In addition, Studebaker engineers admitted they were having trouble working out the right combination for supplying fuel to the supercharged engine. They felt it was running lean the way it was set up at the time.

I went back to South Bend for the advance press showing of 1957 models several weeks later and one of the engineers I’d worked with on my previous visit greeted me with a smile. “We’ve got it licked!” he told me.  (A part of the solution was going to larger gas lines, I believe.) I drive the hawk again and it did feel quicker, although I didn’t have an opportunity to put a watch on it. Apparently it was, too, because in an acceleration test the ’57 took a ’56 by a comfortable margin. The ’56 led by the nose for the first few car lengths: then, as the ’57 got it’s revs up, it took over, and was ahead all the way up to 80 mph or so when both drivers backed off. (Studebaker, incidentally, is claiming “up to 15 per cent” better performance for the new Golden hawk.)

The engine that furnishes this urge – with the help of the blower, of course – has a bore of 3.56 inches and stroke of 3.63 inches for displacement of 289 cubic inches, as mentioned earlier. Compression ratio is only 7.7 to 1 because the supercharger is used.

The supercharger itself is a McCulloch unit modified slightly to conform to Studebaker’s specifications. It delivers a five pound boost – and does so pretty much all the way thru the speed range, even the low end, thanks to McCulloch’s variable speed pulley design. It’s claimed that this unit permits normal fuel economy at cruising speeds.

Motor Trend, January 1957 – Studebaker

The Hawk series, still based fundamentally on the original Loewy design of 1953, is as close to a sports car as you can get at a reasonable price and still carry the whole family in closed comfort. A McCulloch supercharger is standard equipment on the Golden Hawk hardtop. Silver Hawk V8s and sixes come in coupe form use unsupercharged engines.

McCulloch supercharger on Golden hawks is a five-pound boost, full pressure system,makes ’57 version as hot as big Packard-engined ’56 Golden Hawk.

Big news is the McCulloch blower, last used on an American production car by Kaiser in 1955. Studebaker doesn’t have to try and make gold out of bricks though. The 289 cubic inch, Studebaker built V8 responds beautifully to the boost. Although the 65 added horsepower claimed (to 275 from 210) seems extravagant, the performance belies our doubt. Our check (Motor Trend, Dec. 56) shows the supercharged Hawk to perform almost exactly on a par with last years Packard powered model; further testing may prove it’s better!

This year, the light engine with supercharger (that only weighs about 40 pounds installed) proves to be an ideal combination for both performance and handling, though reliability may suffer.

Hot Rod, March 1957 – How Hot is the Hawk?

In an era where potent passenger car performance is the rule and not the exception, the 1957 Studebaker-Packard “Golden Hawk” is in it’s own nest. In fact, it can and does outperform nearly all of the current crop of production automobiles with the exception of some of the “super stock” machines, which are, of course, in a class by themselves. The line that separates the Golden hawk from the super stocks is indeed fine but unmistakable; Golden Hawk performance may be purchased “as is” without resorting to a long list of sometimes unobtainable power plant options. In  other words the Golden hawk is a completely stock automobile and as such, it is hard to beat.

The engine used in all Golden Hawks is a 3 9/16 inch bore, 3 5/8 inch stroke, 289 cubic inch overhead valve V8. The engine of our test car had the standard compression ratio of 7 ½ to 1. The optional compression ratio is 7 to 1. Standard equipment on all ’57 Hawks are dual exhausts and the “Jet Stream” supercharger, a new name for an old friend of hot rodders, the McCulloch variable ratio centrifugal blower, which accounts for the use of relatively low compression ratios. With the standard compression, the rated output of the supercharged engine is 275 brake horsepower at 4800 rpm and 333 pounds-feet of torque at 3200 rpm.

Engine compartment is loaded, making routine maintenance plug checks, valve adjustments - difficult.

The ’57 Golden hawk thus becomes the fifth production car in the history of American passenger vehicles to incorporate a supercharger as standard equipment. This point alone supplies enough material for a full-sized story; however, there are other factors, which, in conjunction with the blown engine, make the “Golden One” a different but very interesting and highly desirable package for performance lovers.

The manner in which out test car breezed through the gamut of acceleration runs left little doubt that it is one of the hottest stock passenger cars available. For these trials, our standard starting procedure of holding the brakes and flooring the throttle was used with the transmission in low range. Even with the Flightomatic, some wheelspin occurred but the Twin traction differential equalized the traction causing both rear wheels to break loose for about five feet off the line. With the transmission in low, the engine was wound up to 5000 rpm (about 51 mph) and a shift was made to drive, which shifted the transmission into intermediate. The transmission selector was then moved back to low, locking the transmission in intermediate until the run was completed. The average zero to 60 mph time was 8.8 seconds. The average zero to 80 mph time was 16.0 seconds. The average speed at the end of the standing quarter mile was 82.3 mph, which is equivalent to an engine speed of just 5000 rpm in intermediate. The speed at the end of the quarter is not too impressive but the zero to 60 mph runs, the zero to 80 mphs runs and the average quarter mile elapsed time of 16.72 seconds speak for themselves. Other shift points were tried as were all three forwards speeds but the best results were obtained when the 5000 rpm shift-point was used. In drive range, the average zero to 60 mph time was 10.2 seconds and the average zero to 80 mph time was 17.0 seconds.

The above implies that the Hawk is a real terror off the line but such is not the case. In fact, it is a bit sluggish until about 2500 rpm is reached at full throttle. In this range, the blower starts delivering some positive boost pressure into the intake manifold and things begin to get more lively. In terms of distance from a standing start in low until 2500 rpm is reached is only a matter of 50 or 60 feet because the stall speed of the transmission is 1800 rpm, which means that only 700 rpm must be covered before the engine comes to life. In view of a rather slow start, this makes the acceleration times all the more impressive. Engine response in the 2500 to 3500 rpm range is really good, which spells excellent mid and top range performance. Beyond 5200 rpm, the “punch” falls off and at 5600 rpm, valve float is encountered. It seems logical to expect a slight improvement in acceleration times if the engine had about 5000 miles or son on it. But as it was, the odometer registered a mere 1600 miles when the acceleration runs were made. I might add that the acceleration times were measurably better by increasing the initial spark advance from the specified four crank degrees before top center to eight crank degrees before top center, which gives a total advance of 32 crank degrees.

The top speed of our hawk, as checked out on El Mirage dry lake, was 122.7 mph one way with a return run at 119.5 mph, the faster speed being the equivalent to 5100 rpm. It seems likely that a properly tuned and well loosened up Hawk with the right gear ratio could turn in excess of 127 mph on a good surface.

There were no special tricks involved in obtaining decent mileage with the supercharged car, The throttle was treated with respect and the intake manifold vacuum reading was kept on the high side of 10 inches of mercury whenever possible. The supercharger itself imposes no threat to good economy under these conditions other than a slight parasitic drag on the engine. In other words, the blown engine behaves just like an unblown engine at cruising speeds or during other light load duties because the supercharger is “loafing” and is not producing a positive manifold pressure. The supercharger pressure output is governed by the throttle and the load on the engine and as the throttle is opened and the load is increased, the supercharger goes to work at overcoming the vacuum in the induction system and building up a positive pressure head. When the Hawk engine is at full throttle, the supercharger starts to produce a positive intake manifold pressure in the 2000 to 2500 rpm range.

A timing adjustment is made to ignition. Predominant in foreground is well planned supercharger equipment featured on ‘57’s.

The Hawk induction system is rather unique and shows considerable thought in relation to carburetion problems, which are sometimes encountered with supercharged engines. The supercharger unit is mounted at the forward end of the V between cylinder banks and is belt driven from the crankshaft drive pulley. Proper belt tension is maintained by a spring loaded idler pulley. Air enters the center of the impellor casing at the back of the supercharger from an offset air cleaner and attaching hose. The air then passes the impellor and out the discharge volute to the air “box” or chamber. The box completely encloses the entire carburetor, which is a two barrel Stromberg WW6-121 with 1 1/8 inch diameter venturii. With the carburetor so enclosed, it is thus automatically balanced against variations in air pressure and no internal equalizing devices are necessary. A pressure line with an integral check valve is connected to the air box and the top side of the fuel pump diaphragm so in effect, the fuel pump is “supercharged” to maintain a constant differential pressure in delivering fuel to the carburetor.

Maximum boost pressure is regulated to approximately five psi measured at the supercharger outlet and is the point at which a gauge connection is made. There is a pressure drop of about 1 ½ psi at the carburetor so the maximum intake manifold pressure is about 3 ½ psi. During our test, the highest boost pressure indication was five psi in the 3000 to 4000 rpm range under full load full throttle consitions. At top speed, this dropped off to about 3 ¾ psi.

Autocar, April 1957 – 1957 Packards

A variable delivery McCulloch supercharger, similar to that of the Studebaker Golden Hawk, supplies pressurized air up to a maximum of 5 lb sq in above atmospheric through the carburetor.

The engine of the new Clipper is identical with that of the Studebaker Golden Hawk (4,736 cc vee-8), and includes a supercharger which increases its performance by 15 per cent. In this form it produces 275 bhp (gross) at 4,800 rpm., with a maximum torque of 333 lb ft at 3,200 rpm corresponding to a b.m.e.p. of 175 lb sq in. The supercharger is a centrifugal McCulloch type, belt driven from the front of the crankshaft. It features a clever variable-ratio pulley assembly which automatically holds the rated boost of 5lb sq in in the speed range from 3,000 to 5,000 rpm. This gives a large increase in medium speed torque, as well as in peak power.

The engine is small in comparison with it’s competitors, and supercharging undoubtedly has been adopted to keep pace with the present American fashion for high acceleration. Performance figures issued for the new Clipper state that it can reach 60 mph from a standing start in 10.45 sec and, in the more normal passing speed range, from 30-60 mph requires 6.51 sec.

Motor Life, August 1957 – Golden Hawk Road Test

The Studebaker Golden Hawk is one of the most distinctive cars of 1957 in many ways. One facet of it’s individuality is it’s styling. It is almost impossible to confuse a Hawk with any other car on the road. It’s engineering adds to the car’s distinctiveness. It is one of the two makes featuring a supercharger as standard equipment.

Studebaker calls its Hawk models “family sports cars”, and that is probably as good a description as any.

The car’s performance adds to the sports car flavour. The Hawk tested was not the hottest model checked this year, but it was far from the slowest. Acceleration times were more than adequate, as shown by the times quoted in the test data table. They would have been even more impressive had the car been equipped with standard shift rather than the optional automatic transmission. (Judging from past performances and checks made in overdriven cars driven briefly, but not fully road tested, 0-60 mph times would have been down around 8.5 seconds with stick shift.)

Things are pretty crowded under the hood of a hawk, particularly on those equipped with power steering and brakes. This is an almost universal fault in these gadget happy days, however, and the supercharged Hawk is no worse than most in this respect.

Motor Trend, November 1957 – 1958 Studebaker & Packard

Golden Hawk shares 120.5 in. wheelbase chassis with President – supercharger on 289 cu. In. engine is on Hawk only. There’s more power with 8.3 compression.

Little change has been made in any of the S-P engines from the L-head Champion unit shared with the Scotsman to the largest 289 inch ohv V8 unit which, combined with the “Jet Stream” McCulloch made supercharger, powers the Golden Hawk Stude and the Packard running mate. Compression ratios have, in the V8s, been raised about one point. At this writing little else can be said other than that ’58 will probably see the blower confined to the Studebaker and Packard high performance Hawks.

Hot Rod, May 1958 – Packard Hawk Performance Test

Only one engine is available in the Packard Hawk. It is a 289 cubic inch V8 with overhead valves and is basically the same engine used by Studebaker for the past several years. The Stude Golden Hawk uses the same engine for 1958. With 7.5 to 1 compression ratio and only 289 cubic inches in this day of high compression and large displacements, a supercharger is needed to provide the muscle for a 275 horsepower advertised rating.

Area beneath the fiberglass hood of the Hawk is well filled. Variable speed supercharger, center, feeds pressure to the cat aluminum box that encloses carburetor.

The supercharger, or blower, is made for S-P by McCulloch Motors and is the same basic design as when introduced by McCulloch about five years ago. The unit is mounted on top of the engine and is driven by a single wide belt from the crankshaft through a variable diameter pulley. Inside the centrifugal blower, a planetary ball bearing unit changes ratio as the drive pulley diameter is changed to make possible impellor speeds in excess of 25,000 rpm. The impellor drive ratio changes are adjusted automatically by controls in the blower that are energized according to the engine demands.

A maximum manifold boost of approximately 5 pounds is provided by the blower under high rpm, full throttle use. The air is ducted to a cast aluminum housing which encloses a single Stromberg two barrel carburetor with 11/8 inch venturii. The fresh air supply to the blower is protected by a paper pack air cleaner.

The engine is rated 275 horsepower at 4800 rpm but as we have discovered while testing other ’58 automobiles, twisting the engine to advertised speed is not always possible. Adjustable lifters are used but valve spring pressures are 45-55 pounds closed and only 105-115 with the valve open so even when used with the Hawk’s comparatively mild cam timing, valve float started at 4500 rpm with our test car. A couple of attempts to exceed 4500 rpm during acceleration tests brought clattering protests from the valve department and a definite power loss so we never did get to feel the 275 horses supposed to be lurking around at 4800.

The exceptionally low, 7.5 to 1. compression ratio of the Hawk engine is designed to prevent excessive pressure and detonation when the blower is providing a positive boost to the engine but is also instrumental in knocking low speed power for a loop. Getaway speeds from a stop are on the mediocre side even in low gear and the engine only starts to feel strong when the tach nears the 3000 rpm mark and the blower gauge registers a positive manifold pressure. From 3000 to 4500 rpm, the blower starts to apply the pressure and the little engine feels healthy. From our viewpoint, it would appear more practical to start with a compression ratio of about 9 to 1 and then restrict maximum blower pressure the amount necessary to keep pressures within safe limits. The extra compression would not only provide better low speed power but also improve gasoline economy while cruising down the highway. A boost of 3 pounds should do then do the job required by five with the present 7.5 c.r.

Taking a look at the acceleration figures you will notice that that the hawk is not the fastest car on the road. Zero to 60 mph in 9.2 seconds is not bad but there are several cars on the road that will do it in eight seconds or less. The figures do not disclose the whole story however. We mentioned earlier that the low engine compression hurt the low rpm power and this is quite noticeable when starting from a dead stop. Revving the engine while holding the brake didn’t produce more than just a slight wheelspin on the start but once the engine reached the 3000 rpm mark, the car felt strong. Standing start quarter mile times of 17.5 seconds also fail to show that the start was slow but the engine was running very strong at the end of the quarter with a speedo correction showing 85 mph for the ¼ mile.

A single high speed run was made on a flat desert road and the speedometer indicated 115 mph but  calculations made by tachometer readings indicated the true speed nearer 108 mph. At this speed the tachometer indicated 4600 rpm and the engine was “missing” badly enough to keep the engine rpm from increasing. This bore out our earlier findings that the valves started to float after 4500 rpm.

A strange condition exists with a variable speed centrifugal blower such as that used on the Packard Hawk with this condition noticeable only when all side windows are closed tightly so that the engine can be more easily heard. A centrifugal blower will cavitate when it is not pumping air and will therefore require less power to drive the blower. If the engine is being run at full throttle with full blower pressure being used and then the throttle suddenly closed, the blower will cavitate and speed up several hundred rpm as the load is relieved from the impellor, and the drive ratio increases. This condition also exists in the hawk when top speed is reached and the engine will not take in as much air as the blower is supplying. The blower rpm will increase slightly even though the engine speed remains constant.

The fact that this cavitation occurs at top speed indicates that a few modifications to the engine would permit it to use the blower pressure being wasted and probably produce a lot more power. Increased valve spring pressure together with increased cam timing and more carburetor venturi area should do wonders for this engine especially in the upper rpm range. With its streamlined design the Hawk could have a pretty good top speed.

Special Interest Autos, December 1979 – 1957 Thunderbird F-Model Driving Impressions

Don Antilla’s car is pure American Graffiti, the culmination of a crew-cut high schooler’s dream sketched out in notebooks during long, boring study halls. It develops nearly one hp per cubic inch of engine. It has fins of a sort, if you’ll allow us to define fins in this case as not rising above the uppermost body line. It’s a convertible, And it has that strong American V-8 rumble accentuated by the hottest cam available in the 312 that year and, by the owners choice, a lack of resonators in the exhaust system. This F-Bird is authoritative without being strident in its exhaust note, and the pleasant, loping burble at idle seems just right for the character of the car.

The engines behavior bespeaks exciting performance, but unless you were told you’d never know there was a supercharger under the hood. It’s virtually noiseless in operation and there’s not one identifying mark on the entire outside of the car to indicate the extra poke lurking there.

Our drive report car was the hottest off the shelf T-Bird that could be ordered in 1957. Besides the McCulloch supercharger and the wilder camshaft, it has a three speed stick shift coupled with overdrive, reinforced cylinder heads, and a 3:70 rear end ratio. The supercharger on this car is set up to give a five psi boost above 3000 rpm. On paper, it should go like the hammers. On the road it does.

Snapping its nose upward, the F-Bird takes off with a menacing growl which grows in ferocity as the revs climb. A quick shift to second, a chirp of the tires, and again this growling crescendo as the torque presses you back in the seat and the tachometer swings over toward the 5000 mark. Yet there’s no straining feel to the engine. It acts like it could just keep climbing forever. No fuss. No fumes. Just very rapid transit. We didn’t put a stopwatch on the car, but it feels like 0-60 comes in five to six seconds. For all of its breathtaking acceleration, though, the car can behave in a downright civilized manner when pottering through town, its dual exhausts quietly bubbling away as it docilely glides along at 25 mph in high gear without a stumble or stutter.

The F-Bird’s performance reminded us very much of the three speed Corvette from the same era. There’s that same endless rush of power. In a face-off, however, the Vette driver would have the upper hand in the shifting realm, for the ‘Bird’s spacing between gears is quite long and um, well, somewhat vague and awkward.