In a day and age where most people are overly concerned with making their vehicles more "efficient," it doesn't seem too practical for someone to even consider installing a device that would worsen the efficiency of their engine, does it? Well, save for the daily drivers, our trucks are essentially hot rods, right? Pop the hood on yours to reveal a shiny new two-barrel carb and you're not likely to get many "oohs" and "ahhs"...but flip that same hood and expose an ominous supercharger, and let the comments fly. That's just the ego-boost aspect associated with most viable high-performance additions-the real satisfaction comes when you're behind the wheel and that particular addition is doing its thing. You're now in a territory where eco-awareness takes a back seat to peak horsepower and torque...literally.
Granted, the majority of us don't have the funds to slap a "serious" blower on our engines, let alone build a stout blower motor from the get-go. And to be honest, we probably would never want to-while the whine of a 6-71 (or bigger) blower can be impressive, some don't find scoops protruding through hoods to be that attractive. Furthermore, for all-around driver-friendliness or long-term economical performance, the bigger and badder you go, the less you get. If it's a blower you want, though, and one that won't break the bank-or your engine-but still afford you a decent boost in horsepower, consider the Edelbrock E-Force supercharger.
Unlike the Roots-style blowers we're all familiar with, Edelbrock's E-Force supercharger is based on Magnuson's MP122 supercharger-an Eaton positive displacement-type unit that can virtually be bolted onto a stock engine with no additional modifications (which we're about to do). With its supplied 5 pounds of boost, you can easily add in upwards of 100 hp-out of the box. No valvetrain upgrade, no special bottom-end work, and no compression ratio adjustments are required. Additionally, modern superchargers such as the E-Force do not have a severe adverse effect on fuel economy. And with the user-friendly amount of boost combined with a programmable MSD ignition and 91-octane fuel (minimum), it's virtually impossible to detonate this blower combination to death.
Now, along with getting some test results out at Westech Performance with the E-Force blower on our stock 290hp 350 from GM Performance Parts, we also wanted to see what would happen if we spent about the same amount of money on just a valvetrain upgrade. After testing the base engine with the supercharger kit (which included an Edelbrock Thunder Series AVS 800-cfm carb), we threw on a set of RHS Pro Action 200cc aluminum heads (flat-tappet, 2.02/1.60 int/ex, 72cc chambers) with Comp Cams Ultra-Gold aluminum rocker arms, Pro Magnum hydraulic lifters, and a Comp 222/226 flat-tappet camshaft. Initially, the GMPP small-block was outfitted with an OE-style intake manifold and a 650-cfm Holley carb; in this scenario, an Edelbrock Performer Rpm Air-Gap (with the same carb) was used instead.
Finally, we wanted to find out what the maximum potential was, so with the new cylinder heads and cam in place, Westech pulled the E-Force supercharger out again and bolted it back on, but this time with a Holley 750-cfm carb. During the last round of dyno pulls, we also played around with different blower pulley sizes, ultimately increasing the boost to around 7 pounds (and sometimes higher), which definitely proved to have positive results with noticeable horsepower gains. So, are you curious what the outcome of each scenario was?
In its completely stock form, the GMPP 290/350 did better than advertised, putting out a peak 323 hp @ 5,500 rpm and 347 lb-ft of torque @ 4,200. With just the addition of the E-Force supercharger and 800-cfm carb, Westech was able to squeeze an admirable 400 hp @ 5,300 and 443 lb-ft @ 4,000. The RHS/Comp Cams valvetrain setup came in just under the base blower, netting 372 hp @ 5,700 and 384 lb-ft @ 4,100. On our final configuration with heads, blower, a Holley 750-cfm carb, and the supplied 3.6-inch blower pulley, the numbers increased to an equal 453 hp @ 6,000 and 453 lb-ft @ 4,000. But with a quick swap of blower drive pulleys to a 3.2, we ended our dyno session with a fairly impressive 480 hp/465 ft-lb. All of this without ever touching the engine's four-bolt-main bottom end.
So, depending on how you want to look at things, if you simply want to add a decent amount of horsepower to your small-block, but don't really feel up to a cam/head swap, then a Compact blower such as the Edelbrock E-Force might just be the ticket. Dollar for dollar, you can't beat the supercharger. However, without the cylinder heads and cam to handle increased power (we weren't able to find stiffer springs for the stock iron heads), you're limited to whatever "boost" the blower provides. In the end, it all factors on how far you ultimately want to go-and more importantly, how much you want to spend. The numbers don't lie-if you want to milk 500 hp out of your 350, now you know what it'll take.
So, you think a measly 290hp GM Performance Parts crate engine is nothing more than an ave
In its semi-stock configuration (with the addition of a Holley 650-cfm carb) on the Westec
As mentioned in the accompanying story, the E-Force blower is essentially a Magnusson M112