Pushed to its Limits

We Push Vortech’s New Third-Generation Blower Kit for the Small-Block Chevy to its Limits to Find out Just How Much it can Take

By Jeff Huneycutt   –   Photography by the Author

You’ve probably seen the memes on social media that show a ludicrously gigantic, locomotive-sized blower or turbo mounted up to an engine on some car with a caption that reads something like, “After a week, John decides he needs more power.”

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And it’s funny because, by and large, it’s true.

If being a car guy or gal is a disease, then symptom number one is a constant, unslacking thirst for power. After all, what’s more fun than a hard hit off the line, or turning a set of perfectly good tires into smoke? It’s addictive, right?

002 Vortech's complete fit kit vortech blower install
The full kit from Vortech is pretty comprehensive, and everything fits exactly like it should. This includes the compact V-3 Si-Trim compressor, all the plumbing necessary, a blow-off valve, all the bracketry needed to mount up not only the blower, but also an alternator, a power steering pump, and an A/C compressor. We ruined it by laying everything out on the table for this photo, but the components are bagged up in logical “families” so when you are working on one section of the kit, everything you need is right there in that bag.

That’s where Vortech Superchargers has made its mark on the industry, both among hard-core racers and hobbyists. Their rock-solid centrifugal blower designs and mounting kits are one of the easiest ways to make absolute gobs of dependable power in practically anything that turns gasoline into motion.

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003 Changes to block new gasket and intake to fit vortech blower install
We made a couple of changes to our 427ci stroker small-block to make it applicable for this test. Mainly, we swapped out the standard 0.030-inch-thick MLS head gasket for a special extra-thick head gasket we sourced through Summit Racing with a 0.070-inch compressed thickness. That knocked the compression ratio down from 10.1:1 to 9.35:1. We also added an Edelbrock Super Victor single-plane intake to make sure we didn’t restrict any air from the blower getting into the combustion chambers.

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One of their latest designs is the third-generation blower kit for the venerable small-block Chevrolet. The kit uses Vortech’s compact V-3 Si-Trim compressor and a modular serpentine belt setup for the accessory drives, which allows you to run an A/C compressor and/or power steering if you like.

And possibly the coolest thing about the kit is it is designed to meet the greatest desire of us car guys and gals: an affordable, easy horsepower boost to our rides that we can do ourselves right in the garage or driveway. In fact, Vortech says the kit can be installed in four to six hours. The basic kit is pretty affordable, at just a smidge over $5,000–impressive considering all that’s included.

004 High Horsepower Blow Through Carburetor vortech blower install
In its marketing materials, Vortech mentions this kit working with a blow-through carburetor, and it certainly will, but we wanted to see just how many curveballs we could throw and bolted up one of Holley’s 4150-sized Sniper Stealth EFI systems. This is the high-horsepower unit that packs eight 100 lb/hr injectors (instead of the usual four) and can handle as much as 1,250 hp in boosted applications. Although we monitored everything on a laptop, after going through the setup program on the handheld, we basically let the ECU handle the fuel maps and ignition tables.

Now, understand that this is not a no-holds-barred, horsepower-at-all-costs blower kit. Instead, this is an intelligently designed kit for a specific purpose that many of us can appreciate. It is designed to bolt directly to a stock, or lightly modified, small-block Chevrolet and boost the horsepower between 35 to 65 percent. So, we’re talking a significant boost to both horsepower and torque without the need to swap out the stock camshaft, stamped steel rockers, valvesprings, or anything else. You will need a blow-through carburetor or boost-capable EFI system, the radiator fan must be electric, and if you want to run A/C you may need to swap out for a different compressor unit. But for the most part everything else you need is either in the kit or already on your engine.

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005 Main Supercharger Unit vortech blower install
Here is what this whole project is all about. Vortech’s V-3 Si-Trim supercharger is incredibly popular because it packs a big punch in a compact package. The unit operates efficiently with a 3.61:1 step-up ratio and a max speed of 52,000 rpm. At max boost of 22 psi, it can move 1,150 cfm of air and produce as much as 775 hp on highly modified engines.

So, when we recently got our hands on a Gen 3 small-block Vortech blower kit for some testing, we wanted to see just how far we could push the design. Instead of a stock Chevrolet 350 small-block, we decided to bolt the kit up to a bored and stroked small-block capable of roughly double the horsepower of most stock 350 engines. (Yes, we understand that the 350 was produced by Chevrolet for decades with a wide range of power levels, but we went with the average spec of 250 peak horsepower, the majority of 350s were capable of producing.)

006 Specific and necessary long snout reverse rotation water pump vortech blower install
This shot represents where we nearly messed up, and it would have been entirely our fault. Vortech provides a list of all the ancillary components you will need along with the proper part numbers. That includes a specific water pump. We had a handful of water pumps sitting around the shop and just bolted up one we assumed would fit. That’s it on the right. But the serpentine system requires a long snout, reverse-rotation water pump (left), which we discovered at the last minute (by reading the instruction manual, which very plainly states which pump you need). To fix the issue, we called the guys at Summit Racing with a list of part numbers. They had everything in stock and had it shipped the same day. No muss, no fuss.

The reason for this decision is simple. We know the guys at Vortech and have used their blowers and kits for years. They don’t blow smoke with their marketing, so when they say it will produce approximately 5 psi at 5,500 rpm on a stock or mildly modified 350, then that’s what it will do.

If we bolted up the kit to a stock 350 small-block, we knew the results would be exactly what we were told to expect. Instead, we decided to have a little fun and try to find just how far the Vortech kit can be pushed. What are its weak links? Where does it shine? It’s time to get down to the real nitty-gritty.

007 Main Supercharger Bracket vortech blower install
This is the main bracket for the supercharger. It also mounts up the power steering pump, which you can see at the bottom of the bracket, as well as the alternator. The bracket is a mixture of aluminum with some steel where necessary, and the best word to describe it is “beefy.”

Our test engine has a 4.125-inch bore and 4.00-inch stroke, giving it a displacement of 427 ci. For cylinder heads we’re running a pair of aluminum Brodix Dragon Slayers with 68cc, CNC-cut combustion chambers, and 225cc intake runners. They are outfitted with stainless valves sized at 2.080 for the intakes and 1.600 inches for the exhausts and can flow over 300 cfm at 0.600 valve lift.

The valvetrain is a hydraulic roller spec’d out by Comp Cams. Our cam is designed to be streetable using a torque converter with a real-world stall level, so the duration is relatively short. It is ground with 231 degrees of duration for the intakes and 243 for the exhausts—both at 0.050 inch of tappet lift. Gross valve lift is 0.598 inch for the intakes and 0.600 for the exhausts. Right up against the peak 300-cfm flow numbers of the Brodix heads, if you remember.

008 Side View of the Bracketry setup for vortech blower install
A side view of the bracketry setup on the right side of the engine shows just how beefy the support structure is. All the bolts slot through machined aluminum spacers with plenty of attachment points to the block or cylinder head. As you can see, this side mounts up the A/C compressor and a tensioner for the serpentine belt system. If you choose not to run air conditioning, the compressor is replaced with an idler pulley.

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To help move plenty of air into those heads, they are topped with an Edelbrock Super Victor single-plane intake manifold. And since this is 2023, we ditched the carburetor for a Holley Sniper Stealth EFI setup for tuning ease and superior overall performance.

One change we made specifically for this test was to knock the compression down a bit. With the big bore and 4-inch stroke, as originally built the 427 had a compression ratio of 10.1:1. That’s fine for pump gas naturally aspirated, but possibly a bit much when the Vortech blower starts adding compression. So, we called up Summit Racing and they sent us a set of extra-thick, multi-layer steel head gaskets that are 0.070 inch thick when compressed. That’s 0.040 over the standard, which knocked the compression ratio down to 9.35:1. This way we can still reliably run pump gas.

009 Drive belt system setup relying on reverse rotation water pump vortech blower install
Now that the serpentine accessory drive system is complete you can see how everything is set up. There are lots of belt engagement with all the pulleys, which is nice. Also, you can see how the serpentine belt routes underneath the water pump pulley, requiring a reverse-rotation pump.

One of the cool things about Vortech’s kit is that it is flexible according to your needs. Got a lightweight, bare-bones hot rod? Then the standard kit is for you. Do you enjoy the finer things in life and want to keep your power steering and/or air conditioning? Then you can have either or both with a couple of add-on brackets. The modern serpentine belt system easily accommodates whatever setup you like.

While Vortech does offer the bracketry needed, you may need to come up with a few components if they aren’t already on your engine. That’s the situation that we ran into. Our 427 small-block had previously spent its life as a dyno test mule. As such, all we had was a single belt driving the water pump.

010 Extra Thick Steel Cut Bracket vortech blower install
The bracket securing the supercharger unit is cut from steel for extra strength. Vortech definitely didn’t scrimp on the Grade 8 fasteners to make sure everything is mounted solid.

But Vortech provides part numbers for everything necessary to make it all work. We wanted to test the complete setup, so we dialed up Summit Racing’s website and ordered the power steering pump, A/C compressor, alternator, water pump, and all the associated pulleys we needed and had it all delivered to the shop two days later.

Naturally aspirated, our small-block Chevy performed surprisingly well. Even with the lowered compression, dyno testing showed the 427 made 524.1 hp at 5,700 rpm and 529.7 lb-ft of torque at 4,800. Not bad.

011 Dents on supercharger provides clearance for the float adjusters vortech blower install
You can tell that the engineers at Vortech worked very hard to keep this kit as low and compact as possible to help make sure everything would fit underneath a stock hood. An example is the underside of the included cast carb hat. Notice the “dents” 180 degrees apart from each other at approximately 12 and 6 o’clock here. These provide clearance for the two fuel level float adjusters on either side of a four-barrel carb allowing the carb hat to sit lower. We found that the bosses on the Sniper Stealth are thicker than the fuel level adjusters on an actual carb, causing the hat to rub here and not seal securely to the top of the throttle body. Thankfully, the bottom plate on the carb hat is thick cast aluminum, so we were able to grind the extra clearance we needed. It’s just one of the things you run into when you mix-and-match parts on your engine build.

But when we bolted on the Vortech blower—even though it is one of the smaller units in the Vortech lineup—things really took off. We chose to run a Holley Sniper Stealth EFI unit along with their Hyperspark Ignition that’s designed to mate perfectly with the Sniper setup. So instead of fiddling with jets in a blow-through carburetor, we simply let the ECU handle both the fuel and ignition curves. Tuning was literally a matter of giving the built-in ECU time to do its thing.

012 Kit put together vortech blower install
In this shot you can see how everything fits together now that the discharge tube is attached between the blower and the carb hat. The silicone sleeves allow for a little flex when the engine gets warm. We’ve also got the 10-rib blower drive belt and the tensioner installed. Everything is super sanitary and looks great.

It turns out the Sniper EFI and Vortech blower go together like ham and eggs. After running the Sniper setup on the engine in naturally aspirated mode, we bolted up the discharge tube connecting the blower to the carburetor hat, reinstalled the blower belt drive, and let ’er rip. Within a couple of pulls we were making a consistent 689.4 hp at 6,100 rpm and 642 lb-ft of torque at 5,000.

That, by the way, is an improvement of an astounding 165.3 hp and 112.3 lb-ft of torque! Maybe best of all is the fact that the torque was already sky high at 629.7 when we began the pull at 4,500 rpm and didn’t drop below 600 until all the way up in the range at 6,100 rpm. It’s torque that makes any car or truck fun to drive, and this kit provides it in spades.

013 Race Bypass Valve bolted to mounting pad vortech blower install
Hidden out of the way on the back side of the discharge tube is one of Vortech’s Maxflow Race bypass valves, which can flow 320 cfm. It bolts right up to the mounting pad that comes already welded to the discharge tube.

The strength of Vortech’s newest kit is it does exactly what they say it will do. It bolts right up, the bracketry is all beefy while also being compact, so the blower should fit under the hood of most cars, and the V-3 Si-Trim compressor is efficient and runs cool.

The one thing we noticed during testing that could conceivably be called a weakness was blower belt slip around 6,300 rpm or so. You could hear it and notice power and boost dip on the dyno graph. With that said, Vortech offers a cog setup for this kit as an upgrade that takes care of the slippage.

014 Complete Setup on dyno 5 pounds of boost vortech blower install
On the dyno, the package fared very well. At just 5 pounds of boost, the setup produced absolute mountains of torque all through the range with a peak of 642 lb-ft at 5,000 rpm. The horsepower jumped from 524.1 naturally aspirated to 689.4 under boost. By the way, we started our testing naturally aspirated by pulling the discharge tube and carb hat off the Sniper Stealth and removing the 10-rib blower drive belt.

At first blush, you might think the 10-ribbed belt for the blower drive isn’t good enough, and a cogged belt, which practically cannot slip, is called for. And that was our first reaction. But then we took a moment and thought about why Vortech did purposely spec out a ribbed blower belt. The kit is engineered specifically for stock or mildly modified small-blocks, so the redline is almost always going to be well below 6,300 rpm. Before seeing that much rpm, you are going to get valve float, or the HEI distributor is going to run out of spark, or a whole host of other issues is going to get in the way. If you aren’t going to be running enough rpm to slip the belt, then a ribbed belt is the much-preferred option over cogged. That’s because a cogged belt causes a lot more parasitic drag on the engine and literally eats horsepower. So, for this application, the 10-rib blower drive belt is the smart choice. It will be more efficient to save horsepower, last longer, and work just as well in the correct rpm range.

015 Dyno graph vortech blower install

Overall, we couldn’t be happier with how Vortech’s newest blower kit performed. It turned out so good, in fact, that we’ve decided the 427 in its current form would be too much fun not to take advantage of. So, it’s being retired from duty as a dyno mule and will be installed in a car—blower and all—in the near future.

Stay tuned!

Sources

Edelbrock
(888)799-1135
Edelbrock.com

Holley
(866) 464-6553
holley.com

Summit Racing
(800) 230-3030
summitracing.com

Vortech Superchargers
(805) 247-0226
vortechsuperchargers.com

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