When it comes to forced induction, most enthusiasts battle internally between a supercharger or turbocharger setup. The difference in powerband or nuances each one is known for can cause many to stumble into the pitfalls of paralysis by analysis. I’m not one to throw stones though, as most of my builds have catapulted me into the dark side of researching efficiency maps on a fairly basic setup. However, once one opts for a centrifugal supercharger, another menu option quickly pops up.
In recent years, self-lubricated blowers have started to make headway into the market. From a non-engineering standpoint these make a simplistic candidate for any build, as the lack of plumbing creates less engine bay dilemmas and rely on its self contained oiling system instead of engine oil. While these units have their place, that place might not be your vehicle depending on your horsepower goals, future aspirations, or even the motorsport you participate in. We sat down with Brian Ellis of Vortech Superchargers to discuss the pros and cons of self-lubricated and engine-oil-fed superchargers.
As you might have guessed, a self-lubricated supercharger does exactly what its name describes. The supercharger contains its own fluid internally, and Vortech has designed a specialized oiling system to direct lubricant to the bearings. While Vortech’s modus operandi has been geared around the engine-oil-fed units for years, the company wanted to provide clients with the supercharger they desired, but one that could live up to the standards set at Vortech.
“Self-lubricated superchargers were something that we looked into doing because we had clients who had an aversion to tapping their oil pan,” Ellis states. “We wanted to create a product that fills that niche, but provides the quality you can expect from Vortech. Three years before we even started talking about them publicly, we had already designed our unit, performed durability tests, and continued to modify them for improvement over the years.”
Vortech designed a completely new front cover to create an oil reservoir to properly lubricate the internals of the supercharger. This cover is unique to the Self Lubricated superchargers. -Brian Ellis, Vortech
Although the self-lubricated supercharger might sound like an oil tank slapped in place of an oil feed line, there is more to it than that. “The self-lubricated supercharger contains an internal baffle, an oiling system, and vent,” Ellis says. “During the previously mentioned testing, we discovered a lot of superchargers on the market lacked said vent. These superchargers built pressure and ended up pushing the seals out. These are things we engineered around to improve on.”
Vortech went on to design a proprietary blend of lubricant that was based around its units. After years of testing, 4 ounces of oil was determined to be the correct amount of lubricant to control bearing wear and control heat dissipation. Service intervals for the self-lubricated superchargers start at 2,500 miles for the first change and then increase to every 7,500 miles, subsequently.
Opposite of the self-lubricated superchargers are the more traditional engine-oil-fed units. These setups use a high-pressure line that is tapped from the engine, typically from an oil pressure sending unit, to supply oil to the supercharger. The oil is then drained from the supercharger via a return hose that sends the oil to the engine’s sump. Once again, this is a simplistic approach to oiling, but provides massive thermal difference between the two setups.
“Engine lubrication allows us to remove excessive heat from the bearings. Along with venting the gearcase, this too allows for controlled bearing temperatures in extreme applications,” Ellis explains. “The engine-oil-fed superchargers are equipped with heavy-duty bearings, seals, and gears that allow proper lubrication that can stand up the stress and strains of additional requirements in racing.”
Although plumbing might be the reason why self-lubricated superchargers came to fruition, the engine-oil-fed superchargers only require you to tap your engine in two areas. “The best place to tap on the engine for pressure is the oil pressure sending unit,” Ellis says. “For the return, we recommend installing an -8 to -10 drain line as high on the pan and as far forward as possible, making sure the return is higher than the oil level in the pan for proper drainage.”
Now, if you happen to lack budget constraints and find yourself equipped with a drysump setup, then Ellis offers some quick advice. “For proper dry sump applications, you will need a scavenge stage along with a pressure stage, or you can tee off the oil pressure sending unit for a pressure-fed line. The drain for the supercharger will attach to the scavenge stage of the dry sump pump.”
The Hard Limits Of Self-Lubricated Superchargers
So, does having an engine-oil-fed supercharger just dissipate heat more efficiently on its bearings, but require more plumbing? Well, not really. The unfortunate truth is that self-lubricated superchargers have a horsepower limit based on impeller speed. While Vortech offers several different compressor stages for the self-lubricated units, these compressor stages are attached to a transmission that will not increase impeller speed.
Where self-lubricated blowers lack ability to increase impeller speed, engine-oil-fed blowers thrive. “Engine-oil-fed units have a higher impeller speed to start with. They can be overspun to a point and still be fine,” Ellis explains. “An engine-oil-fed supercharger might have a 65,000-rpm maximum speed on paper, but a self-lubricated Vortech supercharger will have a hard limit of 52,000 rpm. That’s a huge difference in how much faster you can spin a blower.”
Choosing Based On Motorsports
It’s safe to assume that if you are installing a supercharger onto your vehicle, then you may have plans to drive in a spirited manner. Everyone’s opinion may vary on how aggressive that is, but if you’re choosing between the two superchargers you’ll want to take into consideration how the vehicle is used.
“Our approach to self-lubricated blowers is that they are meant more for daily driven or street-driven applications,” Ellis explains. “Once you enter any motorsport or competition-level racing that involves hard cornering, drag racing, or even drifting, you 100-percent need an engine-oil-fed blower.”
Switching From Self-Lubed To Engine-Fed
At this point you might think your faithful scribe is getting kickbacks on engine-oil-fed supercharger sales, however, that’s far from the truth. When the topic was originally introduced, I actually began to think about how I could potentially turn my Vortech V-7 YSi into a self-lubricated unit. Turns out, while both self-lubricated and engine-oil-fed superchargers might share the same impeller, the majority of the unit has different components. This idea was quickly dashed when we started talking about motorsport usage.
Now, if you’ve had a change of heart after experiencing your first sensation of boost, but chose a self-lubricated supercharger based on ease of install or previous driving habits, Ellis has good news. “Vortech offers a trade-in program that allows you to trade in your fully functioning unit for a credit towards the purchase of a new one. We even accept damaged, painted, or even welded units, but you will get less in exchange.”
The Choice Is Yours
Was all this to persuade you to buy an engine-oil-fed supercharger? Not really, but knowing the limitations of the self-lubricated unit in its horsepower rating and motorsport usage can help you make the right choice. If you’re one who wants to add more horsepower to your daily driver and likes the ease of installation, then the self-lubricated supercharger makes sense. However, if you’re like me and have intentions to get down 1,320 feet of drag strip as quickly as possible, then you’re going to want to continue with the engine-oil-fed. In any case, Vortech has you covered with a large line of superchargers.