TECH TALK WITH PRO LINE RACING: EFI vs BLOW-THROUGH CARBURETOR ON PROCHARGED ENGINES

Centrifugal superchargers are very popular and effective power-adders for drag racing due to the linear power bands they produce and the quick throttle response of a mechanical drive. As a result of being the technology leader for decades, ProCharger’s name has become synonymous with “centrifugal supercharger.” Even though this information applies to all centrifugal superchargers, our focus is on ProCharger because of their technological innovation, proven history of success, and their partnership with Pro Line Racing. Although there are many advantages to running a ProCharged combination in drag racing, the primary focus of this article is to help people get the most out of their ProChargers through optimal fuel delivery.

Pro Line Racing is extremely fortunate to work with respected companies that have deep roots in drag racing. Atomizer Fuel Systems and FuelTech are two fuel injection powerhouses that partner with PLR, and along with ProCharger, make a very quick trio. We invited the tech gurus from each company to weigh in on the discussion: Jack French of Atomizer Fuel Systems, Luis de Leon of FuelTech USA, and David Werremeyer of ProCharger.

Pro Line Racing: What are the benefits of electronic fuel injection when compared to a blow-through carburetor on a ProCharged engine?

Jack French: Blow-through carburetor setups are power limited for a few different reasons. There is only so much fuel and air that a ProCharger can push through a carburetor vs pushing air through a big throttle body and fuel being injected directly into the intake ports. Tuning is another reason for power limitation.  The air/fuel ratio of a blow-through carb will need to be as balanced as possibleat the track to enable low rpm drivability and high rpm fuel delivery under load to avoid burning up the engine down track.  This is especially criticalwith changing weather conditions.  A rich tune is safer butmakes less power.

Luis de Leon: Electronic fuel injection removes the mechanical part of the fuel delivery out of the equation. Fuel is no longer being delivered based on vacuum, or boost, with a bunch of jets or similar. When using EFI, the fuel goes in not because air is flowing or there's a resonance or some kind of turbulence, but only because of what the tuner commands. Additionally, there's no need for a venturi with EFI, and that means more air flow at the same throttle body size; the fuel is not drawn into the engine – it is sprayed - and that will slightly bump up the volumetric efficiency of any engine. How that fuel, and also timing, is made, is very important, too. Because there's a high speed computer doing all the work, you have a huge amount of set points, 1024 for fuel and 1024 for ignition on the FT500/FT600. This gives you a high precision form of fuel and timing control that’s not available with a carburetor. That means you can have your engine leaner on idle and with the exact mixture you desire under load, and if by any means the engine requires an specific amount of fuel on an specific rpm/load, you also can do that without compromising other parts of the rpm and load range.

David Werremeyer: In my opinion the biggest advantage is being able to have better control of individual cylinders. With this control, the engine is able to operate more efficiently and accelerate quicker down track.

PLR: Are there any drawbacks to EFI on ProCharged engine?

JF: Parts cost may be the only drawback, but good blow-through carburetor tuners are hard to find and that puts a premium on their services. The high cost of blow-through tuning may offset the EFI parts cost, though.

LDL: The only drawback is that if something is newer, there are fewer "recipes" out there. EFI will require a tuner, to at least get you a base tune to work off of, but for someone that has never tuned a car, there will be a sharp learning curve on how to deal with it. It’s not hard, but if there's any drawback, it would be this need of understanding computers and electronics, not just wrenches.

DW: Traditionally, the main drawback was cost. When you’re looking to make 2,000+ horsepower with a ProCharger, that cost factor between carburetors vs. EFI is even.

PLR: How easy is it to convert a blow-through ProCharged system to EFI?

LDL: It's pretty simple. Remove the blow-through, add a throttle body. Then, replace your existing fuel pump for one capable of higher pressure since EFI uses at least 43 psi of base pressure, and add a fuel pressure regulator, capable of keeping the pressure going up 1:1 with the boost going up. Replace your intake with one that’s ready for fuel injectors or modify yours to be able to receive injectors. Sometimes, the crank trigger that commands the ignition system is already supported by the EFI, but in a worst case scenario, you just need to add that to your crankshaft pulley and then the EFI is ready to be installed and control your fuel and timing.

DW: Converting from blow-through to EFI is fairly simple, especially when EFI systems are pre-wired with each harness labeled, it makes the install very straight forward. Also, customer service is a critical part for the end user. If the customer doesn’t have manufacturer support, the odds of the customer being able to navigate and to use the full potential of his or her EFI system goes down substantially.

PLR: How expensive is it to convert a blow-through ProCharged system to EFI?

JF: Fuel injector cost for a 2,000+ horsepower engine would be roughly $200 per hole when using race gas, and $350 per hole using methanol.

DW: When you’re starting from scratch, the expense is pretty much the same. Especially when you factor in ignition, data logging, boost control and traction control systems that a carburetor customer would have to potentially purchase in order to remain competitive against their competition. With EFI (depending on the system) all of those features are built into the system.

LDL: Just the ECU will cost about $1,800 on the FT500 version and $2,800 on the FT600 version, and all the other components can vary more than the ECU itself. Keep in mind that a FT600 unit is able to control the whole car. It can control your engine, your transmission, your boost or/and your nitrous, and be your dashboard and data logger too. It’s not just an EFI system; it’s a complete car controller! FuelTech makes it easier to install and use any other electronics and is capable of accepting further changes. For example, if you change your combination, you don't have to change the brains of the car - it's only a matter of putting the new tune in and going racing. More and more people are moving away from carburetors, so the later a user decides to convert to EFI, the less money they will get when selling the carburetor setup.

The prospect of switching your trusted ProCharged beast to electronic fuel injection may be a little intimidating for those considering the change, but the experts at Pro Line Racing are more than willing to help every step of the way. Our friendly sales technicians are ready to help you get the most out of your ProCharged engine!