The Who And Why Behind The EFI Swap
Your standard bracket racing vehicle isn’t as complex as a high-end heads-up race car; its set up to run a specific elapsed time repeatedly with deadly accuracy. For this project, we’re using a 225-inch hardtail dragster that was originally built by Horton Race Cars. Powering the dragster is a 509 cubic-inch big-block Chevy that’s topped off with a set of
Brodix cylinder heads and a
Wieand intake. Before the swap, fuel and air was mixed by a 4500 Dominator carburetor that had been worked over by Davinci Carburetors.
The best pass the owner had made was an 8.49 in bracket racing trim and the car would run within a few hundredths depending on the weather. Those are some respectable numbers, but the car did have consistency and tuning issues with the carburetor at times, so that made it an ideal candidate for this EFI swap. This project is as real as it gets: no big shop, dedicated mechanics, or trained tuners doing the work…just two racers in their home garage.
EFI provides precise fuel delivery, and the Holley Sniper can do that through its self-learning ability. With EFI, you are also using a laptop to do your tuning rather than physically changing the metering blocks, air bleeds, jets, power valves, and squirters on a carburetor. – Matthew Lunsford, Holley
Introducing EFI into the picture for a bracket car can be a catalyst for improved consistency. A carburetor can only be tuned for one specific set of conditions, and we all know that weather is a very dynamic thing. EFI has the ability to adjust the fuel and spark the motor receives on the fly, thus eliminating some of the consistency issues you might have at the track.
Matthew Lunsford from Holley is part of the team that developed the Sniper EFI system — he explains why the Sniper is a great fit for a bracket racing application.
“EFI provides precise fuel delivery, and the Holley Sniper can do that through its self-learning ability. With EFI, you’re also using a laptop to do your tuning rather than physically changing the metering blocks, air bleeds, jets, power valves, and squirters on a carburetor. There’s also the added safety features EFI offers; for example, if your engine starts to go lean, the ECU will automatically add fuel to keep your target AFR (air/fuel ratio). There’s also built-in data logging with the Sniper system, so you can see exactly how your engine is performing.”
How To Feed The EFI Beast
If you’re contemplating an EFI swap, the first thing you need to address is the fuel system. The fueling needs of a carburetor versus that of an EFI system are very different in terms of design and parts. Roughly the same volume is needed with both types of fuel delivery, since the same old equation applies (fuel + air + spark = horsepower). However, EFI requires significantly higher fuel pressure than a carburetor, so you’ll need to change the fuel pump to something that can continually produce the minimum 58psi of fuel pressure required by the Sniper system. You’ll also need to add are pre- and post-pump fuel filters to the fuel system; we will cover that more in a minute.
The Holley Dominator billet fuel pump is the perfect choice for a project like this. The pump flows more than enough fuel and has a footprint that allows it to be mounted easily in tight spaces.