A carbureted AND fuel injected modular engine? That’s right. The clever and unique engine combination is the brainchild of engine builder Mark McKeown of McKeown Motorsport Engineering in Waldorf, MD, and actually represented his entry in the 2009 Popular Hot Rodding Engine Masters Challenge.

To learn more about MSD’s Mod 6 ignition module, check out www.msdignition.com

The engine began as a standard 281 cubic inch, two-valve modular motor, and was built using a set of TFS cylinder heads. It was built primarily for the competition, and follows all of the constraints of the rules set forth for the Engine Masters, including the compression ratio. McKeown topped the engine with an Edelbrock intake manifold and a carburetor, and utilized an MSD Ignition Belt Drive Distributor and a MSD Mod 6 ignition box, and on occasion, their Coil-On-Plug driver. Mark ran the ignition on the mod motor in a couple of different ways.

An example of a carbureted modular motor in a ’65 Mustang Fastback

“We ran a carburetor in conjunction with the FAST system – so it was carbureted and EFI all at the same time. I could run it on carburetion, on fuel injection, or a combination of both.”

To achieve this, McKeown modified the carburetor by adding a throttle position sensor, thus when the engine was run on the carb alone, the injectors could just be turned off. In that manner, the carburetor simply served to deliver the fuel into the engine. The spark function was still controlled by all the same parameters as it would be in a fuel injected configuration. Mark has run a similar engine setup both with a distributor and with coil-on-plug.

MSD’s Mod 6 Ignition

McKeown pointed out that he does see particular advantages to this combination, and went the carburetor/EFI route for several different reasons.

“When I ran the engine at Engine Masters, we’re only allowed to use either carburetion or EFI, but not a combination of both. So I had to pick and choose how I wanted to do it. But in my own testing, I have it run with a combination. The main purpose of doing this combination is that when the engine is used on EFI, the carburetor is essentially just a throttle body. And since I was able to test both through the same throttle body using the same spark, it actually gives you a very good test on the effects of EFI versus carburetion, because you’re using the same manifold, throttle body, same spark, everything. The only thing you’re changing is the point of delivery of the fuel.”

McKeown’s piece pulled a peak of 465 horsepower at 6,700-6,800 RPM. He hoped to attain a 2:1 ratio of horsepower to cubic inch from the 281 inch engine on pump gas, using a manageable compression ratio.