Since the engine has a Y-block design, dropping the sides of the block all the way to the
"All the testing that I did with carbureted and fuel injected was with the same carburetor and the same manifold. The good part about doing the testing the way I did was that I used the carburetor as the actual throttle body. That takes anything out of the equation of whether one was a restriction or the other. And just to see if it was a restriction, I did test with a 100mm throttle body." It was so big that under wide-open throttle, it was the same as essentially running with an open intake. What did he find? "Nothing," Mark says. "It made identically the same power."
Asking Mark what the overall difference was between the carburetor and fuel injection, he says: "You know what, I didn't find anything between the two of them. You can overlay the carbureted version with the injected version, and it is so close to identical you could hardly tell the difference from one to the other. Even the air/fuel ratio was the same." Looking back at previous engines and data, Mark suggested that differences in the two setups and more specifically comparing individual cylinders' air/fuel ratios compared to power output, it was not so much whether or not the engines used a carburetor or EFI, but rather the design of the intake and exhaust systems and the way that they correspond to cam timing events. The pulses of air through the engine and out the exhaust have more of an effect on the engine's output than the method of fuel delivery.
Shelf-stock Probe rods and pistons make the combination practically fall together to save
"My preliminary theory on the carburetor was that it was going to be so much worse due to the fact that the manifold has right-angle turns in it. But you actually get a better, denser charge with the carburetor than you do with the injector. I think the injector has got a little better potential to put the actual fuel itself into the chamber, simply because it's aimed directly at the back of the intake valve. I think there's definitely positive power to be made with a carburetor over injection on certain manifolds because you get a cooler, denser charge, and the fuel is better atomized. However, on this particular manifold, I think that part of it is negated because of the design of the manifold. Having a plus and a minus gave you a zero."
When asked as a side question whether he had tried to run both a carburetor and fuel injection at the same time to take advantage of both systems' positive inputs, Mark's simple yet slightly evasive answer was "yes." Was it beneficial? "Yes." Take that as food for thought and discuss amongst yourselves.
White or wheat? Soup or salad? Carburetor or fuel injection? The answer might be as simple or complex as you want to make it, but in the end, it may be a matter of personal taste and the confines of your components.