Carb to EFI hp gain?
 

Had a conversation with a friend over the holiday week. We talked about hp gains from Carb to EFI . I used my 620 horse 572 pump gas crate engine as an example. I say hp gains would be very small maybe 5 to 10 hp. He thinks more like 20 to 30 depending on what type of injection . I don't think so what do you guys think????

Im not buying 20 to 30 hp, a well set up carb vs efi should be pretty close at peak hp/torque. Its under the curve with an efi system that I believe 20 is obtainable, throttle response is the biggest eye opener for the carb to efi swap, of course cold start and cruise become more effecient as well.

Rich

I'm with you Rich

What he said.

carb should make more power, especially on the top end. What I hear is that a carb atomizes fuel better than efi. efi should have more bottom end and be more responsive, but other than that shouldn't make more than a carb

As mentioned a carb should actually make a few more hp at peak than an EFI. But the trip there will normally be better with a well setup EFI system.

Not quite true. EFI injects fuel at a much higher pressure differential than a carb, and thus achieves much finer atomization. What is true, though, is that the longer path from fuel introduction to intake valve on a carb setup provides slightly greater time for evaporative cooling, and thus possibly slightly higher charge density. But the overall point remains - with identically configured intake systems, carb and EFI will produce almost identical peak power within the margin of error.

Of course, one of the great advantages of EFI is that port injection allows much more flexibility in intake configuration, which can and does yield benefits in mid range performance in particular.

Depends on the manifold. If you're just swapping out the carb for one of those EFI throttle bodies that has the injectors in it, you won't see too much difference other than cold starts, MPG improvement, and easier tuning. Switch to an MPFI setup with separate injectors for each intake runner in the manifold and you're going to see further improvement in throttle response also and MPG. It's not until you change the manifold to a tunnel style unit with the throttle body mounted on the front(like an Edekbrock Pro-Flo XT) will you see any noticeable increase in horsepower. So I agree with others. A straight carb-to-EFI swap using the same manifold will not make much difference in horsepower, with the slight edge on peak HP going to the carb. Several magazines have proved that already also. I just recently spent some $K's to swap from carb to an MPFI setup and I could care less about extra HP because this EFI stuff is the bomb. Well worth it once you get all the sh_t plumbed and wired.

Otherwise your info is correct but that statement isn't.
Pro Flo XT's etc aren't for every application. If the rest of your combo isn't well mated to the power band that intake will provide you may actually lose hp/tq.
I've seen measurable gains on mild builds by doing multiport EFI on dual planes, have one on my car. I started out with an EFI'd single plane intake, went to a dual plane modified for EFI and the difference was night and day, from idle to wot. The added runner length and/or smaller plenum area proved beneficial, the exact opposite of the Pro Flo/Mini Ram type stuff.

I don't think people are doing EFI for hp/tq gains --- I think people are choosing it for drivability.