That depends on the specific EFI system, or at least on the approach taken.

Some years ago when I was researching EFI for the Malibu in my sig, I looked at several different systems. For what I was after, TBI didn't make the cut.

Edelbrock's Pro-Flo was a multiport system that sort of did, at least to the point of warranting a little further research. What I found was that since it didn't involve much more than converting a Victor Jr manifold to dry flow and sitting a throttle body on top of the carb pad - the shape of the resulting torque curve pretty much mirrored what you'd get with the right carb sitting on top of it instead. Saggy lower midrange and all. You'd still gain in terms of overall driveability, with some potential for a slight mpg improvement. But it wasn't a magic bullet for either more power or more midrange torque. Seemed to me like a lot of money that mostly just let you say that you had EFI instead of a carb.

I'd expect a TBI system backfitted to where a carb previously lived to behave similarly in terms of power/torque.


BTW, I ended up with one of Lingenfelter's SuperRam setups. With about 50 ft-lb more torque in the 3000 - 4000 rpm range than the Pro-Flo could muster (355 SBC). A laptop is required, but you can do tuning things with the fuel and ignition maps and other parameters that unless you're already a carb and distributor guru (or know one who will work for dirt-cheap) you can only dream about doing.


Norm

 

Torque curves are more of a manifold design issue than carb vs EFI. But carb intakes do tend to favor the top end with shorter runners.

And Edlebrocks Pro Flo system is almost a waste, it's not actually true multi-port. There's an injector in each port, yeah, but it's batch fired, not sequential, which totally defeats the purpose of multi-port....the ability to tune each cylinder individually. FASTs XFI is multi-port, but it's also like $4,000+.

And there's been much ado about nothing when it comes to carb vs EFI....engines are generally pretty insensitive to AFR changes in the +/- 3-5% range....power difference is minimal or non existent. EFI is nice though for some setups because of tuning features....especially on blower engines.

What I find amazing is that there are still hardcore believers out there that EFI is immensely greater than carb, even though NASCAR Cup engines are running vastly undersized restricted carburetors with restricted flat tappet cams, and are only a few % behind efficiency levels of F1 engines, that are $330,000+ with the best technology on the planet. Each system has advantages and disadvantages.

 

you wont find a modern carb for a 200 and yes usually a well tuned carb will make more peak power than most efi systems but everywhere else efi shines furthermore the new style TBI's use 45-60psi vs 15-18psi and wideband 02 sensors, and because they use the same intake the carb was on even over a perfectly tuned carb they will usually make the same or more peak hp and TQ and way better drivabilty and mpgs usually go up as well.

I can post up numerous carb vs efi dyno and drive tests that show this, I know we are talking a 200 6 with low pressure TBI but in the case of a v-8 the new TBI's rock (powerjection and ez-efi)and in my experience efi is the best switching to efi even tamed my cams for some reason, smoothed out a lopey cam big time and out the tailpipe passed emissions test (way back then none required now).

I am going to dyno my 408 with a 750 mighty demon annular which runs not perfect but pretty close via my WB 02 sensor, I will be installing my powerjection 750 and will do it again, they both flow about 900ish cfm so it should be a fair test....we will see.

 

htwheelz67, I'd be very interested to see what happens when you do your testing. As far as all the posts go, I think I'll just stick with my carb for now. I have one of the annular fuel technology pony carbs and I think it can make a big difference over the holley car that's on there now from what I've read. I'd love efi, but I'm not sure it's worth the expense and if the properly tuned carb runs just about the same, there's no sense spending the extra $1000 on the efi. Thanks for the input and if anyone else has any suggestions, I'm open to listen.

 

Actually, you can get good 1bbl carbs, there is a demand due to class specific racing. Hard to come by though. And yeah, the newer TBI systems are nice, most of the advantages of a carb, but with easier tunability. As far as power, mpg and drivability, it depends on the system, but a good properly set up carb should have the same drivability as EFI. FWIW I'll probably eventually switch to the FAST EZ-EFI, I think of it as a carb with pushbutton tuning.

Of course on a stock I6 200 it's pretty pointless anyway...even with the best fuel system in the universe, it's still on a no compression, no head, no cam, under performing engine. It won't make any difference because the lack of performance is due to the whole engine package and not just that it has an old 1bbl carb.

 

Single planes, yes. Dual planes tend to have better midrange, if typically with greater cylinder to cylinder variation in AFR.


The original SuperRam was also batch-fire, being essentially a higher flow, higher rpm version of GM's Tuned Port Injection (IIRC the SR developer was originally a GM engineer). Assuming that the injectors are reasonably close in flow, you get a fairly consistent AFR among the cylinders. A sequential version was under development around the time I got mine.

The advantage of less variation in AFR really comes in when your car is subject to periodic emissions testing with 1980-ish ppm limits for HC and CO and is required to have a catalytic converter. Exhaust "cleanliness" isn't quite as critical on 1960's cars, though it's still easier to tune for with an EFI setup.


Norm

 

That's one of the things I found interesting...read an interview with the FAST guys that did the EZ_EFI....they said they you get better fuel distribution with a dual plane intake instead of a single plane.

The new Pro Flo 2 from Eddy though looks like, pricey but it comes with a really nice intake, and has better tunability than the previous generation. I'd still stick with the EZ-EFI myself though, or XFI on an insane setup.