What are the pros and cons of fuel injecting a big block? Does it really add more power?

You can get more power if you can tune it. Not peak power but average power.

So youll go faster, yes.

A lot depends on the manifold design you choose.

When perfectly tuned, on the same intake, they will make about same power.

However there are many other benefits, WB02, datalogging, drivability is much better, and many other features.

I will never run a carb on anything and the racers I set up with EFI, 80% will never go back to a carb.

Peak power will improve slightly, by virtue of it's timing control. You are no longer constrained by the linear advance curve of a mechanical dist. The driveability benefits that make them really attractive, as they can really tame a big cam at idle and part throttle. Then the next big benefit is the data logging.

Originally posted by Tex66:
What are the pros and cons of fuel injecting a big block? Does it really add more power? Are you talking about MFI or EFI ??

MFI and EFI are relatively the same thing.

MFI = Multi-port Fuel Injection
EFI = Electronic Fuel Injection

Now there is another type of EFI which is the throttle body injectors.

Lots of small benefits to EFI, but the killer is $$$ ... basically it is capable of making a car a little more drivable, but full-on HP is about the same.

Neal

I would say it is more than just a little more drivable when it comes to a big cammed car.

When building a race big block it is not a ton more expensive than a race Dominator, race pump, etc.

For a street car it certainly is more expensive.

You have to remember if you're building from scratch you have to include the price of the intake and fuel system with a carbed system as well. So really the big diff is in the cost of the CPU. Most people wouldn't flinch at spending 2K for a laptop, but get all excited when it's for their car. What sold me was seeing a local 9 sec 502 vega, that idles around like my crown vic. Really impressive.

Originally posted by Neal Wright:
MFI and EFI are relatively the same thing.

MFI = Multi-port Fuel Injection
EFI = Electronic Fuel Injection
Neal MPFI = Multi Port Fuel Injection

MFI = Mechanical Fuel Injection

A bit of a difference to me

I guess in this day and age when ever anyone mentions fuel injection .. people automatically assume its EFI.

MPI = Mechanical Fuel Injection

Guess I'm not old enough. I've seen, and barely touched a Rochester FI ... but don't think there would be any practical reason for a street car?

Can I ask, Is there really a benefit anymore to mechanical fuel injection ... with proper electronics today? Why would mechanical even be mentioned?

Actually, if you're considering fuel injection ... you might check out an ECU called MegaSquirt.

Thanks, Neal

I have played with both and agree manifold design is huge as is tune with the fuel injection.

In my experience you will get a broader power band with the efi. If you have a good carb you can squeeze more peak power out of it. An outta the box or slightly less then optiomal carb tune would probably give the edge to efi.

Hmm...is EFI really worth the extra cost? I'm using it for street applications, so engine sound, drivabilty, and gas milage are my main concerns. How would EFI (or MPFI) affect these?

My engine with a tuned Dominator for max power went to fat lugging around.

After 1000 miles i need honing and new rings again.

You can drive a 671hp car around @1,36l per 10km with fuel injection. Under 2,5l is hard with carb.

3100lbs, 4.56 rear 33" 3500 stall.

Doug and others, does the EFI give you any advantage on a race only engine/car over a carb? More specificaly, does it improve consistency, and also is a sequential unit needed for a NA race engine, or bank to bank is fine?

Thank you

Unless you need individual cylinder control, sequential isn't needed IMO. You run at a 80-100% duty cycle at WOT, how can it help?

My friends that run EFI in IHRA and NHRA S/C S/G QR etc really like the consistency, especially throttle stop cars. There are several areas you can tune that you couldn't do near as well with a carb, including timing control. Obviously there are many with success with a dominator, but those guys are looking for thousands and 10 thousands in consistency. It is there if you can tune it.

Others comment it is nice just to start the car cold and walk away, etc as well.

The datalogger that comes std. with some systems with a WB02 is a great tuning tool as well such as the Holley.