[rsmithline]

For those of us that just mastered changing of a tire on our Camaro, could one of the experts here put together short guide on EFI vs. Carb?

Some questions i would love answered are:

What is the mechanical difference?

What are the advantages/disadvantages?

What additional Gauges might you want?

What else might have to be changed?

Potential Pitfalls?

Approximate costs?

Best venders?

Mileage difference?

and anything else i forgot.



Robert

[JimM]

Like wow, Robert, looking for a good book or 2?
Have you read the few posts in this new forum, as well as searched the other forums for EFI related threads?
There are a number of other sites that I can't think of right now...

To try to hit your questions as concisely as I know how...

EFI blows, carbs suck. Carbs function by vacuum, by pressure drop across the venturi's. Problem is a car engine has to deal with too many operating conditions, and a jet and a venturi can't handle it. So we get idle and transfer circuits, power valves, accelerator pumps, and various air bleeds and emulsion tubes, all trying vainly to fill the holes in the fuel curve, while our engine is operating anywhere beteen zero and 8000 rpm, vac levels between zero and 25 inches, power levels between near zero and maxed out, and every possible combination.

Carbs simply cannot do the job accurately over all these conditions, not ever, no matter who tuned it or how well. What we end up with is a compromise, which hopefully is "too rich" enuf to cover up all the holes.

EFI injects fuel under pressure, the amount is controlled by the solenoids in the injectors, orchestrated by the computer. EFI can in facxt be tuned to be perfect under all possible conditions.

EFI will have a high pressure pump / regulator system of some sort, a throttle body to meter the air, injectors to inject the fuel, a computer and software, often user tunable via a laptop, and various sensors to monitor the operating condition of the engine and determine it's need for fuel at any given moment.

Some can in fact individually determine the amount of fuel for each individual cylinder, each and everytime they fire.

Advantages include easier starting, smoother operation, lower emission (and less stinky exhaust), and more power with less fuel.

To help keep track of my soon to be installed EFI system, as well as to try to tune my existing carb better, I've recently added a fuel pressure gauge, a vacuum gauge, and a wideband O2 gauge. I try not to look at the wideband, other than idle, cruise, and WOT, it's all over the place.

Changes will include the fuel system, pickup, pump, filters, and a return line. Most EFI systems include the regulator built into the throttle body or fuel rails.

A place will need to be found to safely mount the computer, and wiring will need to be run including relays foir the injector power and fuel pump, as well as all the sensors.

Many companies make complete bolt on kits. Holley and edelbrock, and msd just released their system, as well as companies like FAST and Accel, who's system are a bit more involved and may require additional fabrication or professional tuning. I bought a used 900 cfm holley throttle body system, complete, for $700, and it will serve me well. new holley and edelbrock port injection systems run 2 - 2 1/2 k, fast and accel are more. Many hard core DIY types have retrofitted various factory (often junkyard) systems very inexpensively.

Most of the complete systems include a "loaded" intake manifold. The injectors, fuel rails, regulator, throttle body, and many of the sensors are preinstalled on the intake, you just bolt it on, install a few more sensors, and wire and plumb the system.

And the thing you forgot is timing control. Most of these systems can control the timing, using a GM late model small body distributor intended for an EFI car, or aftermarket equivalent, such as an msd 8366.

[Rodder]

There's a couple of first guys over on ls1tech with stock LS1's and T56's, and they all seem to be getting 26-27MPG on the highway. I haven't measured mine yet.

[rsmithline]

Yes I read all of the posts here, but none had those answers.

Thank you so much for explaining. That was just what I was looking for.

Robert

[glide]

As for cost, I am expecting a donor car soon, for the cost of towing. After I swap the TPI, it goes to the boneyard. Everything I have read so far says it should be a bolt in swap from the 87 small block to my 69 307. Since it is a MAF system from a 305, and going on the 307 I may net even need a new chip. Just waiting now for the wife to look the other way, long enough to ask forgivness instead of permission.