FI, more hp....http://www.twminduction.com/faq/faq.html

Carbs are a thing of the past... For early 911s and 912s and 356s, or hot-rod 914s.

In the maintainance aspect, carbs and EFI will only continue to run good if you maintain them. That means: making sure your vacuum lines are good (no leaks), rubber seals are good, parts are working: Auxilary Air Regulator, Cold Start Valve, injectors aren't plugged, MPS/AFS work correctly, etc.

Programmable EFI is the new technology, affords more driveability and more power than carbs.

Although, you see a power increase over stock injection with the proper cam. Stock cam is for the stock induction system.

perfect summary trek!

you've learned how to deal with the shortcomings of carbs and i prefer a system without shortcomings ...

we both win!
Andy

yep PEFI is even superior to carbs... im surprised peak power wasnt the same tho... but EFI was better all over teh curve.....

AA

so if a guy wanted to learn how to operate a digital volt meter and how the stock fi works, then where would he do that

this will get you started:

http://members.rennlist.com/pbanders/

Andy

I like to stir things up a bit ( as you know ). :naugthy:

I wonder why the PRC 911 Toyo spec race class runs Weber's.
I'll have to ask Rich.

( Rich runs Weber's, BTW, and almost always wins )


KT

Come on down to Nor Cal, we have some carb'd T4 cars that will eat fuel injected cars for an appetizer. Once you figure out where to set floats and set proper fuel pressure starvation isnt much of a problem.



So whats wrong with havig a dumb redneck pouring the gas as long as he's getting the job done?

Mechanical Fuel Injection

300PSI sequential fuel injection, corrected for altitute and load, Individual runners..... and NO COMPUTER.......


And that Heavenly Scream at 6 grand!!!

Sooooo, if you want to have a good running, efficient, reliable car, run FI.
If you want to run around a parking lot dodging cones while making the vroom vroom noises, run carbs

Carburetors have an idle circuit, a main circuit, and a transition circuit which is nothing more that an overlap of the idle and main.
that means that if it is set up perfectly, it can meter the air/fuel ratio perfectly during three places in the RPM range. the rest is a compromise where it's close enuogh.
Fuel injection has an unlimited number of circuits and it adjusts the metering constantly. It is more accurate.
Now, the real point when talking about power isn't the a/f ratio, it's about letting the engine breath with the least amount of intake restriction and the most accurate fuel metering. Stock D-jet is choked down a little and restrictive, but it is good enough for stock cams.
Carbs only make more power because they are less restrictive at higher rpm, but the only time you can benefit from the lower restriction is if you have hotter cams that will let the engine spin higher.

The absolute best set up (besides turbocharging) would be hotter cams and individual throttle bodies with a programmable EFI system.

Of course this whole debate about which gives you more power is only for the normally aspirated (handicapt) folks among us
If you have a turbo, you don't have to argue about what will give you that additional 5 hp

Using race cars as examples of 'how carbs are good' doesn't prove much to me. Other than a brief moment at the start of the race, a race car will live in it's upper rpm range the whole duration of the race. It's probably pretty easy to tune a carb for the engine's high rpm range at WOT.

A pure AX car would probably get much more adantage than a track car by using EFI. The best setup would be EFI with crank fired ignition. That way ignition advance can be maximized at every rpm and the engine could have the best possible torque curve.

But most people build AX cars on a budget and putting several grand into crankfire EFI and the nece$$ary tuning is beyond most budgets. And that doesn't take into account how many points you'll get for EFI or which class it might push you into.

I laugh at these posts, everyone says that what they have is the best, even if they have never used anything else.

We are the Weber, all others are irrelevant, you will be assimilated, you must comply

On a AX car torque is good as coming off a corner and accelerating to the next is where its at. Now the poster was talking about

"I just bought a 1976 914 and am thinking about replacing the
FI with carbs. Is this a mistake?"

Now this isn't a six nor a race car but a stock 4 so I think FI is the ticket UNLESS he changes the cam. I don't think he will be driving around at WOT like Miles.

Here is my problem. At the low end when I step on the gas pedal the car does not accelerate smoothly. I press the pedal a little and nothing much happens. I press it a little more and still very little happens. I press it so more and it takes off with a jerk. Its like either on or off. Making a smooth take-off is very difficult. Is this a characteristic of the FI? My other 2 Porsches ('81 911SC and '69 911S)have carbs (Weber and PMO) they don't do this. What is the cause?

Don from Philly

I would venture to say throttle position sensor needs to be cleaned/replaced from what you're saying.

Who sells these?

I have Weber 40s, with corresponding cam & dizzy & exhaust changes. Usually my car runs great. But until yesterday when I pulled 'em, disassembled, cleaned and blew out, etc, I had somewhat reduced performance from crap in the passeges- again.
BUT
At the SEC, I ran along behing Jason (D1A4 I think is his club name), with a completely stock 2 liter. His car was so SMOO-OOTH sounding, and my "hot rod" engine had to work really hard to keep up.
Summary-
I wish I had the FI. My carbs have been pretty reliable, but just not as balanced as FI, and never will be. And carbs can be frustrating too as Brad Anders experienced. I think it would be worth it to go through the FI system, make everything righty-tighty, and think pure thoughts from now on.

Can be a bunch of issues:

check the advance plate for sticking in the dizzy
check the MPS for proper #'s and is it rebuild by AA?(a incorrect rebuilt MPS works like your symptoms)
check for vacuum leaks
check for a sticking throttle plate inside the TB
etc....