EFI FOR SBC

[40 Chev Coupe]

Im looking to get a EFI system for my 383 SBC, any suggestions or experiences with any one system?
Any negatives about any one system?
Looking for any suggestions before I choose a system. So, your input is needed.

[wayne petty]

there are several self tuning systems out there..

it all depends on what you are going to do and how computer literate you are...

most require a PC laptop for tuning..

you can do a GM throttle body fuel injection system.. they are fairly straight forward.. a 383 stroker small block requires more injector flow rate than a conventional 5.7 injector.. you will want to find a 91 to 95 police version 9C1 pair of injectors.. that will be just about right for a stock 5.7 EFI system and a 383 displacement. you can also go to the smaller of the 7.4 injector sizing versions..

there are dozens of different ways to go..

with any fuel injection system.. you will need to think ahead and plan for oxygen sensors in the exhaust.. usually in the collectors or in an adaptor/spacer that goes between the collector flange and the adapter flange.  these usually require heated oxygen sensors.. so they give you an accurate signal at idle rpms where there is NOT enough heat from the exhaust flow to keep them above 600F and working.

lastly grounds. grounds grounds..  half the circuit is on the ground side.. and that is the side with the electrons..  battery negative to engine block. battery negative to body.. engine block to the body..  cars with frames.. depending on what accessory gets grounded to the frame.. body to the frame ground connection..

[BFS57]

Hello;
Been shoppin for EFI for a couple years. Expensive to say the least. But 2 systems come to light here.
MSD makes the Atomic. This is a stand alone system (no laptop) that learns as you drive. The other is (couple of systems) made by FAST Efi.
These systems are also self learning.
Now for the bad news (sort of) Both these and other systems require that your fuel delivery system be re done! You have to install an electric fuel pump (some supplied some not) to get the fuel from the tank. Then, if that isn't enough, you have to run a fuel return line back to the tank. These systems work on recirculating the fuel.
Then there is the question of where do you want to mount the computer. Some can mount outside some have to be mounted inside. Then, as Wayne said, there are the sensors. With these self learning systems most of the wires hook up to the part that replaces your carburetor. Did I mention that you don't have to remove your intake?
More bad news, sort of. You also have to replace your distributor so that these systems have control of your spark! (Fuel, Air, Spark!)
I think a lot of pre planning has to go into adding efi to a car that has been carbureted but once you (from what I have read) convert everything, you get way better throttle response, faster start up, and way better fuel economy.
Hope you make educated decisions on this upgrade.
There are more systems available but it mainly boils down to just what do you want out of the EFI you choose, so break out those reading glasses and educate yourself!
Bruce

[kb426]

One of my friends just installed the msd on his 37. It's a normal 350 setup. He's using an inline pump that eventually will cause problems somehow. He's not using the ignition control portion. It runs so much better that he wishes he would have done this long ago. The difference in the 2 fast versions is in the capabilities. One is basic, one is advanced. Don't let fear keep you from moving forward. This can be one of the best items you can do for performance.

[Uncle Bob]

Another positive comment about the MSD Atomic FI.  If you do a Google/Bing search for tech articles there's plenty to learn.

Several things motivated me to go with the Atomic.  I first learned about the system about 3 years ago at SEMA show.  Approaching the MSD outside display I saw a familiar car........Jim Shelton's burgundy '32 roadster.  Jim was there, so a conversation ensued.  He had been tapped by MSD to field test the then newly produced system.  They had heard he really drove his car and felt it would be a good test vehicle for the street rod slice of the market.  They were right, he's nearing 100k miles on the beast he first got on the road just over 10 years ago.  He's got roughly 10k miles with the Atomic system.  After roughly 3 years of use he still raves about it.  The only changes he's made since initial install were to load software updates, some additional tuning tweaks to see if he could coax more mpg than the self learning had provided, and to install a fuel return circuit that had initially not been done as this system can operate without a return line.  

Some of the positives that I liked were that TPS, MAP and IAT along with the ECU are all a part of the throttle body.  You end up with a very simple seven wire pigtail that hides easily.  That connects to a smallish (about the size of a cell phone) power/control module that will supply the O2 sensor, as well as other options such as fan.  To that will be connected the even smaller "tuning" module with display screen, no laptop necessary.  We mounted the latter two items under the passenger kick panel, though the display could be unplugged and put in the glove box or wherever.  Since we're in the final throws of assembly and upholstery I don't have a lot of driving data, we've probably only got about 3 miles of use, and maybe a total of 1-2 hrs of messing with the settings, mostly just to see what if anything can be noticed.  It idles nice, starts readily, and for a new installation by non techno geeks works very well just about out of the box.  I'm using an MSD plug and play distributor, but no 6al or similar box.  We could add those to give the ECU and controller more things to do, but so far it's worked well as is.

Some of the other systems are more complex which could be good if you're really into the electronics thing and think you might want to get more involved in the options that affect various tuning solutions.  I'm somewhat technophobic so opted for a more simple solution.  If mine performs anything like Jim brags about his, I'll be tickled.

[papastoyss]

Another option would be an LS conversion. Whichever way you go, Wayne's advice concerning grounds is spot on. Any resistance in the ground circuits will cause sensors to lie to the ECM. I built my '40 coupe with an LS motor & I love it. 5.3 truck LS engines can be had very reasonable & will run a long time w/ proper care.

[40_Tudor]

I have a Tune Port in my 40 Tudor. Starts great, runs great, I get a little over 30 mpg with a T5 and 9" with 350 gear. Stock motor out of an 87 Iroc. I see the TPI intakes at swap meets all of the time. Check with Street and Performance on set up and parts. They'll send you a DVD on setting up fuel injection on any car. They have been install FI in street rod since FI first came out.

[Okiedokie]

30 mpg? Wish I could get that in my TPI powered 40 coupe. 2004r and 3.25 rear gets me about 21 at highway speeds. Any tips?

[wayne petty]

30 mpg? Wish I could get that in my TPI powered 40 coupe. 2004r and 3.25 rear gets me about 21 at highway speeds. Any tips?

yes... but you will need to access with a scan tool...





without my comments ...




and the ECM HAS TO SEE VSS... it must know how fast you are going if you expect it to set the proper timing and fuel mixtures..

do you have a scan tool for your set up..

do you know what year the computer is...  89 and earlier or 90 up..

this is possible on ford EFI 5.0 motors also.. after i fixed everything on my older sisters 87 town car efi 5.0.. she can knock down 29MPG on the highway with it.  she did learn to drive from a pilot friend who taught her to roll slowly into the throttle for best fuel economy...


here.. have some more...

http://forums.superchevy.com/corvette-fever/70/8585187/c4-corvettes/which-used-scan-tools-for-82-to-94-corvettes-with/

[Okiedokie]

Yes Wayne I have a scan tool that I acquired while following your leads on making it run in the beginning. It is a speed density set up, 90 and later ecm. I will check your highlighted items. Thanks again for your input.

[rumrumm]

I was really interested in these FI systems when I read that you could employ their pump that does not require a return line. But then I read that you should not employ that if the car is driven in hot weather. What? I only drive it in the summer! No longer interested. I would have to remove all the upholstery from the trunk, replace the fuel tank, and plumb a return line. Not worth the effort and expense. Maybe on the next car if I build one.

[wayne petty]

return lines can be easy to plumb..  you can plumb them into the filler neck.. being creative of course.. using an elbow thru the filler neck that has a tube on it aiming down into the tank..

return lines are for several reasons..

#1 reason..  fuel pressure regulator operation..

with vacuum controlled fuel pressure regulators.. the pressure changes about 10 psi while the vacuum changed 15 to 18 inches of vacuum..

but let me go deeper ... fuel pumps used in most fuel injection system DO NOT have any kind of bypass.. the pump pushes fuel into the regulator and bypasses any pressure above its set point... this reduces load on the pump motor..  so it only needs to pump pressure up to 39 psi with the engine running on some systems and at wide open throttle 49 psi..

what.. when the manifold vacuum drops the pressure regulator increases pressure.. its like a power valve in your carb..  load sensitive... more load.. less manifold vacuum .. more pressure for increased richness to make more power..

if you look at the specs that are available most 39 psi regulated fuel injection system pumps can make 75 to 90 PSI deadheaded... this is very hard on the pump..  causes the brushes and communtator to be overworked and have significantly shorter lives.

kinda like trying to start a 14 to 1 nascar motor with a stock starter motor and 4 gauge battery cables..  it might work a few times.. but its in overload..


reason #2 for the return...  fuel temps...  fuel boiling from heat soak when parked with a hot motor..  

fuel at low pressure can actually Boil and become vapor in the fuel rail..   this will make for some very rough running when you restart after a heat soak and enough time for the fuel pressure to bleed off..

so instead of fuel sprayed from the injectors.. you get vapor..  your motor will not like it.. as the vapor will usually be pushed to the end of the fuel rail..

i can go on...

and please... a request from wayne...   put some super magnets in the fuel tank...  down on the bottom... this will really extend your fuel pump life... what.. your fuel pump should have a sediment screen on it.. a sock sort of device.. but fuel sediments are now so small that they can get thru that screen..  the sediments are RUST particles.. these go into the pump where the magnets in the pump catch them and hold on to them.. some get spun thru. and clogs the filter.. some may get thru the filters and clog the injectors..   magnets attract most if not all of the sediment and keep it out of the fuel system...  i actually keep a stack of them and one gets installed in every fuel tank i have open for sending unit.. fuel pump or what ever.. be sure they drop to the bottom.. i dropped on in a rubber lined C4 fuel tank and looked in.. and it was gone.. darn thing was so strong when i dropped it.. it made a u turn and stuck to the top of the tank..

oh... and if you look at some returnless fuel systems.. you may note that some have a return line built right into the fuel filter..

fords return less fuel system has a motor controller that varies the pump speed to control the fuel rail pressure.. so they have a pressure sensor on the fuel rail to tell the computer ... those are starting to fail now that they are coming up on 10 years old..

hope this broadens the understanding..