Injecting you car the EFI way Options

[computers4kids]

Great reading. THX. A good terminology reference for FI imbeciles such as myself.


You know what would be neat? An DIY article on which GM junkyard FI fits our basic T4's e.g. 1.7, 1.8, 2.0
SBC
and a step by step article on how to install and dial one of these units in. With our antiquated FI systems wearing out every day, we would enshrine you. Especially if we coud do this on the cheap!

So you think I could put together a good working EFI system for my 305 SBC for around $500? Vortec Heads, roller rockers, mild cam, Eldebrock torquer manifold.

So what should I look for at the junkyard?
Interested in putting together a plugnplay system if I scrounge the parts?(IMG:http://www.914world.com/bbs2/uploads/post-4253-1252300281_thumb.jpg)

[Mike Bellis]

Great reading. THX. A good terminology reference for FI imbeciles such as myself.


You know what would be neat? An DIY article on which GM junkyard FI fits our basic T4's e.g. 1.7, 1.8, 2.0
SBC
and a step by step article on how to install and dial one of these units in. With our antiquated FI systems wearing out every day, we would enshrine you. Especially if we coud do this on the cheap!

So you think I could put together a good working EFI system for my 305 SBC for around $500? Vortec Heads, roller rockers, mild cam, Eldebrock torquer manifold.

So what should I look for at the junkyard?
Interested in putting together a plugnplay system if I scrounge the parts?(IMG:http://www.914world.com/bbs2/uploads/post-4253-1252300281_thumb.jpg)

The easyest way will be a TBI from a 1990's GM truck. Almost all of them had TBI. It is not the most high end FI system but it is much better than a carb. Remove the Dizzy, intake and components. Find the ECU onder the dash take it and the harness.(usually right side kick panel) remove ALL engine electronics. Such as: MAP sensor, Spark control, any thing attached to the ECU. The ECU will have other wires to it: Fuel pump output power, starter input signal, battery 12V+, ground, ignition and maybe a transmission input and a VSS (vehicle speed sensor). The transmission input will be from the neutral safety switch. There is also a brake light input. ONLY the stuff in the engine bay will you need. You will also need a water temp sensor and oil pressure switch. These will be on the engine. finally you will need the O2 sensor. for this, buy a new one. It is a single wire O2 sensor and new ones are about $20. You will need a bung on your exhaust collector (right or left) Bungs are about $7 plus welding.

If you butcher the harness, Painless Preformance has them available. Not all wiring is required to run the system. VSS is not needed but can make it run "cleaner" and is required for smog. The Tranny stuff should be left disconnected. The fuel pump output wires go to a relay and not directly to the pump. Painless also has wiring diagrams to help you.

If anyone wants some PDF's with wiring info just PM me.

[underthetire]

I currently have a WB O2 sensor setup for the electrically adjustable jet kit in the 390cfm carb. Would a 5.0 part not be too big for my 3.1L engine?

The size of the throttle body does not matter as long as the fuel mixture is stoich. If you use one that is too small, you will have performance problems. I could fab four 50mm TB's, one to each cylinder as long as I size the injector and pulse width correctly. (IMG:style_emoticons/default/aktion035.gif)

Actually, i disagree here. Too big of throttle body can make driving difficult. If your on and off the gas, fine. Too big tends to make constant throttle hard to maintain, as it get very snappy and violent with a manual trans.

[Mike Bellis]

Lets take my 283 FI conversion.

If I were picking a carb I would calculate like this...

CFM=CIDxRPMxVE/3456

CID=283
RPM=max 6000
VE=Volumetric Efficiency 80% (maybe, mild cam, 9.5 comp ratio)

This calculates to a max CFM of 393

So I would look for a carb around 400CFM to be a match for this engine.

The TB setup has dual 400's. 800CFM total. Twice what this engine should need. with the fuel ratio matched to the air this engine runs great. Cruising at speed with little throttle input creates no surging or jerking. If I were to double the CFM again it is concievable that surging could accur. This can be compensated for by "camming" the throttle. Similar to the throttle cam on the 944. This would be done to make the throttle pedal action Non Linear. So at crusing, the pedal opens slightly, when the pedal is pushed to the WOT position the throttle will open at an exponential rate. instead of a 1 to 1 ratio on a linear pedal. No matter how large the throttle body is, the engine is limited mechanically to how much air it can take in.

[Dr Evil]

Very interesting (IMG:style_emoticons/default/popcorn[1].gif) (IMG:style_emoticons/default/smile.gif)

[computers4kids]

The easyest way will be a TBI from a 1990's GM truck. Almost all of them had TBI. It is not the most high end FI system but it is much better than a carb.

Thanks for the ideas and tips. I'll have to take a trip to the local pick a part and see how available a mostly complete 90's truck EFI system would be and how much they would want....just for a starting point. I know last summer I read and read about adding FI on my motor and the more I did, the more I realized I needed help.

Originally, I thought I was going to get a TPI system off a vette or camaro, but later found because of my Vortec heads, it became much more complicated of an adventure...and costly.

Then I started looking at the TBI systems from Holley. It appeared new plug and play complete kits were around $1100. Their systems appealed to me because they had directions and would be tailored for my motor (somewhat). I just couldn't get myself to spend that kind of money when my car runs great as it is and gets 24mpg on the highway, which isn't too bad. Anyway, not really understanding all the parts well enough, I didn't feel confident enough to purchase used systems or go to the junk yard and pull a system. Heck, I 'm not entirely sure I could find all the related parts you have mentioned that I would need. It would be like "looking for waldo." (IMG:style_emoticons/default/sad.gif) Anyone have a "looking for waldo" book but with pictures of what all the EFI parts looks like and where their normally located? (IMG:style_emoticons/default/biggrin.gif)

[Jacob]

Very cool (IMG:style_emoticons/default/thumb3d.gif)

I look forward to doing this to my corvair engine some day (IMG:style_emoticons/default/smile.gif) I was thinking CIS, but I like to program.

Here is a site showing a GM EFI on a Corvair engine:
http://www.corvairnut.com/corvairTBI.htm

[Dr Evil]

Bad ass, Jacob! Thanks (IMG:style_emoticons/default/smile.gif)