MPFI vs. TBI

[brubakes]

Pros and Cons of both? The EFI kit from Edelbrock tops $3,000 versus Howell's $1,300 TBI kit. My J20 has the Howell kit already installed, but I wonder what might make an EFI better then a TBI. Is it just the difference of the EFI being electronic?

[tgreese]

Pros and Cons of both? The EFI kit from Edelbrock tops $3,000 versus Howell's $1,300 TBI kit. My J20 has the Howell kit already installed, but I wonder what might make an EFI better then a TBI. Is it just the difference of the EFI being electronic?

Wow, I would not spend $3000 to go from TBI to multiport injection (MPI - both TBI and MPI are types of EFI). MPI will give you somewhat better mixture control, but it would take a long time to make back that $3000 in fuel savings.

My understanding is that much of the motivation to go to MPI from TBI was emissions related. You might also get a noticeable improvement in performance and mileage. Very unlikely $3000 worth IMO.

The Howell system is basically an electronic carburetor: no spark control, no knock sensor. If you are handy with electronics stuff, you could add spark control (advance under the control of the ECU) to the Howell system. They use the GM ECU, and it's there but not being used.

[Billygoat]

and if you work with Howell they will mod your system for ignition contorol if you don't think you can tackle it yourself

[brubakes]

and if you work with Howell they will mod your system for ignition contorol if you don't think you can tackle it yourself

I don't think I totally understand the meaning of "ignition control" and its benefit.

[tgreese]

I don't think I totally understand the meaning of "ignition control" and its benefit.

I think it's more commonly called electronic spark control (ESC) and is a feature of the GM TBI systems. This puts the spark advance under the control of the fuel injection computer (electronic control unit, ECU). It's part of the whole TBI package, but ESC should give you better starting and idle, and potentially better power and economy. ESC allows more accurate control of ignition advance, which on carbureted engines is controlled by engine vacuum and spinning weights in the distributor. ESC also provides the opportunity to retard the spark in case of preignition (pinging), and allows the use of higher compression ratios without high octane gas. You'd have to have a higher compression engine and install a knock sensor to take advantage of this, however.

[Billygoat]

I don't think I totally understand the meaning of "ignition control" and its benefit.

Instead of vacum and mechanical advance, the computer controls the advance of the dizzy. The knock sensor picks up ping before any human could and that combined with the O2 sensor (and probably temp and TPS) it runs the dizzy at optimum advance for best fuel burn.

[Eugene 1]

call howell and they can explain

EDIT thanks Billy

[Billygoat]

tgreese was faster on the draw

It took me a bit working with Howell to get then to mod my kit, but I think they were cautious that they wanted to make sure I knew what I was talking about since it was up to me to mod the dizzy and add the ingnition module, but I had a secret weapon - this forum!

[FSJ Guy]

It's EASY to add timing control to a Howell system. At the very least, you need the GM ignition module, a donor ECM plug with some wires still in it (to pilfer from), an ALDL cable and a way to reprogram the chip in your ECM.

http://www.binderplanet.com/forums/f...splay.php?f=75 is a good place to start.

Everything is the same, except that we don't have to modify our distributors as much. All we have to do is lock out the mechanical advance (weld it yourself or have a shop do it. Very easy) and disconnect the vacuum advance.

You could add a knock sensor to the system if you wanted to, as well. Your choice.

[brubakes]

It's EASY to add timing control to a Howell system. At the very least, you need the GM ignition module, a donor ECM plug with some wires still in it (to pilfer from), an ALDL cable and a way to reprogram the chip in your ECM.

http://www.binderplanet.com/forums/f...splay.php?f=75 is a good place to start.

Everything is the same, except that we don't have to modify our distributors as much. All we have to do is lock out the mechanical advance (weld it yourself or have a shop do it. Very easy) and disconnect the vacuum advance.

You could add a knock sensor to the system if you wanted to, as well. Your choice.

Sounds like adding to the Howell kit is beyond my comfort level.

[Billygoat]

Sounds like adding to the Howell kit is beyond my comfort level.

I think it was about $200 plus shipping to have them mod mine - you have to send the the harness...unless they can make up an add on piece and your chip.
You sill have to mod your dizzy and add the GM module and coil (they sell the plugs for the coil) i could probably even get you a parts list together.
My dizzy is an MSD so the mechanical and vac advance lock out was supper easy since it is a built in option.

[FSJ Guy]

One of these days, I'll put together a write-up. It's not terribly complicated. My conversion took 6 months and that was because I was doing it PT (SlushPuppy is not my daily driver) and I had an issue with the ZIF socket I got from Moates.

If you installed the Howell system yourself, it's not a big step up from that. The only "scary" parts are welding your distributor and you can have someone else do that for you.

[brubakes]

Part of this is to get the most efficient 360 I can. The past owner has already done many things to the 360 to up its reliability and power. If mod increase MPG great! My J20 serves daily driving duties.

NOTE: I know we drive generally fuel inefficient FSJs, but in the end any MPG is worth it for a FSJ. I know they are bricks on wheels and I am NOT complaining.

[Billygoat]

I think the multi-port is probablly a little better, but not $3000 worth.
I am going to try do a MPI on my new 401 (if the 401 pans out) but working with another member on a DYI system.

Since you already have the Howell kit I would mod it for spark control (either them or you) you should see a little gain in MPG, at least drivablity.

Unless you have a bunch of extra cash laying around and want to do the Edelbrock kit, then you can post up camparisions for us on the same vehical.

[brubakes]

Unless you have a bunch of extra cash laying around...

You're a funny funny man.