MPFI vs. TBI

[Serious Johnson]

Have a look at most modern engines that were designed around port injection. You'll see that the injectors are placed such that they shoot directly onto and pretty much perpendicular to the intake valve head. Short of designing new AMC V8 heads, you'll miss this advantage with any sort of add-on MPFI. Another advantage of port injection is that it allows a "dry" manifold, rather than mixing fuel at the manifold inlet where it can separate in certain scenarios (like rapid throttle opening or very high velocity). So, as tgreese said, it can allow somewhat finer mixture control compared to throttle-body injection, but on an add-on setup, that difference is vanishingly small.

There are other reasons why some people choose multi-port, including more modern, more reliable pieces, sometimes a little better tuneability, and the nth degree of power potential at high revs. If I were building a 6,000 RPM 401 I'd sure try to cobble up a multi-port system. But for a Jeep doing typical Jeepish things, I think the GM TBI is 98% as good.

S.J.

[Billygoat]

S.J. for got 1 thing about multi-port on an AMC engine - the COOL factor

if I can get a DIY multi-port put together for about the same price as the Howell kit with ECS add on, it is worth it, especiall saying it is a DIY.

Now ask me this time next year and see if I actual have it done....

[brubakes]

The 3K for the Edelbrock kit is a lot to stomach. If I was going to throw that much into the AMC 360, I would really have to start looking at swapping in a while drive train from something else.

[chr1s]

I would take the $3000 for the MPFI kit and buy a 401, get a 4bbl manifold of chioce, and run a PROPERLY TUNED Quadrajet, Edelbrock 1406 or Holley Truck Avenger.

I just (2 weekends ago) removed the CustomEFIs TBI setup from my wag. (yes look for it in the For Sale section very soon ) and installed a Edelbrock Performer intake and 1406 Carb. I also have a rebuilt/modified Q-Jet Im am going to try out once I get all of my vac, fuel lines, etc situated.

Im not knocking the TBI setup in any way. Ive run it on this Jeep for 4 or 5 years as a daily driver. I surely enjoyed the cold weather starting and the jeep firing up at the blip of the ignition.

However:

For the time invested in chip tuning and burning and the money for different things for the system along the way (external fuel regulator, chips, zif socket, programmer, etc..) I dont think I gained anything over a truley PROPERLY TUNED carburetor.

Especially in the "perfomance" department.

I personally rebuilt the 1406 and Quadrajet carbs that I am experimenting with, and my Wag fired up on the first crank with the new setup and Ive got insane throttle response.
Im going to the Dyno to finish PROPER TUNING of the carb.

I dont mean to hijack your original question, but for 3 grand you could see reliability equal to the FI (in my opinion) and performance to boot.

If torn between the MPFI and TBI, go with TBI hands down.

[Sunshine]

Here's a multi-port EFI manifold for a 304/360/401....

[red mistress]

Aluminum Welds !

Here's a multi-port EFI manifold for a 304/360/401....

man...who made that manifold? Injector boses look great.

Fuel rails are real nice as well and I like the adjustability!
Whole deal looks better than a new Jeep.


Get a fuel/ spark management system that is fully programable.
Pro- flow not enough parameters for performance on built AMC.

[reddawn222]

man...who made that manifold? Injector boses look great.

Fuel rails are real nice as well and I like the adjustability!
Whole deal looks better than a new Jeep.


Get a fuel/ spark management system that is fully programable.
Pro- flow not enough parameters for performance on built AMC.

Is this set-up available from Edelbrock?

[reddawn222]

And what is the source of the throttle body?

[brubakes]

Is this set-up available from Edelbrock?

Yes.

[Sunshine]

This manifold was custom made starting with a dual-plane manifold. All of the aftermarket manifolds I have seen are single plane(like the Edelbrock version) which is good for RPM but not so swell for low end torque. The other issue with the Edelbrock Pro-Flo manifold is the availability of injector sizes. As stated earlier, the Pro-Flo electronics leave a lot to be desired to say the least. The air valve on the above manifold is the generic billet style. Nothing too special.

[Sunshine]

Is this set-up available from Edelbrock?

Not this set-up...

[Sunshine]

It looks like a production piece doesn't it?

[gte901m]

I made my own tbi system from junkyard parts and some new parts. Even with the cost of a chip burner, you will still spend less than $500.

I originally had a 4 barrel motorcraft carb, and got 10mpg cruising at 55mph or 60mph (which is what I drive to work, 30 miles each way). This sounds kinda bad, but I have small 29" tires and 3.73 gears. At 55mph, I tachin' around 2500rpm.

With my tbi set up, I now get 14mpg.

So to answer your original question, go the tbi route. When I started, I had no idea what to do. Read the link someone posted from Binder Plant. Thats where I got my info from.

Others have knocked down consistent 16-17 mpg with taller gears on their junkyard tbi rigs.

[vintagetrks]

You might want to check the tech archives. If I recall correctly I have seen a couple of threads on junkyard TBI conversions from GM 305's.

[PlasticBoob]

Sunshine, that is exactly what I plan on doing for my next 401.