Best EFI System
 

I've been reading lots of posts here about various types of EFI, and find myself wondering about the pros and cons of 8 stack vs TBI vs MPI vs whatever else there is available. Is one type better for all out performance? One better for overall driveability? What kind of CFM flows are found in 8 stack vs throttle body systems? Most EFIs run same kind of fuel pressure? All use a return line?

Anyone here used the new Terminator system from Holly? It seems pretty much like the Avenger system with a slightly larger and new design TB. I'm liking the idea of a self learning system that will continue to fine tune for changes in altitude, temps and octane.

I'm planning a stroker 385 series engine, 514 to 532 for a cobra that I want to drive alot on the street, that is I plan on puting plenty of miles on it. I'm to the fuel and brake line stage of my MKIV, and need to mount a fuel pump, filters etc, so I kinda need to make a decision.

I know it's probably redundant to many of you, but thanks in advance for your patience with another noob.

lvhdude,

Since you posted in the EFI Forum it is safe to think you saw this, right? http://www.clubcobra.com/forums/fuel...enger-efi.html

Tom

Speak with Brent. He'll give you all the details and pros/cons.

Ford EFI pressure was 39 psi with vacuum line disconnected and the pressure drops 1 psi for every 2"Hg of vacuum. This makes the pressure from the inlet side of the injector to the outlet side constant. This is true with the older systems that had a return line.

The return line was done away with sometime after 1995. I read it was done to meet EPA requirements. I believe the fuel pump speed is modulated to control the fuel pressure on the newer cars. They may also run more fuel pressure.

The earliest systems used MAP sensor (measured manifold vacuum), throttle position, and engine rpm to estimate the amount of air entering the engine, via a complex calculation. You change anything that affected engine breathing and the calculation would be off.

Then they went to a Mass Air Flow meter to directly measure the air going into the engine. MAF is superior and can handle a lot of engine modifications. Few aftermarket EFI uses MAF. MassFlow is one company that does.

The throttle body injection systems basically mimic a carb. They are a little better than carb in accuracy. A lot of expense for little improvement in my opinion.

Thanks Tom, yes I did read that thread. I have to say I'm really leaning to EFI. I'm just hopeing to pick the right system the first time that will be the best for me. The Avenger seems good, I wonder what makes the Terminator different or better? And if the 8 stack systems are better? They are, without doubt, tops in looks and cool factor. It seems the Terminator may be able to be used with a MPI system. Is that better than the stand alone TB?

I love my TWM/Borla 8 stack with Big Stuff 3. Not a lot of talk about the BS3 system but it was the system my installer was familiar with so that's what I ended up with. As I hear, the BS3 is popular with the racing crowd. I think having somebody to turn to locally with experience in tuning with the system you have installed is a big plus. For me the initial learning curve was somewhat steep as I had no prior experience with EFI.

After a couple dyno tuning sessions and playing with the fuel and timing tables the system is running very well. Starts right up every time and idles smoothly.

Has a solid flat tappet cam that the cam mfg. says with a carb would "shake the fenders off the car", but with the 8 stack individual runner EFI system idles with very little lope and is very easy to drive on the street.

This way to go is not cheap but has it's advantages over other systems. Just my .02.
http://i1303.photobucket.com/albums/...ps2ea15c65.jpg

lvhdude,

Ahhhh....

What can I say? Aside from the fact that an induction system works, there's much more weight to the subjective, i.e. your tastes and wishes.

Any system is going to take plenty of time and cash to implement, so the "beauty in the eye of the beholder" really does apply! It's your resources, so select the one you are willing to spend time installing and debugging and let the good times roll. :)

Don't entirely rule out a carb, though. When they work, they work. When they don't, they can be as bad as any other induction system - my 1981 Zephyr has a 557 and a Holley. I (and others) have spent about as much time getting it to (mostly) work the way it's supposed to, as I have on the the EFI system on the Cobra's 521. It still has some quirks - like flooding the engine after a run, but only occasionally...

Ten years ago it was a Demon carb (aptly named :mad: ) that drove me to the Cobra's EFI.

So enjoy the hunt, consider all options and pick the one that makes you feel good about getting the result you're after!

Tom

Another question you may ask yourself is how much of it are YOU willing to learn and do yourself.

There are off the shelf "self learning" units that have been set up to work OK with as many engine size and behaviors as possible to recoup as much R&D as possible, then there are the real systems where you pick the hardware and configure an ECU to work it.

Two questions you must balance. How much extra hair do you have that you are willing to pull out and how deep are your pockets.

I did a megasquirt 2 running a Victor intake with bungs and a 4 barrel looking throttle body. The only thing I would consider doing different (If I had it to do over) would be 8 stack.

Ill preface this by saying this: I'm not looking to argue or debate the point, but these are a summary of my findings after many years of researching this topic (summary only, cos the research is too much to assplain in a single post or two or three or four!)

Best looking: eightstack.
Best performing (street): twm
Best performing (track): kinsler, but there are others also.
Most knowledgable group on this topic I found were: EfiHardware (Mitcham, Vic)
Best ecu: MoTec

Not a fan of the self tuning ecu systems.
They can cause more headaches than the problems they solve.

YMMV!

Now FWIW: after all this research, my multipurpose performance street engine is being built with carbs - 2x4 tunnel wedge. I can't tell you how it compares, I'm yet to test it. But I trust my engine builder ;)

Good luck with your build.


Edit:
Ill qualify my comments by saying that this is my findings for FE engines.

So....Just what are the benefits or your system over MPI or stand alone TB? And what size CI Mill are you useing it on?

Not sure what you mean by MPI? Multi Port Injection? Do you mean sequential? My TWM/BS3 setup is full sequential even though there is some argument over the advantages/disadvantages of sequential and batch fire.

Anyway I think the looks is the biggest factor. That's what drew me in this direction in the first place. Why does one choose dual quads over a single four barrel? Performance is probably better with a single carb but the looks of the 2 4's is better in my opinion. To each his own. Let your budget guide you through your journey.

My engine is a 4.375 bore and stroke square motor coming in at 526 CI. Dyno at the tires is 654hp and 780hp at the flywheel. I couldn't be happier with the drivability on the street. I do wish it had more of a lope at idle though... the IR intake smoothes out the big cam at idle.

Yes I meant multi port (I think) an injector at each port in the manifold. I don't know what sequential injection is. Batch injection? Is that same as a throttle body with the injectors incorporated into it, what I refer to as a stand alone TBI? (not meaning without an ECU.)

I didn't first notice you had an FE motor, nice.

There are a couple of good books on the subject of performance EFI. So I won't try and provide all the data here. I'v been working with performance EFI for about 12 years now. The learning curve is steep. But once you get the hang of it, EFI is so much better than a carb, I never want to go back.

First, the best way to think of it is two seperate systems, the EFI hardware and the computer and associated software.

The hardware has three basic types:

- 8 stack: Looks the best. But is more difficult to tune because the linkage is more complicated. It is an individual runner intake system, so you have to be very careful about head and cam selection. Power can be limited in big inch motors, simply because throttle body sizes can be limited.

- TBI: the throttle bodies also contain the fuel injectors. Cheapest. Easiest to install on any intake manifold. The downside is that you still have a wet manifold, and are subject to those limitations.

- MPI: best for power production in big motors. Still uses a common plenum. Can (in theory) use any single plane manifold, any heads, and any cam, and yet still get excellent low rpm street performance. Like any engine, all those parts should match (of course).

The computer system is where it can get tricky. Mild to wild, minimal tuning to all out racing including traction control, data logging, GPS, and accelerometers are available. It all depends on what you need and what you can afford.

You can save some money buy building it yourself with a Megasquirt kit. Then you can custom build the system and harness to exactly fit your needs.

You can even have the computer control a distributorless ignition system, with a coil pack and wasted spark, COP, or simply modify the spark signal from your distributor. If your engine is fairly radical, I highly recommend this.

"Self Tuning" is not all it's cracked up to be. The computer uses a wide band sensor and you tell it where you want the mixture to be. Driving it around will get it really close. But you'll still need to do some manual tuning to fill in the gaps. If you'll be racing, then some dyno time will really pay off.

If the engine isn't going to be too radical, I would take a serious look at Mass-Flo EFI. It uses Ford parts, and a Ford computer. Dead nuts reliable, and easy to install and tune. Mike Forte is a dealer for that system.

Don't get too hung up on sequential vs. bank vs. batch fired. Sequential is only good to about 2,500-3,000 rpm's or so. After that, the hardware can't keep up, so it switches to batch fired or bank fired. The goal of sequential was improved emissions and idle quality.

I would never run any EFI system without dyno time, even with a self learning system. EFi and a dyno go hand in hand in my book. I'm going carb, get a carb tuner to build it for you and from what I hear they are pretty good for kicking ass and taking names...:eek:

Thank you sir, I see I still have some research to do, but gives me the kind of input I was looking for

lvhdude,

Whoops!

Forgot one thing: There's a 385 series manifold that already has the MPI ports cast in and machined, and will fit under a Cobra hood: the Edelbrock 50665, http://www.summitracing.com/parts/edl-50665

I wish it had been around when I built mine!

Tom