Is multiport injection worth the extra cost??

[Keith58]

Hi
Like many others I am considering a switch from carb to EFI as being based in Scotland starting a Ford 418 stroker in the cold when it hasn't been used much can take a long tome to get to smooth idle.
I have actually purchased a Holley Sniper stealth kit but various advice including this forum suggests that multiport is the only way to go.
Problem is that setting up MPEFI on an older Ford V8 is VERY EXPENSIVE and looking at around £14000 ($11000) for a set up comprising the whole kit.
My question to those that have done it is pretty simple - although MPFI is recognised as the best does a TBI system such as the Holley do a good enough job??
If the answer to that is yes would I be better going for the Terminator kit with separate and more flexible ECU?
My motor is a 418 stroker with AFR 205 heads, Edelbrock Performer RPM air gap and 780 cfm profuel carb with MSD 6al, Tremec TKO 600 and weighs around 2000lbs.
Any real life advice from experience would be much appreciated. Want to get the bast from the car so if MPFI is the way to go then so be it but £14000 is a lot of money......

[Tommy]

No expert here, but I am a regular watcher of the show Engine Masters. A topic that has been discussed there several times is the difference in air/fuel ratio from cylinder to cylinder. They point out that a MPFI is the way to go to solve that problem IF you have an O2 sensor on every exhaust pipe. Otherwise, the computer cannot take full advantage of the multiple injectors. The alternatives (i.e., carburetor or TBI) need to be tuned to protect the leanest cylinders for prolonged wide open throttle use, resulting in something less that the maximum possible peak power. ... So IMHO, if you plan on prolonged wide open throttle AND eight O2 sensors, then MPFI is the best choice. Otherwise, why bother.

[eschaider]

MPEFI is the correct choice. It will not cost you $11,000.

Use one of the excellent Plug and play systems from DIY AutoTune <= clickable.

If you are n/a like most of the Cobra's then you want the 99-04 New Edge Mustang controller. Get the wiring harness out of a salvage yard. If you are supercharged get the 03/04 SVT Cobra ECU. Same comments on the engine harness.

If the harness is too difficult to come by get the MS3Pro EVO with harness and trim the harness wires to fit your installation.

The MS3Pro systems will work with just about anyone's sensors. Many are preprogrammed others you can easily add.

You will need a set of injectors, fuel rails, electric fuel pumps a return style fuel pressure regulator and some motivation. You will probably easily come in under $4K.

Go to Calibrated Success navigate to the DVD section and get their Advanced Tuning Series DVDs on tuning. Alternatively there are other very good training programs available from sources like High Performance Academy


Ed

[joyridin']

We have a 66 Corvette that has a FAST TBI style set-up. It is night and day over the carb no matter how you look at it. The car has a 396 that has a decent cam. It was an original 427 car, but that engine was long gone. The nice thing about the TBI is it starts right up all the time, is easy to tune, and except for the fuel line, you cannot tell it it is EFI, so it looks original.

MPFI by far is a better route to go, but I would still go TBI over a carb any day.

[cycleguy55]

FI seems to fall into the law of diminishing returns. Is MPFI the best / ultimate way to go? Probably. Do you pay for it? Absolutely.

Will TBI get you most of the benefits for less money? Probably. Seems like a good example of the Pareto principle - 80% of the benefit for 20% of the cost.

IMO Carburetor < TBI < MPFI (in benefits as well as $$). If cost is no object (when I win the lottery) I'm going MPFI. Until then TBI is on my radar screen.

Only you can decide what's good enough for you, and whether the extra $$ of MPFI is worth it over TBI.

[Keith58]

Thanks for the comments.

I am leaning towards TBI which brings me to the next question....

For my engine does the Terminator ECU give significant advantage over the Sniper??

I am not keen on needing to keep adjusting my setup but want to try and get the best I can during initial set up, including live rolling road tuning but then just want to forget it.

What limitations does the Sniper have over the Terminator?

Thanks to all for your advice and guidance

[bobcowan]

The big advantage to MPI is the injectors are placed almost directly above the intake valves. At low rpm's, you don't need to worry about charge velocity, and the fuel falling out of solution at low air speeds.

This is important with a big engine, that's built with big intake ports, big valves, and a big cam. Essentially, a race engine.

For a near stock engine, or an engine that's built to make low end power, you really won't see much of a difference.

[cycleguy55]

Originally Posted by Keith58

Thanks for the comments.

I am leaning towards TBI which brings me to the next question....

For my engine does the Terminator ECU give significant advantage over the Sniper??

I am not keen on needing to keep adjusting my setup but want to try and get the best I can during initial set up, including live rolling road tuning but then just want to forget it.

What limitations does the Sniper have over the Terminator?

Thanks to all for your advice and guidance

No personal experience yet, but you might want to check these out:

• https://www.efisystempro.com/efi-pro...h-buyers-guide
• Post #2 here: https://forums.holley.com/showthread...ator-vs-Sniper

[Thor maine]

TBI is fantastic , night and day over a carb. Easy to install and less than half the price of MPI . Like I said night and day over a carb the difference between TBI vs MPI is just about 45 minutes.

[cycleguy55]

Originally Posted by Thor maine

TBI is fantastic , night and day over a carb. Easy to install and less than half the price of MPI . Like I said night and day over a carb the difference between TBI vs MPI is just about 45 minutes.

45 minutes? I don't know about you, but I can't change an intake manifold in 45 minutes - and that's something I definitely have to do for MPFI, but don't have to do for TBI.

[Tommy]

Originally Posted by cycleguy55

45 minutes? I don't know about you, but I can't change an intake manifold in 45 minutes - and that's something I definitely have to do for MPFI, but don't have to do for TBI.

I took the 45 minutes reference to mean the performance difference between carb and TBI is day and night (figuratively twelve hours), while the performance difference between TBI and MPFI is much less (45 minutes compared to 12 hours). I doubt he was referring to installation time.

[eschaider]

Irrespective of whichever model, TBI or MP-EFI, you choose, the fueling strategy you use will determine how sensitive the system is to atmospheric, temperature and baro (altitude) changes that the tune has to accommodate. You have two models to choose from, speed density or mass air flow.

Mass Air Flow (MAF) based systems are correct everywhere. It is what Detroit uses to insure emissions compliance no matter where their cars are driven. Speed density systems will fail emissions compliance testing when you get altitude, temperature, barometric or humidity changes in the ambient air.

Most of us do not need to worry about emissions compliance so, the compliance part is gone. The remaining headache for us however is component changes in the engine and ambient air conditions. Different heads, air cleaner, cam advance, cam shaft, compression, headers etc will all require a retune. When your altitude changes by more than a a few hundred feet so does your tune — ecxcept speed density can not accommodate the change in ambient conditions without, you guessed it — a retune.

Keep the car in one location and you'll be fine until you modify anything on the engine to improve performance or go up a mountain or down into a valley and then you will need a new tune.

MAF based systems comfortably side step these issues because the MAF directly measures the mass air flow into the engine — hence their name. The MAF based ECU can take the mass air data data right from the MAF sensor and directly calculate injector pulse widths to provide the commanded AFR or lambda you coded into the tune irrespective of ambient air conditions.

Changes in ambient air conditions or air pressure from alititude changes have no effect on the tune whatsoever, because the MAF is making a direct measurement of the air being consumed by the engine. The direct air measurement allows the ECU to do an immediate injector pulse width calculation based upon your commanded AFR or lambda for the engine operating condition at that instant. Speed density fueling models can not do this.


Ed

[twobjshelbys]

Originally Posted by eschaider

Irrespective of whichever model, TBI or MP-EFI, you choose, the fueling strategy you use will determine how sensitive the system is to atmospheric, temperature and baro (altitude) changes that the tune has to accommodate. You have two models to choose from, speed density or mass air flow.

Mass Air Flow (MAF) based systems are correct everywhere. It is what Detroit uses to insure emissions compliance no matter where their cars are driven. Speed density systems will fail emissions compliance testing when you get altitude, temperature, barometric or humidity changes in the ambient air.

Most of us do not need to worry about emissions compliance so, the compliance part is gone. The remaining headache for us however is component changes in the engine and ambient air conditions. Different heads, air cleaner, cam advance, cam shaft, compression, headers etc will all require a retune. When your altitude changes by more than a a few hundred feet so does your tune — ecxcept speed density can not accommodate the change in ambient conditions without, you guessed it — a retune.

Keep the car in one location and you'll be fine until you modify anything on the engine to improve performance or go up a mountain or down into a valley and then you will need a new tune.

MAF based systems comfortably side step these issues because the MAF directly measures the mass air flow into the engine — hence their name. The MAF based ECU can take the mass air data data right from the MAF sensor and directly calculate injector pulse widths to provide the commanded AFR or lambda you coded into the tune irrespective of ambient air conditions.

Changes in ambient air conditions or air pressure from alititude changes have no effect on the tune whatsoever, because the MAF is making a direct measurement of the air being consumed by the engine. The direct air measurement allows the ECU to do an immediate injector pulse width calculation based upon your commanded AFR or lambda for the engine operating condition at that instant. Speed density fueling models can not do this.


Ed

I wish to elaborate on Ed's post. A few excerpts:

"Different heads, air cleaner, cam advance, cam shaft, compression, headers etc will all require a retune. When your altitude changes by more than a a few hundred feet so does your tune — ecxcept speed density can not accommodate the change in ambient conditions without, you guessed it — a retune."

Keep the car in one location and you'll be fine until you modify anything on the engine to improve performance or go up a mountain or down into a valley and then you will need a new tune.

These examples are enough. Do the conditions [change anything] and correction ["retune"] sound familiar? Does it sound like what happens, with, say, a carburetor?

That's because it is.

A "speed density" EFI system is essentially a very expensive carb.

If you're using an EFI system and NOT using the MAF configuration, you've essentially got an electronic carb.

Why bother? If you go through any of the changes to the engine or alititue and want to keep peak performance, you need a "retune". But here's the catch: A EFI retune costs 10x more than a couple of carb jets.

Use MAF or save your money. Unless you stay at one altitude and don't change anything.

You are forgiven if your altitude change is transient. Going from sea level to the Eisenhower tunnel will cause you to run rich until you get back. But so will a carb. You'll survive... When I was a kid we had a Suburban. We took it from Iowa to Rocky Mountain Park and drove Trail Ridge alot. After that first time my dad had the carb rejetted before we left.

[6TNCRZY]

I absolutely LOVE my Sniper Stealth EFI. Old school Holley look, starts great, good cold performance, super responsive, no flat spots and easily adjusted. I also use it to control my distributor timing and even added a little "vacuum advance" for cruising, plus all the EFI wiring is hidden in the air gap manifold.

[6TNCRZY]

Holley Sniper EFI

[Steve Gallegos]

I am using the Edelbrock ProFlo4 direct fuel injection. Runs really well, self-tuning after install and setup adjustments. Works great in the mountains

[eschaider]

To the OP,

Tony and I are attempting to give you the information you need to avoid throwing good money after bad. Every EFI system that has been identified as doing a good or great job so far has been a speed density system. Like Tony has already said it is an electronic carburetor. If you know what you are doing with carbs you can buy jets and air bleeds waaaay cheaper than a speed density EFI system — and get very comparable results.

If you are unhappy with the behavior of your carbureted fuel delivery system right now and think you will fix the problem with a TBI EFI system because the task of tuning your carbureted engine is a bridge too far, you are fooling yourself thinking that an electronic carburetor (speed density EFI system) will be any easier.

The proper tuning process for the system to produce good drivability and power will be orders of magnitude more difficult than your existing carburetor. In the end you will spend somewhere between $1,000 and $2,000 for tuning and dyno time to tune the engine, depending on the ante at the dyno poker table where you live. That little Tupperware party at the dyno shop will repeat each time you change any of the variables I identified to you earlier, just like on a carbureted engine.

This is one of those upgrades where the penalty tax for cutting corners is extraordinarily high. To use the Knight's Templar quote from the Indian Jones and the Last Crusade movie, "Choose wisely. He did not!" If you didn't see the movie, the he being referred to is a dead Nazi lying on the floor of the cavern housing the many fake grails and the one real Grail. The Nazi chose poorly, he selected a fake grail and paid a high price.

You are Indy and Tony and I are the Knight's Templar. Unlike the Nazi, you won't die if you choose incorrectly — only your check book will.

Choose wisely ...


Ed

[bobcowan]

A carburator will only be better than EFI on the drag strip. And then only on some cars.
To say that EFI is just an expensive carb is just... I don't know... silly? Ignorant? Simplistic? It's like saying your barretts sniper rifle is just an expensive shotgun.

Speed density systems can be tuned to be extremely accurate - much more than any carb on the market. 80% of the tuning is done almost automatically. All of the tuning is done by pushing buttons on a laptop, without ever taking your seat belt off. No tuning kits to buy, no replacement gaskets. I'll never mess with another carb. Unless your racing class specifically requires it, there's no reason to ever mess with a carb anymore.

This engine ran on a speed density system. It made over 500hp to the pavement. I drove it and raced it from 1800 ft to 11,500 feet above sea level. Never had to retune it, just turn the key and drove it away. It adjusts for altitude as you drive. And, it would get better than 20mpg driving around in the mountains. Easily switchable between premium pump fuel, and E-85. Find me a carb that can do that, and I'll buy it.



This engine is also speed density. It's a track only car, and makes over 400hp. Once again, turn the key and drive. It does it's own altitude adjustments. Runs only on E-85.



Racing the Exocet

[eschaider]

There is a (very) limited capability to accommodate altitude changes in some (but not all) speed density EFI systems. There is a reason the auto manufacturers worldwide use MAF based systems to meet emission targets — speed density systems can not and the fines for non-compliance are impressive.

We don't care about emissions non-compliance. For the most part our cars have been exempted. We do care about performance and drivability. That along with proper fueling under all conditions is the calling card of the MAF based systems. That doesn't mean the speed density systems can not, in controlled scenarios, perform similarly — they can.

The challenge is when you start to change ambient air conditions and / or engine components. A retune will be necessary to bring the engine back to where it was. Small changes are sort of like a carb. So what, when I return home it will work fine. Large changes are a different story.

If speed density systems were capable of that sort of performance, automobile manufacturers worldwide would embrace them in a New York minute! An auto manufacturer would sell their mother to save a few pennies on each vehicle. The difference in cost between the two different fueling models is significantly more than a few pennies — even at the OEM level.

With respect to racing, unless you are rules limited to using old fashioned mechanical fuel injection, the top classes today rely on MAF based systems for the same precision in fuel metering that the commercial auto manufacturers use it for in emissions compliance. The difference is not an emissions compliance issue, it is a fuel management issue, power production issue and engine responsiveness to driver inputs issue, among a slew of other considerations that causes F-1 cars to use it.

We are no different, unless we choose to be and that is all right — as long as it is a conscious election. The self learning or auto calibration logic in the various ECU's will get enough of the tuning job done to allow you to drive to a shop to get the car properly tuned. The self learning tuning result is not the same as a knowledgeable and skilled fuel system calibrator (tuner).

Tuning for max power is only a snippet of what a properly skilled tuner does for you at the dyno. The meat and potatoes will be all the drivability work, MBT calibration, fuel cut at higher manifold vacuums, tip in fuel enrichment and ignition timing management throughout the engine's operating range, at part throttle cruising, WOT max power and deceleration fuel cutting.

This stuff is absolutely doable by anyone wiling to take the time to learn — but learning it is a much steeper hill climb than you might at first anticipate it to be. In the end everyone's car is his own toy and the choices he makes do not need to be the same as someone else's.

Think for a minute about all the posts on CC asking how to do simple things, like which wire goes where, why does my engine stumble or perhaps why doesn't my car start when it is hot? This is kid's stuff compared to proper engine calibration with EFI. Do things that make your hobby easy and fun. Your 'simple' carb is already misbehaving and frustrating you. Why expand and complicate the problem?

Here is an interesting conundrum to ponder. How do you describe the color blue to someone who has been blind from birth? It is impossible! Without ever having the ability to see any color, the blind person has no known reference for comparison — and you have no ability to describe the color blue to him.

Watch how the auto manufacturers have evolved their fueling technology and strategies. Take advantage of their research and copy what they did — as luck would have it, it turns out to work pretty well!

We have enough hard things to do in the real world. These cars are supposed to provide escape and attitude adjustments for us after we have been abused all week long in real life.


Ed

[joyridin']

Originally Posted by eschaider

To the OP,

Tony and I are attempting to give you the information you need to avoid throwing good money after bad. Every EFI system that has been identified as doing a good or great job so far has been a speed density system. Like Tony has already said it is an electronic carburetor. If you know what you are doing with carbs you can buy jets and air bleeds waaaay cheaper than a speed density EFI system — and get very comparable results.

If you are unhappy with the behavior of your carbureted fuel delivery system right now and think you will fix the problem with a TBI EFI system because the task of tuning your carbureted engine is a bridge too far, you are fooling yourself thinking that an electronic carburetor (speed density EFI system) will be any easier.

The proper tuning process for the system to produce good drivability and power will be orders of magnitude more difficult than your existing carburetor. In the end you will spend somewhere between $1,000 and $2,000 for tuning and dyno time to tune the engine, depending on the ante at the dyno poker table where you live. That little Tupperware party at the dyno shop will repeat each time you change any of the variables I identified to you earlier, just like on a carbureted engine.

This is one of those upgrades where the penalty tax for cutting corners is extraordinarily high. To use the Knight's Templar quote from the Indian Jones and the Last Crusade movie, "Choose wisely. He did not!" If you didn't see the movie, the he being referred to is a dead Nazi lying on the floor of the cavern housing the many fake grails and the one real Grail. The Nazi chose poorly, he selected a fake grail and paid a high price.

You are Indy and Tony and I are the Knight's Templar. Unlike the Nazi, you won't die if you choose incorrectly — only your check book will.

Choose wisely ...


Ed

People have been using these systems for ages and love them. You also don't need tuning and/or dyno time unless you have a really hefty engine with a pretty large cam.

For a Cobra that isn't driven daily (or even weekly in many cases) with and engine that isn't a killer race engine, these systems work great. Quit trying to lead somebody down a rabbit hole when one doesn't exist.