Another "Is Fuel Injection a Worthwhile Upgrade?" Question

[goldduster318]

There are plenty. Carbs dump fuel no matter what the motor wants via the accelerator pump. The motor basically catches up to the carb then it just pulls what it wants rich or not depending on the jetting. EFI has to catch up to the motor (in feedback loop mode), ie. you mash the gas, the MAP goes down, the car goes lean and the computer has to play catch up metering the injectors duty cycle to get it to stoich (or whatever the tune says) and this is an injector chasing the RPM scenario. Meanwhile the carbed motor is pulling away. Now this sampling happens in milliseconds but EFI are designed to be clean, metering the motor what it can burn. you can tell them to be rich at WOT past what they are supposed to be at but that is the tune not the EFI itself. Many WOT's go out to open loop and override the O2 feedback and now your tune better be spot on as its running blind, computing the RPM with the MAP to a table....keep an eye on the AF guage! Cold starts, emissions, ease of driving...it was an evolution of the carburetor to meet current emissions standards. Start an EFI in the -10 night and drive it away, try that with a choke in under 20 seconds. You cant really carb a motor with a supercharger on it and have it idle all day in traffic with the A/C on, and warranty it for 50K for any driveability issues like the current Hellcats, and Mustangs. High pressure pump is the easiest part. then its about 3-4 sensors and the TB (or MPFI injectors) go bank fire so its only a 2 channel system, no need for sequential-no performance gains there. Batch fire is just TBI closer to the valves as they all pulse at once. If you adapt the Ford EEC-IV with its mass air valve, it self tunes to a stock or slight cam. Lots of older 5.0's still running around with their original ECU's and stock tunes. IT doesnt care what its powering as long as the inputs line up. About half of them dont matter on the ECU plug, ie. transmission temp, what gear its in, A/C, seat belts, etc. Modern bolt ons dont have that stuff and are self tuning too nowadays. Good luck. TBI it and carry a carb and a fuel pressure regulator in the trunk if it makes you feel safer.

The EFI doesn't have to catch up, right in the MS3 and a Holley it allows you to do all kinds of mapping from something that mimics an accelerator pump when you even move the TPMS at all, with ramp outs. So you can do some level of accellerator pump, map dot (change in map over time), and a time based accellerator enrichment ramp out. The carb has zero chance against this. The EFI only needs to be in a feedback loop with a proper tune under a somewhat steady-state mode and it uses a PID controller that you can set the gains on and it will come back and make extremely minor corrections from an already decent table if you tuned it anywhere near right. If your table is smooth it even interpolates between your set points. It's also doing a control loop roughly every 10 ms. You can even have the ECU update the tables every so many seconds even in non-self tuning mode.

It uses MAP, TPS, and RPM to run both the fuel and the spark tables simultaneously. Having had both on the same engine, the EFI is far more responsive always and to be honest I don't even think I have the best possible EFI tune since I road tuned it by myself. It also has a warm up enrichment adder that you can base either on the water temp or the intake air temp, your choice.

When I first installed it, the car fired immediately, I let it idle in the driveway for 15 minutes on self learn and drove around the block 3-4 times then went directly to a cruise in. Remember this is not a bolt on kit either. In under an hour, it was on par with the carb. To be honest most people don't have good carb tuning skills either so even a mediocre tune on an EFI like the self learning TBI styles like the Holley Sniper will probably run a lot better.

I also have a car that doesn't mask fuel/spark problems like an auto with a loose converter would. 6-speed with a 3.23 rearend, you need it to be right. I also drive around at 1400 rpm in 6th which would be hopeless in a carb with this combo. I also get about 15mpg in normal short trip driving.

The accelerator pump in a carb just covers the lean spots before the boosters catch up, which the boosters are always a compromise. Go with too big a carb and it will be extra lazy and need a lot of accelerator pump.

Any good EFI system isn't a 1980s TBI, or really anything from them. The carb will lose with today's systems. If it worked like you say, everyone's turbo car would have exploded a long time ago.

 

[pishta]

I was trying to explain the basic theory of EFI to a carb guy. Your higher level of understanding of tuning is beyond what a carb to EFI curious guy may know off the bat. Most of your response is the programming aspect of a great tune, necessary on our MS's...I'm talking about systems that just bolt on, have limited user adjustablilty (for safety and operation) and are expected to work better than a Holley 750, without a laptop on the passenger seat and in depth knowledge of Alpha-n or enrichment tables. Self tuning systems should work themselves out in the time it takes a cam to break in. Your quote included "any good EFI system isnt a 1980's TBI" yet most of the bolt ons are in fact ancient TBI with all the shortcomings of that wet system...fuel puddling, cold intakes, cylinder balance, etc. Go MPFI or dont go at all would be my recommendation.

 

[rumblefish360]

@goldduster318

If you want to win at an EFI conversion and have it be reliable, no matter what, you need an IN-TANK fuel pump with a return system where the regulator is AFTER the fuel rails. Your fuel will not boil off, you won't have fuel pressure issues,

Given I know nothing about the aftermarket systems and set up, pit falls & nuance’s, why is a regulator after everything in the return line?
*I Thought* the regulator was before throttle body. And the return line was free flowing into the fuel tank.

 

[rumblefish360]

@Pista

Go MPFI or dont go at all would be my recommendation.

Is there a sequential system out there?
I’d like to not use a batch fire.

 

[rumblefish360]

I have come very close to pulling the trigger on a fuel injection unit several times. I have considered the Holley and Edelbrock units. I have decided against it each time because of the multitude of posts both here and other places where people who claim the are competent mechanics have had TROUBLE with them. I understand the potential advantages FI can offer, but what about all of these people with all of these problems?????

Overall, when the FI system is right and tuned to the 9th degree, the only place I see a carb being best is at WOT @ the top end in power making. It is the charge cooling that takes effect.

I met a few people with the FITech set up. They were not good at tuning carbs. (Not that I’m great ether, I just need time on the carb.) There system always had a slight issue they hated. IMO, you can not just bolt on one of these system’s and go and expect it to be a golden fix and out perform a carb, even more so when that persons carb tuning skills are at best, mediocre, or worse.

 

[yellow rose]

If the EFI guys spent as much time learning carbs as they do EFI they wouldn’t change to EFI.

A carb is self tuning IF it’s close. In fact, Ben Strader of EFI University (a guy who isn’t a run of the mill tuner by any stretch of the imagination) finally got an EFI engine to beat a carb’d engine and that wasnt by much.

If you looked at the system, it looked carb’d. It was a tunnel ram and it was essentially was carb’d because all the fuel went through the throttle bodies.

If you’re carbs are even close, you can get almost everything EFI will do without the rest of the bullcrap. But you’ve got to put in the same effort with a carb as you are willing to do with EFI.

 

[rumblefish360]

If the EFI guys spent as much time learning carbs as they do EFI they wouldn’t change to EFI.

A carb is self tuning IF it’s close. In fact, Ben Strader of EFI University (a guy who isn’t a run of the mill tuner by any stretch of the imagination) finally got an EFI engine to beat a carb’d engine and that wasnt by much.

If you looked at the system, it looked carb’d. It was a tunnel ram and it was essentially was carb’d because all the fuel went through the throttle bodies.

If you’re carbs are even close, you can get almost everything EFI will do without the rest of the bullcrap. But you’ve got to put in the same effort with a carb as you are willing to do with EFI.

That’s the problem, everybody wants a cheap magic bullet.

 

[67Dart273]

EFI is for sure not for everybody. The big problems as I see them:

(Bear in mind the auto manufacturers have spent millions? billions? of dollars "getting it right.")

1...There are SO many variables in installations, including different pumps/ fuel systems, and improperly sized regulators and return systems

2...Different injectors, senders, and sensors, especially with "home built" systems such as Megasquirt

3...Even in the case of "packaged" systems such as Holley sniper or FItech, you have the problems with electrical interference (EMI/ RFI) which is a LOADED boat. This is even more complicated because of very high power ignition systems and alternators.

You MUST be careful with wiring / routing, and often should add properly shielded / protected wiring. It is a well known fact that ignition systems such as MSD can cause electrical interference. In fact, MSD if improperly wired CAN TRIGGER ITSELF. The high power radiating from plug wires can be induced into the pickup/ trigger wiring and re-trigger the MSD!!! No EFI needed for that problem!!!

4...For certain programming the system is a learning curve. I barely know what to do, and certainly would not go digging around--at this point--in another person's system.

They aren't for everybody.

 

[dano]

Modern fuel is what makes a carbureted system difficult to tune and maintain. Up to 10% ethanol means every fill up will be different. It lights off at the drop of a hat and the ethanol draws water. Letting the carb sit for long periods causes the bowls to dry up and leave residues behind. EFI can eliminate for all these issues. Sure a electric fuel pump can help a carb system but it doesn't adjust for fuel differences, changes in weather and/or altitude. But I have a carb. Someday I may switch.

You will see out of the box failures on any product. Be it EFI or Carburation down to underwear. It is going to happen. Buy what you are comfortable with tuning wise, know the pluses and minuses of each and install both correctly.

 

[j par]

Carb..???.. Carb's..!!!... ......

 

[goldduster318]

@goldduster318

Given I know nothing about the aftermarket systems and set up, pit falls & nuance’s, why is a regulator after everything in the return line?
*I Thought* the regulator was before throttle body. And the return line was free flowing into the fuel tank.

It's after because you want to maintain the fuel pressure in the circuit the injectors are on. The injectors are essentially a controlled leak. This makes the fuel pressure more consistent and you won't have the restriction of the regulator before the fuel system. This is a bypass regulator setup, you can even run one this way on a carb and it's probably the best system for that also.

If the EFI guys spent as much time learning carbs as they do EFI they wouldn’t change to EFI.

A carb is self tuning IF it’s close. In fact, Ben Strader of EFI University (a guy who isn’t a run of the mill tuner by any stretch of the imagination) finally got an EFI engine to beat a carb’d engine and that wasnt by much.

If you looked at the system, it looked carb’d. It was a tunnel ram and it was essentially was carb’d because all the fuel went through the throttle bodies.

If you’re carbs are even close, you can get almost everything EFI will do without the rest of the bullcrap. But you’ve got to put in the same effort with a carb as you are willing to do with EFI.

I did and it won't cover up the inherent issues with carbs like carb icing, bad fuel atomization on a cold engine, the inherent change of fuel levels in the carbs while coming up and down hills or going around turns, the effect of ethanol, etc. I like to drive my car, it gets cold here in the midwest before it snows and the carbs never liked cold running in vehicles without a crossover, especially when you factor in the stick shift and the tall gears. It's literally been two years since I messed with my tune at all.

I literally spent entire days working with accelerator pump cams, air bleeds, jets, etc on the QFT 750 Annular and the AFR was dialed in to run extremely strong, the issue is that when it's cold would either lean pop or the choke would have to be on, it just drank fuel in high vacuum, low load situations, and there's a drift in how it would perform due to other ambient conditions. I had the 4-speed in there but I literally went from 11 to 13.5 mpg overnight with the EFI and it drove better.

The amount of carb cars that run like absolute trash is astounding. My friend has a ratty 71 Demon that has a carb I tuned on it on it's 318 magnum and we actually had people commenting about how good the car started, ran, idled, everything at a cruise in, and even it's trash compared to EFI. It also has a properly set up distributor which is also another issue that people run into.

 

[yellow rose]

Modern fuel is what makes a carbureted system difficult to tune and maintain. Up to 10% ethanol means every fill up will be different. It lights off at the drop of a hat and the ethanol draws water. Letting the carb sit for long periods causes the bowls to dry up and leave residues behind. EFI can eliminate for all these issues. Sure a electric fuel pump can help a carb system but it doesn't adjust for fuel differences, changes in weather and/or altitude. But I have a carb. Someday I may switch.

You will see out of the box failures on any product. Be it EFI or Carburation down to underwear. It is going to happen. Buy what you are comfortable with tuning wise, know the pluses and minuses of each and install both correctly.

All my carb’d stuff runs on pump gas with 10% ethanol. It doesn’t matter unless you have a carb with the fuel bowls over the intake and an exhaust crossover heating the hell out of it.

 

[pishta]

Its like a carb..its what you put into it, but you dont end up smelling like gas afterwords with EFI!

 

[yellow rose]

It's after because you want to maintain the fuel pressure in the circuit the injectors are on. The injectors are essentially a controlled leak. This makes the fuel pressure more consistent and you won't have the restriction of the regulator before the fuel system. This is a bypass regulator setup, you can even run one this way on a carb and it's probably the best system for that also.




I did and it won't cover up the inherent issues with carbs like carb icing, bad fuel atomization on a cold engine, the inherent change of fuel levels in the carbs while coming up and down hills or going around turns, the effect of ethanol, etc. I like to drive my car, it gets cold here in the midwest before it snows and the carbs never liked cold running in vehicles without a crossover, especially when you factor in the stick shift and the tall gears. It's literally been two years since I messed with my tune at all.

I literally spent entire days working with accelerator pump cams, air bleeds, jets, etc on the QFT 750 Annular and the AFR was dialed in to run extremely strong, the issue is that when it's cold would either lean pop or the choke would have to be on, it just drank fuel in high vacuum, low load situations, and there's a drift in how it would perform due to other ambient conditions. I had the 4-speed in there but I literally went from 11 to 13.5 mpg overnight with the EFI and it drove better.

The amount of carb cars that run like absolute trash is astounding. My friend has a ratty 71 Demon that has a carb I tuned on it on it's 318 magnum and we actually had people commenting about how good the car started, ran, idled, everything at a cruise in, and even it's trash compared to EFI. It also has a properly set up distributor which is also another issue that people run into.

Why annular boosters on a single 750 application?

It gets very cold where I live. I haven’t used a choke since 1983. I’ve never had a carb use up and I don’t run a heat crossover. In fact, a heated intake manifold and annular boosters work against each other.

 

[my68barracuda]

If the EFI guys spent as much time learning carbs as they do EFI they wouldn’t change to EFI.

A carb is self tuning IF it’s close. In fact, Ben Strader of EFI University (a guy who isn’t a run of the mill tuner by any stretch of the imagination) finally got an EFI engine to beat a carb’d engine and that wasnt by much.

If you looked at the system, it looked carb’d. It was a tunnel ram and it was essentially was carb’d because all the fuel went through the throttle bodies.

If you’re carbs are even close, you can get almost everything EFI will do without the rest of the bullcrap. But you’ve got to put in the same effort with a carb as you are willing to do with EFI.

If you’re carbs are even close, you can get almost everything EFI will do without the rest of the bullcrap.

lets do a test,, you have a carb set up, I have MPFI FI
after looking at plugs or AF meters or what ever tool we choose, we both decide that the motor is a bit lean on the top end and way to rich at mid throttle, we both decide to make the desired adjustment to address that.
1 - 2 -3 we both start
in 30 second or less I am done,, do you even have the air cleaner housing off yet?

it is Bullcrap to those that don't understand,
To those that do, it is Easy.

 

[goldduster318]

Why annular boosters on a single 750 application?

It gets very cold where I live. I haven’t used a choke since 1983. I’ve never had a carb use up and I don’t run a heat crossover. In fact, a heated intake manifold and annular boosters work against each other.

Small-ish engine for the size of carb, they're more responsive to throttle opening than downleg boosters. Stick cars are wicked sensitive to tip in.

I previously had a 360 with magnum heads and a 600 VS holley and it had quite literally the same exact issues. My friend's demon has that same carb on his 71 Demon with an auto and it masks it a lot. It's still not what I'd consider good.

I have some serious doubts about you being able to crank your car at 40F and 80% humidity and then just put it in gear within 10 seconds and have it run perfect, no stumbles, no revving, no nothing. Otherwise it's got to be very stock.

 

[pishta]

there is no sequential in a TBI, not possible as they run into a common plenum. all TBI is batch fire. MPFI can be sequential...my Pro-Flow is 4 channel, 'semi sequential' as it groups 1-8, 4-3, 6-5, and 7-2 injectors with the same pulse . Sequential is mainly for start up and low speed emissions as sequential is still hitting a closed valve after about 3000 RPM as the duty cycle is not fast enough to trigger to an open valve after that. The max effort engine pull and F1 12K plus RPM stuff is way up the tunnel ram runner, even a fogger system at the plenum or even over it, just like the old Holley Pro-Jection systems and others that use the 2-4 injector pods over the blades and have an idle servo that kicks the throttle open a hair for idle.

 

[Backally]

There’s a learning curve with both carb and efi. I don’t know carbs very well, still learning the efi. One big difference I see is with efi if I make a change and if the 408 doesn’t like it I pull over and in 20 seconds readjust. I had some issues initially, be proactive with the install addressing issues. But right now Duster is running better than it ever did with a carb.

 

[pishta]

Distributor timing is another gorilla in the room.....we also must factor in distributor curve changes that an EFI system can do on the fly. Many factors over the RPM and vacuum a distributor can see are used to change the timing on the fly...Big plus for EFI right there.
Try and get a vacuum/mechanical advance distributor to do this:

 

[yellow rose]

Small-ish engine for the size of carb, they're more responsive to throttle opening than downleg boosters. Stick cars are wicked sensitive to tip in.

I previously had a 360 with magnum heads and a 600 VS holley and it had quite literally the same exact issues. My friend's demon has that same carb on his 71 Demon with an auto and it masks it a lot. It's still not what I'd consider good.

I have some serious doubts about you being able to crank your car at 40F and 80% humidity and then just put it in gear within 10 seconds and have it run perfect, no stumbles, no revving, no nothing. Otherwise it's got to be very stock.

I start my junk at 15 degrees and I couldn’t tell you the humidity but it’s pretty damn dry here. I don’t even let an EFI car start and move that quickly. When it’s that cold I spend about 30 seconds and head for the gate, which is about 75 yards away. At the gate it will sit and idle just fine.

And that’s on a Strip Dominator. This spring it’s getting a tunnel ram. It will be the same.

 

[yellow rose]

If you’re carbs are even close, you can get almost everything EFI will do without the rest of the bullcrap.

lets do a test,, you have a carb set up, I have MPFI FI
after looking at plugs or AF meters or what ever tool we choose, we both decide that the motor is a bit lean on the top end and way to rich at mid throttle, we both decide to make the desired adjustment to address that.
1 - 2 -3 we both start
in 30 second or less I am done,, do you even have the air cleaner housing off yet?

it is Bullcrap to those that don't understand,
To those that do, it is Easy.

I get it. All carb guys are stupid and EFI guys are brilliant.

IDGAF about your A/F meter or anything else expect what the dyno says, what the time slip says and how it drives.

 

[yellow rose]

Distributor timing is another gorilla in the room.....we also must factor in distributor curve changes that an EFI system can do on the fly. Many factors over the RPM and vacuum a distributor can see are used to change the timing on the fly...Big plus for EFI right there.

What happens when the curve is correct? Do you need to change it “on the fly”?

I heard the same type of thing with gear changes with the 8.75 and 9 inch. Mostly just guys repeating things.

 

[my68barracuda]

I get it. All carb guys are stupid and EFI guys are brilliant.

IDGAF about your A/F meter or anything else expect what the dyno says, what the time slip says and how it drives.

Never said that you or anyone else is stupid,
I did say, just because you don’t understand something it does not make it Bullcrap.
Look, you probably have much more knowledge than I do on cams, that does not make me stupid or you brilliant. Technology changes, it’s ok to change with it, or not. It’s your car. Build what you want.

 

[jrcr_15]

I have the Fitech Dual Power Adders on my Duster with a 6-71 blower, some of the best money I have spent on it. Runs amazing and easy to tune. People critique Fitech, but I think most of the problems people seem to have are user related. I followed the instructions to the letter, and got some great help from other people on this website when in doubt and it fired up and ran great right away once I was finished installing it.

 

[yellow rose]

Never said that you or anyone else is stupid,
I did say, just because you don’t understand something it does not make it Bullcrap.
Look, you probably have much more knowledge than I do on cams, that does not make me stupid or you brilliant. Technology changes, it’s ok to change with it, or not. It’s your car.

I agree. But I’ve seen this stuff on the dyno and it’s not all that. Like someone above said, the last shop I worked out of will no longer do EFI conversions for just anyone. They charge extra for all the tuning work. They are sick of guys coming back and saying it’s just not like a carb. And they tue it on a wheel dyno before it ever hits the street for more tuning.

In fact, when I was there in November there were two cars in there getting the EFI off and going back to carbs. I have to go back in there in February and I’ll see how it’s going.

I know before I left there in 2008 we were all big on EFI. Not so much any more.

BTW, Braswell has a whole package for guys going back to a carb from EFI.