Looking to ask the hive for their input on EFI vs Carb’s. Looks like there has been a new wave of technology and development in the EFI world and I’ve been looking heavily into EFI and transitioning my build into more of a restomod with the engine sorta being the jumping off point.

Wondering what the pro’s are, con’s are and any personal experiences people have had with it.

I’ve been looking at the Holly Sniper or the ACES EFI. Both seem to have perks and limitations (money would be a heavy incentive on moving towards the ACES)

 

Over on the 2nd gen Camaro website, we had this exact conversation recently...

https://nastyz28.com/threads/is-efi-...daches.348278/

As you'd expect, everyone has their own opinions.

I've been EFI since 1996 and I'll never go back to a carb, and that's even running an ancient early 90's TPI computer (although I've learned how to really dive into it as far as tuning it out to the hilt). The newer stuff is probably a lot more user friendly for people not that familiar with how EFI works on a detailed level... plus the self learning capability, etc.

Overall I think the consensus that you won't get more top end power than a carb, but you will get much better overall driveability and street manners... the torque curve will be heavily influenced by the manifold design.

 

It's a loaded question to be sure. Everyone has an opinion. Sorta like asking what kind of oil to run.
That said. I'm in the EFI camp. I run a Summit MAX500 throttle body and computer. And I would never go back to carburetor as well.
As per Pros and Cons with EFI. Well, Pros are many. From easy starts, warm ups , fan control and just way better drive ability in all conditions. Power? About the same. Throttle response? Perfect, always. Low RPM running under load? Perfect, always.
Cons, No they do NOT Self learn. That's total bullshit. They can adjust the main fuel map and That's all.
If you choose your system based on price alone, factor in the cost of tuning if this isn't in your skill level.
Every system tunes differently. Most of these systems are basically the same thing. But the differences in computer programming is what makes up the big differences in these systems. I can tune the FiTech / Summit stuff real well now. The Holley system is so different I haven't a clue!
Really do your homework before buying a system. Installing it is the easy part. Tuning it takes the time.
Once everything is dialed in. Bloody fantastic.
Love my EFI.

 

The other thing too... I don't think you'd ever get the kind of throttle response with a carb that you can get with EFI... especially just with part throttle city driving.

When I was running my old Holley 4 barrel, I played around with the accelerator pump for a long time and I think I got it about as good as it would have gotten. It was a 600 CFM on a Performer RPM dual plane, with a mild cam in a 350, so definitely a setup that should yield snappy response. And it was pretty good.

But with my properly tuned EFI set up now, there's no comparison. The EFI throttle response is just sooooo crisp and smooth... it feels like any late model car today.

 

Here’s the bottom line. SFI, Batch fire, throttle body injection, and carbs all have one thing in common. They all mix fuel and air BEFORE the intake valve. Making fuel atomization before the intake in the right ratio is what makes power and efficiency. Direct injection is a whole different ball of wax. You will make the same max power with fuel injection as you will with a carb. Tuning a carb for max effort HP from say 3000-6000 rpm is pretty easy.

Where GOOD fuel injection systems shine over their mechanical counterparts is the ability to infinitely adjust the engine timing advance and retard due to engine load and speed. While you can do a lot of the same things with vacuum advance and such on a mechanical distributor a well done EFI setup is far more flexible in this regard.

The same can be said about fuel control. I’m not saying that carbs can’t be well tuned for drivability because they sure can be. The problem is that a lot of folks just slap a carb on an engine and expect it to just “work. When in reality it takes a lot of work and tuning to get them dialed in. Particularly if it’s a non stock carb on a non stock engine. The manufacturers had that figured out. That’s why they made so many different versions of carbs. Some aftermarket carbs are dead nuts on out of the box, but that’s more the exception than the rule.

I’ll use a Holley 4150 for example. Tons of people have issues with these having a rich idle and bogging off idle. The damned idle mixture screws aren’t doing a damned thing and they blame the carb. Well, it’s probably not the carb. It’s the carb setup. Where are your throttle blades set? That matters. If you have the throttle blades cracked open past the transfer slot the car is basically idling on the main jet. That will render the idle mixture screws useless. There are a couple of ways to work around that issue, but that’s just an example. Carbs are surprisingly complex devices and seldom can you just bolt one on and go. It needs to be setup properly. Fuel injection you can make changes within seconds via a laptop. With a carb if you need to change an idle air bleed you gotta pull the aircleaner, shove a rag in there so the air bleed doesn’t fall into the motor and install the different size. That or you might need to drill a secondary bleed in the throttle blade due to cam size etc. With EFI you can change that in 30 seconds.

All that plus the ability to add things like traction control and electronic transmission control to fuel injection it makes the whole car better.

Cliff notes: Wide open with your foot on the mat they are basically the same. Where they differ is the drivability.

 

Thanks for the input!
I’m really looking for the drive ability aspect. I have an after market manifold, and cams, but not needing much more power. Really looking for the start up and go reliability that fuel injection gives. Also I live in Texas where it’s consistently 100+ and have heard horror stories of boiling gas in the carb and vehicle fires and do not want that.

 

Think you saw on my build thread about the new Edelbrock AVS2, well they back ordered my part and gave me too much time to think about alternatives….

I appreciate the input, after reading so much about the different systems over the past few days it seams like it should be a pretty night and day difference from what i had been experiencing.

 

I have the profile 4.. from what I read before purchasing is that some work fantastic from the very first start, and others run like crap and have issues, now I knew right of the bat, I would be the one with running issues, and I was correct.. how ever, the car ran terrible, to running decent, I have maybe 250 miles on it, and it keeps getting better, just down low rpm maybe below 1800 rpm it's choppy as rpm increases it smooths out.. but it's getting better. It has a lot of features I have not even touched on.. so as long as it improves as it has been, I am happy... This was installed on a new build..

 

Appreciate the cliff notes haha (and the full run through). Thats exactly what I’m looking for, just some reliability and drive-ability. More power equals more problems with 50 year old vehicles!

 

That setup looks great. The “learning” aspect is something i still find as questionable but the ability to look through numbers and edit them on a screen rather than messing with mechanical things. It’s the unfortunate part of my generation not having any experience with that, but plenty of experience with moderating fuel injection systems.

Thanks for your input!

 

Fan of the Port Fuel injection style with injector per cylinder , it makes the Intake manifold just a Air Flow device with no rich center cylinders and lean out boards cylinders especially for makes that don't have the intake ports side by side like Olds and Ford , 426 hemi ect and this system usually requires a lap to tune and hardest to install of the FI systems, break downs require tow trucks

Sniper systems are kinda meh , obviously if you have a Sniper 1 and then the new and improved Sniper 2 comes out you have to wonder when the Sniper 3 is coming out , it still uses the intake manifold to carry fuel but is self learning is a plus if you don't know what you are doing and altitude compensating and easiest install of the injection systems, but break downs require tow trucks

Carburetor , obviously the cheapest and easiest to fix in an O'Reilly's Auto parts parking lot , requires some tuning , not altitude compensating in case you are planning a trip from Florida to Colorado , potential vapor lock with todays fuel but when operating correctly it's unbelievable bang for the buck

 

Go read the "Sniper for Dummies" Thread. It should be a STICKY.
Sniper for Dummies
I'm working on my Sniper 2 EFI right now. I've had some issues but I expected that going in. There is a learning curve with any EFI system but they are getting smarter and smarter every day.
I suggest you check your engine out thoroughly before going to EFI. Make sure you don't have any vacuum leaks and your exhaust system is in good, leak tight, working order. Check your timing if you are not going to have the ECU control that. Also, electrical wiring is crucial to do it right.

 

Built for show? (NCRS) Carb
Built for go? EFI

 

Just went through and rebuilt the top end with a cracked manifold and leaking rear seal, and all new vacuum lines. So i should be at least good on that part. Small crack in the headers I’ve sealed up with the extreme heat JB weld. Might have to take that in to get welded.

 

That’s great info! Thank you!

 

I origonally went with a Holley Sniper Stelth on my Vortec Pro Built 468 and had mixed results. While it did run ok it never had the pop that I knew it should have. I know that the Sniper does best with a single plenum intake but, I am using the Air Gap as Mark built the engine with it for best performance. I started to have inconsistant AFR readings and the system was constantly over compensating due to a bad O2 sensor. Long story short I finally had enough and ordered a custom ATM carburator, built to match the specs of my setup and will never consider anything else for this car again. It has never run better and alway starts on the first crank, hot or cold. K.I.S.S. is a rule to live by.

 

BurntOrange_C3,

It seems I have this type of conversation at least once a week with someone... I need to write this down and be able to copy and paste it! The EFI vs Carb discussion is a mixture of personal preferences and technical preferences. Now we could outline the advantages of one over the other, but in the end, it will boil down to how you intend to use one fuel delivery system over another. If you want to keep it simple (as described above) and you want a bolt on part that can be tuned with some simple tools and parts, stick with a carburetor. I well tuned carburetor (well tuned with an O2 sensor and different driving conditions) can be jetted to give you good enough fueling for all your driving needs. Once it is set up, you'll have many miles of reliable fuel delivery. If that is all you are looking for in your classic corvette, stick with the carburetor. The carb technology has 100 years of refinement and millions of aftermarket experiences.

On the other hand, if you want something that will adjust fueling dynamically in all atmospheric conditions, start in all conditions, control your timing in ways a mechanical distributor cannot, tune with a laptop, data log your driving, run fans or other I/O devices, EFI may be for you. When EFI is properly tuned and working as it should, it is superior to a carburetor period. Are you going to get more power out of one or the other, not really. The biggest myth of aftermarket EFI (I don't care who it is) is the self tuning claim. All of the systems that I am aware of - ONLY SELF TUNE THE BASE FUEL TABLE. That means the other dozen or so fuel tables YOU have to tune. That means you have to learn how to get into the weeds with your EFI system. That also means you are going to have to deal with some of the problems that some of the units have coming out of the box. The added complexity of the EFI system means there are more things that can go wrong. So yes, there is a trade off there. The best analogy I have is the slide rule vs the computer. For those who do not know what I slide rule is, google it. A slide rule would never fail because of its simplicity. Computers do fail due to their reliance on many parts and electrical components. Slide rules were cheaper (by far) then the home computer. However, the computer was vastly superior to the slide rule in capability, and now no one uses slide rules anymore. The capability overruled the simplicity and reliability.

Most of the frustration I see and deal with are users who convert to EFI who expect to treat the EFI system like a carburetor. If that is your desire, do not convert to EFI. It's a different animal. It will also find flaws in your engine / exhaust / ignition systems that you didn't know you had. A carburetor will mask many running condition issues, but EFI will reveal them. If I had a dollar for all the times I heard / seen "my engine didn't have a problem before installing EFI, now it does", I'd be doing something else... A properly running EFI system doesn't cause problems, but it reveals other issues. However, EFI will generally take the blame for engine running problems that you didn't even realize you had with the carburetor setup.

 

actually, a fair bit of that is exactly what I had already said. Just he went deeper. Very accurate.
I would add however, I've actually seen it the otherway around. Where EFI will actually mask a issue that a carburetor would stumble on.

 

ive been i the same boat and bought the aces killshot a week ago. I havent installed yet but if watched and read all the content I can find on it including a thread here in the c2 forum of someone wh installed a killshot earlier in the year and is very happy with it. I bought it for the ability to also control timing with a locked out stock tach drive distributor and a pertronix module.

My understanding is peoples experiences with these systems vary quite a bit and a lot of it has to do with the amount of time , thought and energy that goes into implementing it. I have decided to try to do it right by using a baffled fuel tank with the internal pump and ptfe lines with both stages of filters.

While the EFI does NOT typically give any peak horsepower gaines over a carb setup it does offer gains in other areas throughout the driving rpms as well as better starts with less warmup time and the ability to self adjust for things like climate/elevation changes. I also like the way the unit can monitor ad control some other functions like the rad fans.

I dont even need to read the other comments to know that due to the general nature of this group there are a lot of folks that will have some bias against it as even electric radiator fans are a debated topic here despite the generally accepted advantages elsewhere in other car forums. And I'll admit I once also had a negative bias against any TBI form of EFI having any benefits over a carb setup.

 

Ive also read the opposite about the manifold type having a greater impact on the torque output. Ive read that there needs to be an open spacer or divider cutout on a dual plane but also that due to the lack of the need for a venturi signal to "pull fuel" into the manifold Ive read folks can get much better lower rpm torque numbers at lower rpms with a single plane than with a carb making them more forgiving if anything.