Carb vs EFI? Not sure where to go.

[FSJ Guy]

If you're willing to do some work yourself, you can do TBI WITH computer controlled timing for under $1,000.

But if you aren't comfortable with computers, stick with a turnkey system and you'll be fine.

[Blake]

the age old debate continues

FWIW, my old Honcho has been sitting for several days without being ran. I got a wild hair today and decided to drive it to the grocery store, 1 mile away (the looks I get from people at the grocery store are priceless). Anways, I went out to the garage, patted the gas one time, hit the key, and smiled as it roared to life at a perfect fast idle. It started and ran perfect, just like always.

My point is that a properly tuned carb can run just as good as any TBI system on our engines.

[Blake]

Automatic trannys are also black box magic to me. That is why I keep at least 2 or 3 spare trannys here that can be used in a pinch. I don't work on them (yet) but I can R&R them. I like them better for ease of use compared to a manual. Personal preference.

You really should dive into one of 'em and take a peek. They are relatively easy to work on if you pay close attention and keep the parts in order. I think you would enjoy ripping one apart and putting it back together.

I'm the same way - I love automatic. I hate shifting

[MjrWraith]

Will E you hit the nail on the head in my opinion. That is what I meant about the 360 being an older motor. It's not that EFI won't work on them, they're not setup to be the most efficient with it. If I'm going to put out money for it I want the best of the best. So I'm going to wait save my money and right now my old carb setup always crank with no probs no matter the temp. Then again here in the Texas Panhandle we're not exactly known for being very cold.

[PlasticBoob]

That is what I meant about the 360 being an older motor. It's not that EFI won't work on them, they're not setup to be the most efficient with it.

If that were true, then there would be no power or MPG increase after switching to TBI from a carb, but there is. Emissions tests from members here even prove the latter, Google proves the former. Or maybe you're trying to say that they work more efficiently than a carb, but not as efficiently as an engine designed for TBI/MPFI. To that, I say:

* Many manufacturers in the '80s slapped TBI on their regular ol' carbed blocks. HP, torque, and MPG all went up.

* You can always swap out the intake manifold and do other common mods to improve power and efficiency, in fact this is where you'll see the most gains. I believe the AMC head and exhaust manifold design works just fine with TBI. If you're talking about stuff like Vortec heads, then yes, you've got me there, but I bet you could get close with a simple port and polish job. That's still nothing a good cam can't fix.


If we're not talking oddball or racing applications, then I believe it goes something like this (though you can get TBI units that flow huge CFM if you really want that):

Carb -> TBI -> TBI with timing control -> MPFI -> SPFI -> Direct Injection

[Blacksmith01]

All I know is that one pump of the gas pedal and one bump of the key and mine starts right up. No computer to short out during a nuke or zombie attack.

[will e]

The improvement the car manufactures may have seen could be, and I say could be, from using a different cam more suited to Fuel Injection. Fuel injection is probably more consistent from one factory installation to the next compared to carbs. Also, I am not sure if the EPA rules are different when calculating MPG.

On our rigs, a well tuned carb is going to perform pretty darn close to as well as a TBI does. Perhaps better depending on who set up the fuel curve.

The discussion about engine design, to me, is for the port fuel injection. You might be able to get close to what a clean sheet of paper designed head would be but if it wasn't designed with injectors spraying gas into the port it isn't going to be as good as something that was.

Even intake design is basically just a single plane with a throttle body on top:




You look at the modern fuel injected engines and their intakes don't look anything like that.

The injectors look like they are shoot straight down into the plenum, not down into the head itself. Perhaps optimized, perhaps not. Most of the modern fuel injections shoot towards the intake valve.


So I think there is some validity to say the old iron engines won't get 'all' of the benefits of port fuel injection. Is it enough to not bother with it at all? Heck I don't know.

[FSJ Guy]

Someone buy me that Edelbrock MPFI kit and I'll be sure to post up a build thread with lots of pretty pictures and results.

[will e]

You can go with this:


Or you can go with that:



You can swap out the carb in about an hour, the fuel injection installation is going to take 'a little longer'.

The holley will run 'pretty good' right out of the box. If you are not at sea level a jet change would help. A different power valve isn't a bad idea either. That's about a 15 minute job.

[Blake]

No computer to short out during a nuke or zombie attack.

I think an HEI dizzy module could still short out - perhaps. I keep a spare though....

[Blake]

This carb

Or you can go with that:

Will allow you to do this at an idle, with no stumbling or issues at all.

[PlasticBoob]

On our rigs, a well tuned carb is going to perform pretty darn close to as well as a TBI does. Perhaps better depending on who set up the fuel curve.

Well for the record, I'm no Ristow, but I had a Truck Avenger and learned how to tune it. I even bought two books on how to tune Holleys in order to maximize my performance. Changing it from "out of the box" to the finely-tuned beast that it was did not take a few minutes, it took many hours of playing around with jets, accelerator pump cams, accelerator pump nozzles, power valves, etc. I eventually had the system tuned perfectly, and with a modified timing curve. I loved my Truck Avenger and it was a pleasure to drive, but I'm sorry to say that TBI, without timing control, still beats it. It has even more power now, and runs more efficiently ALL the time, not just in the conditions I tuned it for.

Additionally, let me state that tuning EFI is actually a bit easier because I have datalogs (specifically the AFR) that eliminate a lot of the guesswork and cut down on the repetition that comes with tuning a carb. If you haven't gone through all the previously-discussed trouble tuning your carb, then I dare say it's not tuned as well as it could be. You either need to install an AFR gauge or start shutting it down and pulling plugs. Fun. EFI can be tuned while you drive, or sitting in your favorite cozy chair, or laying in bed later that night.

We simply can't deny that EFI makes more power and runs more efficiently over a wider range of conditions than a carb, otherwise you'd still see carbs on vehicles sold today. Even TBI is a huge step up, theory-wise, mainly for the fact that carbs simply do not atomize the fuel as well. The TBI spits out a superfine mist of 13-16psi fuel that, in effect, no vacuum can create with a carb. And we all know that better atomization means more power, more control, and thus more precision. It doesn't matter if the engine is designed for EFI or not - the engine will have specific fuel requirements at different RPM+MAP, and EFI will supply those requirements better than a carb over the entire operating range.

[content deleted - I no longer support MS]

[Walt]

We simply can't deny that EFI makes more power and runs more efficiently over a wider range of conditions than a carb, otherwise you'd still see carbs on vehicles sold today. Even TBI is a huge step up, theory-wise, mainly for the fact that carbs simply do not atomize the fuel as well. The TBI spits out a superfine mist of 13-16psi fuel that, in effect, no vacuum can create with a carb. And we all know that better atomization means more power, more control, and thus more precision. It doesn't matter if the engine is designed for EFI or not - the engine will have specific fuel requirements at different RPM+MAP, and EFI will supply those requirements better than a carb over the entire operating range.

X2. Of course, that doesn't mean it will be a justifiable upgrade for the OP though...

[MjrWraith]

Lol wow didn't realize this post would get this big this quick. Ok to try to get my point a little more narrowed down so everyone can understand. Yes you will see gains going to EFI hands down and no doubts about it. If you want to get the "bang for your buck" though. You'd be better off doing a little machining to the heads and intake. Like what was mentioned earlier a good port and polish would do the trick. You're definitely going to have to change up the drivetrain. If you do this and I've seen it done. You can actually get up to almost 20 MPG. Yes I said 20 MPG a guy my dad gets Scout parts from has a 345 Scout getting 20 MPG and has done everything I mentioned and probably more. I think he's running Multi-Port Injection as well not sure on that though. He went to an overdrive tranny, knocked the gear ratio down to 3.31 in front and rear, and is running 32's with a 4" lift. If I am going to spend the time and money on this big a mod I want something similar to his getting almost 20 MPG. So anyways maybe some of my past comments make a little more sense now or maybe I just made a bigger mess either way oh well.

[PlasticBoob]

If you want to get the "bang for your buck" though. You'd be better off doing a little machining to the heads and intake.

Yup! Get the engine the way you want it with a carb first, and then consider switching to EFI for that pièce de résistance, lol.

X2. Of course, that doesn't mean it will be a justifiable upgrade for the OP though...

I agree, just putting more info out there so people can make better-informed decisions.