Carburetor vs EFI Shootout!
Should you run a carburetor
Category
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MotorTranscript
00:00 [Music]
00:20 This is Engine Masters presented by AMSOIL.
00:22 And you know what we're going to do this time?
00:23 Absolutely burn ourselves into the ground all night long to answer your questions about what's better.
00:29 That Holley 750 carburetor or Holley Terminator Self-Learning Throttle Body EFI.
00:34 Today's engine is a 5.3 liter LS Chevy.
00:38 It's actually an LM7, which is the type of engine you'd find in a 99-07 Chevy or GMC truck.
00:44 This is actually a crate motor from GM that they used to sell.
00:47 It's now discontinued.
00:48 It was called a 327HO.
00:51 It's a bone stock truck motor, but it has an LS1 camshaft in it.
00:55 And they sold it with single four barrel intake manifolds.
00:58 And that's what we're going to be running today.
01:00 You'll see us test both the Edelbrock RPM dual plane and this Victor Jr. single plane.
01:05 And we'll be running it both with the carburetor powered by MSD for the ignition controller.
01:11 And then we'll be running it with Holley Terminator EFI, which is a throttle body self-learning setup.
01:17 And they make a kit that plugs into all the factory sensors on the LS motor.
01:21 And the carburetor that we're going to use is the Holley 750HP.
01:25 This has got the nice radiused inlet on it, and you'll notice no choke horn.
01:30 If you look at the EFI throttle body, you'll see that it's got four big blades and no obstructions whatsoever.
01:36 You've got a lot of airflow right there.
01:38 Now, we go back to the carburetor, and you can see that you've got boosters in the barrels.
01:44 Those are in the way of airflow.
01:46 Now, the reason those are there is that the carburetor works by drawing gasoline through those boosters
01:52 because of a pressure drop across the venturi, whereas the fuel injection squirts the fuel in under pressure.
01:59 Therefore, you can run more throttle valve area for more airflow and not have to risk problems with fuel flow
02:06 that you might if you ran an oversized carburetor.
02:09 So, I believe that's going to be an advantage on the EFI.
02:12 I think this is going to make a little bit more power than the carburetor, but we're going to find out right now.
02:17 Since it's an OEM spec motor, we'll be using an OEM grade of oil, 5W-30.
02:23 This is AMSOIL synthetic.
02:25 It offers quite a bit more protection than your basic auto parts grade oil,
02:29 so we're pretty confident it's going to do the job here.
02:33 [MUSIC]
02:59 Okay, that's exactly what I expected it to do.
03:01 That pull was almost 380 pound-feet, and it was 350 horsepower.
03:05 Yeah.
03:06 351.7, you know, from a bone stock 325 cubic inch motor with a lame LS1 cam in it, that's not bad.
03:15 That's pretty good.
03:16 Kind of makes a 365-horse 327 look a little silly.
03:19 I know.
03:20 For an average guy, I will say that if you took that carburetor out of the box and put it on this motor,
03:25 it's pretty well calibrated.
03:26 Oh, yeah.
03:27 Yeah, it's safe. It drives.
03:29 Absolutely.
03:30 [MUSIC]
03:34 Now we get to the EFI part of the program, and I bet you all the hardcore EFI guys are groaning right now
03:40 because this isn't real EFI.
03:42 This is self-learning EFI.
03:44 It's the Holley Terminator setup, and self-learning is a little bit of a misnomer.
03:47 Actually, what these things do is they have tables built into them.
03:50 You go into your handheld controller and tell them what your engine is.
03:53 It starts with a base table and modifies it from there.
03:56 This is a four-barrel throttle body.
03:58 It's got all of the sensors built in so that you don't have to worry about mounting a map sensor
04:02 or a throttle position sensor or any of that, and it has four injectors built right into it,
04:09 so there are no injectors in the manifold.
04:11 This is the only self-learning EFI that I'm aware of that you can run completely in self-learning mode
04:17 or you can plug in a laptop and actually tweak it.
04:21 People fear wiring, and they don't want to deal with it,
04:24 so we're going to show you everything that it takes to wire this thing,
04:27 and you can decide for yourself whether it's a nightmare or not, but that's it.
04:32 Okay? Let's go throw this thing on that motor.
04:34 So I was thinking about guys who freak out about fuel injection being $2,100,
04:41 but if you're going to go this way with a carburetor--
04:44 like this manifold's $300, which you can use either way.
04:47 This is $550. This is $500.
04:50 So you've already spent more than $1,000, so then you've got $1,100 into the fuel injection.
04:56 Although the other thing is that if you actually get a junkyard motor
04:59 that already has all the injectors in it, the manifold and everything,
05:03 Holley has a kit that's way cheaper that just plugs in that doesn't have a throttle body.
05:07 So you think it's going to be an upgrade?
05:12 I think it's going to make more power.
05:14 Yeah, but the Holley was--it was gold, it was nice, it was good.
05:17 Oh, no.
05:18 The gold is so happy and this is so mean.
05:20 Now the wiring, which looks like that.
05:22 Do you know what to do with it?
05:24 Yeah, it's all labeled.
05:25 Really?
05:26 You can't go wrong. It's idiot-proof.
05:27 This tells you right here, "Odd ignition."
05:29 Look at that. Boom.
05:31 This says "Coolant temperature sensor."
05:33 Here's the cam sensor.
05:35 But I'm presuming that we're going to need one to plug into this somewhere, right?
05:39 Yeah.
05:40 That might be a little kid.
05:41 Oh, there you go. Yep.
05:42 Dude, I'm schooling you on this stuff.
05:43 I know. See, I told you you could do it.
05:45 What's left?
05:47 Try plugging the computer and power it up.
05:49 So the only thing that we've changed right now from just straight out of the box
06:04 is that we went into the laptop computer and reduced the coolant temperature
06:08 at which this thing starts doing the self-learning deal
06:11 because we just can't get it that hot on the dyno.
06:14 Other than that, this is just like what you'd have in your car.
06:17 We're going to make Dulcich a believer right now.
06:23 Wow.
06:26 Pretty impressive, right?
06:27 That was pretty good.
06:28 Everyone at home is going, "You guys faked that. You already had it running."
06:30 No, no, no.
06:31 I swear we didn't.
06:32 That was first turn of the key, so to speak.
06:35 No pump shot or any of that stuff either.
06:37 What pump shot?
06:38 No pump shot, no choke.
06:40 I think what we need to do now is just drive it around a little bit
06:42 and let it learn some stuff.
06:44 What we're doing right now is looking at how the idle speed is really fast,
06:58 and that might just be because it's cold
07:00 because he's got the throttle blade all the way shut,
07:03 and he can't tell the difference between an inlet air temperature sensor
07:07 and the IAC right now.
07:08 Dulcich.
07:10 Neanderthal when it comes to EFI.
07:13 The issue we're having right now is that it sounds like it has a little bit of a misfire.
07:22 You're educating that thing.
07:28 Yeah, so if you gave it a grade right now, what would it get?
07:31 Can I say I stayed out too late and got drunk last night to get a chance to study?
07:35 I'll always let someone say that.
07:38 [engine revving]
07:42 Why does it run bad?
07:45 I don't know.
07:46 Man, I learn something every single time I come to the dyno and run an engine,
07:50 and sometimes you just have to take it the hard way,
07:53 and this morning was a fiasco.
07:56 Through a lot of A/B testing and tuning and beating our heads against the wall,
07:59 we just discovered it is a fuel distribution problem.
08:02 We switched over to a GM single plane, and that ran perfectly.
08:08 Okay, so what are our parameters? Let's see.
08:10 Ease of installation.
08:11 Check one for carburetor.
08:13 Okay, carburetor wins that.
08:14 Initial fire up.
08:15 I'm going to give this a 10 and the carburetor a 9.
08:18 Cold start. I'm going to give the carburetor a 7.
08:21 We'll have to give three times the score value for outright horsepower.
08:26 So the winner of that gets like 30 points.
08:29 What's our score for chicks dig it?
08:31 That's really important.
08:33 Yeah. I'm going to say chicks don't like getting stranded or smelling like raw gas,
08:38 so therefore the EFI might have an edge.
08:40 My wife hates it when I spend money,
08:42 so EFI is more expensive so that she wouldn't dig the EFI as much as the carburetor.
08:46 Yeah, but she would hate your junk car that doesn't run anymore.
08:48 Oh, that's true.
08:49 So the EFI would probably--
08:51 So they're both getting a 5 on chicks dig it?
08:53 Chicks just don't like EFI or carburetors.
08:55 That's true. Okay. So they both get a 5. It's a draw.
08:59 [engine revving]
09:02 That's not bad. 370. I thought--
09:14 Bam! Yeah.
09:15 Watch. Look at that. 373 horsepower, 373 pound feet of torque,
09:20 and that is an exact layover of the curve that we did off screen.
09:24 Yes.
09:25 Exactly.
09:26 This is getting kind of convoluted, so let me spell out what has happened and what we're going to do.
09:30 First of all, go ahead and forget everything that we did with that first intake manifold.
09:34 We had some sort of weird vortex of cam mismatch with the plenum and the fuel spray pattern
09:39 that made it just not run right.
09:41 We've seen that every once in a while with a carburetor,
09:43 but in this case, the dual plane and the EFI just didn't add up.
09:47 So you saw us put a single plane manifold on the 5.3,
09:50 and all of a sudden, the EFI was flawless,
09:53 and in fact, the self-learning made a little bit more power than a custom tune-up we made while we were troubleshooting.
09:58 But we need to go back and put the carburetor on our new single plane intake manifold
10:03 so that we have a scientific test, A/B, of the carbon EFI on the same intake.
10:08 Okay, carburetor. Win, lose, or fail. I'm out of here.
10:15 I think what this is going to be all about is looking at the curve compared to the self-learning EFI
10:21 and getting it close, and then looking at the power numbers from there.
10:24 I hate to break this to you, Dolcek.
10:30 Oh, no. What?
10:31 The carburetor's losing.
10:33 I thought you would say that.
10:34 Yeah.
10:35 It looks like I may be in trouble.
10:37 Sure.
10:38 Here's what we have right now.
10:39 No, we're not done yet.
10:40 Not done?
10:41 No.
10:42 This is what we have right now.
10:43 Okay.
10:44 We're not done yet.
10:45 The EFI is the black line, and it is still winning.
10:47 [Music]
10:52 Okay, what did I walk in on because that was creeping me out.
10:55 [Engine revving]
10:59 I will get there.
11:00 Really?
11:01 You insist?
11:02 But wait, let's re-rank the tuning of carburetor versus EFI
11:06 because I don't remember you leaving the seat while tuning the EFI, whereas you've been actually sweating.
11:12 Ooh, getting closer.
11:14 [Music]
11:19 [Engine revving]
11:32 Well?
11:33 It's just not there.
11:35 Oh, I can see the despair.
11:37 Oh, God, I hate to even push the button.
11:40 Oh.
11:41 Oh.
11:43 So what we're looking at here is the carburetor is the black line,
11:46 which is really the same as the EFI all the way up to 4,100 RPM, and then wah, wah, wah.
11:54 Okay, so we're going to add up the scores.
11:56 Carburetor, ease of installation, nine.
11:59 Initial fire up, nine.
12:01 Tunability, six.
12:03 Troubleshooting, nine.
12:05 Cold start, seven.
12:08 Throttle response, nine.
12:11 Chicks dig it, five.
12:13 Wide open throttle performance, 24.
12:16 Sensitivity to intake manifold, nine.
12:19 Mileage, seven.
12:21 Price, ten.
12:24 Appearance, eight.
12:26 So it scores 112 for the carburetor.
12:29 Ooh, that's pretty good.
12:30 I know.
12:31 That's over 100.
12:32 That's pretty hard to do.
12:33 It's true.
12:34 So now EFI, ease of installation, six.
12:36 Initial fire up, ten.
12:38 Tunability, nine.
12:40 Troubleshooting, five.
12:42 Cold start, ten.
12:44 Throttle response, nine.
12:46 Chicks dig it, five.
12:48 Wide open throttle performance, 30.
12:50 Sensitivity to intake manifold, five.
12:53 Mileage, nine.
12:55 Price, five.
12:57 And appearance, five.
12:59 And 108 to 112.
13:02 Carburetor barely edges it out.
13:04 Carburetor.
13:06 If chicks just would have dug fuel injection a little bit more.
13:09 A little bit more would have been over the edge.
13:11 It would have been a tie at least.
13:13 Dude, it's been a long day, but what did you do to your head?
13:16 I don't know.
13:17 Tell me.
13:18 Today is Back to the Future day, and you've got the Doc Brown thing going on big time.
13:21 Not the Marty McFly.
13:23 [laughter]
13:26 And we sort of went back to the future with the carburetor on an LS motor.
13:30 By the scientific industry accepted analysis that we went through, I guess this thing barely edged out the EFI in your world, right?
13:36 Well, we were really thorough.
13:38 Let's establish that right now.
13:40 Yeah, we did explore absolutely every nook and cranny of the situation.
13:43 Yeah, but really when you come right down to it, I think your fuel injection did outdo the carburetor.
13:49 It did.
13:50 You know, I think the pros and cons are things that we went through.
13:53 This is cheaper, easier to tune, probably doesn't drive quite as well, doesn't make quite as much horsepower.
14:00 It's not as modern and swanky.
14:02 Okay, I mean we had a couple of horsepower loss with the carburetor.
14:06 We also didn't achieve as good of a flat fuel curve from the bottom RPM range all the way to the top.
14:11 But it was pretty good, you have to admit.
14:13 It was pretty good, but the EFI was even better.
14:16 By the time we sorted out that debacle with the dual plane intake manifold.
14:20 I thought we weren't going to talk about that.
14:22 I know, that was brutal.
14:24 But then when we put it on the single plane, you were actually out of the room.
14:27 It was like magic.
14:29 Everything fired right up and boom, first pull, it ran exactly on the curve that Brulio had tuned in perfectly.
14:37 It was really good.
14:38 I have to concede, Fryburger, you got me again.
14:42 And I will again next time.
14:44 No.
14:45 I will, on Engine Masters, which is presented by AMSOIL.
14:48 And I'll say that you can also visit us in between shows on social media.
14:52 Have you got that all dialed in yet?
14:54 Are you on Instagram?
14:55 I'm a king, a monster of Instagram.
14:57 Really?
14:58 If you're not creating Instagram, what's your account?
14:59 Engine Masters.
15:00 That's right.
15:01 And on Facebook, we're Hot Rod Engine Masters.
15:03 And last thing, don't forget MotorTrendOnDemand.com.
15:07 You can see us there, which is really going to sell that, I've got to tell you.
15:10 But you can also see live motorsports, movies, TV shows, and nothing but GearHead video content.
15:15 Check that out, MotorTrendOnDemand.com.
15:18 And then come back next time for Engine Masters, presented by AMSOIL, where we're going to give Dulcich a comb.
15:25 I bought one today.
15:26 I just haven't used it.
15:29 [Music]
15:36 [Music]
15:40 Where are you?
16:03 Ah, there you are.
16:04 This is a lot more like a periscope.
16:06 Sort of has a line across here in the middle of it.
16:10 This one smells much better, too.
16:12 Plus, I think I look better in gold than black, don't you think?
16:15 [Laughter]
16:17 (door slams)