Carb vs EFI - Dyno Testing a Holley Double Pumper vs Custom Stack Injection

Today we tackle the age-old question: What's better, carburetors or EFI? Electronic fuel injection has many advantages when it comes to producing great driving quality in all conditions, but what can the engine dyno tell us about horsepower?

We test a couple of Holley four barrel carburetors on an Edelbrock Victor Jr. single-plane intake against a custom setup utilizing four dual-injector units from Borla Induction. Both are on 400 cubic inch small block Chevrolets with Molnar crank and rods, Mahle pistons, AFR heads, and a Crane Cams valvetrain. The stack injection EFI is run by a FAST electronics system.

Also, this is a working engine shop, so please excuse the background noise in the first minute of the video.

Here are some of the major components used in the builds:

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TIMESTAMPS:
0:00 - Introduction
1:00 - Dart SHP block, Molnar crank and connecting rods & Mahle pistons
1:33 - Crane Cams hydraulic roller valvetrain
2:04 - AFR Eliminator Street aluminum cylinder heads
2:50 - Carbureted setup w/ Holley carbs and Edelbrock Victor Jr single-plane intake
4:07 - Holley 750 Brawler carburetor vs Holley 830 cfm double pumper
4:43 - Borla Induction fuel injection setup
5:00 - MSD Cam Sync
5:23 - FAST (Fuel Air Spark Technologies) ECU, Ignition controls and coils
8:16 - Carb vs EFI dyno test

[UncleTonysGarage]

Good video, and I AM a confirmed carb guy, but it really looks like that FI system was strangled upstairs by that manifold.

[kduzick]

With a self learning ecu and no knock sensors I don’t see how the ignition timing can really be on point to provide the maximum power for that efi setup. It’s impressive it did that well without proper tuning to be honest.

The real benefit of efi is to precisely control the fuel and timing so you can push the limits: In order to do this you need to tune the ecu.

[nrivera]

I appreciate your engagement beyond making the content, that you are willing to get involved in the comments section. Your explanations are well written and make sense. I like your graciousness in the comments, good on ya.

[garydecker]

Loved the look of the older fuel injection...loved the video..finally got someone who commented on where the torque curve could be acknowledge on street where it will be used most of the time ...sure we all like to get on it full throttle at times ...I'm a big fan of torque and useable torque...I'll trade 20 ft lbs of torque for 20 PEAK hp anyday !!!
Thanks for relating to what I would want in any buildup ...

[timhallas]

I once had a 77 Buick Station Wagon that had a 455 cid engine, with a very small two barrel carb on it. I looked up the HP and Torque numbers and found something that surprised me. 155 peak HP at 4800 rpm, but 415 ft lbs of torque at 2800 rpm. That is when I learned about restrictive intakes, long stroke cranks, and torque. That land yacht must have weighed in at over 5, 000 lbs without the 13 passengers, and their stuff.., yet that engine pulled it up a mountain at 65mph, with the tach hovering around 2, 600 rpm. It actually got around 28 mpg on the highway.

[johnbarker]

That 4/2 throttle body setup is gorgeous. Jewelry on top of the engine.

[BOSSMAN]

Intake was made by Inglese, they only ever cast around 18 of those for use in a Road Race series. I have one of those manifolds.

[robmotown]

Welding beads (stack of dimes) of the rtv silicone on the china wall!!!! That's funny!!! It was very neat.. so well done!!!

[timewarpvideo]

It is nice to be able to brag about a big horsepower number, but I never drive around a 6 grand on the tach. Think I would prefer the extra power down low.

[danmallery]

This brings up one of the misconceptions about Weber type setups. With the short runners and the racing applications that they are used in, it has been assumed they are all about the top end. In truth, those that run them have found the make surprising amounts of low end power. Even though the runners are short, they each have their own barrel for airflow and metering so a plenum is not needed. I wonder if drilling the holes actually hurt performance. (I understand it might have been needed for the map sensor). If you look at traditional weber intakes, they have no plenum area and each runner is basically isolated. But obviously, those throttle bodies were just too small, designed for much smaller engines, so that was the cause of most of the lost power on the top end.

[Tomyp]

Some body wrote that a carburetor is basically a calibrated fuel leak.

[colehara]

For the $$$ difference, I'll stick with my Holley.

[autonomous_collective]

Thanks for sharing. I too love that bottom end torque!

[CobraVeight]

I am sure the EFI could do better, sometimes the manifold is restrictive, and may need porting, looks cool though, has a old school look .

[archygrey]

Then you also got the mechanical fuel injection that sits nicely between the two.
My old mercedes has the old Bosch Ke-jet system from the 80s. It looks wacky at first but its actually a pretty smart setup once you figure it out.

[johnparrish]

I would love to see a properly ported old school Cross Ram intake with a pair of old 660 Holleys on it as a comparison to both.
1960's tech was not bad.

[victorgirouard]

The problem is carbs cant self adjust for temp change or altitude changes like efi can.

[doctorgille]

At the end of the day, its all about use-case. Dragstrip vs. Drivability. Higher HP numbers are useless on the street if the throttle response is boggy down low and has lower torque numbers. Or non-linear throttle response.

[lucascb]

First, I will state that this is an awesome looking setup and congratulations to your manifold porting guy for taking an antiquated design and getting it within striking distance of modern stuff.
However, I tire of the non apples to apples comparisons of EFI and Carbs and then the pronouncement that carbs are still superior. Modern EFI is designed for a non wet flow manifold, and yet they stack EFI throttle bodies on top and say, carburetors still better at peak hp. Love to see it reversed, lets put a carb on a dry flow intake and see how it does. Just google LS intake comparisons, there is one where they use the stock LS6 and Trail Blazer SS intakes, and included was a Holley Tunnel Ram Dual quad, Holley Mid rise dual quad, Holley single plane, Eddy Hi-rise dual plane carb, and Eddy Victor Jr single plane run with holley 950xp carbs on the single carb apps. The closest the hp got was within 10hp on the eddy single plane, and the eddy dual plane torque got within 25, of the best factory intake the trail blazer ss. When it came to the Hi-ram dual quad run with dual 950xp's, yes it made more power then the stock intakes, but when it came up against the EFI Tunnel Rams it still lost 5-10Hp and tied for torque, and lost by 5-6hp and 30ft lbs of torque to the Fast/MSD factory efi style intakes. I'm not saying carbs aren't good, but the truth is a well dyno tuned, proper EFI setup will put it down for HP, TQ, and drive-ability.


Still that motor is sexy looking lol.

[dominicdo]

The old man is a good tech, takes pride in his work and set the most beautiful bead of silicone i have ever seen in my life, this guy is a pro builder. I could hear on the first dyno run when you switch to efi that the engine was running too rich. He knew it too and taking the screens out was brilliant.