World’s Fairest Carburettor vs EFI Test

[@redbackspider]

Thank you for ALL your honest and easy to understand results with this test. I am just about to update from a 32/36 Weber (which has been running super rich) on my 1966 1500cc Isuzu Bellett to a 38/38 Retroject EFI Throttle body and Autronic ECU.....this is a great insight to the fact it is NOT going to make it into a horsepower monster. All I am trying to achieve is better acceleration and driveability, as currently it is a slug off the line. I am also aiming to turbocharge it next year to get just a little bit more get up and go. Thanks.

[@davidrandall9964]

EFI is great. The only thing that stopped me going EFI over my twin (a million hours to tune) webers is that I wanted to keep my car true(ish) to its 1970’s heritage. I already have modern EFI cars and I find the webers quite fun from an enthusiast aspect.

[@jamesford3549]

Really good test. I think to make it better you could get someone to 3d print some new velocity stacks with an identical bell mouth profile and length to the webers big with a flange for the jenvey bodies.

[@kepamurray1845]

That's a properly racy rana! Love it. I think you have done a great comparison.

[@jasmenter]

Honest test mate. Very well presented.

[@ThePaulv12]

Charge cooling from carbs. You're getting the effect of phase change in the Venturi since at WOT Venturi vacuum is inversely proportional to manifold pressure. In this low depression the fuel tends to boil due to pressure drop around the boosters. There isn't really enough time for it to properly boil per se because manifold pressure = atmospheric pressure at WOT (minus air cleaner restriction but close enough) the constant phase change in the Venturi area is having an effect on power by increasing air density slightly. In injection systems the fuel is injected but the system doesn't require a Venturi, but it seems you've compensated by playing with ram tubes positively varying volumetric efficiency.

[@GlennLittleford]

I think a 12 port head would be better for this testing, the weber DCOE's thrive on a single runner setup. If I had to choose between injection and carbs for a "fun" car, I would use carbs, they have character.

[@anthonybedford8553]

Great video and very informative. Thanks for sharing your knowledge with us minions.

[@Blenzo480]

Good test. Have you ever heard of Keith Frank? He makes a replacement emulation tube that works on a totally different operating principle. He calls them Venturi Pump Tubes, or VP tubes. He is not great at marketing but i really want someone like you, with a dyno and weber ecperience to check them out. He also makes a bunch of other trick parts like idle jets with adjustable air bleeds.

[@mitchelllaughton9891]

Excellent vid. I'm a hard-core efi guy and tuner, but I'm surprised to see the carbs proved hard to beat in terms of outright performance. I feel we can take away from this that there was quite possibly a bit more throttle bore size than necessary, and I feel the other let down that may have helped efi win was in part being restricted to batch injection instead of sequential and being able to adjust injector timing, and possibly the 9 port head. Atleast with efi the customer will have a win in terms of fuel economy, cold starts, oil dilution etc, but I would be curious to know which one feels or goes better under transient throttle conditions!

[@themacgyverinstitute5340]

Good test , thanks for doing it , I have a turbo EFI car and a turbo blow through carb car , no problems with either of them.

[@jasonmorahan7450]

Good video and I like the car (I had an LC with a 202 at 11:1 on 36/72 with triple SU), it serves as a good reminder of what we used to know when aftermarket EFI was hitting the streets with Holley throttle bodies, that the main difference is you don't have to retune EFI every time you change elevation. A perfectly tuned multiple carb setup on dialled runners for the throttle response is basically the same performance as multiport EFI on the same ignition, except you have to pull over and retune if you drive up or down a mountain or lose power with altitude change. Seasonal weather too. Basically I had to retune the SUs and reset the valve lash every second weekend plus whenever I changed elevation, which was the difference between beating or losing to a Brockie. Different story but the same my now ride is an 80s Merc six with a big cam and that was on K-jet, tried a franken standalone but couldn't reconcile the Bosch system so that's getting EFI now. On the milder cam though you wouldn't have got any benefit, the K-jet is a remarkably adaptive closed loop for a narrow band, being a vacuum system, it'll self adjust and auto-retune for any mods you throw at it until you do significant valve overlap, then it goes haywire. For a mild power build K-jet is better than EFI with barely any sensors, no wonder Porsche and Ferrari used it.

[@michaelmarchei8539]

Needs a pop bang tune if anything g. Get her spitting flames

[@GarageItYourself]

Wouldn't having the injectors as close to the cyl head ports be better for atomisation and spray pattern in the direction of airflow?

[@zorbzzsterio6406]

Where did you get the wig from I need one :) Top vid by the way

[@malbirrell]

Would have been interesting to see what happened with the throttle bodies spaced off the head

[@RestorationWatch]

My friend had a long reach manifold on his triple SU LJ Torana. No long reach manifolds for triple Webers?

[@danielace4699]

Great video gents.

[@HuntingOldYella]

I do and I dont miss my LC, it was a 192 with tripples, when the SB barina GSI came out, it absolutely distoryed the LC lol Plus all the 12'a and 13b's went turbo, so I had no hope racing them anymore. Then i started playing with the 1986 60 series Landcruiser.12Ĥ-T diesel 250hprwhp and 650 NM of torque lol

[@Catfish4000]

I'm forever amazed that a self-contained metal contraption, with only 3 inputs (throttle position, engine vacuum and airflow), can do such an amazing job of keeping the engine running in all situations, and be not too far from what EFI can do. The problem is that people expect to bolt on the "house brick" and somehow have everything optimised by the factory that built it. They dont realise that the carby doesn't know what it's bolted to. Just as with EFI, it needs to be tuned to the engine. If the owner doesn't know how to do that, that's on them, not the poor old carby they got off marketplace for $180. I'm running a "dog" of a carby on my 302C, a Holley spreadbore double pumper. I built it to my specs and can safely say that after messing with 3 others before it, it's the best by far in all areas except maybe off-idle torque (the Street Demon was the best for that). Joe you might remember my car from a dyno day a few years back. A brown XE wagon 5-speed that you were pretty impressed with despite its mediocre power output (but your dyno is savage)

[@Junkers024]

but would the carbs have gained from longer tubes ? as well

[@ToreDL87]

Well adjusted carbs exactly to your local weather can't be beat. But that's not easy to do, and ideally you need standalone ignition, expensive, and just all the jets alone are also starting to get pretty expensive now. Carbs are also expensive, DGV's aside, a full double or triple set DCOE's with intake, linkage, funnels = Not cheaper than ITB's, and Weber's are now Spanish made and can have quality issues, as opposed to the older Italian made ones. Fuel consumption isn't the best with carbs either, can be temperamental, and may require a certain throttle technique. That's where EFI shines, you trade a few horses for overall health of engine, fuel economy, QoL & driveability. For me, it's EFI all day until solar flare.

[@justin3131ify]

Enjoyed this alot! You obviously do customer cars?

[@mrivantchernegovski3869]

Man miss my LJ it was a import from Oz to here in New Zealand put a JP 202 in it had a 350 2 br Holley then a 465 4br holley bit soft down low and a 2 br weber off a V6 Capri for long trips or daily ,holley for Fridays and weekend ,semi hi stall converter frankinstein Trimatic guy built me at work from HQ,HX,VB bits he had lying around had to buy new seals and few other little bits and a cut down EL Xr6 LSD 3.3 maybe fast sorted car ,commo front brakes big sway bars ,gtr wheels on 225 low and fast with a cheesy XU1 rear spolier,early 90s they wernt worth alot lol got rid of it for a Yamaha FZR1000 that i got into heaps of trouble getting chased by cops losing licence uuug should of keep the Torana it was a happy car

[@geoffmcwiggan2814]

Very hi psi injection via fuel pumps and injection can make a increase in Hp. Very costly for a top notch system. A cold air box on that application would also pick up around 10 or so Hp

[@Hydrogenblonde]

I don't see a problem with running different trumpets with the efi compared with the carbs. That's all part of it. Each system needs its own special parts and equipment. It would be a bit like saying we will run fuel injection but we won't use injectors because the carbs don't have them. That's silly, each system has its own parts it needs that will be different to the other system. If the combination of parts in the injection system gives you more power or it drives more to your liking, then that is the superior system for you and whatever combination of parts it consists of works for you.

[@brendanmccabe8769]

Totally agree, this was exactly my thoughts. Presumably the ram tubes on the carb's had been optimised (if not why not?) for them so why should the EFi system not have the same treatment rather than be stymied by something specific to the carb's? This is not the same as changing fuel and ignition systems at the same time. I don't see why the results are surprising though, why one fuelling system optimised for WoT create more power than the other, it's the engine which is making the power, as long as air and fuel restrictions were similar the overall power should be the same. In fact it seems 8BHP extra was developed, maybe not life changing but that's still >5%. Point is that carb's are always a compromise, optimising one area of the fuelling always seems to give suboptimal performance or behaviour elsewhere with EFi it's much easier to optimise fuelling (within the physical limits of the hardware) across the RPM and load ranges as well as giving benefits such as over-run fuel shut-off and closed loop control (and diagnostics).

[@einarb86]

great video by the way, keep up the good work

[@peterfuchs7822]

Good on you. Thanks

[@Circlotron]

Much difference in fuel economy?

[@peterolson8350]

Very interesting video. But have to ask, the car is very similar to the Opel Ascona A here in Europe, is it the same?

[@Circlotron]

Looks somewhat similar around the nose, but not in other angles. The car has it's origins with the English Vauxhall Viva.

[@robhazell179]

Hi mate, I'm running triple 45mm webers. I'm interested in what you have done with the computer ignition set up, and also the throttle linkage. Can I get some help or info please

[@davidgalea6113]

If its a classic car, the mechanical beauty of the carbs is where its at. Just my opinion.

[@cuda6496]

I have A Deceleration fuel Cut out system in my 750 demon carburator !!! These Webber style carburetors Have so many adjustments that you can get the correat fuel ratio at all Engine demands More so than a Holley Style carburetor !!! IT CAN BE DONE !!! If you have $8000( My friend wants to buy one for his Subaru) to buy an Aftermarket ECU for your fuel management by all means go for it to each their own ! 🤷‍♂️

[@busarob1969]

What about the fact the efi bodies don’t run chokes and the Webber do run chokes, did you think the over all size of the throttle Bodie bore where too Leigh in diameter , Been here done this! Been a engine builder/ tuner for a very long time, car engines and bike engines, fuel control via efi is always better, you just need to make sure your intake air speed is correct for the engine, the fact you needed to speed up the air flow with the carby ram tubes is telling me , with the chokes in the carby increasing air speed, the throttle bodies bore size was too big. After all this is a street car with a small cam, I have the best results by choking Webbers down to 38mm and seen power losses when going to Webber style throttle bodies cause of the slower air speed due to larger bore size

[@Peter-b6q5f]

I agree. He didn't tell us what size the carbs were (or the chokes in them) or the ID of the ITB's, but that little HP won't even need 40mm ITB's, especially as it has a nine port head. It would be interesting to see the power graphs on different throttle percentage openings (which he would have done) to see what that engine needed.

[@donwest5387]

nice fair comparison

[@simonm8586]

Presents a lot of good points. I think you missed mentioning one of the key benefits, much cleaner emissions.

[@michaelbyrnes7944]

You know what you can do with your emissions bullshit

[@simonm8586]

@@michaelbyrnes7944 I'm guessing U want me to do what you do daily?? Nah. I'm good.

[@cartermackenzie1135]

I agree with this comment.​@@michaelbyrnes7944

[@mikeg4163]

Not true… catalytic converter is easier to control with efi, but carbs can be very clean, but not ever changing based on converter needs…. That’s the hiccup

[@simonm8586]

@@michaelbyrnes7944 obviously your understanding of combustion is set in the 70's. The world has learnt much in the last 50 years about getting a more efficient burn. FYI - cleaner emissions means more of the fuel energy is turned into power. Maybe you can rethink your Neanderthal ways

[@amraceway]

Have you tried an Aussie Rotec ITB?

[@carlmitchell4297]

Do you have a Rotec TBI fitted to a car or bike

[@amraceway]

@@carlmitchell4297 Will be fitted to my next project.

[@carlmitchell4297]

@@amraceway I have a pair of 34mm Rotec TBI's which are going on a 1959 6 cylinder engine.

[@amraceway]

@@carlmitchell4297 Mine will be going on a 202 inch Holden six cylinder..

[@carlmitchell4297]

@@amraceway Mine is for a 132 grey motor in FC Ute

[@donwest5387]

no air cleaners?

[@leighsaunders3278]

Why would you not use an EFI Hardware DCOE throttle body's being they are manufactured here in Australia? I will say though Webber DCOE style carburetors are the closest thing to injection due to the way the fuel travels into the chokes & into the cylinder head. EFI hardware throttle bodies are a lot more direct & simpler design. By the looks of things the efi throttle bodies your using look very complicated.

[@benaresq]

The Jenvey heritage throttle bodies are designed to look like carbs, they keep things looking period.

[@theworkshopmechanicchannel3296]

What model Haltec is that running ?

[@jdfilms1426]

It’s a Haltech Elete 750. It could be a 550? It was a while ago so I can’t quite remember. In any case, it’s one of the lower spec Eleite’s. 99 percent sure it’s a 750.

[@theworkshopmechanicchannel3296]

@@jdfilms1426 Thanks for your reply. Im building an engine for my EH with an Irving stage 2 cylinder head with triple Webbers. I was going to run a wideband o2 sensor until I saw what you did.

[@einarb86]

the most interesting part, how much stronger did the engine get? its torque that matters

[@ldnwholesale8552]

Fact you can run more cam on a analogue engine. Webers dont care about manifold vaccuum. Everyone wanks themselves silly about efi but there will be more power made with an engine built for carbs. Near certain it will not be as smooth to drive so efi does make some sense on a road car. But not on a race car. Computerised ign is MAYBE an advantage, on a road car. I have always used factory Commodore HEI which is better than most others. BUT I would love to try a MSD. On V8 racecars an improvement, on V8 road cars chalk and cheese. Starts easier, runs smoother and uses a bit less fuel. I have it on my mild 400 Ford and have fitted it to a Mustang and a 350 Chev for a ski boat. My 400 is using white wire on a points dissy. The electronic dissy died. Though I have had [Crane] ign boxes die on the 400 and the 351 raceengine. So far ok with basic MSD. Streetfire on the 400 as it never runs past about 4500. MSD 6 on the racecar. Those rock strainers over the ram tubes is killing power,, effects the standoff which usually makes it richer and less driveable. Unifilters, K&Ns etc on the ram tubes resolves this. Been there and done that. 45s on a healthy road race 202 with 40mm chokes. Engine ran between 3500 and 6500. Weber ram tubes always seem to be the best, I once tries some with a bigg entrance and lost power, so put the originals back on. This on a chassis dyno. Holley efi is never an answer, just continual dramas. And will make less power

[@MrBlackbutang]

That’s not fair 🦣🦓🐆🦒

[@bluejayfabrications2216]

Its interesting i have always had the thought EFI injectors were an odd design very clumsy when you consider the better part of 60 70 years of development went into carb design and we arrived at a Venturi to deliver fuel at the ideal position in the intake stream with little fuel Pressure (relative) Why move it and redesign the wheel then try to compensate with higher injection pressures Why not retool the carb body and use the efi injector to metre the fuel to the Venturi then you get the best of both worlds

[@jarmominkkinen9409]

I have run with Dellorto Carborators 48mm Chevy 356cui 0.40 borr 4 bult block.Corvette 1974 No no transbrake run 10sek taimes 1992 1600kg car.Th400 (Aut) 201M 6.9sek Real Street car..I Build Twin Turbos 95-96 Efi Vems In may Corvette.Hope com tou The Streets 2025...Real Street car offcors..Turbos are smal K27 Have k29 if I want more flow...I tink thes K27 are god.Have Bigger Rear end 12 bult 31 splains.Toms parts..

[@guilt-toyracing3588]

Is that the customer who is banned from many workshops / machine shops in Sydney because he just hangs around like a bad smell? I think i met him at Dominator Engines one day

[@petergehle4222]

I always found carbies made more peak power then efi. I always put it down to better atomisation with a carburettor

[@MickH60]

nope, if that was the case, all performance cars would still run carbs. I wouldn't even be looking at cars for this test, motorcycle carbs and injection is leaps and bounds better than anything running on cars, and you won't find a carb that works better than injection on a race bike ever.... Motorcycle tech is miles ahead of anything car related, always has been...

[@petergehle4222]

@@MickH60 it's because new cars have efi. Pro stock stayed carbs until forced to go efi to keep up with emissions and what people have in their every day cars. I owned a Dyno so I am telling you that carbies made more peak hp every time on my engine Dyno. That was 10 years ago. That is NA car engines I'm talking about.

[@3rd-eye-neenja563]

1000%

[@hatface547]

@@petergehle4222 Sounds like you don't know how to tune EFI

[@petergehle4222]

@hatface547 haha 😂 or you don't know how to tune carbies