Webers run cleaner than EFI?

[woldson]

As these motors are simplistically an air pump, I absolutely believe that your "air pump" is MORE efficient with the webers than the stock FI. The stock FI intake system is far more restrictive compared to the webers on a short runner manifold. You are definately able to supply more fuel AND AIR into the motor for better combustion. With a good tune, this better combustion with more air/fuel means more HP, and this results in more flow out the exhaust due to the motor running more efficently.

 

 

You raise a great point here.

 

I would add though, the ability for a complete burn of a smaller amount of fuel with X air will not change between the two systems.

 

Just with the carbs you will could have more fuel and more X air, more power. You can do this with FI as well.

[ozconnection]

Two things I'll mention

 

EGR.

 

Ignition advance.

 

Same or different on each setup?

[randy 77zt]

if the old version of the engine with efi had original injectors i would bet that the spray pattern was not very good.why?because back in thhe day when z's were built the gas did not have injector cleaner in it.i owned a shop and worked on a lot of 75-78 z's.the exhaust manifolds would crack because the injectors would be running lean on some cylinders because the injectors were partially plugged.the stock cam and some good ignition timing settings will make good manifold vacuem at idle.the more vacuem the better the carbs work.where efi works better is on an engine with a big camshaft.nothing takes the place of proper tuning.

[Tony D]

Yes, it's an oranges to apples comparo, the reason such anecdotal snippets are best not turned into irrational jumps to judgement.

 

People now committing suicide have been in CLOSED garages and have failed to kill themselves due to CO percentages being catalyzed to nothing. And most will tell you that if the injection is working and calibrated properly the catalyst is along for the ride until you make a transient (accelerate, decelerate, etc) at which point 'scrubbing' occurs. Later four way catalysts actually result in cleaner air out of the vehicle than what went in in some bizzare cases! The Engelhardt Catalyst Company was working on Low Temperature Catalysts for the radiator fins and taking hot engine bay air on some Loncolon Mercury products because the latent HC in the ambient air was enough to throw the emissions readings off enough to skew and fail a federal testing regimen!

 

It's a flawed anecdotal comment not thoroughly researched with a hasty conclusion drawn to make the original statement. Empirically it has not been proven, but then again a 30 year old system being compared to something new and adjustable is not the best thing to start with...

[cygnusx1]

Statement?  You did notice this in the subject>?

[Tony D]

Statement?  You did notice this in the subject>?

 

Sorry, I wasn't paying attention in school when simply tacking on a "?" to a statement is considered proper form.

 

You Suck!

You Suck?

 

Two different meanings.

 

Do you Suck!

Do you Suck?

 

Two different meanings, and different than the first two. (BTW, "Statements" can be classified to all FOUR above...)

 

Now:

Do Webers run cleaner than EFI?

 

Webers run cleaner than EFI?

 

Which is a QUESTION, which is a STATEMENT?

 

Floor needs mopped front to back.

The floor needs to be mopped front to back.

 

Which is correct? Dropping articles and prepositions might be cool in Philly, but I refuse to endorse someone who says 'he disrespected me'... It's 'he was not respectful' or other permutation. Regardless (or would you prefer irregardless?), a dropped word changes the meaning, regardless of a poorly tacked on punctuation. "Do you suck!" doesn't even make sense as a sentence...So in the same vein Do Webers run cleaner than EFI" does not simply change from question to statement with the addition of merely punctuation. At least not in proper English. Written or spoken. Even with inflection, your intent of asking a question would still be taken as a statement for refutation if uttered according to the punctuation alone. It's the dropped 'DO' that makes it egregious.

 

You made a statement, then tacked on a question mark on the end. Not proper form, not a question. Interrogatory statement perhaps, but still a statement.

 

Which you then backed up with anecdotal quips involving your nose and different setups.

 

I think what I said about sums it up pretty well, poor anecdotal stories drawn to make a flawed statement.

If it makes you happier:

Poor anectotal stories drawn to make a flawed interrogatory statement.

 

But a statement nonetheless...

Edited April 20, 2010 by Tony D

[cygnusx1]

OK.  The weber fed version of the motor still smells less than the FI motor.  I am not making up stories.  At idle, which is a condition where I can control the volume of A/F mix on the Webers, to obtain a "nice idle", the motor smells better than a "nice idle" obtained with timing, air bypass screw on the AFM, and throttle stop, on the factory EFI.  Is my observation wrong?  Tell me.

 

 

 

Poor anecdotal stories?  Wow.

Edited April 20, 2010 by cygnusx1

[yetterben]

FWIW my best lean idle on my 40's is 11.5 and it stinks to high heaven So bad when the ol' Lady comes out to talk to me i just start the car and count the seconds till she leaves. I love it. I love polluting. I love rotaries. I love lime jelly. I love playboy. I love running threw the streets naked smoking a cigar covered in lime jelly reading playboy.......oh wait this is not a Dennis Leary special.

[bjhines]

I can see the general thinking behind the title. The main difference here is related to ATOMIZATION of the idle mixture and not general TUNING of the E.F.I. vs CARBY systems. This has been alluded to by several people. You can tune a carb lean or rich, the same goes for EFI. The way the fuel is introduced into the ports is very different though. You can't just assume that EFI will run cleaner than a carby. The EFI is more responsive and MUCH more reliable than the old carbys ever hoped to be. EFI really does not know how much fuel is IN THE MIX! It relies on O2 readings to determine mixture ratio. Poorly atomized fuel(beatup injectors) will not completely burn in the chambers. The O2 readings are spot-on but you are still dumping large amounts of unburned hydrocarbons out your tailpipe. This is your stink!!!

 

EFI at IDLE: (with worn-out injectors?)

The EFI system relies on the spray pattern of the injectors. The EFI fuel is squirted right on top of the valves. There is almost no time for further vaporization before the fuel enters the chamber.

 

CARBY at IDLE:

The carby provides PRE-emulsified fuel to a point just under the throttle plate. The air here is high velocity and low pressure which WHIPS the already emulsified fuel into a fine mist. Furthermore, any remaining droplets have a long time to completely vaporize before the fuel enters the combustion chamber. There is at least 12" between the idle ports and the intake valve.

 

 

I could easily street-tune my DCOE 45's to run clean/lean enough to leave tan-white deposites in my tailpipe. My track-jetting would foul the plugs if driven on the street and blacken the tailpipe, but on-track it ALSO left tan-white soot in the tailpipe. I ran TRIPLE F/A ratio meters and they were right around 13-1 under most conditions in the appopriate application for the jetting.

 

There is more to this than meets an inexperienced tuner. Tuning for street vs track required more than just jet changes. Things like main venturi "chokes", and accelerator pump must also be changed. Smaller chokes make everything easier to tune, larger chokes make a little more power at high RPM but make transition and midrange tuning hell.

 

The IDLE and MAIN circuits are the most basic tuning points for ANY carby. These should be relatively easy to get right. It is transition and low-vauum compensation that are tricky.

Edited April 21, 2010 by bjhines

[cygnusx1]

Thanks, BJ.  You summed up what I had a hunch "might" be occurring.  Put aside all the tuning, and jetting.  I have seen my injectors fire, albeit not into a vacuum, and they look more like garden hose than mist.  These are the injectors I am running in my turbo car.  I don't want to compare that car with the Weber car or with factory Z injectors.  I just want to show what the spray pattern from an injector can look like.  Keep in mind, liquid fuel resists ignition, when you see this:

 

 

That does NOT look like a well dispersed, fine mist.

 

This looks much better, and I am glad the guy's cell phone didn't ring!   

 

 

 

When playing with Webers, I have seen a fuel mist resembling a foggy day on the west coast; (Tony no I am not assuming because I saw that, the carbs always fog fuel like that) certainly finer than what I see on the first video of non-direct-fire injectors.  Thanks for the Weber tuning tips.  I have read almost everything there is about Weber carbs, and have played with DCOE's for about 25 years.  I feel I have a really good grasp of what is going on inside them. 

 

 

I hope this post sharpens the coordinates of where this thread is going.

Edited April 21, 2010 by cygnusx1

[cygnusx1]

  I also have a question about running poor atomization.  If the fuel were poorly atomized when it got to the combustion chamber, what would the AFR's read, compared to the same mass of air and fuel injected with proper atomization?  Would they read lean and cause a closed loop system to increase injection, or just the opposite?  Certainly HC would be UP.  

 

It's highly likely that my injectors were toast, even though I had them cleaned and flow tested, explaining why the carbs smell better.  

Edited April 21, 2010 by cygnusx1

[bjhines]

The fuel does not burn so there is extra O2 left over, so the EFI increases richness until O2 comes down to the calibrated level.

 

BMW for one decided that this was worth fixing on a high end motor. The later inline-6 motors had an entire manifold dedicated to idle air and mixture vaporization. It looks like a second fuel injection rail, but it is only Idle air that is introduced to the ports to improve atomization of the injector spray.

Edited April 21, 2010 by bjhines