Carb (s) vs EFI / EMS

[Ed-vancedEngines]

Troy,
I agree mostly with everything you just said. I say partly becuase there are also several other considerations with carbs that do affect the tuning, and there are also some of the same things affecting tuning with EFI. Most of us know that the engine does not pull air/fuel in. The air/fuel is pushed in becuase of the greater positive atmospheric pressures as opposed to the few inches of negative atmospheric pressure inside the runners/plenum of engines with carbs. When we put big scoops on top everything changes becuase it is not now a still and ambient atmospheric pressure that is pushing it all in.

The carb will self-compensate to it's limits of jetting circuits boosters etc. The EFI will not change unless someone recalibrates it for changes.

For these discussions when I mention EFI, I am not talking about OEM Factory EFI that compensates of varying loads to the range of how it was programmed to respond. I am talking aftermarket stuff that in open loop does not self calibrate. Only in closed lop is it doing any self calibrating. Even in closed loop though regardles of the sensed load from which ever load source it will only calibrate to preset limits.

If the EFI tuner is on top of his game he can build in or set up compensation calibrations that will self calibrte when in closed loop mode.

Now once it is all calibrated and you are happy, at least with the Haltech units, any change of Barametric pressure rangine from below sea level to thousands of feet above can n be recalibrated for and the compensation done in a matter of seconds. So I can have a car that is running great in Dallas Tex with current pressures and take it to DEnver and hit two buttons turn switch off and back on and viola I am re-calibrated for the Mile High atmospheric presures which go hand in hand with the barametric pressure levels.

Sonny Leonard made a statement which I will agree with; If I can get an EFI engine to dyno even 20 hp less than my carbed engine, the EFI engine will get down the track quicker. I did not do quotations, because I paraphrased his comments.

Most serious non FI Outlaw N2o engines are running carbs.

Ed

[Troy Patterson]

I do see the advantages of the various aspects of fuel injection to self compensate for atmospheric conditions and so forth.

I dare say, that if most racers wanted carburetors to do the same thing, the smart guys could easily apply it to Holleys and Demons as the auto manufacturers did some twenty seven years ago.

Hey, it's great to have self compensating system on your tow vehicle. How many racers want to install the added complexity on their race car? For that matter, how many guys race at Pikes Peak?? What percentage of the market would that number be? One tenth of one percent? Is that an adequate number for a valid basis of argument? How many fuel injection systems run in a "carb only' class? See the point?

With regard to handling G forces, again, most racers don't experience F1 type "G" forces, so do they need a device which can handle it? Would the extra expense net them a worthwhile or any gain?

Someone, or a number of people stated in this thread an issue about carburetor recovery after launching at the drag strip. I know this to be a non-issue with correctly calibrated carburetors. Too many times, people assert their personal (unqualified) expereince as absolute. No offense, I just would rather speak straight.

I happen to have spent years dealing with the type carburetors we speak of on a wide variety of applications. I don't mean that I delt with carburetors also. I mean I spent virtually every waking moment working to learn all I could and experimenting. Now, the guy who has delt with carburetors incidentally in the course of his business or racing isn't equivalent.

I do acknowledge the roughly fifty year old carburetor design has its short comings, and that I formerly built and marketed successfully an upgraded version. (The duration of time I had to market what I called the Premier Series was cut radically short, not by market forces or lack of interest and successful results, but by unfortunate circumstance. Read my posting on the "Pirates of Carburetion" thread, page 6.)

A carburetor "metering" the air flow through an internal combustion engine is a DYNAMIC process.

A fuel injection system "monitoring" operatinal parameters is not. I would make the analogy of fuel injection monitering the engines operation and the subsequent programming to be like the State of California or Windows operating systems. You take a great thing, then strangle it with layers and layers of regulation or programming on top to attempt to make something different based on our highly educated and enlightened understanding of the universe. (Not!)

If racers wanted the minimal benefits of added electronics added to their carburetor, Edelbrock, Holley Performance Products, Demon Carburetion, DaVinci Carburetors, etc., etc., could easily create such a product.

People seem to think humans, some people think themselves, are smarter than God, and that we / they can manage the laws of physics better than God. Never mind what we have yet to learn.

I don't think so, no offense intended. For all the time and energy attempting to one-up God or all the yet to be learned and understood laws of physics pertaining to the internal combustion engine, we miss the boat all together.

I don't think what little knowledge I have about anything, comes from me, but through me. I'm not trying to usurp the natural order of things. I am also not suggesting any one here is either. I'm just rambling on.

P.S. DYNAMIC is a good thing!

TMPCarbs.net

[airflowdevelop]

Do these carbs adjust for elevation changes like say at the pikes peak hill climb?

PFM

PFM,

Actually most fuel enjection systems do not adjust properly going from sea level to Pikes peak if you're comparing apples to apples.

Heh?

Doug,
Do you know anything about EFI? Not trying to be a smart-ass...but this is the most bogus post I have seen!

Dennis

[F1Fever]

I once heard a fellow say something to the effect of "If the fuel injection was invented first then another guy came along and designed the carb he'd be hailed as a hero"....or something like that. and I can relate.

That's not to say the FI isn't a superb tool, it's just in it's teenage years right now.

[Doug Schriefer]

Do these carbs adjust for elevation changes like say at the pikes peak hill climb?

PFM

PFM,

Actually most fuel enjection systems do not adjust properly going from sea level to Pikes peak if you're comparing apples to apples.

Heh?

Doug,
Do you know anything about EFI? Not trying to be a smart-ass...but this is the most bogus post I have seen!

Dennis

Dennis,

I actually may not be as dumb as you think. Will go through it real simple. Most EFI systems work based upon a VE chart of some sort. As the altitude changes vastly (such as going from sea level to pikes peak) the barometric pressure changes, based on this change the computer thinks the VE is now lower. Since the VE doesn’t change the computer actually takes too much fuel away. The majority of OE computers do this, and must be recalibrated for very high elevation usage. Most systems can overcome this problem with some simple programming, but to date not many do it. By the way this information comes from EFI people, not from me.

[airflowdevelop]

Which logic are you refering to? I have seen this problem with the original OEM bosch type logic (similar to what ford used in the early EEC pcm's).

Most if not all of the new logic centers the MAP on boot. I have seen newer GM pcm's take 3-4k altitude changes with no change in ultimate AFR.

You've got my attention.

[bobqzzi]

MAP systems use manifold pressure to determine the A/F, so they compensate for altitude.

Most systms now also have a baro sensor.

Many systems use a MAF which directly measures air mass

ALL systems made in the past 3-4 years have a wideband O2 sensor that operates under all conditions to trim the A/F- they even adapt the injector pulse width table over time according to historical data.

The only area in which carbs can compete is WOT power...
driveability, emmissions and power under the curve are all better with injection..and have been since the 70s.

[Doug Schriefer]

Which logic are you refering to? I have seen this problem with the original OEM bosch type logic (similar to what ford used in the early EEC pcm's).

Most if not all of the new logic centers the MAP on boot. I have seen newer GM pcm's take 3-4k altitude changes with no change in ultimate AFR.

You've got my attention.

From my understanding even with the new logic it will only recalibrate in your 3-4k change once the system is cycled (turned on and off) if they would continually monitor the map it wouldn't be an issue.

[devilbrad]

I've had multiple customers drive their new Mazdas from San Francisco up to Tahoe or Reno, shut the cars off, and have a hell of a time restarting them. Once they learn the altitude, they recover in the first drive cycle, and once again, the long drive back down here, they will run horrible on first start up. This is on OEM systems and I actually havent seen this problem in a while, was most likely, as someone stated, the Ford EEC systems Mazda was using.

[Cobra]

Having driven a variety of carbureted and EFI vehicles to Reno and Tahoe, the only problem I have experienced is retaining enough $$$$ to buy gas for my trip home!

[Ed-vancedEngines]

Cobra,
Good and praticle response that applies no matter where we drive to..

Possibly some of us are not talking apples to apples in this thread when we are talking EFI.

I see many referrals to the EFI systems that are factory OEM on new vehicles, that after a brief warming period are always running in closed loop and that are self compensating based on the parameters that are programed in from the factory. This is not for performance but is for drivability with emissions as a key importance where 14.7 stoich is the norm for cruising.

I see only a few of us talking about Racing or aftermarket EFI systems that are mostly only self compensating in a narrow bnd of parmeters, only when in closed loop mode. With normal usage being in an open loop mode there is no self compensating of any tuning parameters. Now if we happen to understand the system and what an engine wants and the effects of when we make any tuning change, we can program them do be as good as it can get. IN the more expensive systems we can even do individual cylinder tuning of individual injector tiimng as well as individual cylinder ignition tuning. We adjust all of the settings based on load sensors which are in either and sometimes both for throttle position, Barametric Pressure, and air/fuel. We can adjust for each load condition the sensors will pick up with hundeds of adjustments or settings available for us. Withoout doing the adjusting the EFI systems will not have any clue what to do until someone tells it by doing programming of the ECM.

Carburetors for racing or for street on the other hand are in my words self compensating within their design and tuning parameters. The flow of fuel pulled from the fuel bowls does change as the load conditions of air speed and ambient atmospheric pressure changes. EFI does not. It does what we tell it to do and nothing more or less. We can not tell a carb when to increase or decrease fuel flow, or how much to flow. We can with Electronic injectors.

Racing or even aftermarket street driving injection is not the same as the factory supplied stuff is.

Ed

[Troy Patterson]

I am intentionally provocative in my responses. I find it's good to spark debate. I hope no one takes offense and I apologize if anyone has.


Troy Patterson TMPCarbs.nets TMP Carbs

P.S.

DYNAMIC is good. DYNAMIC is your friend.

[autorace]

I have not read the whole post but in reference to altitude and aftermarket efi systems, not many adjust to elevation. Unless you are running a Motec with two MAP sensors, most other aftermarket systems need to be retuned.

[Ed-vancedEngines]

It takes hitting a button and a space bar and turning off the ignition and turning it back on to recalibrate the older Haltech basic ECU systems. That takes no more than maybe a few seconds time. If you have one of the later models you can also have a companion MAP Sensor that will keep it constantly calibrated for air and pressure changes. Easy stuff.

Ed

[dragv6]

The Australian Autronic efi adjusts for barametric pressure every ignition cycle, but this wouldnt help with pikes peak.
Matt