Why are carbs still use in racing if F.I. is so much better

[Dodge Freak]

Just was thinking about F.I. after seeing a nice looking EDELBROCK PRO FLO EFI FUEL INJECTION unit for many motors now. Unit's are not cheap @ around $3000 but should give better gas mileage one would think.

But F.I. is not use today in too many race cars. The Indy 500 still use the Holley carbs.

My guess is with a good hot spark, like a good MSD racing box and intake manifold, the carb performs better.

Others are like no way, they still use carbs to keep the top speeds down.

Why do you think the reason is ?

[Ed-vancedEngines]

Sponsor money goes a long way towards dictating rules.

It would surprise me though if they were using carbs on IRC Engines. Most if not all are turbochraged.

If is also debatable if EFI can make the same max power as a good carb combintation. Regular fuel Injection mechanicical systems seem to still be working fine in a variety of racing where it is allowed.

Ed

[jmarkaudio]

EFI is more easily tunable, but racing versions are a bit more initial expense. There are benefits to using them on engines with power adders, but I don't think the high end NA engines would gain much power over carbs as they operate over a limited power band. I think the racing organizations are afraid of running up the expense for racers and race teams. You would need a computer programer just for the EFI system on each team. And another area for tech to have to police. Look what happened to CART. The expenses were astronomical. You have to stop somewhere.

[CamKing]

First off, there hasn't been a Carb on an Indy Car in 50 years, and there hasn't been a turbocharger since 1996.

EFI is much more efficient then carbs. The only reason you don't see it in NASCAR and Sprint Cars is cost. As soon as you open that door, development costs will go through the roof.

The new systems check temps and EGT's on each cylinder and adjust the fuel and spark for each cylinder individually to keep each cylinder at the optimum operating range. No carb can compete with that.

[Ed-vancedEngines]

there hasn't been a turbocharger since 1996

Shows how current I am with Indy car racing. lol.

Ed

[Warpspeed]

Several reasons I can think of.

First, the rules in some racing classes say carbs only, so that settles it.

Cost is another factor, not only are carbs mostly cheaper (but not always !) it does usually simplify things, especially in the lower classes.

Lastly, EFI is vastly more tunable, and much more flexible for a street engine that must have good cold weather behavior, and good small throttle fuel economy. But a race engine is not run like that. What a race engine does at wide open throttle over a fairly limited rpm range makes a carb just as good as EFI.

.

[bobqzzi]

The only reason carbs are still in use in racing is because the rules require it.

[Ron E]

In drag racing, they don't want anymore electronics to police.

In 'cup racing, Better performance isn't even desired by the rules makers. They're restricting them now.

[panic]

Carb rules?

In 1960 these same "market-driven forces" would have attempted to impose mandatory use of Stromberg 97s, Ford flathead engines, and LaSalle transmissions - because the vastly superior parts furnished on new cars would ruin their industry (how could they make money selling you a 4 bbl., a 392, or a T10 when you could buy a used car with them?).

We would have greeted such obviously incestuous and self-motivated trade restraints with disbelief, shock and adamant resistance - why not now?

[allblowdup]

Does a carb not do a better job at at cooling the incoming charge due to latent heat of vaporization? Would this not increase potetial output of the engine everything else being equal.

[CamKing]

Does a carb not do a better job at at cooling the incoming charge due to latent heat of vaporization? Would this not increase potetial output of the engine everything else being equal.

I don't see how.
The high pressure EFI nozzles do a pretty darn good job, and can be put anywhere in the intake tract.

The other thing to remember about carbs, they need vacuum to work, and EFI doesn't. Vacuum costs power.

[Engguy]

A carburetor actually does a very good job of atomization, the big down fall is distributing it into the cylinders evenly.

[CamKing]

A carburetor actually does a very good job of atomization, the big down fall is distributing it into the cylinders evenly.

Wouldn't the high pressure used in EFI do a better job?
I've seen 40hp just from moving the nozzle location in the intake runners.

[Troy Patterson]

Carbs are still in use for a bunch of valid reasons:

1) they make more horsepower
2) they make more torque
3) they have the capability to metering the fuel significantly more accurately than f.i.
4) they atomize fuel better than f.i.
5) they are a "dynamic" metering device whereas f.i. have sensors which only read what comes out after the fact - like an autopsy of the combustion process
6) carbs are cheaper
7) carbs provide greater throttle response
carbs develop more "accelerative torque" than f.i.

But, there are lots of carbs so to say carburetor includes a very wide range of possibilities.

The reason f.i. is used on Indy and F1 cars is no ones bothered to develop a float bowl to handle the G-forces those cars are capable of generating.

If you do a little research, you find that tens of thousands more aftermarket fuel injection systems have been sold in the last tens years, than are currently used, but people keep trying any way.

When people make comparisons and claim fi was better, you've got to consider that what they were comparing to may not have been the cats meow - although they probably thought it was. Another thing is that there really is a lot of carb tuning that those doing it believe to be top notch, when in fact it's just okay - present company excepted, of course.

For fi doesn't atomize fuel well untill you get up to 200 psi and more, then you're squirting the fuel in the chamber so there's not time for the mixture to homogenize as it does with a carb or to a less degree a TBI.

Troy Patterson TMPCarbs.net TMP Carbs

[ThomasL]

Here are my thoughts. The engine tells the carbs "real time" what it wants, and the carb reponds on that cycle. Injection sends the engine what "we" tell it to in the maps. Feed forward system. "We" tell the engine what it's going to get, right or not. Yes there is O2 feedback but it is after the fact. It has to see the error from previous cycles (where the mixture wasn't right) to make trimming adjustments to get the motor what it needed cycles ago. It does those trim adjustments and OOPs, conditions changed slightly since then and the mixture is off again. Basically always chasing it's tail but never truely catching it. ???