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

[Troy Patterson]

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

The question really implies the answer. They're not!

If you haven't had the experience of a carb outperforming fi, you haven't had the right carb, or haven't had it tuned well - enough.

Carbs make more power across the rpm range than fi - as well as at peak.

It's true that many of the fi proponents lump fuel delivery, the ignition system and intake manifolding into one, where as they refer to carburetors as though they are all alike and as a stand alone.

If fuel injection is so great, why aren't there dyno tests confirming this that we can all agree upon?

Troy Patterson TMPCarbs.net TMP Carbs

[WUNKMAN]

Think about this: A carburator MUST cause a restriction to air flow to operate. Not may, MUST.
FI systems can be designed with no restriction.
FI gives even cyl-to-cyl distribution.
FI can run, on average, 7-10% leaner than a carb system, and make the same power.
FI systems not acceleration sensitive, run the same in the car as they do on the dyno.
FI does not rely on accelerator pump to cover inertia caused lean spot. (Another waste of fuel) Fuel under pressure has NO lag. MUCH more responsive than carbs.
FI systems EASILY adapted to ram tuning. Doesn't need to stick through the hood.
FI fuel usually sprayed on the back of the intake, making the FI engine "warm up" faster than a carb/choke system.

Although carbs DO atomize fuel, vaporization takes place on the compression stroke for carbs or FI. Atomized fuel does not burn, only vaporized fuel.

A throttle body injector IS NOT a fuel injection, it is an electronic carb. By the way, it DOES atomize better than a carb, so if atomization is what it is all about, then it should be the best system; but it isn't. Doesn't work as well as a carb or FI.

Too bad Lingenfelter can't chime in on this.

Refer back to first line.

[coolchevy]

fact is and remain, even for Oldschoolers, if an EFI system doesn't outperform a carb then they guy did not know how to tune the EFI. However, a mechanical FI ist a thing from the past anyway although simple.

None of the modern high performance engine (F1, Rallye, endurance racing like 24h, etc..) runs a carb anymore except dragracers because in most classes EFI is not allowed (yet). If it would give more pwoer they would use it, they have multi billion budgets and money is no constraint so why are they not using it if a carb is so much better?

Let's look at the setup, you can run the biggest wildest cam with the wildest single plane intakes along huge throttle bodies (I am sure we all agree now that this is good for power) and still have decent idle and part throttle response, with a carb, nil nada, maybe idles at 2000rpm if you are lucky.

I do so many EFI conversions and engines and never ever had it happen that a similarly build carb engine had better drivability, fuel consumption or top end power. And those carbs have been mega expensive custom tailored applciations tuned on the dyno for max. power, not out of the box thingies!

[coolchevy]

What about reversion and narrow LCA cams? My experience with EFI showed there was a limit to how far you could go with the two.
I couldn't go over a duration of 225 @ .050 or any narrow that 114 LCA before the motor 302 ford would burp and fart. This was an 88 mustang. I even switched to mass air system didn't help. The cam was to wild.
A carb doesn't care, changing optimum cam timimg to make a computer happy is expensive and illogical.
I'm sure EFI has progressed alot further, but I'll take a carb anytime thank you very much.

Can't confirm that, I run 258/258 @ 0.050 cams (110 LSA) and larger on the street with reprogrammed (HPtuner) LS1 engines and they idle smoothly as silk at 950rpm. No burping, instant power from idle onwards to 7200rpm. If it burps then most probably only because of tuning short comings or limitations in the stock EFI or bad injector placement

[WAWA]

No doubt fuel injection has evolved. I will point out an example.
a buddy of mine has an 89 mustang with a stroked facorty 302 block to
331 c.i. (cant remember exactly) has gt40 heads and intake, approx 9.8:1 compression., naturally aspirated.
The problem is the engine builder I feel played it safe by using ford B303 cam only due to playing it safe with the ECM.
I'm going on memory but that cam spec'd @ 225 @ .050 114 LCA
Now imagine what if compression was bumped up 1 point and another 25 degress in the cam switch to solid, single plain intake, and match it up with a proper sized carb. I'm guessing 60 hp easy. Thoughts anyone?

[robert1]

No doubt fuel injection has evolved. I will point out an example.
a buddy of mine has an 89 mustang with a stroked facorty 302 block to
331 c.i. (cant remember exactly) has gt40 heads and intake, approx 9.8:1 compression., naturally aspirated.
The problem is the engine builder I feel played it safe by using ford B303 cam only due to playing it safe with the ECM.
I'm going on memory but that cam spec'd @ 225 @ .050 114 LCA
Now imagine what if compression was bumped up 1 point and another 25 degress in the cam switch to solid, single plain intake, and match it up with a proper sized carb. I'm guessing 60 hp easy. Thoughts anyone?

Couda bought an LT1 Camaro!
350 ci
10.5 comp
340 hp out of the box

[coolchevy]

would not see an issue with bumping CR. On my street LS1/2/6 or now LS3's I run between 11.2 to 11.8 on our 98 octan pump gas with timing up to 34 degrees depending on heads. Zero knock retard if the tune is right, but VE tuning is needed not just WOT adjustments. I could not see myself doing that with a carb and still getting 25mpg

If I take another extreme, the English Street Eliminator guys F.e, they run around 8.5 to 9:1 with Monster turbos as big as a washing machines on pump gas and make up to 2200hp and can drive around all day long in eveyday traffic. Actually, they must perform a 20 mile cruise before putting down high 7*s on DOT approved tires. This guys are so extremely comptetitive, there is no match anywhere in the world as we could see this year in Orlando. Andy Frost with his Red Victor has been miles ahead of competition.

So it is like always in the tune. The tune sucks, you are down on power.

on the other side let's look at some undisputable facts for a moment.
A carb has at best 3 "real" adjustment points from idle to WOT, once the carb is mounted onto a manifold its location is fixed and A/F purely depends on the vacuum in the manifold resulting in a certain air flow pulling fuel from the boosters. If it is a huge carb great for top end power, but very little usable signal at idle and idle is sloppy at best. So naturally, there are numerous points along the rpm band where the carb can not be optimally adjusted.

a good EFI system has an adjustment point every 100 rpm and each point can be easily tailored to give best AF. Atomization of injectors is better and not depending on a vacuum signal although EFI automatically compensates for vacuum changes as well. I can easily have injectors near intake valves for good idle and response and a second set further near or on top of the throttle blades and switch between as I need to. Now combine that with a proper tune and let me know how a carb can outperform that - it simply can't. It can be close at some points but not everywhere in the rpm range. That's why race engines who do not only need WOT power like dragsters no longer use them. They need instant power at every range at anytime under all conditions, if hot or cold, damp or dry.

I think there is too much anxiety to step outside the box and to adjust to the fact that a laptop is the new tool. But once done, I almost guarantee you won't go back unless rules dictate it. I have often long bench racing discussion with guys who believe that if 3 wires go to an engine it is already too much. I understand that and accept that.

One should not look at dragracing alone, simplified thinking dragracing has only two points WOT power (you leave with it from line) and idle to cruise around in pits whilst idle quality doesn't really matter. There is no part throttle issue, no emissions issue, no idle Quality issue. Perfect for a carb because EFI seems like overkill for that application.

[Troy Patterson]

I respect that you guys have opinions, and that you are entitled to them. More power to ya!

Ya'll are really just splitting hairs. Keep in mind, carbs are "dynamic."

Troy Patterson TMPCarbs.net TMP Carbs

[Dodge Freak]

I do know one thing, a carb keeps working great longer than F.I. does.

[mv-martinez]

Well i look at it like this. i like them both because arent they basically the same concept? Your inducing a metered amount of air and fuel into the cylinders. On the EfI side, you can tune much easier because you have so many variables you can change and play with, to get a good tune. The computer knows what's coming in and whats going out. If you go carb you can still get the same tune by using a wideband o2 to get the right A/F ratio when tuning the carb. You know how much is coming in because you know what your carb size is. You know what your rpm range is and the engine specs. Its not so much EFi or CARB system, its what type of electroinc control you have over it to get to that perfect tune. Its the tuner themselves. They are very hard to find. You always here stories about carbs that are getting like 60 miles to the gallon. Its a real good Post to talk about.

[Doug Schriefer]

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

There are pros and cons to both sides of this coin.

The goal of a good fuel injection system is to atomize fuel as well as a carburetor.

The bottom line is cost! If you look at from this simple perspective. Racing doesn't have to have the latest or even the greatest technology they have to have competition to put on a show. The spectators could care less as to what's under the hood as long as their guy is winning. So why add more cost (in design, support, service, tech, etc) that doesn't add to the bottom line. Think of it this way we all know that hard coated aluminun parts last longer than non coated items. So why not hard coat our cylinder heads, and everything else? It's not cost effective. The first rule in business is to stay in business. To stay in business you have to make money.

Now going forward to "open class" racing where racers have the option. It is still more cost effective to build an engine with carburetors than with EFI.

As far as the comments that a carburetor can't make as much power as an EFI system I'll take that bet. I've done it many times. This is why the big three are now offering modern EFI engines for street rods and muscle cars with carburetors. I've been there doing the testing multiple times and have beat the EFI hands down. That's not say there aren't some really cool advantages to an EFI system.

There is a place for everything.

[Troy Patterson]

Fuel injections use of electronics and it's "limited" tuning capabilities is a major reason fi doesn't make the power.

Yes, I said "limited" tuning capabilities. Why? Believing we completely understand the internal combustion engine is the first mistake. Somehow we figure at this moment in history we've got it all figured out and that's all there is to it - and by the way, we've got it ALL programmed into your fi computer or allow you to control EVERY aspect necessary.

This idea suggests there is nothing more to learn or understand - ever, and assumes I'm not going to prove you are wrong tomorrow. Come on, we know more about the internal combustion engine today than tomorrow, and we'll know or understand more about it next week.

The cool thing about a carburetor, is it's dynamic. It's reading the signal prior to the all critical combustion process and doing and responding to things we haven't even dreamt of yet because it is "dynamic" abiding by the laws of nature and physics without us telling it to do so.

Fuel injection? It's the Titanic sailing forward at full speed in the North Atlantic!

Troy Patterson TMPCarbs.net TMP Carbs

[crazycuda]

I think a better way to seperate everyones ideas here sould be.

Stock carb Vrs stock FI

Aftermerket card vrs stock FI

Aftermarket carb vrs aftermarket FI

Then Fuel systems for the unlimited wallet

[Masher Manufacturing]

Fuel injection? It's the Titanic sailing forward at full speed in the North Atlantic!

Troy Patterson TMPCarbs.net TMP Carbs

I guess others have said the same about electric starters, spark ignition ( rather than a hot bulb ) multi speed transmissions, ball joints, rack and pinion steering.

I agree to a extent that carbs are self adjusting to air flow where a FI needs tuning and given a limited budget/time/knowlege a carb is better than a poorly tuned FI because if this self adjusting capability.

In a people car, FI wins because it is more consistent over many unattended miles. In a race car where someone is constantly making tuning adjustments, the gap is somewhat narower.

[PbFt]

[quote="Doug Schriefer"]This is why the big three are now offering modern EFI engines for street rods and muscle cars with carburetors. quote]

The General makes an intake manifold for their LS engines that converts FI to a carb. They must be trying to corner both type of customers/market.