Which is better? (in making horsepower) I'm having an argument here with a coworker of mine and he says that a carburated engine makes more horsepower than a fuel injected engine. What a fuel injected engine is good for is for fuel economy. I need some more guys on my side because I'm just not getting throught to him, It's like talking to a brick wall.....

 

There is no right answer. Fuel injection has its benefits, but neither one will make any more power than the other when configured correctly.

Fuel injuected engines are, typically, much better in terms of fuel economy, emissions reduction, smooth running, and reliable starting. The same cannot always be said of carburators.

The gual of either the fuel injection system or a carb'd system is to deliver fuel to the incoming air. A carburated motor typically can deliver a greater volume of fuel to the engine. That being said, modern fuel injection systems can deliver similar amounts of fuel, but in far, far, FAR more precisely metered quantities. Gone are the days of having to synch carbs to each other, constantly tweaking them to make it start, idle, and run smoothly with any little change to the intake or exhaust.

I use the example of my motorcycle: In 2000, they used a carb, and in 2001 they used EFI. Same engine internals in every other way, but the EFI head had slightly different porting to accommodate the fuel injectors. The carb'd bike made 95 Hp, the EFI bike made 96. Now, try and tune them for maximum power on a dyno, and the EFI becomes WAAAY easier to max out than the carb.

You're never going to win the argument, and neither will he.... someone will always build a faster or more powerful motor with one or the other.

-Joe

 

Both Hot Rod mag & Car Craft had an EFI vs Carb shootout last year. In the end, the EFI motor made a few horse more, but it is really moot. at WOT, they are very even, but at partial throttle, EFI will always win, hands down.

I have been building/racing small block Fords for over 15yrs now. My II used to be carbureted. I just converted it to Mass Air Flow EFI two years ago and wish I would have made the change much sooner. I gained a few tenths in the ¼ mile after the conversion, but this could be due to the carb not being tuned 100%.

Carburetion remains a viable alternative to EFI for hotrods/race cars due to its price and ease in tuning. A good carb is going to run you around $400-700 depending on application. A good Mass Flow EFI setup will cost you $4000 in the end.

The differences in how much power one will make vs. the other is inconsequential. If you can afford an EFI setup, it is by far the better set up for the street.


Check my gallery to see my nearly 600hp 347cid both b4 and after EFI conversion.

 

I forgot to mention that too.... A carb is easy to tune for a racer because they'll be tuning primarily for one throttle condition: Wide open. But I completely agree with everything else you mentioned... Can you imagine trying to tune a carburator for an indy or F-1 car?

Here's something else to consider: Why can't you buy a carburated vehicle new today? Why did every carburated small block motor eventually get converted to EFI by the OEMs? Why did those same EFI motors make more power than their carb'd predecessors?

Kind of off-topic, but what about Busch and Nascar motors? Are they EFI or carbeurated?

-Joe

 

Well, I would have to say that one of the reasons they are still carb'ed is that it's a lot easier to regulate the race cars with carbs. As far as OEM cars making more power after the move to EFI...the automakers were able to tailor the drivability of the car with EFI throughout the RPM band without the worry of atmospheric conditions. Carbs can be tuned to run perfect in one condition only. Everything else is a compromise.

I’m so glad I made that move. Retuning the carb for a 95 degree day vs a 60 degree day was becoming a pain!

Robert

 

Sorry to hijack this thread, but just wondering why would that be? A restrictor plate is a restrictor plate, whether it's on an EFI manifold or a carb. If the rules mandate that all the air entering the combustion chamber must pass through that restrictor plate, what makes the carb easier to regulate?

-Joe

 

One of his arguments is that carbs can rev higher I say otherwise who is correct on this?

 

I'm not saying that's the only reason, but one. EFI offers too many variables.

As far as the rev'ing argument goes, it sounds like your pal is very inept.

 

X2

So EFI limits the revs somehow?? I'd love to see what that opinion is based on.... ROFLOL!!

-Joe

 

Unless this guy is alluding to the fact that you can't redline some modern cars, or at least, go OVER the red line, I was surprised to notice this on my VW Golf one day, of course it was a product of the engine management system that oversaw all aspects of the engine, and of course, incorporated efi as most, if not all, computer-controlled engines do now.

So I suppose a carburetted non-computer engine might be allowed to thrash itself to death whereas a computerised efi engine might not. (it's all in the programming, since by adding a 'chip' you can alter a computer controlled engine's performance, whereas the only option in a well-tuned carburetted engine would be adding a carburettor that'd pump more fuel through) But I think the 'friend' is talking a lot of misunderstood half-truths.

 

There's only two kinds of people who run carbs. Those who don't know any better (BillyBob Autoshop's junker-dragster), or those who's class requires it. Nobody, NOBODY else runs carbs and are competitive with them when other, much better options are available.

Injection is it, period. Now it may be mechanical rather than electronic, but that all changes somewhat drastically depending on what you want to do with it. But at the end of it all, with electronic injection, you _can_ have a near perfect tune that stays that way no matter what the temp/pressure/humidity/etc. is. Anybody who has ever tried racing a carb knows it's a real pain in the *** to keep it dialed in. You might, if you're really lucky, only have to change jets 2 or 3 times a season. Or you might change them 3 or 4 times a day. It depends. With a system like F.A.S.T., you still have to make some changes throughout the day (portable weather-stations are handy), but it's just point and click.

For me, there's really only two choices, electronic injection (like what any modern car has, or aftermarket) or a flying toilet on methanol (mechanical injection). The ultimate is mechanical injection. Just ask anybody with a 7000hp Top-Fueler and they'll tell you the same. A lot of people confuse these systems with carbs because they lack a standard injector and have no wiring.

 

That's complete nonsense. Neither the injection system or carb has anything to do with how high the RPM's can go. That's something you determine with a rev-limiter, which works on the ignition. Some systems can, and do, cut fuel as a rev-limiter, but they are not preferred. But in any case, that's something that's set to protect the engine, not just an arbitrary affect of the fuel delivery system. Carbed motors run rev-limiters too. Just look at MSD!

If anybody ever tells you that carbs are better because they "rev higher", they are beyond inept, they are a f**king idiot.

 

oops. Double post.

 

tritonpwr
Yes, EFI computers typically have some rev-limiting programming that carbs obviously don't. Of course, it's limited for a GOOD REASON, so I don't consider a carb's lack of limit to be any advantage.

Bottom line: the best carb you could find won't run as well (overall) as stock EFI. And if you want an affordable MAF conversion for an old sports car, just buy a wrecked '90-up Mustang - the newer, the better. I had the chance to buy a whole '03 last year for ~$1,000, but I didn't have a project to use it in.

 

The only reason manufacturers converted to EFI was because the federal air quality standards became too difficult to meet with a carburetor. They put up a good fight for a long time, building more and more complicated carburetors, but they finally had to throw in the towel and go EFI. If not for emission standards, they would still be using carburetors today. As far as horsepower goes, the EFI engines weren't always better. In 1985, the carburetted 5.0L Mustang had 30 more horsepower than the fuel injected model, and 10 more than the 1986 SEFI model that also had higher compression pistons.

It's easier to fine tune a fuel injected engine, which results in better efficiency, and more power, but the manufacturers weren't hard up for where to get more power from. The EFI engines with higher horsepower also had significantly higher compression, better cams, etc.


I crewed for a Cup team in 1998, and helped with a Busch team in 2005. Through 2006, all Busch cars and Craftsman trucks used a Holley 390cfm 4 bbl double pumper. Cup cars can have up to 830cfm.

If you've ever watched a Busch or truck race, it's rather impressive that they were only using a 390cfm carb.




Our sprint car uses mechanical fuel injection, which affords us much more power than we ever would have gotten with a carburetor.



No way.