EFI or carb
Thread Starter
2nd Gear Member
Joined: Jan 2011
Posts: 341
From: NC
Why does it need EFI if it's a daily driver? Because EFI is magic and can defy the laws of physics? A properly tuned carb'd car should drive exactly the same as EFI, if it doesn't then something is wrong.
Carb will be cheaper and easier to adjust to changing engine combinations in the future. EFI you can get different ECM's to work on pretty much any cam.
Carb will be cheaper and easier to adjust to changing engine combinations in the future. EFI you can get different ECM's to work on pretty much any cam.
Thread Starter
2nd Gear Member
Joined: Jan 2011
Posts: 341
From: NC
That '93 EFI system should work fine with the cam and heads you're using. It's a mass-air system rather than the old speed-density type, which means it'll adjust to most things you throw at it. Take a look at James W's website (google 'James W Mustang') for a good reference on an EFI swap into a classic.
I'm not anti-carb, but if I had a working EFI setup and more time, I'd happily swap a mass-air EFI system onto my car.
I'm not anti-carb, but if I had a working EFI setup and more time, I'd happily swap a mass-air EFI system onto my car.
Last edited by Dennis Marks; Apr 7, 2011 at 10:09 PM.
Thread Starter
2nd Gear Member
Joined: Jan 2011
Posts: 341
From: NC
The EFI on the engine I just bought functions perfectly so the only extra cost will be the computer, harness, and return to the fuel tank.
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
Many factory EFI systems are calibrated for emissions more than power. Especially when you throw in cam, heads, intake etc. They still need to be tuned. EFI systems can generally be easier to tune than carbs, it can be done in a day. To have that level of tuning in a carb you need a carb that can be tuned to that level in the first place. Webers(IDF, IDA, DCOE, EMPI), or a Holley type with adjustable emulsion. And you have to really know what you're doing.
The new systems that use adaptive learning algorithms are even better. It's told what the target AFR should be, and as you drive the system senses AFR based on O2 readings and recalibrates the base maps to correspond to the target AFR. Provided the O2 is functioning correctly and is accurate, it makes tuning extremely easy. That's how FAST's new EZ-EFI works.
Yanking a junk yard swap factory EFI system can actually be a quick and easy way to get running. You can get junk yard pickings for cheaper than a good carb setup in some areas, get it tuned and you're good to go. Some base Holley carbs are reasonably close for most applications, and with a bit of jetting, or on the HP series some air bleed changing, for even less money you can get moving just as well.
It really comes down to how much you're willing to spend and what level of tuning you're looking to get involved with. If you're spending $400 and slapping a basic Holley on a car, don't plan on competing with something like FASTs XFI. If you're slapping a stock 80-90's EFI system on a car, don't plan on competing with someone running a Pro Systems carb.
Like I said, it comes down to the level of tuning you want to get into. But this "EFI outperforms carb" nonsense, is just that, nonsense. Case in point, compare my times in my pushrod carb'd 5.0 to the new 2011 Mustang GT with the DOHC 5.0. The few 2011's running at the track I've run at post similar times for stock GT's, but in September when it's 50* outside. I ran when it was 85* outside. The new EFI variable valve timing 2011's run basement 13's at ~109mph at that track with a DA of around sea level. When I ran with a DA of ~2,500' I went 13.20's at 107. DA correct the times to account for whether and that puts my carb'd 5.0 at least as fast, or slightly faster than the new 2011 GT(my times correct to 12.80's at 110mph, for whatever that's worth).
And then consider, that while the new 2011 is about 300-400lbs heavier, I'm also running with a non variable valve timing, pushrod head engine with less gearing. The 2011 has more gearing, a bitchin 4v head, and independently variable camshaft timing. And that was BEFORE my exhaust/cam swap and more advanced tuning system. So clearly I'm not being power limited by having a carburetor.
The new systems that use adaptive learning algorithms are even better. It's told what the target AFR should be, and as you drive the system senses AFR based on O2 readings and recalibrates the base maps to correspond to the target AFR. Provided the O2 is functioning correctly and is accurate, it makes tuning extremely easy. That's how FAST's new EZ-EFI works.
Yanking a junk yard swap factory EFI system can actually be a quick and easy way to get running. You can get junk yard pickings for cheaper than a good carb setup in some areas, get it tuned and you're good to go. Some base Holley carbs are reasonably close for most applications, and with a bit of jetting, or on the HP series some air bleed changing, for even less money you can get moving just as well.
It really comes down to how much you're willing to spend and what level of tuning you're looking to get involved with. If you're spending $400 and slapping a basic Holley on a car, don't plan on competing with something like FASTs XFI. If you're slapping a stock 80-90's EFI system on a car, don't plan on competing with someone running a Pro Systems carb.
Like I said, it comes down to the level of tuning you want to get into. But this "EFI outperforms carb" nonsense, is just that, nonsense. Case in point, compare my times in my pushrod carb'd 5.0 to the new 2011 Mustang GT with the DOHC 5.0. The few 2011's running at the track I've run at post similar times for stock GT's, but in September when it's 50* outside. I ran when it was 85* outside. The new EFI variable valve timing 2011's run basement 13's at ~109mph at that track with a DA of around sea level. When I ran with a DA of ~2,500' I went 13.20's at 107. DA correct the times to account for whether and that puts my carb'd 5.0 at least as fast, or slightly faster than the new 2011 GT(my times correct to 12.80's at 110mph, for whatever that's worth).
And then consider, that while the new 2011 is about 300-400lbs heavier, I'm also running with a non variable valve timing, pushrod head engine with less gearing. The 2011 has more gearing, a bitchin 4v head, and independently variable camshaft timing. And that was BEFORE my exhaust/cam swap and more advanced tuning system. So clearly I'm not being power limited by having a carburetor.
Thread Starter
2nd Gear Member
Joined: Jan 2011
Posts: 341
From: NC
At the risk of simply repeating the same old crap I'll quote a couple more mind-bogglingly ignorant people, from 'How to Tune and Modify Engine Management Systems' by Jeff Hartman (Motorbooks Workshop).
Knowledgable racers and hot rodders soon discovered that well-tuned modern programmable EFI systems almost always produce significantly higher horsepower and torque than the same powerplant with carbureted fuel management, especially when the engine is supercharged or turbocharged. This increased performance is in addition to improved drivability, cleaner exhaust emissions, and lower fuel consumption. . . .
Advantages of Individual Port Electronic Fuel Injection
Greater flexibility of dry intake manifold design achieves higher inlet airflow and consistent cylinder-to-cylinder air/fuel distribution, resulting in more power and torque, and better drivabiility.
More efficient higher engine compression ratios are possible without detonation.
Extreme accuracy of fuel delivery by electronic injection at any rpm and load enables the engine to receive full air/fuel mixtures at every cylinder that fall within the tiny window of accuracy required to produce superior horsepower.
Computer-controlled air/fuel mixture accuracy enables all-out engines to safely operate much closer to the hairy edge.
EFI can easily be recalibrated or adapted to future engine modifications as a performance or racing vehicle evolves.
Electronic engine management with port fuel injection is fully compatible with forced induction, resisting detonation with programmable fuel enrichment and spark-timing retard and enabling huge power increases by providing the precisely correct air/fuel mixture at every cylinder.
EFI powerplants have no susceptibility to failure or performance degradations in situations of sudden and shifting gravitational and acceleration forces that might disturb the normal behavior of fuel in a carbureted fuel system.
Electronic injection automatically corrects for changes in altitude and ambient temperature for increased power and efficiency and reduced exhaust emissions. (9, 10)
After explaining how different A/F ratios are needed based on engine load and rpm, even during WOT runs, he summarizes:
The main difference between computer-controlled engines and earlier modes of control is that the computer's internal tables of speed and loading can have virtually any desired degree of granularity and can generate spark advance and fueling that are essentially unrealistic with mechanical systems.
Bottom line, computer-controlled engines eliminate compromises of mechanical fuel delivery and spark control. Multi-port injection eliminates problems with handling wet mixtures in the intake manifold that are associated with carbs, resulting in improved cold running, improved throttle response under all conditions, and improved fuel economy without drivability problems. (22)
Or more of the same old crap, 'Engine Management, Advanced Tuning', Greg Banish (CarTech Books).
The biggest compromise here [carburetors] is that, other than at idle where the mixture screws have enough authority to change things, we are locked to one flow ratio of air to fuel for the primary circuit and one ratio for the secondary circuit, if so equipped. This means tuning a carburetor often boils down to a compromise of desired air/fuel ratios between cruise, light throttle, and wide open throttle. With crude adjustments at best to control transition and no real way to adjust for nonlinear performance across a wide RPM range, there is room for improvement. Additionally, since actual fuel flow is proportional to air velocity in the venturi rather than actual air mass flow, air/fuel ratios can change slightly with changes in ambient conditions. The term 'good enough' works for many racers, but leaves a lot to be desired on a daily driven car expecting good economy and emissions. (19-20)
Apparently there are at least a couple of mind-bogglingly ignorant automotive engineers who are repeating the same old crap.
Knowledgable racers and hot rodders soon discovered that well-tuned modern programmable EFI systems almost always produce significantly higher horsepower and torque than the same powerplant with carbureted fuel management, especially when the engine is supercharged or turbocharged. This increased performance is in addition to improved drivability, cleaner exhaust emissions, and lower fuel consumption. . . .
Advantages of Individual Port Electronic Fuel Injection
Greater flexibility of dry intake manifold design achieves higher inlet airflow and consistent cylinder-to-cylinder air/fuel distribution, resulting in more power and torque, and better drivabiility.
More efficient higher engine compression ratios are possible without detonation.
Extreme accuracy of fuel delivery by electronic injection at any rpm and load enables the engine to receive full air/fuel mixtures at every cylinder that fall within the tiny window of accuracy required to produce superior horsepower.
Computer-controlled air/fuel mixture accuracy enables all-out engines to safely operate much closer to the hairy edge.
EFI can easily be recalibrated or adapted to future engine modifications as a performance or racing vehicle evolves.
Electronic engine management with port fuel injection is fully compatible with forced induction, resisting detonation with programmable fuel enrichment and spark-timing retard and enabling huge power increases by providing the precisely correct air/fuel mixture at every cylinder.
EFI powerplants have no susceptibility to failure or performance degradations in situations of sudden and shifting gravitational and acceleration forces that might disturb the normal behavior of fuel in a carbureted fuel system.
Electronic injection automatically corrects for changes in altitude and ambient temperature for increased power and efficiency and reduced exhaust emissions. (9, 10)
After explaining how different A/F ratios are needed based on engine load and rpm, even during WOT runs, he summarizes:
The main difference between computer-controlled engines and earlier modes of control is that the computer's internal tables of speed and loading can have virtually any desired degree of granularity and can generate spark advance and fueling that are essentially unrealistic with mechanical systems.
Bottom line, computer-controlled engines eliminate compromises of mechanical fuel delivery and spark control. Multi-port injection eliminates problems with handling wet mixtures in the intake manifold that are associated with carbs, resulting in improved cold running, improved throttle response under all conditions, and improved fuel economy without drivability problems. (22)
Or more of the same old crap, 'Engine Management, Advanced Tuning', Greg Banish (CarTech Books).
The biggest compromise here [carburetors] is that, other than at idle where the mixture screws have enough authority to change things, we are locked to one flow ratio of air to fuel for the primary circuit and one ratio for the secondary circuit, if so equipped. This means tuning a carburetor often boils down to a compromise of desired air/fuel ratios between cruise, light throttle, and wide open throttle. With crude adjustments at best to control transition and no real way to adjust for nonlinear performance across a wide RPM range, there is room for improvement. Additionally, since actual fuel flow is proportional to air velocity in the venturi rather than actual air mass flow, air/fuel ratios can change slightly with changes in ambient conditions. The term 'good enough' works for many racers, but leaves a lot to be desired on a daily driven car expecting good economy and emissions. (19-20)
Apparently there are at least a couple of mind-bogglingly ignorant automotive engineers who are repeating the same old crap.
Thread Starter
2nd Gear Member
Joined: Jan 2011
Posts: 341
From: NC
Ok, so you can quote someone in a book who makes a series of generalized statements, but has no scientific data or explanation to back it up. Saying that EFI has better control over fuel curves is 1 thing, but saying HOW it does that is another thing entirely. And that makes his statements true because why? Even engineers are wrong, and arguably they are wrong much of the time and can't allow their egos to let them admit that they're wrong. I work in the engineering field with engineers, who sometimes are wrong more often than they're right. Designers(who are mostly not engineers) are the ones who do much of the actual designing, because what the engineer tells them to design while great on paper, doesn't always work in the real world.
Automotive engineers are arguably some of the worst in that regard. How many decades were they ignoring performance engine builders and producing engines that generated terrible power levels and got terrible mileage in order to clean up emissions? Only to, decades later, build production engines like high performance engines(the way performance engine builders told them to in the first place), and lo and behold the power and mileage got way better, and they produced low emissions.
You have to be careful when you listen to engineers sometimes, since "dumb engineer" jokes aren't necessarily without warrant. Many of them spend more time in a lab or an office than they do actually building and testing. It's one thing to believe something is true because you read it in a textbook, it's another to actually go out and test those theories and find out what works and what doesn't. And in that regard, in high end racing applications that have different induction systems tested(carb vs EFI), the carb setups make better power more often than the EFI setups. Based on that data alone there's obviously something going on that's causing carbs to make more power.
While some of what was stated is accurate, such as manifold distribution and dry flow manifold design(which has advantages and disadvantages), some of it is outright wrong. Carbureted engines have been proven to be FAR more detonation resistant than EFI engines, for the reasons I stated in my previous post. Wet flow manifolds plus the Joule-Thomson effect, combined with better fuel distribution, means carbureted engines are far less likely to detonate under the same conditions, tune and on the same engine.
Some of what he states is just plain not accurate. Like I stated, the emulsion system in a carburetor is there to account for changes in load and rpm to deliver the proper amount of fuel. Air and fuel both flow through the system, air is less dense and more reactive than fuel in that circuit. But properly sizing and locating the emulsion, jetting and air bleeds, along with venturi size and booster design, you can develop a carburetor that delivers the proper AFR over the entire range of load and rpm.
Carbs can be run with blowers just fine, and actually run FAR better with blowers than EFI, again because of the wet flow manifold design. Blower carbs are properly calibrated to account for the additional air flow, and because the fuel in the manifold absorbs heat energy, it acts like an evaporative cooler(because it is). In fact, blow-through carb blower engines can on the same engine and with the same fuel octane, run similar boost pressures WITHOUT an intercooler, than the same engine with EFI can run WITH an intercooler. The fuel flowing through the manifold alone generates a similar adiabatic efficiency for cooling the incoming charge that an air-water intercooler can. And carb'd blower engines with intercoolers can run ungodly amounts of boost on pump fuel. If you don't believe me, go read on ProCharger's site, they list the boost pressure vs compression ratio you can run for a given octane. And they clearly state carb'd engines being able to safely run HIGHER boost levels WITHOUT intercooling that EFI can WITH intercooling. http://www.procharger.com/faq.shtml#5 But hey, they only build superchargers used on some of the fastest blower cars on the planet, so what do they know.
Of course, properly setting up a carb'd blower engine is another matter entirely, and is much less forgiving.
As far as fuel slosh affecting carburetors, that depends on how the carb is set up. There are floats and baffles available for carbs to account for g forces under high loading conditions. So that's not an issue.
And this.....
"The biggest compromise here [carburetors] is that, other than at idle where the mixture screws have enough authority to change things, we are locked to one flow ratio of air to fuel for the primary circuit and one ratio for the secondary circuit, if so equipped. This means tuning a carburetor often boils down to a compromise of desired air/fuel ratios between cruise, light throttle, and wide open throttle. With crude adjustments at best to control transition and no real way to adjust for nonlinear performance across a wide RPM range, there is room for improvement. Additionally, since actual fuel flow is proportional to air velocity in the venturi rather than actual air mass flow, air/fuel ratios can change slightly with changes in ambient conditions. The term 'good enough' works for many racers, but leaves a lot to be desired on a daily driven car expecting good economy and emissions. (19-20)"
...and this statement....it makes me want to slap my forehead with an anvil. Does this guy know anything about how a carburetor works or how airflow affects fuel flow AT ALL?
First of all, fuel flow is NOT proportional to air flow in the venturi, that's why carburetors HAVE air bleeds and emulsion(invented by Stromberg a century ago), because fuel flow is ENTIRELY non linear and non proportional. Fuel flow is actually EXPONENTIAL to air flow, in other words as air flow through the venturi increases linearly, fuel flow increases EXPONENTIALLY, NOT proportionally. The purpose of the air bleeds an emulsion, is in working with main fuel well levels, to introduce air into the main fuel supply to lean out the fuel mix under increasing air flows as well as to reduce booster signal to prevent over fueling under increasing air flow. THAT'S the real guts inside a carburetor. The combination of jetting, main well sizing, fuel level, emulsion size and placement, air bleed sizing, venturi sizing and booster design and placement, all work together to ensure proper fuel flow for the given level or air flow across all ranges of rpm, load and throttle.
Now, since carb's do respond to air flow VELOCITY and not necessarily mass, yes, AFR can change some with differing atmospheric conditions. But not as much as people think. That air flow generates pressure in the booster....atmospheric pressure on the fuel in the bowl and on the air bleeds pushes fuel through the main circuit and air through the emulsion circuit. So a carb is really just responding to changes in PRESSURE and not necessarily air flow velocity(which generates that pressure). The nature of the emulsion system and boosters will determine how much the carb is effected by changing atmospheric conditions. But again, remember that engines don't really respond to fueling changes of as much as 3-5%....so while the AFR may change somewhat, it's unlikely to be enough to matter.
My setup generally changes by about 0.5 AFR at most across 4,000ft of elevation change. So if I'm 12.5:1 at WOT and 6k rpm at high altitude, at ~ sea level it's 13:1. It's unlikely there's more than 1% power gains to be had by recalibrating. On a competitive race car it can matter, so you'd want to rejet, but on a street car it doesn't.
EFI has it's advantages and disadvantages. Carburetion has it's advantages and disadvantages. But most of what people believe about both is the same old information that people have been accepting as gospel truth for decades. So what if it's in a book by some guy? So what if that's what "all the engineers" say.
Remember too that the greatest scientific minds of the world all agreed for centuries that the world was flat, the sun revolved around the Earth, and big rocks fell faster than small rocks. Everyone believed it to be true, everyone KNEW it to be true. And anyone who disagreed with them was laughed at and called crazy. But it turns out those crazy guys were correct. Because they did something that everyone else didn't....they actually went out and TESTED those theories. They gathered data and looked at the evidence.
Automotive engineers are arguably some of the worst in that regard. How many decades were they ignoring performance engine builders and producing engines that generated terrible power levels and got terrible mileage in order to clean up emissions? Only to, decades later, build production engines like high performance engines(the way performance engine builders told them to in the first place), and lo and behold the power and mileage got way better, and they produced low emissions.
You have to be careful when you listen to engineers sometimes, since "dumb engineer" jokes aren't necessarily without warrant. Many of them spend more time in a lab or an office than they do actually building and testing. It's one thing to believe something is true because you read it in a textbook, it's another to actually go out and test those theories and find out what works and what doesn't. And in that regard, in high end racing applications that have different induction systems tested(carb vs EFI), the carb setups make better power more often than the EFI setups. Based on that data alone there's obviously something going on that's causing carbs to make more power.
While some of what was stated is accurate, such as manifold distribution and dry flow manifold design(which has advantages and disadvantages), some of it is outright wrong. Carbureted engines have been proven to be FAR more detonation resistant than EFI engines, for the reasons I stated in my previous post. Wet flow manifolds plus the Joule-Thomson effect, combined with better fuel distribution, means carbureted engines are far less likely to detonate under the same conditions, tune and on the same engine.
Some of what he states is just plain not accurate. Like I stated, the emulsion system in a carburetor is there to account for changes in load and rpm to deliver the proper amount of fuel. Air and fuel both flow through the system, air is less dense and more reactive than fuel in that circuit. But properly sizing and locating the emulsion, jetting and air bleeds, along with venturi size and booster design, you can develop a carburetor that delivers the proper AFR over the entire range of load and rpm.
Carbs can be run with blowers just fine, and actually run FAR better with blowers than EFI, again because of the wet flow manifold design. Blower carbs are properly calibrated to account for the additional air flow, and because the fuel in the manifold absorbs heat energy, it acts like an evaporative cooler(because it is). In fact, blow-through carb blower engines can on the same engine and with the same fuel octane, run similar boost pressures WITHOUT an intercooler, than the same engine with EFI can run WITH an intercooler. The fuel flowing through the manifold alone generates a similar adiabatic efficiency for cooling the incoming charge that an air-water intercooler can. And carb'd blower engines with intercoolers can run ungodly amounts of boost on pump fuel. If you don't believe me, go read on ProCharger's site, they list the boost pressure vs compression ratio you can run for a given octane. And they clearly state carb'd engines being able to safely run HIGHER boost levels WITHOUT intercooling that EFI can WITH intercooling. http://www.procharger.com/faq.shtml#5 But hey, they only build superchargers used on some of the fastest blower cars on the planet, so what do they know.
Of course, properly setting up a carb'd blower engine is another matter entirely, and is much less forgiving.
As far as fuel slosh affecting carburetors, that depends on how the carb is set up. There are floats and baffles available for carbs to account for g forces under high loading conditions. So that's not an issue.
And this.....
"The biggest compromise here [carburetors] is that, other than at idle where the mixture screws have enough authority to change things, we are locked to one flow ratio of air to fuel for the primary circuit and one ratio for the secondary circuit, if so equipped. This means tuning a carburetor often boils down to a compromise of desired air/fuel ratios between cruise, light throttle, and wide open throttle. With crude adjustments at best to control transition and no real way to adjust for nonlinear performance across a wide RPM range, there is room for improvement. Additionally, since actual fuel flow is proportional to air velocity in the venturi rather than actual air mass flow, air/fuel ratios can change slightly with changes in ambient conditions. The term 'good enough' works for many racers, but leaves a lot to be desired on a daily driven car expecting good economy and emissions. (19-20)"
...and this statement....it makes me want to slap my forehead with an anvil. Does this guy know anything about how a carburetor works or how airflow affects fuel flow AT ALL?
First of all, fuel flow is NOT proportional to air flow in the venturi, that's why carburetors HAVE air bleeds and emulsion(invented by Stromberg a century ago), because fuel flow is ENTIRELY non linear and non proportional. Fuel flow is actually EXPONENTIAL to air flow, in other words as air flow through the venturi increases linearly, fuel flow increases EXPONENTIALLY, NOT proportionally. The purpose of the air bleeds an emulsion, is in working with main fuel well levels, to introduce air into the main fuel supply to lean out the fuel mix under increasing air flows as well as to reduce booster signal to prevent over fueling under increasing air flow. THAT'S the real guts inside a carburetor. The combination of jetting, main well sizing, fuel level, emulsion size and placement, air bleed sizing, venturi sizing and booster design and placement, all work together to ensure proper fuel flow for the given level or air flow across all ranges of rpm, load and throttle.
Now, since carb's do respond to air flow VELOCITY and not necessarily mass, yes, AFR can change some with differing atmospheric conditions. But not as much as people think. That air flow generates pressure in the booster....atmospheric pressure on the fuel in the bowl and on the air bleeds pushes fuel through the main circuit and air through the emulsion circuit. So a carb is really just responding to changes in PRESSURE and not necessarily air flow velocity(which generates that pressure). The nature of the emulsion system and boosters will determine how much the carb is effected by changing atmospheric conditions. But again, remember that engines don't really respond to fueling changes of as much as 3-5%....so while the AFR may change somewhat, it's unlikely to be enough to matter.
My setup generally changes by about 0.5 AFR at most across 4,000ft of elevation change. So if I'm 12.5:1 at WOT and 6k rpm at high altitude, at ~ sea level it's 13:1. It's unlikely there's more than 1% power gains to be had by recalibrating. On a competitive race car it can matter, so you'd want to rejet, but on a street car it doesn't.
EFI has it's advantages and disadvantages. Carburetion has it's advantages and disadvantages. But most of what people believe about both is the same old information that people have been accepting as gospel truth for decades. So what if it's in a book by some guy? So what if that's what "all the engineers" say.
Remember too that the greatest scientific minds of the world all agreed for centuries that the world was flat, the sun revolved around the Earth, and big rocks fell faster than small rocks. Everyone believed it to be true, everyone KNEW it to be true. And anyone who disagreed with them was laughed at and called crazy. But it turns out those crazy guys were correct. Because they did something that everyone else didn't....they actually went out and TESTED those theories. They gathered data and looked at the evidence.
Thread Starter
2nd Gear Member
Joined: Jan 2011
Posts: 341
From: NC
In reading your stats, you are injected but your words to me support a carb application. What am I missing? Thanks.
Thread Starter
2nd Gear Member
Joined: Jan 2011
Posts: 341
From: NC
This thread amuses me
67m302, one thing I think you're discounting when talking about carbs is the level of carb most people are using. Most people pick up a base level Edelbrock or Holley carb, tweak it a little, and leave it at that. No annular boosters, no adjustable air bleeds, just a basic carb in basic form. Yes, everything you've done with your carb makes it superior to EFI in most regards, but that's far more than most people running carbs are going to go through. It requires lots of time, knowledge, and money. Conversely, I can go yank the mass-air EFI system off a fox body and make a working fuel injection system for well under $500. And unlike a carb, it won't require any tuning. Fire it up, let it 'learn' for a bit, and you're good to go.
Personally, I'd love to have your carb. But lacking that, a cheap 5.0 mass-air fuel system is a perfectly acceptable substitute, IMO.
67m302, one thing I think you're discounting when talking about carbs is the level of carb most people are using. Most people pick up a base level Edelbrock or Holley carb, tweak it a little, and leave it at that. No annular boosters, no adjustable air bleeds, just a basic carb in basic form. Yes, everything you've done with your carb makes it superior to EFI in most regards, but that's far more than most people running carbs are going to go through. It requires lots of time, knowledge, and money. Conversely, I can go yank the mass-air EFI system off a fox body and make a working fuel injection system for well under $500. And unlike a carb, it won't require any tuning. Fire it up, let it 'learn' for a bit, and you're good to go.
Personally, I'd love to have your carb. But lacking that, a cheap 5.0 mass-air fuel system is a perfectly acceptable substitute, IMO.
Thread Starter
2nd Gear Member
Joined: Jan 2011
Posts: 341
From: NC
Many factory EFI systems are calibrated for emissions more than power. Especially when you throw in cam, heads, intake etc. They still need to be tuned. EFI systems can generally be easier to tune than carbs, it can be done in a day. To have that level of tuning in a carb you need a carb that can be tuned to that level in the first place. Webers(IDF, IDA, DCOE, EMPI), or a Holley type with adjustable emulsion. And you have to really know what you're doing.
The new systems that use adaptive learning algorithms are even better. It's told what the target AFR should be, and as you drive the system senses AFR based on O2 readings and recalibrates the base maps to correspond to the target AFR. Provided the O2 is functioning correctly and is accurate, it makes tuning extremely easy. That's how FAST's new EZ-EFI works.
Yanking a junk yard swap factory EFI system can actually be a quick and easy way to get running. You can get junk yard pickings for cheaper than a good carb setup in some areas, get it tuned and you're good to go. Some base Holley carbs are reasonably close for most applications, and with a bit of jetting, or on the HP series some air bleed changing, for even less money you can get moving just as well.
It really comes down to how much you're willing to spend and what level of tuning you're looking to get involved with. If you're spending $400 and slapping a basic Holley on a car, don't plan on competing with something like FASTs XFI. If you're slapping a stock 80-90's EFI system on a car, don't plan on competing with someone running a Pro Systems carb.
Like I said, it comes down to the level of tuning you want to get into. But this "EFI outperforms carb" nonsense, is just that, nonsense. Case in point, compare my times in my pushrod carb'd 5.0 to the new 2011 Mustang GT with the DOHC 5.0. The few 2011's running at the track I've run at post similar times for stock GT's, but in September when it's 50* outside. I ran when it was 85* outside. The new EFI variable valve timing 2011's run basement 13's at ~109mph at that track with a DA of around sea level. When I ran with a DA of ~2,500' I went 13.20's at 107. DA correct the times to account for whether and that puts my carb'd 5.0 at least as fast, or slightly faster than the new 2011 GT(my times correct to 12.80's at 110mph, for whatever that's worth).
And then consider, that while the new 2011 is about 300-400lbs heavier, I'm also running with a non variable valve timing, pushrod head engine with less gearing. The 2011 has more gearing, a bitchin 4v head, and independently variable camshaft timing. And that was BEFORE my exhaust/cam swap and more advanced tuning system. So clearly I'm not being power limited by having a carburetor.
The new systems that use adaptive learning algorithms are even better. It's told what the target AFR should be, and as you drive the system senses AFR based on O2 readings and recalibrates the base maps to correspond to the target AFR. Provided the O2 is functioning correctly and is accurate, it makes tuning extremely easy. That's how FAST's new EZ-EFI works.
Yanking a junk yard swap factory EFI system can actually be a quick and easy way to get running. You can get junk yard pickings for cheaper than a good carb setup in some areas, get it tuned and you're good to go. Some base Holley carbs are reasonably close for most applications, and with a bit of jetting, or on the HP series some air bleed changing, for even less money you can get moving just as well.
It really comes down to how much you're willing to spend and what level of tuning you're looking to get involved with. If you're spending $400 and slapping a basic Holley on a car, don't plan on competing with something like FASTs XFI. If you're slapping a stock 80-90's EFI system on a car, don't plan on competing with someone running a Pro Systems carb.
Like I said, it comes down to the level of tuning you want to get into. But this "EFI outperforms carb" nonsense, is just that, nonsense. Case in point, compare my times in my pushrod carb'd 5.0 to the new 2011 Mustang GT with the DOHC 5.0. The few 2011's running at the track I've run at post similar times for stock GT's, but in September when it's 50* outside. I ran when it was 85* outside. The new EFI variable valve timing 2011's run basement 13's at ~109mph at that track with a DA of around sea level. When I ran with a DA of ~2,500' I went 13.20's at 107. DA correct the times to account for whether and that puts my carb'd 5.0 at least as fast, or slightly faster than the new 2011 GT(my times correct to 12.80's at 110mph, for whatever that's worth).
And then consider, that while the new 2011 is about 300-400lbs heavier, I'm also running with a non variable valve timing, pushrod head engine with less gearing. The 2011 has more gearing, a bitchin 4v head, and independently variable camshaft timing. And that was BEFORE my exhaust/cam swap and more advanced tuning system. So clearly I'm not being power limited by having a carburetor.
4th Gear Member
Joined: Feb 2006
Posts: 1,538
From: So. Cal,the O.C.
I now have the Powerjection III fuel injection. I can tune it within 20 minutes of driving.I can make changes with my laptop if i feel it needs more or less fuel.With the new ECM they are releasing, you can also adjust the timing.It self learns and self adjust.It starts on the first turn of the key WITHOUT touching the gas at all. I bellive it is total crap that carb will do the same in ANY weather condition or altitude.I dont belive it, i have never seen it.I worked for Ford for about 10 years as well as worked for Ford Dearborn so I have been around long enough to not be talking out of my a$$ and have experience in what i say, not what I read or heard.