Pitching the EFI!

Unit 5302 · 04-26-2001, 07:17 PM

Hmmm... I'm looking at my car the way it sits.

87GT K&N panel, BBK 2.5" hiflow cats, 2.5" catback.

If it was in tune I could probably pull a 13.90@102 out of it with the 2.73's. If I slapped the right suspension setup and 4.10's or 4.55's on it, I'd be in the high 12's@104. This is with 145k miles on the block. Now that's all fine and dandy, but I don't want a racecar. I want a street car that I can have fun in the corners with, and get the best fuel economy with. Honestly dropping my gears to a 3.27 or 3.55 would probably do that in town, but it would hurt a little on the road.

Why carbs are inferior. Like my discussion noted with juiceman the carb cars form fuel droplets (in the intake) which decrease the overall efficiency of the intake air/fuel mixture. Droplets don't burn for **** and you wind up richening the mixture (so you don't burn lean) and blowing raw fuel out the exhaust. The only benefit to the raw fuel is cooling in the cylinder. This is where you lose fuel economy too by the way. Where you lose torque is the shorter runner intake. Due to opening intake valves single plane manifold cars get beaten down in a bad way. The disturbance at low rpms is significant enough to hamper air fuel mixture flow into the cylinder. They make more power up top because there is less restriction. Dual plane manifolds make better on the low end than single plane manifolds because they allow some extra distance from the intake valve which makes for smoother airflow at lower rpms; however, that limits the maximum potential of the manifold for high rpm usage by restrictions in the direct airpath into the engine. Due to the inability to tune a car to perfection (without running lean) you are going to lose all out power. You just can't get it to atomize perfect, which is also why if you look at a dyno sheet EFI vs carb straight up, the carb dyno will be wavy, where EFI will be smooth as a baby's bottom.

EFI manifolds feature long straight runners that optimize low end and midrange power. They are very resistant to turbulence created by the valves which enables them to smoothly flow air into the cylinders even at low rpms. Throttle response is much slower than carb due to the distance of the T/B from the heads. It has absolutely nothing to do with the computer, which is just as fast as the carbs manual throttle linkage in measureable input anyway. Under high rpms the manifolds begin to show more weakness, mostly because of the restriction the upper manifold creates in efficiently flowing air into the lower. Mustangbelle306 has experianced first hand what happens when you slap an unrestrictive plenum onto the EFI setup. You lose lot's of low end, and you gain on the top end. Basically the large opening hiflowing Cartech intake plenum makes the EFI lower into the equivelent of a single plane carb manifold.

Onto the actual performance of the venturi operated low pressure atomization of fuel with the carb to the forced atomization of the fuel injected car. EFI is superior to carbs when it comes to the perfect atomization in terms of airfuel ratio due to it's controlled environment. The carb, while good at initially atomizing the fuel, as was noted by juiceman himself, the intake manifolds tend to cause droplets to form with the fuel vapor forms on the ridges and imperfections. Since EFI injects the fuel just above the intake port on the head, this effect is minimized allowing for more accurate air/fuel ratio tuning. This is where you pick up your fuel economy and pass emissions folks.

How many times have you heard all the emissions **** hampers EFI? BS all over the place. The airpump has been around since the 1960's, my Uncle's 1969 Mach 1 428CJ has one. The O2 sensors input along will the rest of the input from emissions related components get ignored during wide open throttle acceleration on SEFI cars. Instead the computer defaults to a more aggressive performance database. That's what's called "Open Loop". The EFI cars also remain in open loop until the vehicle warms up. Ever wonder just how rich open loop is??? It's the equivelent of a sticking electric choke on a carb. Welcome to Mileage Reductionville. Ford intentionally made open loop run rich, especially on SD cars so that Joe Schmoe wouldn't be bringing his car back with a burned piston 35,999 miles after purchase. They made it run on the safe side of things. One of the major problems with the 5.0 Cobra computer is it's lack of speed switching to open loop running. Under WOT acceleration the Cobra computer remains in "closed loop" for a full 7 seconds before going into the performance oriented *laughs* (not really since the Cobra's computer takes out a shitload of timing and has sick *** fuel and timing curves) open loop cycle.

As far as reliablility. Any one saying a carb is as reliable as EFI needs to go back to the padded room. Why in the hell do you think people love EFI over carbs? Cause the ******* things start in the winter without pumping the gas pedal, even if you don't know how to tune them. For proper operation carbs MUST be tuned. Not everybody takes a course on how to properly tune carbs before they get their cars! I've personally seen EFI cars with 100,000mi on them and stock <insert explicative describing the people who do this> spark plugs!!! Vacuum leaks, cracked vacuum lines, necessary tuning, burned out electric chokes, inaccurate manual chokes, and overall irritability hurt carbed cars in reliability. When an EFI car has a problem, it usually ignores or compenstates for the lack of input data.

Unit 5302 on the conclusion. EFI car's that use the long runner type intake plenum suffer from intake restriction on the top, and single plane style intake lowers. Increasing the upper hurts low end, increasing the lower doesn't help top end (much). The properly tuned and matched upper/lower combo throw's a lot of that problem out the window, though. Carbs suffer from lack of low end torque, period. They can suffer from lack of upper end performance, but not to the significance of an EFI car with the plenum style intake. Due to the lack of accuracy in the fuel metering (no amount of tuning can perfect it), carbs lack optimal average hp and trade it for maximum peak hp. They do not dyno smoothly like the proper functioning EFI car will, and they lose average hp/torque performance because of it. As far as low end, the EFI has no near rivals, even the dual plane manifolds. True, you can eliminate bog with tuning, but even the best tune cannot compensate for the lack of low end grunt. The car won't BOG, it just lacks low end, as rpms increase the power output should be smooth with no lag time in power production. Obviously in a drag scenerio, you shouldn't ever be running at 2000 or 3000 rpms (you should have the tires and suspension to allow for only peak power running), which throws the carb's lack of low end out the window. On the street from a stop or slow roll EFI will exceed the carbs performance off the line considerably. The way EFI is tuned increases drivability significantly, it's smooth, predictable, and it's got excellent low end/mid range power production.

EFI when tuned WILL beat a carbed car hands down, (it requires a completely new computer calibration.) It WILL be a better street performer. It WILL provide significantly better fuel economy, especially due to the low end power's ability to run well with taller rear gears. It WILL be more reliable for the average person. It WON'T cost much more than a carb to get good street performance out of.

Carb when tuned WILL outpower an EFI car for absolute peak hp production. It WON'T be as streetable. It WON'T equal the economy of the EFI car, and it WON'T be as reliable.

As far as getting a carbed car to outperform the same EFI car with heads and a cam, you're outta your frickin mind. You obviously know less about how EFI works than I do about your carb.

Or are you saying you keep a bag of Juiceman's Magic Carb Powder in your shop. "Just sprinkle a little bit on the top of your carb and pick up 150hp!!!" If you do, that's great, I'm betting there are a few people who keep a bag of Magic EFI Whoop A$$ on their shelves. "Just get a little into your schrader valve and pick up 150hp!!!"

04-26-2001, 07:17 PM	#21
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Hmmm... I'm looking at my car the way it sits. 87GT K&N panel, BBK 2.5" hiflow cats, 2.5" catback. If it was in tune I could probably pull a 13.90@102 out of it with the 2.73's. If I slapped the right suspension setup and 4.10's or 4.55's on it, I'd be in the high 12's@104. This is with 145k miles on the block. Now that's all fine and dandy, but I don't want a racecar. I want a street car that I can have fun in the corners with, and get the best fuel economy with. Honestly dropping my gears to a 3.27 or 3.55 would probably do that in town, but it would hurt a little on the road. Why carbs are inferior. Like my discussion noted with juiceman the carb cars form fuel droplets (in the intake) which decrease the overall efficiency of the intake air/fuel mixture. Droplets don't burn for ** and you wind up richening the mixture (so you don't burn lean) and blowing raw fuel out the exhaust. The only benefit to the raw fuel is cooling in the cylinder. This is where you lose fuel economy too by the way. Where you lose torque is the shorter runner intake. Due to opening intake valves single plane manifold cars get beaten down in a bad way. The disturbance at low rpms is significant enough to hamper air fuel mixture flow into the cylinder. They make more power up top because there is less restriction. Dual plane manifolds make better on the low end than single plane manifolds because they allow some extra distance from the intake valve which makes for smoother airflow at lower rpms; however, that limits the maximum potential of the manifold for high rpm usage by restrictions in the direct airpath into the engine. Due to the inability to tune a car to perfection (without running lean) you are going to lose all out power. You just can't get it to atomize perfect, which is also why if you look at a dyno sheet EFI vs carb straight up, the carb dyno will be wavy, where EFI will be smooth as a baby's bottom. EFI manifolds feature long straight runners that optimize low end and midrange power. They are very resistant to turbulence created by the valves which enables them to smoothly flow air into the cylinders even at low rpms. Throttle response is much slower than carb due to the distance of the T/B from the heads. It has absolutely nothing to do with the computer, which is just as fast as the carbs manual throttle linkage in measureable input anyway. Under high rpms the manifolds begin to show more weakness, mostly because of the restriction the upper manifold creates in efficiently flowing air into the lower. Mustangbelle306 has experianced first hand what happens when you slap an unrestrictive plenum onto the EFI setup. You lose lot's of low end, and you gain on the top end. Basically the large opening hiflowing Cartech intake plenum makes the EFI lower into the equivelent of a single plane carb manifold. Onto the actual performance of the venturi operated low pressure atomization of fuel with the carb to the forced atomization of the fuel injected car. EFI is superior to carbs when it comes to the perfect atomization in terms of airfuel ratio due to it's controlled environment. The carb, while good at initially atomizing the fuel, as was noted by juiceman himself, the intake manifolds tend to cause droplets to form with the fuel vapor forms on the ridges and imperfections. Since EFI injects the fuel just above the intake port on the head, this effect is minimized allowing for more accurate air/fuel ratio tuning. This is where you pick up your fuel economy and pass emissions folks. How many times have you heard all the emissions ** hampers EFI? BS all over the place. The airpump has been around since the 1960's, my Uncle's 1969 Mach 1 428CJ has one. The O2 sensors input along will the rest of the input from emissions related components get ignored during wide open throttle acceleration on SEFI cars. Instead the computer defaults to a more aggressive performance database. That's what's called "Open Loop". The EFI cars also remain in open loop until the vehicle warms up. Ever wonder just how rich open loop is??? It's the equivelent of a sticking electric choke on a carb. Welcome to Mileage Reductionville. Ford intentionally made open loop run rich, especially on SD cars so that Joe Schmoe wouldn't be bringing his car back with a burned piston 35,999 miles after purchase. They made it run on the safe side of things. One of the major problems with the 5.0 Cobra computer is it's lack of speed switching to open loop running. Under WOT acceleration the Cobra computer remains in "closed loop" for a full 7 seconds before going into the performance oriented laughs (not really since the Cobra's computer takes out a shitload of timing and has sick * fuel and timing curves) open loop cycle. As far as reliablility. Any one saying a carb is as reliable as EFI needs to go back to the padded room. Why in the hell do you think people love EFI over carbs? Cause the *** things start in the winter without pumping the gas pedal, even if you don't know how to tune them. For proper operation carbs MUST be tuned. Not everybody takes a course on how to properly tune carbs before they get their cars! I've personally seen EFI cars with 100,000mi on them and stock <insert explicative describing the people who do this> spark plugs!!! Vacuum leaks, cracked vacuum lines, necessary tuning, burned out electric chokes, inaccurate manual chokes, and overall irritability hurt carbed cars in reliability. When an EFI car has a problem, it usually ignores or compenstates for the lack of input data. Unit 5302 on the conclusion. EFI car's that use the long runner type intake plenum suffer from intake restriction on the top, and single plane style intake lowers. Increasing the upper hurts low end, increasing the lower doesn't help top end (much). The properly tuned and matched upper/lower combo throw's a lot of that problem out the window, though. Carbs suffer from lack of low end torque, period. They can suffer from lack of upper end performance, but not to the significance of an EFI car with the plenum style intake. Due to the lack of accuracy in the fuel metering (no amount of tuning can perfect it), carbs lack optimal average hp and trade it for maximum peak hp. They do not dyno smoothly like the proper functioning EFI car will, and they lose average hp/torque performance because of it. As far as low end, the EFI has no near rivals, even the dual plane manifolds. True, you can eliminate bog with tuning, but even the best tune cannot compensate for the lack of low end grunt. The car won't BOG, it just lacks low end, as rpms increase the power output should be smooth with no lag time in power production. Obviously in a drag scenerio, you shouldn't ever be running at 2000 or 3000 rpms (you should have the tires and suspension to allow for only peak power running), which throws the carb's lack of low end out the window. On the street from a stop or slow roll EFI will exceed the carbs performance off the line considerably. The way EFI is tuned increases drivability significantly, it's smooth, predictable, and it's got excellent low end/mid range power production. EFI when tuned WILL beat a carbed car hands down, (it requires a completely new computer calibration.) It WILL be a better street performer. It WILL provide significantly better fuel economy, especially due to the low end power's ability to run well with taller rear gears. It WILL be more reliable for the average person. It WON'T cost much more than a carb to get good street performance out of. Carb when tuned WILL outpower an EFI car for absolute peak hp production. It WON'T be as streetable. It WON'T equal the economy of the EFI car, and it WON'T be as reliable. As far as getting a carbed car to outperform the same EFI car with heads and a cam, you're outta your frickin mind. You obviously know less about how EFI works than I do about your carb. Or are you saying you keep a bag of Juiceman's Magic Carb Powder in your shop. "Just sprinkle a little bit on the top of your carb and pick up 150hp!!!" If you do, that's great, I'm betting there are a few people who keep a bag of Magic EFI Whoop A$$** on their shelves. "Just get a little into your schrader valve and pick up 150hp!!!"