...for boosting
Now, before you jump up and down on me, let me explain myself. I was reading up on the various superchargers on the market right now, and in one FAQ they said something I hadn't thought about before.

"For carbureted motors, the rules are slightly different. Carburetors deliver the vast majority of fuel in a liquid state, and as this raw fuel atomizes from liquid to gas, a chemical state change actually occurs. Due to this endothermic reaction, which draws heat and cools the incoming air, a carbureted motor can safely handle more boost than a comparable EFI/TPI motor." ... all other things being equal.

It makes sense, liquid to gas eating up some heat thus lowering the intake temps. I am not pro carb or pro efi, I like both and will be using both, for different purposes. I just thought this was interesting. Thoughts?

are you suggesting fuel injectors spray a gas?

injectors actually spray a better pattern for atomization

No, but I would say that the injector sprays a better mist than a carb. If you have 10 small ice cubes vs 1 big ice cube, each totaling the same mass, the small ice cubes will melt quicker than the big one. I don't remember if it takes more heat/energy to melt one over the other, though.

It's procharger's faq, if anyone's interested.
http://www.procharger.com/faq.shtml

I get the point though.

The atomization of the gas in the carburetor happens in a cooler environment than the injector. Generally speaking, if you do your homework on intake manifold temperature and carb temps, you can keep your carburetor well below manifold temperatures. In fact, with a phenolic spacer I've recorded as low as 110* (usually closer to 130*) at the carb compared to 180* at the manifold immediately below.

It makes sense that the cooler mix could be compressed a little better. However, there are a whole lot more factors to consider.

I think it boils down to what other threads have concluded. Each system has its strengths and weaknesses.

Arn

You have touched on something I have already given some consideration to except in a fuel injection environment. It's no secret that PART of the reason GM has switched to a returnless fuel system is due to the heat added to the fuel when circulated through the warmer fuel rail and then returned to the tank eventually raising the over all temp of the fuel, and there is no reason whatsoever to excuse the power gains that can be had if the incoming fuel can be cooled enough to behave in the same manner that a water or alcohol injection system does except fuel would serve a dual purpose requiring only the additional effort to cause endothermic behavior when injected into the airstream. For example, what might be the results on performance if incoming fuel temperature was reduced 30 degrees or more than normal by passing it through and ice or better yet dry ice environment before it hits lets say an insulated fuel rail?

there are fuel coolers. inline, like a fuel filter. in fact, someone here has one.

The heat (energy) required to vaporize an ounce of liquid gasoline is the same regardless the size of the droplets, given the liquid temp is the same in both situations.

A higher air temp would vaporize it faster but the total heat absorbed (work done) by the vaporization of one ounce of liquid gasoline would still be the same as that of a lower air temp.

[This message has been edited by 30+mpg (edited 07-25-2006).]

I couldn't remember one way or the other. But what Arn says still holds true, the temp of the fuel is what seems to make the difference. If you start with higher temp fuel, less temp must be added to it for it to vaporize.

Fuel coolers sound interesting, especially for a boosted application, either in place of or enhancing a water/alcohol injection. Are they something like this? http://www.flex-a-lite.com/auto/html/compact-cooler.html

There are ice buckets with coils in them for greater cooling than the almost fuel radiator in the link. I was actually thinking of something more effective and efficient given that after the initial cooling the time it sits in the rail after leaving the cold bath gives it time to start to warm up again except at high flow rates in the WOT range, even at that point the fuel is still in the rail for quite a bit of time before actually reaching the injector nozzle given the number of pulses necessary to empty the full volume of the rail. I think I'll build my prototype, insulate the rail and test the theory on a dyno.

Time to pull out the old physics book and turn to the chapter on thermal energy. The numbers bring things into perspective much clearer than theory.

Actually, there may be a bigger factor involved.
if things haven;t changed, in a carb setup, the air is not forced thru the top, but sucked thru.. thus the fuel air mix is really swirled thru the turbo/sc then into the cylinders, giving a better vaporization.
in efi, the fuel air mix is only subjected to the boosted air for a short time before entering the cylinder, less chance to vaporize.

I would tend to think that the added turbulance and better vaporization are as big, if not bigger a factor.

quote Originally posted by tjm4fun: if things haven;t changed, in a carb setup, the air is not forced thru the top, but sucked thru.. thus the fuel air mix is really swirled thru the turbo/sc then into the cylinders, giving a better vaporization.

YIKES!!!
not sure about a SC, but this would destroy a turbo
normally, a blow thru carb is used in boost setups to avoid droplet damage to the compressors

quote Originally posted by Pyrthian: YIKES!!! not sure about a SC, but this would destroy a turbo normally, a blow thru carb is used in boost setups to avoid droplet damage to the compressors

Funny, The early 80's Pontiac turbo 301 V-8 Trans Am and Buick Turbo 3.8L Regal never had a problem.
They were not blow-thru, They were draw thru. The Regals used it for a number of years before the EFI version came out.

For more info on the T/A see here:
http://srasco.tripod.com/80ta/80ta.htm

Superchargers (roots type) do it all the time in a carb application.

[This message has been edited by Oreif (edited 07-26-2006).]

One point to remember. A carb atomizes gas and does not vapourize gas. The intake manifolds are left rough surfaced to ensure the air stays turbulent on the sides as it moves to the cylinder.

I don't think there is a particular advantage in terms of atomization for a carburetor. The injectors spray, and I think it can be argued, do a little better and more consistantly in atomizing the fuel. Better on cold starts perhaps.

What is different in N/A applications is that in the carb the vacuum pulls the fuel into the throat and the venturi shape causes atomization due to speed of flow. The cylinder therefore continues to provide suction (vacuum) and pulls the whole mix forward to the chamber. It has some time to continue to mix as it moves.

The fuel injector sprays fuel under pressure into the throat of the intake valve and the incoming air and fuel have only a milli-second to actually mix.

So, both systems have a limitation on mixing the fuel. The cylinders on some engines are actually designed to assist both systems to mix the fuel particles before compression.

It can be argued that the air/fuel mixture actually entering the valve chamber is going to be heated at point of entry no matter what you do. So sending a cooler mixture to the inferno can give a mixture which can expand more than a hotter mixture, both air an fuel.

There are lots of guys who have used both S/C and Turbo on both applications with success. Again, it is what you are more comfortable working with. HP outcomes are often very similar.

Arn

I wonder if any of the F.I. masters here on the forum are gonna call Procharger and tell them they're wrong.

quote Originally posted by Formula88: I wonder if any of the F.I. masters here on the forum are gonna call Procharger and tell them they're wrong.

well, the statement is not wrong. evaporation has a cooling effect. thats all thats being said. what that actually means, once the air reaches the intake valve is the big question

While I believe that it is possible to make the same PEAK horsepower with a carburetor, EFI provides adjustable fuel compensation for all manifold vacuum /pressure readings, engine temps, air temps, throttle position and RPM.s That's why EFI under the same conditions provides far better drivability and fuel economy. For a race car that is driven in a very limted RPM band only under WOT conditions, a carburetor is a sufficient fuel delivery device. However, on a street vehicle the carburetor is both an antiquated and obsolete fuel delivery system.

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quote Originally posted by Dennis LaGrua: However, on a street vehicle the carburetor is both an antiquated and obsolete fuel delivery system.

Dennis, with all due respect, have you ever driven a 1956,57,58,59 Cadillac or Oldsmobile? Or for that matter a similar era Chrysler or Buick? Those cars were immensly smooth and streetable in all kinds of weather. They were all carbureted with carbs that are now completely obsolete (but still work) due to developments and refinements by Holley, Edelbrock, and others.

I agree that when I hotrodded my 2.8 and had to set up the carb by the seat of my pants, it took a whole lot of experimentation that a guy of greater knowledge would have had it done much sooner. My 2.8 was not very smooth at all for quite a while. But if you take 2 engines set up by expert mechanics, (not me) one EFI and one Carb'd, you are going to find very similar drivability and power with the finished product.

This is a case of what system you prefer to play with, not the final HP, Torque and smoothness possible. Again, with respect.

Arn

dont start the old FI vs. Carb.
Carb WILL lose. while for a car guy, who knows what he's doing, either is fine. but for non-mechanical people, carb's are nothing but trouble. If I get a car for my Mom, its NOT gonna have a carb - it will be FI. I am fine either way - I LIKE to mess with my car. My Mom doesnt. Mom's like a car that starts easily everytime, year after year. just go put in gas. go get oil changed every so often. be happy. FI & DIS have made motors so dang reliable & maintance free. cars go 100k without a hicup. back in the carb days - 100k was a miracle.

draw thru on carb can at some time when used with a intercooler result in a huge fire
that was the main reason it is no longer used in main stream production.
imagine 4 tea spoons of fuel in an intercooler and a backfire under pressure.

pushing thru has its problems to huge leaks as a carb is not designed for that
sure the box them up and pray for no leaks but I have yet to see one not leak some.
jmho

As for cooling the fuel I like the idea of ice, but who wants to do this on an hourly basis
any idea on a no maint. way??

I could see running a coil of line by the AC but I am afraid of leaks and air comming in drivers compartment
I smoke so bang no me. talk about flamming

quote Originally posted by Pyrthian: dont start the old FI vs. Carb. Carb WILL lose. while for a car guy, who knows what he's doing, either is fine. but for non-mechanical people, carb's are nothing but trouble. If I get a car for my Mom, its NOT gonna have a carb - it will be FI. I am fine either way - I LIKE to mess with my car. My Mom doesnt. Mom's like a car that starts easily everytime, year after year. just go put in gas. go get oil changed every so often. be happy. FI & DIS have made motors so dang reliable & maintance free. cars go 100k without a hicup. back in the carb days - 100k was a miracle.

No arguement on your logic Pyrthian

Arn

Though I'm not that familure with EFI I do know that with older cars with carbs, if the car didnt start you only had to check for a few things. #1 is it getting gas....very easy to tell. #2 is it getting spark...equally easy to tell. I do know with EFI if it doesnt start or starts to have driveability problems it could be any number of 50 things. Sure efi, when running correctly is much more driveable in different conditions but I dont think many of us drive from hot/humid weather to cold "Pikes Peak" altitudes. So for a regular street car give me a carb. Bottom line is it is cheaper to set up a carbe'd car from scratch than a EFI. IMHO

quote Originally posted by Pyrthian: dont start the old FI vs. Carb. Carb WILL lose. while for a car guy, who knows what he's doing, either is fine. but for non-mechanical people, carb's are nothing but trouble. If I get a car for my Mom, its NOT gonna have a carb - it will be FI. I am fine either way - I LIKE to mess with my car. My Mom doesnt. Mom's like a car that starts easily everytime, year after year. just go put in gas. go get oil changed every so often. be happy. FI & DIS have made motors so dang reliable & maintance free. cars go 100k without a hicup. back in the carb days - 100k was a miracle.

True, for the non-automotive people, EFI would be a better choice as they require a lot less maintanence. But then again these people do not strive to keep their cars in peak performance as well. The regular production engines are all set up to provide low emissions, high gas mileage, and keep the engine running. They are not set up to maintain peak performance. All they care about is that it starts and gets them from point A to point B reliably. Nobody is disagreeing that EFI is great for mass produced vehicles for the daily driving public.But going 100K without a hiccup isn't a reality even with EFI. How many people here have had a sensor go bad or act up on an EFI engine with less than 100k miles on the odometer? Not even the Imports can hit 100k without any maintanence. I know many manufacturers say their vehicles can go 100k miles without problems, But read the fine print, It is only if you follow the maintanence schedule for the car. The computers in the EFI cars can adapt to many changes to keep the engine running and that includes poor maintanence as well. But they do sacrafice the peak performance of the engine to do it.


All I'm going to say is I built two 3.4L engines with using the same long block, one was carb'd the other was EFI and BOTH engines ran nearly identical in power (measured on a dyno) and driveability. It is true that the carb'd engine may require a little more maintanence over it's life but both engines should have no problems going 100k+ miles if they are properly maintained. Finally both engines were normally aspirated, dyno'd, and run on a drag strip. The turbo'd 3.4L has never been on a dyno or at the drag strip, but using the posted 0-60 time (Taken from a G -Tech reading.) there is only an estimated 20hp difference. (and I personally think the 3.4L turbo has less power than the 250hp estimate.)

Each fuel delivery system has it pro's and con's. I just think it's funny how some people think the carb is "obsolete and antiquated" but yet it is still a very profitable business. If it wasn't, Why are there so many companies still making them and spending R&D money to improve them? To think that technological advances for carb's stopped when EFI became popular is just ignorant. Just goes to show that some folks who don't understand something denounce it. (This goes both ways, those who don't understand a carb and those who don't understand EFI.)

[This message has been edited by Oreif (edited 07-26-2006).]

I knew that I was guessing there,, but the grand national, and other turbos; were all draw thru turbo's and lasted forever.

Aside from that, the carb vs fi thing is always a sore point among car people. I will say this, the 2.8 with 150k on it still had vague crosshatching visible on the cylinder walls, and my machinist says it is very common now to see that. the exact amount of gas leaves none left to wash the oil off the pistons/rings/walls, so you see the crosshatch. one plus there, and likely the reason for the lengevity differrence. as far as reliability and driveability, I still say a carb is the easiest. I have only once had an issue where the carb caused me a problem, and that was cause the float sank. on one car that had an electric fp for the carb in the tank, it went bad, I drove home 20 miles on the gallon of gas I put in the windshield washer and spliced the line to the carb line. hit the washer button every few minutes when the car started to bobble and continue on. when the fp died in my 86 fiero, I had to tow it home.
each as it's merits, and drawbacks, but as was pointed out, the carb is not for the non mechanics.
for me, I am happy either way. tweak the electronics, or turn a screw,change a metering rod, etc makes little differrence, as long as I'm happy with the end result that's all that matters.

I dont have it in front of me, but one of my Dodge books has a manufacturer that sells new crate Hemis (5.7, 6.1 ltr) in both configurations ready to run complete with required computers and wiring harnessess. Whether you go with FI or 4bbl carb, there dyno sheets show nearly identical horsepower and torque ratings. These are of course non boosted engines.

The manufacturers were certainly not gaga over fuel injection in the early '80s and went out of their way to not implement it. The fact was they could not meet the EPA certification requirement that a car remain below the max allowable emissions for 5 years or 50,000 miles with zero maintenance.

Notice I said maintenance, not repair.

If an emissions related device failed and the vehicle would not operate until it was repaired at any time/mileage - no problem. If you don't change the oil or any filters or a spark plug and the engine still operates it has to meet the emissions standards. Carbureted engines just couldn't meet that standard. My '83 Citation 2.8 even had a computer controlled carburetor that had solenoid operated metering rods in an attempt to meet the standards, but...

quote Originally posted by kwagner: ...for boosting Now, before you jump up and down on me, let me explain myself. I was reading up on the various superchargers on the market right now, and in one FAQ they said something I hadn't thought about before. "For carbureted motors, the rules are slightly different. Carburetors deliver the vast majority of fuel in a liquid state, and as this raw fuel atomizes from liquid to gas, a chemical state change actually occurs. Due to this endothermic reaction, which draws heat and cools the incoming air, a carbureted motor can safely handle more boost than a comparable EFI/TPI motor." ... all other things being equal. It makes sense, liquid to gas eating up some heat thus lowering the intake temps. I am not pro carb or pro efi, I like both and will be using both, for different purposes. I just thought this was interesting. Thoughts?

Both EFI and Carb engines are delivered fuel to the point of use as a liquid. The max temperature is going to be at about TDC on the compression stroke. At that point both the EFI and carb engines are going to have fully vaporized the fuel. Exactly where and how fast the vaporization takes place doesn't matter. If the air to fuel ratio is the same both engines will get the same drop in air-fuel mixture temperature. At 12:1 A/F ratio the cooling effect from vaporizing the fuel is about 35 'F.

I remember the carb days when you normally got a fall tuneup. That was normally an oil change, new points in the distributor (or filing them), new plugs and adjusting the timing and carb.

When the car acted up it was normally a bad battery or bad wires. It is absolutely true that the carbs needed adjustment BUT, you did not have an idiot light on your dash telling you to "check engine". You did not need an engine analyser to find an engine miss. You did not need to spend $200 to $500 to find a bad o2 sensor or a bad MAP or the like. You were not completely dealer mechanic dependant. Moreover, if the car died, it could likely be revived on the side of the road to get you home. I don't recall a whole lot of tow trucks. Nowadays, if you car dies, you have to get a tow, and you end up with shop time. Moreover there are many electronic ways for the engine to simply refuse to run. Ever try to trouble shoot a bad ECM on your own or to even know if it is bad?

Anyway, I don't dispute for one minute that the average woman driver needs the reliability of having something that does not need adjustment and that the dealer can service quickly for her.

What I dispute is that EFI is significantly better for guys like us. Again, if you want to use a laptop, buy analyser software and map out electronic data, fine, that is fun for some of us. (not me)

The original question was carb'ing for boosting. It works very well with less hassle. You don't have to re-program a computer you have a mechanical system to deal with only, not a mechanical and electronic system both.

I think I agree with the thread starter on this. (now I'll duck)

Arn

for guys like us, we know what the sensors do, and we know when they need replacing. just like carb, theres just a few simple thing to EFI. they are not some sort of voodoo or black magic, they are a few simple sensors - and you can run without most of the sensors for a limp home. yes, its true that something can go wrong, and leave the car useless - but they are few & far between.

to me, its like argueing over favorite color. I say green, and you will never convince me blue is better. when its all over - it makes no difference. I have been starnded by carbs cars & I have been stranded by EFI cars. and it aint always a not running motor that leaves ya stranded.....

yes, there is ALOT good about the simplicity of a carb. basic mechanical relationships are a great way to go. along with vacuum advance & manual trans. simple cables & pushrods. makes adjustments & temporary 'get her home repairs possible' with simple tools - again - if you know what you are doing.

and another thing - many failures associated with FI are not part of the FI. they may be electronic & computer controlled - and maybe even by the same computer. igition failure is ignition failure - not a FI failure. you can have DIS on a carb'ed car.

quote Originally posted by sanderson: Both EFI and Carb engines are delivered fuel to the point of use as a liquid. The max temperature is going to be at about TDC on the compression stroke. At that point both the EFI and carb engines are going to have fully vaporized the fuel. Exactly where and how fast the vaporization takes place doesn't matter. If the air to fuel ratio is the same both engines will get the same drop in air-fuel mixture temperature. At 12:1 A/F ratio the cooling effect from vaporizing the fuel is about 35 'F.

Actually, I think the "where" is the whole reason for the power difference. If you have port injection, what good does it do to cool the air once it's already in the cylinder? You can't add more air once the valve closes. The carb (and I think TBI would work in the same way) cools it in the manifold, on the way to the cylinders. Cooler air in manifold = denser air in manifold. Being a boosted application, where it multiplies the base power by some amount consistent with the increase in volumetric efficiency, you get more air in the cylinder. 12:1 vs 12.1:1 or 11.9:1 makes a difference when you start multiplying things. That's how I understand it to work, anyway. Also, according to the procharger graphs on their site, it becomes a moot point once a good intercooler is added, either system gets the same power.

quote Originally posted by kwagner: Actually, I think the "where" is the whole reason for the power difference. If you have port injection, what good does it do to cool the air once it's already in the cylinder? You can't add more air once the valve closes.

with fuel injection, the fuel is injected at the back of the CLOSED intake valve. as far as I know, only newer deisels inject directly into the cyl.

quote Originally posted by Arns85GT: When the car acted up it was normally a bad battery or bad wires. It is absolutely true that the carbs needed adjustment BUT, you did not have an idiot light on your dash telling you to "check engine". You did not need an engine analyser to find an engine miss. You did not need to spend $200 to $500 to find a bad o2 sensor or a bad MAP or the like. You were not completely dealer mechanic dependant. Moreover, if the car died, it could likely be revived on the side of the road to get you home. I don't recall a whole lot of tow trucks. Nowadays, if you car dies, you have to get a tow, and you end up with shop time. Moreover there are many electronic ways for the engine to simply refuse to run. Ever try to trouble shoot a bad ECM on your own or to even know if it is bad? Arn

True, true, true. But on the other hand my AutoXray that I bought for my 87 Ford E-150 (ODB-I) only needed an an upgrade to OBD-II to do my 97 Ford E-150 (just needed another upgrade to do my Fieros). And last January when the check engine light came on on the '97 I hooked it up and the code said I had a lean condition in two cylinders. That was easy enough to fix - a container of injector cleaner and a little Marvel Mystery Oil and poof the engine was happy again. So learning about that before the lean burn had a chance to do any damage was, to me, a good thing (should I tell you about the number of people that ignore the check engine light if the engine is still running OK - and I just saw an advertisement for a '98 E-150 with burned valves - and the mechanic says yeah a lot of them seem to have that problem).

And how do you know if the ECM goes bad? The engine just dies. Had it happen twice on my 89 TGP. Both times while driving down the freeway at 70MPH. But that wasn't as bad as the DIS. About every 2500 miles either one of the coils or the module would fail. And they were a royal, royal PITA to replace.

So they're getting better - at least in trucks where the customer base is not as passive as your general consumer. But I certainly do not like having to pay for the privilege of being their test subjects.

[This message has been edited by Fierari (edited 07-27-2006).]

I know this is going to open up another can of worms but, If you looking for more power would it not be better to have the incomming air as cool as possible. if so why not drop the water temp lower. Engine temp has nothing to do with combustion temps. so if the air is kept as cool as possible before it enters the chamber you'll have more "air" for combustion.....no?

quote Originally posted by PhatMax: I know this is going to open up another can of worms but, If you looking for more power would it not be better to have the incomming air as cool as possible. if so why not drop the water temp lower. Engine temp has nothing to do with combustion temps. so if the air is kept as cool as possible before it enters the chamber you'll have more "air" for combustion.....no?

yes, that the main idea behind lower temp thermostats & lower temp fan switches.

quote Originally posted by Pyrthian: with fuel injection, the fuel is injected at the back of the CLOSED intake valve. as far as I know, only newer deisels inject directly into the cyl.

You're right about the positioning of the injector, I was thinking more of the methods used for firing, from my limited knowledge. Batch fire, which fire all at the same time, and you will get some during open and some during closed for the intake valve. Sequential times it for right as the port opens (correct me if I'm wrong), for each cylinder, to get the maximum effect. It's also worth noting that at high rpms, the amount of time between the open and close is so small as to make both systems somewhat equal. This also means the fuel injected doesn't dwell outside of the cylinder for nearly as long (relatively) to travelling from the top of the intake and through like TBI or a carb. There's also all the nuances of reflecting air off the closed valve and what that means for fuel mixture and time fuel spends in the manifold, but I won't pretend I understand it all

The playing field is not exactly level, the majority of the cons for EFI can be programmed out for a more apples to apples analysis. If the FI system was narrowed down to the bare essentials of engine running a more accurate account could be given. An EFI engine goes into limp mode over a faulty sensor because it is programmed to do so not because it has to, it is conceivable that the fuel injection delivery can be made as simple as a variable pulse rate based on engine displacement and rpm alone in the same manner that centrifugal spark advance works. So maybe the sensor part of the cons for EFI should be eliminated and acknowledgement made over the influence of emissions on the sensors that are deployed but are not necessary for operation outside of that.

What it all boils down to is electric fuel delivery vs. mechanical "necessity is the mother of invention" who can argue with the fact that cars now days are grossly over sophisticated and loaded with lots of entirely unnecessary junk. Manufacturers could create a huge increase in mileage by eliminating the unnecessary gadgets.

Attention should be focused down stream on the results under each system comparatively for the exact same amount of fuel delivered by each, what do you get for a gallon of fuel delivered by FI vs. a gallon of fuel delivered by a carbuerator, everything else is just taxes.

quote Originally posted by kwagner: You're right about the positioning of the injector, I was thinking more of the methods used for firing, from my limited knowledge. Batch fire, which fire all at the same time, and you will get some during open and some during closed for the intake valve. Sequential times it for right as the port opens (correct me if I'm wrong), for each cylinder, to get the maximum effect. It's also worth noting that at high rpms, the amount of time between the open and close is so small as to make both systems somewhat equal. This also means the fuel injected doesn't dwell outside of the cylinder for nearly as long (relatively) to travelling from the top of the intake and through like TBI or a carb. There's also all the nuances of reflecting air off the closed valve and what that means for fuel mixture and time fuel spends in the manifold, but I won't pretend I understand it all

sequential injection fires the injector the same time it fires the spark plug, this gives time for the fuel to hit the back of the hot intake valve and vaporize.

As mentioned above there is also direct injection more common to desiels but making more of an appearence on gasoline engines now. Not many use it yet but it sprays fuel directly into the cylinder at a precise time to a high degree of accuracy giving better performance, gas miledge and emmissions. Its more expensive to produce however. The upcoming Turbo Solsitce GXP will have a direct injection EcoTech

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Fiero- mild 2.9 160hp
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--Adam--
IM AOL: FieroGT5speed

The biggest thing against FI is when it screws up your really screwed, usually means a tow somewhere to get it running

with a carb, any trouble and it can usually get you back home. Sometimes even a smack with a screwdriver handle will get you back running.

Both are great when they work as their supposed to. To me, its when they not working that you have the vast difference.

Hell, I cant even adjust my vettes TBI engine to idle a few hundred rpms faster.

[This message has been edited by rogergarrison (edited 07-27-2006).]

I own several older performance muscle cars with carburetors. If you measure the air fuel mix on these engines over the RPM range it is all over the place. Sure the power is there but the mileage and drivability don't come anywhere near EFI. . If one likes a carb that's OK with me, but I would not want to own another car with a carbureted engine ever again unles it's only for use on the drag strip. . A carburetor is old technology and illegal to use on vehicles later than about 1985 while EFI is far more efficient, self compensating and your engine life will increase with it. Most often relactance to use EFI comes from a lack of understanding of how it works and how it is tuned.

------------------
87GT 3.4 Turbo- 0-60 5.2 seconds -Best
Engine Controls, ECM goodies, Chip
re-programming & odd electronics stuff