Difference between 1.2i and 1.4 carb and sub questions!

[UsernameLadiesMan217]

Hey guys!

Is it true that fuel injected cars are faster than carb cars in general and more fuel efficient?
-Also is it true that you can't 'coast' in a fuel injected car to save gas?

Currently driving (but not owning!) a 1.2l Fiat Palio that's fuel injected.
The car is really slow, I don't mind it, because it is fuel efficient and I tend to drive the speed limit and surprisingly it can handle 120 on the N1 very well, or at least it seems to since I don't have that much driving experience and I do often see BMW's blazing past me like I'm standing still.

I'm not too sure if going 120 on the N1 is fuel efficient with such a small engine though, is it? (tbh I usually am in the far left lane though going 90-110 depending on what is needed of me).

However, since my 'next' first car I'll have to keep for probably a good 5 years or more, I would like something a little faster.

Let's say we compare this 1.2i to a 1.4 carb car from the 90's, would they pretty much be the same speed? I have heard that VW Golf's are very fuel inefficient for the size of their engines, so it would suck if I end up getting a 1.4 that's as slow as this 1.2i and has worse fuel consumption.

Also, what's up with old Golfs only having 4 gears? My 1.2i has 5 gears, but old 1.4 Golfs have 4 gears, how does that even work and does it have any significant effect on driving/fuel efficiency and power?

I'll ask more questions once I get more answers!

 

[Ancalagon]

According to this and this, the two cars are roughly equivalent in power, but the Citi Golf can accelerate to 100 quicker. However, the Fiat will without doubt be more fuel efficient than the 1.4 carb engine. Plus, being a more modern car, it will be far safer than the Citi Golf.

Well, generally, the higher you rev your car, the less fuel efficient it is. Lets say you could do 120 in third gear - you would use more fuel than you would in fifth gear, because your engine would need to rev higher to maintain the same speed. So, doing 120 in any car will use more fuel than doing 80, but that is mostly down to the energy required to keep the moving at that speed. It doesnt have much to do with asking too much from a 1.2 engine.

More gearbox gears enable finer control of your RPMs and can lead to better use of your engine. But it depends on the gear ratios offered.

 

[pezulu]

Small engines are designed for commuting, and in that role they do an admirable job. At city speeds (60km/h) they are fuel efficient.
My personal belief is that a 1.2 will be less fuel efficient than a 1.4, with all other factors being equal, particularly at highway speeds.
The engine has to work harder to get the vehicle up to speed, and also work harder to maintain that speed.

Older technology will be less fuel efficient than new technology. Just read the thread regarding the Opel Corsa 1.4.
The Corsa had an engine built in Brazil, and was based on 1980's technology. They are notoriously heavy on fuel. The Golf is the same.

Many older cars only had 4 gears. Gear ratios were longer than they are today, but still, they didn't do anything for fuel economy.
We had a 1980's Ford Cortina 3.0 bakkie, with 4 gears. They were very heavy on fuel.
One of the most common modifications that people did was to put in a 5 speed gearbox, as well as a more powerful fan.
The first four gear ratios were similar to the original box, with the 5th gear being much longer. This meant that the 5th gear acted almost like an overdrive. You would get up to speed using the first 4 gears, then put it in 5th when cruising.
It made a remarkable difference to fuel economy.

Most older automatic gearboxes also had only 3 gears, compared to 7 in todays vehicles.
Fuel usage was higher, at cruising speeds the engines were revving higher, and the engines were therefore noisier.

The newer the car is you can buy, when compared to a similar vehicle that is older, the better.

 

[SauRoNZA]

-Also is it true that you can't 'coast' in a fuel injected car to save gas?
!

Please explain what you mean my this. I hope you aren't referring to letting the clutch in at high speed, because that's not something you should ever do on any car.

Either way it will make no difference whether you do it or not or which type of engine is in the car.

Carbs can be lighter on fuel for a particular period in time than an equivalent car based on particular tuning and running too lean.

However because a carb car cannot change it's fuel mix dynamically it would run quite badly the rest of the time (winter vs summer etc) whereas a fuel injected car can change it's tuning on the fly changing it's fuel mixture based on environmental conditions on the fly thereby overall being more economical.

 

[XennoX]

I have a 2009 VW Citi 1.4i and it is pretty heavy on fuel. I get 11.4 km/l and 12.7 km/l for inner city and highway travelling respectively. My dad has a Nissan X-Trail 2.5 and gets 11.3 km/l doing highway travelling.

If you plotted a curve for engine speed versus fuel economy you would find the optimum point (the turning point) for a vehicle. Some would have that point early on, whereas others would have it later. There also comes a breaking point for engine displacement versus fuel economy. Large displacement engines should be able to get up to speed and maintain it with relative ease, but the sheer amount of displacement they have causes the fuel economy to suffer.

All this being said, FI engines typically run more efficiently than engines with carburettors. Gear ratios and how long it's legs are also make an impact on the fuel economy. Particularly the final gear. Just remember, if you want fuel efficiency keep your engine speed (revs) as low as possible.

 

[Topdoggdbn]

you can coast in a Fuel injected car. just leave it in gear and foot off the gas. the momentum of the car/drivetrain keeps the engine running and the injection has been set to deliver the least to no fuel when in this state.

carbs can be light but not as effeicient is injected. Carbs require an understanding of how they work to extract the most out them. every time time the pedal is pressed fuel pumps in the carb to create a higher flow. every press is wasted petrol also why a carb always feels more responsive compared to an injection. injection has been designed with a delay to also avoid wasted petrol with small pedal movements example being over bumps and driver error.

 

[Ancalagon]

You can coast in any car, whether it be fuel injected or carburetor.

What you need to understand that is that carburetors and fuel injectors are an attempt to do the same thing - atomize the fuel so that it mixes properly with the air, resulting in efficient and complete combustion. Fuel injection is more recent than carburetor technology, and for a time was more expensive. The reason why fuel injection is so popular is that it can change the fuel/air mixture on the fly, by using various sensors to analyze the air coming in, and adjust the fuel flow accordingly. What this means is that when you need your engine to run lean, it runs lean. When you need it to perform, it performs. This results in less wasted fuel. With a carburetor, you essentially set your engine up to perform well at a certain RPM. Because it doesnt adjust on the fly, in certain situations it will run fine, in others it will be terrible.

Also a new related technology is variable valve timing, which further improves fuel efficiency.

 

[UsernameLadiesMan217]

Wow such detailed replies! Thanks a whooole bunch everyone!

Small engines are designed for commuting, and in that role they do an admirable job. At city speeds (60km/h) they are fuel efficient.
My personal belief is that a 1.2 will be less fuel efficient than a 1.4, with all other factors being equal, particularly at highway speeds.
The engine has to work harder to get the vehicle up to speed, and also work harder to maintain that speed.

Older technology will be less fuel efficient than new technology. Just read the thread regarding the Opel Corsa 1.4.
The Corsa had an engine built in Brazil, and was based on 1980's technology. They are notoriously heavy on fuel. The Golf is the same.

Many older cars only had 4 gears. Gear ratios were longer than they are today, but still, they didn't do anything for fuel economy.
We had a 1980's Ford Cortina 3.0 bakkie, with 4 gears. They were very heavy on fuel.
One of the most common modifications that people did was to put in a 5 speed gearbox, as well as a more powerful fan.
The first four gear ratios were similar to the original box, with the 5th gear being much longer. This meant that the 5th gear acted almost like an overdrive. You would get up to speed using the first 4 gears, then put it in 5th when cruising.
It made a remarkable difference to fuel economy.

Most older automatic gearboxes also had only 3 gears, compared to 7 in todays vehicles.
Fuel usage was higher, at cruising speeds the engines were revving higher, and the engines were therefore noisier.

The newer the car is you can buy, when compared to a similar vehicle that is older, the better.

That Palio looks really modern, mine is a 2000 model with almost 200k km's on the clock.
Wow, it's so cool that you were able to install a custom gearbox to make it more fuel effcient, I google'd the Ford Cortina and it looks really heavy as well, must have been nice to drive with a 3.0l engine!
I now have to consider a lot of things, fuel efficiency vs speed vs service costs vs what I can service myself on the car. Can you install a 5 speed gearbox in a 4 speed gearbox golf without it costing an arm and a leg?

It sucks that the Corsa is heavy on gas, does that apply to all Corsa's and if they are still using blueprints from the 1980's does that mean cars from the 1980's were great cars?

Please explain what you mean my this. I hope you aren't referring to letting the clutch in at high speed, because that's not something you should ever do on any car.

Either way it will make no difference whether you do it or not or which type of engine is in the car.

Carbs can be lighter on fuel for a particular period in time than an equivalent car based on particular tuning and running too lean.

However because a carb car cannot change it's fuel mix dynamically it would run quite badly the rest of the time (winter vs summer etc) whereas a fuel injected car can change it's tuning on the fly changing it's fuel mixture based on environmental conditions on the fly thereby overall being more economical.

Uhh, I mean driving the speed limit and then when a light turns red instead of braking you put the car in neutral and coast to the light, hoping it goes green before you reach it.

Thank you for explaining the difference between carb and fuel injection to such great detail.

There's a lot in your post (and others) that I don't understand entirely because of the technical terms so it'll take me a few readthroughs to actually grasp it and then some Googling.

I have a 2009 VW Citi 1.4i and it is pretty heavy on fuel. I get 11.4 km/l and 12.7 km/l for inner city and highway travelling respectively. My dad has a Nissan X-Trail 2.5 and gets 11.3 km/l doing highway travelling.

If you plotted a curve for engine speed versus fuel economy you would find the optimum point (the turning point) for a vehicle. Some would have that point early on, whereas others would have it later. There also comes a breaking point for engine displacement versus fuel economy. Large displacement engines should be able to get up to speed and maintain it with relative ease, but the sheer amount of displacement they have causes the fuel economy to suffer.

All this being said, FI engines typically run more efficiently than engines with carburettors. Gear ratios and how long it's legs are also make an impact on the fuel economy. Particularly the final gear. Just remember, if you want fuel efficiency keep your engine speed (revs) as low as possible.

11.4 km/l is considered heavy? What is to be expected of a 1.4i then? Would your Golf be superior to a 1.4i Golf of the same year?

That graph sounds perfect! If only I knew how to make one, is there a formula or do I just make one according to my own priorities?

Does that mean if I try to save fuel I should go into max gear as soon as possible? So if I go into 5th gear at 50km/h it won't be bad?

you can coast in a Fuel injected car. just leave it in gear and foot off the gas. the momentum of the car/drivetrain keeps the engine running and the injection has been set to deliver the least to no fuel when in this state.

carbs can be light but not as effeicient is injected. Carbs require an understanding of how they work to extract the most out them. every time time the pedal is pressed fuel pumps in the carb to create a higher flow. every press is wasted petrol also why a carb always feels more responsive compared to an injection. injection has been designed with a delay to also avoid wasted petrol with small pedal movements example being over bumps and driver error.

Uuuuu this is what I wanted to know, I had heard that fuel injection doesn't make a difference, but I am glad I can coast (assuming it's not a bad thing apparently)

Do all carb cars have a choke? I have never driven a car with a choke, what's that like?

You can coast in any car, whether it be fuel injected or carburetor.

What you need to understand that is that carburetors and fuel injectors are an attempt to do the same thing - atomize the fuel so that it mixes properly with the air, resulting in efficient and complete combustion. Fuel injection is more recent than carburetor technology, and for a time was more expensive. The reason why fuel injection is so popular is that it can change the fuel/air mixture on the fly, by using various sensors to analyze the air coming in, and adjust the fuel flow accordingly. What this means is that when you need your engine to run lean, it runs lean. When you need it to perform, it performs. This results in less wasted fuel. With a carburetor, you essentially set your engine up to perform well at a certain RPM. Because it doesnt adjust on the fly, in certain situations it will run fine, in others it will be terrible.

Also a new related technology is variable valve timing, which further improves fuel efficiency.

Thanks again for another detailed post This one really put it into perspective.

So, it seems fuel injectors and carbs can both have issues and increase fuel consumption then, I assume working on a carb is easier and as such I should rather get a carb car? Fuel Injection is auto-electrical yeah?

Am I better off trying to learn auto electronics than maintenance?

 

[XennoX]

Yes, all carbs use chokes. Some have manual chokes, others have automatic chokes.

11.4 km/l is considered heavy? What is to be expected of a 1.4i then? Would your Golf be superior to a 1.4i Golf of the same year?

That graph sounds perfect! If only I knew how to make one, is there a formula or do I just make one according to my own priorities?

Does that mean if I try to save fuel I should go into max gear as soon as possible? So if I go into 5th gear at 50km/h it won't be bad?

For a 1.4 yes it is. No, the Citi golf is a lot heavier on juice than a Polo or Golf for the same engine capacity as far as I know.

The graph would be purely empirical and you would then have to fit a curve to get a formula for it. Good luck measuring your fuel usage accurately without having some serious diagnostic equipment.

For best economy, you need to short shift and reach maximum gear as soon as possible. In my Citi, I typically shift at or before 3000 RPM for economical driving. At 60 km/h I'm sitting in 3rd if I'm on the highway or 5th if I'm doing suburban driving.

As for learning auto-electronics? Learning maintenance will give you some basic knowledge about the electrical systems of a car.

Also:

1. Coasting is illegal. [Cops will never know though]
2. I wouldn't recommend doing it by popping into neutral. Reason being is safety. If the situation arises where you need to accelerate to get out of a situation and you're in neutral - you're losing precious seconds to change into the appropriate gear and to release the clutch. I for one will never stand at a stop street or red light in neutral. My car [and bike for that matter] will always be in 1st, ready to accelerate out at a moment's notice.

 

[Ancalagon]

With a carb, you will always be sacrificing performance or fuel efficiency or both. Usually both. With fuel injection, you can achieve performance and fuel efficiency at the same time, at the cost of possibly more complicated maintenance. I hear that carbs are easy enough for the backyard mechanic to maintain at home. I have heard of lots of remedies for removing carbon build up from a carb to help it perform better.

 

[grim]

A well tuned carb will get very near to fuel injection in terms of power and efficiency, sadly these days very few people still know how to give a car a tune-up at home, things like timing, carb tuning, points etc.

In modern fuel injected cars this is handled by the ECU

I had a 1.3 carb Citi Golf and got between 12-14.5km/l depending on how heavy my right foot was, later I had a 1.4i Citi Golf and the best it would do was around 16km/l, the 1.3 was a 4 speed and the 1.4i was a 5 speed.

A 5 speed transmission should return better economy as it's top gear will be geared longer (Lower rpm/km) than the 4 speed.

It's not the hardest thing in the world to do a 4 to 5 speed conversion on a Golf as you can pickup a reconed 5 speed gearbox from a few places that specialize in them and it's mostly a straight drop in except for a few fidly bits with the linkage between the gearstick and gearbox

 

[SauRoNZA]

Uhh, I mean driving the speed limit and then when a light turns red instead of braking you put the car in neutral and coast to the light, hoping it goes green before you reach it.

Thank you for explaining the difference between carb and fuel injection to such great detail.

There's a lot in your post (and others) that I don't understand entirely because of the technical terms so it'll take me a few readthroughs to actually grasp it and then some Googling.

Oh my lord that is even worse that just letting the clutch in.

Please STOP doing that immediately it is incredibly dangerous and doesn't save you any fuel whatsoever. It might save you ever so slightly on your brake system but it's simply not worth it.

Rather learn to use your gears and gear down and let the clutch out appropriately as you approach the stop or robot so that you are in the correct gear for pulling away again when required to do so.

The only time you use additional fuel in your car is when touching the throttle. At any other time it is using exactly the same amount of fuel it would when idling (well scientifically speaking not exactly 100% the same but imperceptibly close to it).


More throttle equals more fuel, no throttle equals no fuel.

*****

If you want to drive the most efficiently then you want to find out what the torque curve of your vehicle looks like and change gear at the lowest revs with the most torque and coast at the same speeds in top gear as well.

 

[UsernameLadiesMan217]

Yes, all carbs use chokes. Some have manual chokes, others have automatic chokes.



For a 1.4 yes it is. No, the Citi golf is a lot heavier on juice than a Polo or Golf for the same engine capacity as far as I know.

The graph would be purely empirical and you would then have to fit a curve to get a formula for it. Good luck measuring your fuel usage accurately without having some serious diagnostic equipment.

For best economy, you need to short shift and reach maximum gear as soon as possible. In my Citi, I typically shift at or before 3000 RPM for economical driving. At 60 km/h I'm sitting in 3rd if I'm on the highway or 5th if I'm doing suburban driving.

As for learning auto-electronics? Learning maintenance will give you some basic knowledge about the electrical systems of a car.

Also:

1. Coasting is illegal. [Cops will never know though]
2. I wouldn't recommend doing it by popping into neutral. Reason being is safety. If the situation arises where you need to accelerate to get out of a situation and you're in neutral - you're losing precious seconds to change into the appropriate gear and to release the clutch. I for one will never stand at a stop street or red light in neutral. My car [and bike for that matter] will always be in 1st, ready to accelerate out at a moment's notice.

Awesome! Thanks for the advice, I didn't know coasting was illegal :s

With a carb, you will always be sacrificing performance or fuel efficiency or both. Usually both. With fuel injection, you can achieve performance and fuel efficiency at the same time, at the cost of possibly more complicated maintenance. I hear that carbs are easy enough for the backyard mechanic to maintain at home. I have heard of lots of remedies for removing carbon build up from a carb to help it perform better.

Hrmm, I'll probably make a carb vs fuel injection thread closer to the time of my purchase when comparing cars and all things considered.

Thanks for your greatly informative responses ITT and others

A well tuned carb will get very near to fuel injection in terms of power and efficiency, sadly these days very few people still know how to give a car a tune-up at home, things like timing, carb tuning, points etc.

In modern fuel injected cars this is handled by the ECU

I had a 1.3 carb Citi Golf and got between 12-14.5km/l depending on how heavy my right foot was, later I had a 1.4i Citi Golf and the best it would do was around 16km/l, the 1.3 was a 4 speed and the 1.4i was a 5 speed.

A 5 speed transmission should return better economy as it's top gear will be geared longer (Lower rpm/km) than the 4 speed.

It's not the hardest thing in the world to do a 4 to 5 speed conversion on a Golf as you can pickup a reconed 5 speed gearbox from a few places that specialize in them and it's mostly a straight drop in except for a few fidly bits with the linkage between the gearstick and gearbox

That actually sounds rather complicated, I hope a mechanic won't charge too much to do it. So does that mean I can just buy any 5 speed VW Golf gearbox and use it in a 1.3/1.4l golf that has 4 gears? Can I purchase aftermarket as well?

Oh my lord that is even worse that just letting the clutch in.

Please STOP doing that immediately it is incredibly dangerous and doesn't save you any fuel whatsoever. It might save you ever so slightly on your brake system but it's simply not worth it.

Rather learn to use your gears and gear down and let the clutch out appropriately as you approach the stop or robot so that you are in the correct gear for pulling away again when required to do so.

The only time you use additional fuel in your car is when touching the throttle. At any other time it is using exactly the same amount of fuel it would when idling (well scientifically speaking not exactly 100% the same but imperceptibly close to it).


More throttle equals more fuel, no throttle equals no fuel.

*****

If you want to drive the most efficiently then you want to find out what the torque curve of your vehicle looks like and change gear at the lowest revs with the most torque and coast at the same speeds in top gear as well.

Oh... I didn't know it was so bad. I was just trying to increase some mileage >.< But now I know.

Sorry!

 

[dj_jyno]

So does that mean I can just buy any 5 speed VW Golf gearbox and use it in a 1.3/1.4l golf that has 4 gears? Can I purchase aftermarket as well?

All 1.4 / 1.4i Citigolfs should have a 5-speed transmission by default. The last 4-speed gearboxes were installed in 1997, I believe.

 

[grim]

Awesome! Thanks for the advice, I didn't know coasting was illegal :s

Hrmm, I'll probably make a carb vs fuel injection thread closer to the time of my purchase when comparing cars and all things considered.

Thanks for your greatly informative responses ITT and others

That actually sounds rather complicated, I hope a mechanic won't charge too much to do it. So does that mean I can just buy any 5 speed VW Golf gearbox and use it in a 1.3/1.4l golf that has 4 gears? Can I purchase aftermarket as well?


Oh... I didn't know it was so bad. I was just trying to increase some mileage >.< But now I know.

Sorry!

Leave the car in gear, it will actually use less/no fuel compared to when you put it in neutral.

Not any 5 speed VW Golf gearbox, a 5 speed Citi Golf gearbox, a 5 speed box from a Golf 4/5 won't fit. Doubt anyone manufactures aftermarket ones but there are places that deal in reconditioned gearboxes that if done properly are as good as a new gearbox.

Not sure what a mechanic will charge as it's something I would do myself.

The 5 speed gearbox for the Citi is the FFZ gearbox, you should be able to pick one up for around R3000-R3500 plus another R500 or so for the mounting and linkages and then the labour for a mechanic to fit it, preferably someone that's done it before.

I see Japan Auto sells new FFZ gearboxes: http://www.japanauto.co.za/?product=vw-gearbox-ffz-velocity-brand-new-2

You'll probably never make up the cost of the conversion in fuel savings unless you keep the car for a very very long time

 

[grim]

All 1.4 / 1.4i Citigolfs should have a 5-speed transmission by default. The last 4-speed gearboxes were installed in 1997, I believe.

+1

1996 actually

1997 saw the introduction of the 1.4 engine to replace the 1.3

 

[SauRoNZA]

Awesome! Thanks for the advice, I didn't know coasting was illegal :s

Hrmm, I'll probably make a carb vs fuel injection thread closer to the time of my purchase when comparing cars and all things considered.

Thanks for your greatly informative responses ITT and others

That actually sounds rather complicated, I hope a mechanic won't charge too much to do it. So does that mean I can just buy any 5 speed VW Golf gearbox and use it in a 1.3/1.4l golf that has 4 gears? Can I purchase aftermarket as well?


Oh... I didn't know it was so bad. I was just trying to increase some mileage >.< But now I know.

Sorry!

It's bad because you have no drive to the wheels and therefore no steering.

Try doing a quick evasive maneuver while coasting and you'll realise your car is a boat.

You need drive to the wheels to steer properly.

At high speeds this is disaster waiting to happen.

Always be on gear even if off the throttle. Coasting will not save you a penny.

 

[UsernameLadiesMan217]

All 1.4 / 1.4i Citigolfs should have a 5-speed transmission by default. The last 4-speed gearboxes were installed in 1997, I believe.

There's a good chance I'll be buying a pre 1996/7 Golf, but I'll actually be on the lookout now for a 5 speed now! Thanks for this knowledge

Leave the car in gear, it will actually use less/no fuel compared to when you put it in neutral.

Not any 5 speed VW Golf gearbox, a 5 speed Citi Golf gearbox, a 5 speed box from a Golf 4/5 won't fit. Doubt anyone manufactures aftermarket ones but there are places that deal in reconditioned gearboxes that if done properly are as good as a new gearbox.

Not sure what a mechanic will charge as it's something I would do myself.

The 5 speed gearbox for the Citi is the FFZ gearbox, you should be able to pick one up for around R3000-R3500 plus another R500 or so for the mounting and linkages and then the labour for a mechanic to fit it, preferably someone that's done it before.

I see Japan Auto sells new FFZ gearboxes: http://www.japanauto.co.za/?product=vw-gearbox-ffz-velocity-brand-new-2

You'll probably never make up the cost of the conversion in fuel savings unless you keep the car for a very very long time

Do you fix cars for a living? Or just a dedicated hobbyist? You know a looot about cars!

Wow, that certainly is expensive and the conversion itself sounds way too advanced for me. I didn't know Gearboxes are so expensive.

Well I'll definitely look for a 5 speed golf then instead of custom installing a 5 speed. Thanks for the website link! I had no idea a gearbox wasn't... well actually a box!

 

[grim]

There's a good chance I'll be buying a pre 1996/7 Golf, but I'll actually be on the lookout now for a 5 speed now! Thanks for this knowledge

Do you fix cars for a living? Or just a dedicated hobbyist? You know a looot about cars!

Wow, that certainly is expensive and the conversion itself sounds way too advanced for me. I didn't know Gearboxes are so expensive.

Well I'll definitely look for a 5 speed golf then instead of custom installing a 5 speed. Thanks for the website link! I had no idea a gearbox wasn't... well actually a box!

I enjoy working on cars, it's a break from working with IT everyday all day. Been at it since I was about 9, so 20 years, helping to service family and friends cars, fixing them when things go wrong etc.