Alfa Romeo Forums banner

1 - 20 of 44 Posts

·
member
Joined
·
453 Posts
Discussion Starter #1
I see some people remove the fuel injection, and replace it with carbs. is there a sound reason for this? or is it just something some people do....
 

·
1966-2013
Joined
·
13,741 Posts
No more sound reasoning than getting up one day and deciding you're never going to walk again and will crawl on all fours for the rest of your life.
There is no sense what~so~ever in retrograding to carbs from EFI.

The two main reasons its done are (1) a complete lack of understanding of EFI and how to work with it, and (2) carbs look and sound cooler.

There is no actual benift to the reversion, and in fact in stock to moderately built engine configurations it degrades pretty much everything from power to economy to reliablity to even ease of starting.

If going for a full on track built engine EFI still makes more sense, but something programmable as opposed to stock non~tweakable components.
 

·
Premium Member
Joined
·
5,684 Posts
IDK, I don't think you can downplay the appeal of retro engineering. After all, Why are we here and not driving Miata's if it didn't matter.

If I had a well running EFI powered Alfa and really, really wanted carbs I think I would just get another Alfa with carbs.

If I had a sick EFI, knew nothing about EFI, and wasn't interested in learning and had a pretty good understanding of carb conversion then maybe.

The assumption is EFI but I suppose you could have a SPICA system. That is little trickier answer.

A good running SPICA should never (IMHO) be replaced with carbs. A poor running SPICA should at least be diagnosed as more than badly set up. If the SPICA is truly worn out then it becomes more of a money thing. A rebuild SPICA will cost a grand. A used carb set up probably about the same.

EFI bores me but is a clear improvement in almost every way over previous fuel delivery systems.

SPICA is really geeky cool and you'll never see another car with it. Performance is amazingly similar to carbs and very reliable. Not very adaptable and does not suffer fools - you need to be willing to learn.

Carbs are just plain cool. They look cool, they sound cool. Everybody knows how to adjust them and they are infinitely adjustable and adaptable. Idiots and brainiacs alike can enjoy them...
 

·
member
Joined
·
453 Posts
Discussion Starter #5
OK, I don't know what I have, but I already have my work cut out for me, so I am not going to change anything right now. car starts right away, but I think I have electrical issues, and that is my favorite thing to have(NOT)
 

·
Registered
Joined
·
1,779 Posts
Where it could be considered semi-acceptable, is on a heavily modified normally aspirated engine where the original long runner EFI manifold was the limiting factor in the engines performance. But ultimately it's still a major step backwards.
 

·
Registered
Joined
·
9,977 Posts
Some reasons to convert to carbs:

1. More easy/cheaper to tune for making performance improvements to the engine. A stock injection pump can probably handle Euro cams and high compression pistons, but that's about it. Anything more will require a high performance pump with a modified fuel delivery 3D cam.

2. If your injection is shot it may be cheaper to convert to carbs. Rebuilt injection pumps cost over $900 now.

Reasons to stay Spica:

1. Originality

2. Spica systems once in tune stay in tune.

3. Slightly better fuel mileage.
 

·
member
Joined
·
453 Posts
Discussion Starter #8
OK thanks'


Reasons to stay Spica:

1. Originality

2. Spica systems once in tune stay in tune.

3. Slightly better fuel mileage.[/QUOTE]
 

·
Premium Member
Joined
·
5,684 Posts
OK, I don't know what I have, but I already have my work cut out for me, so I am not going to change anything right now. car starts right away, but I think I have electrical issues, and that is my favorite thing to have(NOT)
Ok, Bob, what type Alfa and year do you have? That will tell us whether you have a SPICA system (mechanical fuel injection) or EFI (electronic fuel injection).

I'll assume you are new to this stuff and as such, a carb conversion might be a bit too much to start with. Electrical issues on these cars are usually manageable and this forum is your best tool.
 

·
But Mad North-Northwest
Joined
·
11,291 Posts
I'm pretty sure he said he's got a '92. If that's the case you'd be nuts to pull out the EFI and put in carbs. The stock '92 Bosch Motronic is a great fuel injection system and hands down beats carbs all around.
 

·
member
Joined
·
453 Posts
Discussion Starter #11
yes, it is a 92....I was not planning on doing anything to the engine, was only asking about the differences,,,

the electrical looks to be a real problem. none of the instroments work, and I have only one head light and one brake light, and no signals....I checked all the fues and they check. not sure where to go frome there, I am going to order a manual. so I have to wait on that.
 

·
Registered
Joined
·
505 Posts
The only improvement to the EFI is the use of throttle bodies, as that sets your injectors further away from the valves which will improve your mixture.
Otherwise keep your injection or efi.
 

·
Registered
Joined
·
505 Posts
throttle bodies, are added to the injectors?
Don't know exactly what you mean but you replace your EFI intake manifold for a throttle body manifold and throttle bodies. There for your intake manifold will get longer, thus a better mixture.
 

·
1966-2013
Joined
·
13,741 Posts
Not mixture, but velocity.
Longer runners, up to a point, make for faster airflow which in turn can improve lower RPM performance.
Faster airflow gives a slightly bigger mixture charge to the cylinder without having to spool up the revs.
(volumetric efficiency, harmonic pulses, long hair math stuff)
Mixture will be controlled by the ECU via oxygen and other sensor input and/or pre~programmed mapping regardless of runner length or the presence of a single or multiple throttle bodies.

The very loose way about it is long runners improve low end, short runners improve high end. Finding a balance that gets your power curve where you want it and matched to the camshaftery is where actual math needs to be done if you want the most out of it.

AFA the L-jet and motronic EFI standard plenum runners, they are actually quite long already (as long or longer than any ITB's I've seen anyway) and quite efficient at what they are designed for. The single throttle body in those systems could be enlarged a bit, but in general it helps give better off idle and low end drivability over individual throttle bodies as those tend to be lacking a bit on thier ability to actually hold any kind of real vacuum levels in the bottom ranges.

If the vacuum levels are too low, then the mixture flow into the cylinders is inefficient and you end up with things like bog and flat spots until you either tune it out through whatever means (cams usually) or get the revs up into a range where the velocity improves.
 

·
Registered
Joined
·
505 Posts
Thanks Darren, improve the flow there for you will get a better mixture. The ECU will always be in charge of how much fuel will be injected.

You know what you are talking about, that is for sure.

Rob
 

·
Registered
Joined
·
158 Posts
Think about why spica replaced carbs - Emissions control. (2 of the most evil words in existence) Emissions control (verb) Antithesis of power and tuneability

Carbs will allow you flexibility of adjustment if you want to modify the heart of your car
 

·
member
Joined
·
453 Posts
Discussion Starter #18
well, I guess that here in USA, there are controls on everything...I am guessing that if the year is early enough, then emisssions inspection is easier..
 

·
Registered
Joined
·
505 Posts
well, I guess that here in USA, there are controls on everything...I am guessing that if the year is early enough, then emisssions inspection is easier..
The car will be a 1964 TI.
This car is aleady not original. So put a better engine in there will give me more driving pleasure. I also do have a nice
1600 ti super engine for her as spare.

Regards
Rob
 

·
Registered
Joined
·
355 Posts
Correct me if I'm wrong, but I've always been under the impression that Emission Control brings greater efficiency (within the cylinder) despite complexity (outside the cylinder) throughout the RPM range. Carbs can be set and dialed in, but computers (mechanical or electrical) are more flexible in changing conditions.
 
1 - 20 of 44 Posts
Top