EFI Advantages?
Intermediate
Joined: Aug 2004
Posts: 34
Likes: 0
From: Columbus Ohio
the way ive always looked at efi vs. carb for regular driving is this:
when you have a carb, you tune it, and its tuned. thats it. if your driving style changes, the carb tune stays the same.
with EFI its like having your carb tuned every few milliseconds as you drive down the street.
when you have a carb, you tune it, and its tuned. thats it. if your driving style changes, the carb tune stays the same.
with EFI its like having your carb tuned every few milliseconds as you drive down the street.
Thread Starter
Instructor
Joined: Apr 2000
Posts: 165
Likes: 0
From: Vacaville California
I had a 383 built for my '75. I haven't experienced it yet, as I'm still involved in the ground-up project. But, realistically, what kind of fuel mileage difference would I see carb vs. EFI? I don't yet know what mileage I'll be getting: the builder says it'll be 450 hp/450 ft*lb and thinks I'll get 12 mpg (but I suspect he's optimistic on the mileage...?)
Anyway, would EFI make a big diff. on mileage: 2 mpg-worth...or more?
On another note, I only drove my '75 fairly briefly with its stock 350 before tearing into it, and I don't recall any cold-start related idling issues. It seemed to always start, always drive fine, etc. However, my '79 BB Chevy truck is nearly undriveable when it's cold.
Is it a general rule that SB do fine with carbs (regarding idling when cold, avoiding icing, etc.) while BB don't?
Anyway, would EFI make a big diff. on mileage: 2 mpg-worth...or more?
On another note, I only drove my '75 fairly briefly with its stock 350 before tearing into it, and I don't recall any cold-start related idling issues. It seemed to always start, always drive fine, etc. However, my '79 BB Chevy truck is nearly undriveable when it's cold.
Is it a general rule that SB do fine with carbs (regarding idling when cold, avoiding icing, etc.) while BB don't?
Thread Starter
Instructor
Joined: Apr 2000
Posts: 165
Likes: 0
From: Vacaville California
My engine builder recommended Edelbrock's EFI kit if I go with EFI. But what about the later C3s: didn't they have FI? What about fitting my engine with a later Chevy kit? Which would be easier? And what is TPI?
I'm curious: do these aftermarket EFI kits work as well as a factory EFI set-up, or do they have glitches and issues? I don't want a cantankerous system, just one I can use and forget.
Furthermore, I'd actually rather just use a carb for its simplicity; my only worry is that I want my car to idle well on cold, winter mornings without carb icing and dying, etc. Any advice which way I should go? My engine builder is suggesting a Demon carb if I go the carb-route. Any experience?
I'm curious: do these aftermarket EFI kits work as well as a factory EFI set-up, or do they have glitches and issues? I don't want a cantankerous system, just one I can use and forget.
Furthermore, I'd actually rather just use a carb for its simplicity; my only worry is that I want my car to idle well on cold, winter mornings without carb icing and dying, etc. Any advice which way I should go? My engine builder is suggesting a Demon carb if I go the carb-route. Any experience?
Race Director
Joined: Dec 2000
Posts: 10,896
Likes: 2
From: CO
Originally Posted by Gage
but I don't get spending big bucks to get fuel injection on a vintage car...If you want fuel injection and all the efficiency/benefits as well as complexity/wires everywhere, go buy a c4,c5,c6...Part of the fun of a classic car is a simple and vintage looking engine compartment.
It all depends on your intent. I enjoy the sound of a carb at WOT thru the twisties here in the Rocky Mountains. Completes the vintage car feel.
Besides with all the $$$ + effort I would put into modding out the 75 to have a 6-speed / FI / Airbags/ Better suspension I might as well just buy a used 93-96 C4 and get all of it in a factory package.
Carbs have their place, and mine still works very well. Q-jet. Even on cold days it starts and idles high for a few min then its ready to go.
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Originally Posted by singedfur
My engine builder recommended Edelbrock's EFI kit if I go with EFI. But what about the later C3s: didn't they have FI? What about fitting my engine with a later Chevy kit? Which would be easier? And what is TPI?
I'm curious: do these aftermarket EFI kits work as well as a factory EFI set-up, or do they have glitches and issues? I don't want a cantankerous system, just one I can use and forget.
Furthermore, I'd actually rather just use a carb for its simplicity; my only worry is that I want my car to idle well on cold, winter mornings without carb icing and dying, etc. Any advice which way I should go? My engine builder is suggesting a Demon carb if I go the carb-route. Any experience?
I'm curious: do these aftermarket EFI kits work as well as a factory EFI set-up, or do they have glitches and issues? I don't want a cantankerous system, just one I can use and forget.
Furthermore, I'd actually rather just use a carb for its simplicity; my only worry is that I want my car to idle well on cold, winter mornings without carb icing and dying, etc. Any advice which way I should go? My engine builder is suggesting a Demon carb if I go the carb-route. Any experience?
In my experience, most of the well know EFI kits work as reliably and electronically as well as factory setups, but since they are added on, things like fuel pumps and lines won't be as "slick" as factory systems. If your carb needs attention like many carbs do, you will probably see an improvement in mileage. However, a new carb and manifold properly tuned might not be much different in the way of gas mileage. It certainly wouldn't justify the cost of EFI. However, if you plan on driving your car often, you'll need to devote more attention to a carb setup than an EFI one. Think about how people with their Hondas and BMWs never pay a lick of attention to their cars and they just keep running and running - in a large part due to the reliability of EFI.
Bottom line for me - I wanted EFI for long-term reliability, driving and tunability. Since I own a laptop and learned how to program the system, I'll never need to take it in for a tune-up again.
Thread Starter
Instructor
Joined: Apr 2000
Posts: 165
Likes: 0
From: Vacaville California
Z-man: thanks for the info on later C3 units. What aftermarket unit are you running? Were you having any difficulty with your carb idling in the cold? I would be quite happy with just a carb on my 383 if it would idle fine on a winter morning without icing and dying, etc. I'm not super worried about the other "pluses" of EFI, such as MPG or better throttle response. It's interesting you note that a well-tuned, new carb would not be much worse on mileage than an EFI set-up.
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
I've got a Holley Commander 950. My car originally had a Holley carb and it needed to be rebuilt every few years - probably since it sat during the winter. It also leaked at the gaskets - a problem I would also expect with Demons. I switched for a while to an Edelbrock carb and manifold which was very reliable and smooth at idle. Still, I wanted to move to EFI to bring me into the 20th century.
Here's a good reference manual that tells all about the Holley setup and anything you wanted to know about EFI:
http://www.holley.com/HiOctn/ProdLin...Cmdr%20950.pdf
You can check out Zwede's Holley installation here (its a BB, but they are about the same):
http://temp.corvetteforum.net/c3/zwede/
Here's a good reference manual that tells all about the Holley setup and anything you wanted to know about EFI:
http://www.holley.com/HiOctn/ProdLin...Cmdr%20950.pdf
You can check out Zwede's Holley installation here (its a BB, but they are about the same):
http://temp.corvetteforum.net/c3/zwede/
Safety Car
Joined: Dec 2004
Posts: 4,071
Likes: 0
From: San Diego CA
Originally Posted by Gage
Just my opinion here, and I am not opposed to modernizing to some degree (OD trannies, throwing out points for elec ign..not an NCRS purist by any means), but I don't get spending big bucks to get fuel injection on a vintage car...If you want fuel injection and all the efficiency/benefits as well as complexity/wires everywhere, go buy a c4,c5,c6...Part of the fun of a classic car is a simple and vintage looking engine compartment. When my 69 or 72 C3 had a fuel related issue, I popped the hood in the garage and tweaked the carb. With my 89 IROC-Z with TPI, I'd pop the hood and scratch my head. Only mod I felt comfortable was to change the air filters to K&Ns.
When people come over my house and I show them my 72, I pop the hood and they see a big chrome air filter, and they say wow, cool..I couldn't imagine popping the hood and the engine compartment looking like my 16 yr old neighbors' 01 camaro. Just my opinion...
When people come over my house and I show them my 72, I pop the hood and they see a big chrome air filter, and they say wow, cool..I couldn't imagine popping the hood and the engine compartment looking like my 16 yr old neighbors' 01 camaro. Just my opinion...
I want all the cool stuff new cars have in a car that isn't ugly, that's why.
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Originally Posted by Kalway
I want all the cool stuff new cars have in a car that isn't ugly, that's why.
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From: B'Ville NY
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St. Jude Donor '05
I want all the cool stuff new cars have in a car that isn't ugly, that's why.
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Safety Car
Joined: Oct 2004
Posts: 3,725
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From: Minnesota
I was once told that with throttle body FI you gain about 10%. (I don't know if this was efficiency or power). With multi-port FI you gain another 10% and with direct into the cylinder FI another 10%. It would be interesting if anyone has some actual #'s to tell us what really happens. 
