Going from Carburetor to Fuel Injection - Team Camaro Tech
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post #1 of 16 (permalink) Old Dec 4th, 14, 02:20 AM Thread Starter
Michael
 
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Going from Carburetor to Fuel Injection

Hello everyone,

The rebuild of my 69 Camaro SS is nearing the end of a lengthy 16-month process, and all in all I'm really happy with the way it's turning out. There's one decision though that was made by the builder that I question, and I'm hoping to get some expert opinions. That decision was to go with a carburetor instead of fuel injection.

The car has a 572 with good horsepower and torque, and will be used for racing and autocross. The builder felt that a carburetor wouldn't have the same fuel economy as fuel injection, but it'd produce the same power and would "just work", ensuring easy maintenance over the life of the car. His argument against fuel injection was that it was expensive, needed frequent tuning, and would become a source of frustration after a while that required a specialist to maintain.

I really have two questions:
1. Do you agree with the builder's assessment of why carburetors are better for race applications like mine?
2. If at some point in the future I decided to convert to fuel injection, is this a painful and costly thing to do, or is it relatively straight forward to get done?

Thank you for your help,

-Mike
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post #2 of 16 (permalink) Old Dec 4th, 14, 02:45 AM
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Re: Going from Carburetor to Fuel Injection

Costly...yes, compared to a carb.
MPG....very close.
HP/TQ....close.
Need a tuner....depends on the unit you go with I guess, and how much you know/can do.(hand held tuner)

I do like the FAST 2.0 EFI...about $2500.
Most "kits" are good to 500HP and some are good to 600HP....but "may" be upgrade-able ?

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post #3 of 16 (permalink) Old Dec 4th, 14, 03:04 AM
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Re: Going from Carburetor to Fuel Injection

I agree with Doug, I will add drivability will improve.
Just think of the experience between driving a carb'd vs EFI.

A FAST unit may be the way to go, it will learn, and if need be, more is needed to support, add bigger injectors, should be big already.

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post #4 of 16 (permalink) Old Dec 4th, 14, 04:46 AM
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Re: Going from Carburetor to Fuel Injection

Even Nascar went FI, how about the ZR1 or the new Z28, Cadillac V's all are high HP and are FI.
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post #5 of 16 (permalink) Old Dec 4th, 14, 05:49 AM
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Re: Going from Carburetor to Fuel Injection

I just finished reading an article from Drag magazine on comparing a carb system with a fuel injection system. They chose Holley's HP system to test. The results were about 12 hp and about 14 lbs. torque in favor of the carburetor. The fuel savings were about 8 dollars an hour for the fuel injection system. I love driving my 2007 GMC Sierra with EFI and electronically controlled transmission. But for my 1967 Camaro RS/SS I will stick with my Holley 850 than spend $2500 - $3000 on a fuel injection system and all the work installing it.
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post #6 of 16 (permalink) Old Dec 4th, 14, 06:11 AM
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Re: Going from Carburetor to Fuel Injection

EFI IMHO is the only way to go.

The carb/EFI power comparisons are always peak #s and do not point out the improved drive ability across the power band.

EFI also compensates for atmospheric changes which carbs do not do.

Once tuned you do not need to retune unless you make changes to your set up.

The swap is extremely easy to do. Under $2k plus the fuel pump and regulator.

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post #7 of 16 (permalink) Old Dec 4th, 14, 06:24 AM
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Re: Going from Carburetor to Fuel Injection

I've toyed with the idea - at this point I can't justify the expense for a summertime once-in-a-while car. A $100 swap meet Holley and a $17 parts house mech fuel pump that have been working flawlessly for years - vs a $2500 "starter" kit EFI - add more if you go with an in-tank pump and full return fuel system. I'd probably do an LS swap (gasp!) before shelling out that kind of dough on the "old junk".


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post #8 of 16 (permalink) Old Dec 4th, 14, 06:25 AM
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Re: Going from Carburetor to Fuel Injection

I went with the EFI and will never have another carb. I turn the key and it fires right up regardless of the weather and runs smooth with unbelievable throttle response. I'm not a tuner so I went with the Holley Avenger self tuning system that can be upgraded to the HP system by adding a laptop for fine tuning, nitrous and forced induction applications. The system is good for 650hp out of the box and can be upgraded by changing to larger injectors with the right fuel system.
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post #9 of 16 (permalink) Old Dec 4th, 14, 08:38 AM
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Re: Going from Carburetor to Fuel Injection

As with anything else, one has weigh the EFI option to Carb option.
Daily cruiser - yes,
Once in a while - maybe not
Wow Factor of having EFI - Yes.

To each owner, their own opinion/decision.

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post #10 of 16 (permalink) Old Dec 4th, 14, 09:58 AM
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Re: Going from Carburetor to Fuel Injection

FAST EZ EFI 1.0 and 2.0 are amazing systems. I've installed a 1.0 on my car and it was amazing; mileage even went up about 4mpg much to my surprise. The 2.0's that I've helped install are even easier and work better; the varied voltage to the in tank pump removes the need for a pressure regulator and a return line. I don't feel that the frequent tuning concern is legitimate with the aforementioned systems.

- Rob

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post #11 of 16 (permalink) Old Dec 4th, 14, 12:12 PM
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Re: Going from Carburetor to Fuel Injection

Yeah you builder is on the money..
Basicaly carbs have a narrow efficient power band... power and economy... so a track car designed to run say 6500 rpms up, down bottom will not idle well on the street let alone be efficient, power or economy... both go hand in hand.

Injection gives the best of both worlds
In saying that, the cam has a huge influence in the same way... technology is getting there so we can have variable cams profiles eventually... which is the down fall for any high expectations expect 100% best of both worlds

Another area to consider the number gears in the transmission and final gear ratios.. this and monitored injection/ time are the 3 critical things in modern muscle car where one more or less have the best of both world ( fully variable cams in the pipeline)

Or you could run 2 carbs one for track day the other for street.
I have 2 torque converters and 2 diff ratios... a swap on the hoist by 2 guys is just over 1/2 hr now for social track days....I dont need a 2nd carb because dont have as big cam or high rpm range.
This alone makes a near 50% difference in economy on the street.
If had the money at the time I would have gone for a 4 speed trans.. lower 1st, and higher top gear...
Economy boils down to this cubic in that the engine displaces per mile ...
ie the engine requires x mixture ratio at a given load /rpms, the amount is determined by engine displacement per mile.....smaller engine, same final gear ratio.. less mixture required.... or higher (lower numbers) final gear ratio the less the engine turns over per mile.
And how well the engine gets that fuel (carb/ injection system) then burns that fuel (timing, cam profile, dynamic compression ratio)

This all assumes that the engine is dialled in to establish the required tuning specs, which it THEN gets tuned to.

My Spelling is not incorrect...it is creative

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post #12 of 16 (permalink) Old Dec 4th, 14, 03:49 PM
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Re: Going from Carburetor to Fuel Injection

Another nice thing about EFI is that it will run the same at sea level as at 8,000 feet above sea level.

Try that with a carb...

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post #13 of 16 (permalink) Old Dec 4th, 14, 04:43 PM
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Re: Going from Carburetor to Fuel Injection

Once the motor is tuned with EFI you are done. There is no maintenance tuning unless you change parts on the motor.

I've run older aftermarket EFI systems in the past. Edelbrock's Proflo EFI and Holley's old commander system. Both worked great. I put 10K miles on the Edelbrock and 20K miles on the Holley and never had to retune either system.

Carbs can work in autocross or road course but can be more finicky if you don't have your fuel pressure and floats dialed in. But I've seen plenty of classic muscle tearing up autocross events with carbs.


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post #14 of 16 (permalink) Old Dec 15th, 14, 01:13 PM
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Re: Going from Carburetor to Fuel Injection

I guess my wow factor is opening the hood of a muscle car and seeing a period power plant.

Yes LS motors and EFI are modern, nice and don't require warming the car up to jump in and go, but for me, that's part of nostogia of having an ol'muscle car. Part of the fun for me is working on the car and tweaking it.

Nothing wrong with either one, it's a personal choice on what you want, don't let anyone else talk you out of the vision you have in your head for YOUR car.
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post #15 of 16 (permalink) Old Dec 18th, 14, 05:07 PM Thread Starter
Michael
 
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Re: Going from Carburetor to Fuel Injection

Thank you everyone for all of the fantastic posts. I really appreciate it, and you've given me a lot to think about. I'm supposed to get the car in January after an 18-month build so I'm ridiculously excited to say the least. I'll run with the carb and let everyone know how it goes. The track doesn't open until May 1 due to harsh winters where I live, so I'll have to wait a little while before I can really push the car.

Thanks again, and I wish everyone very happy holidays!

-Mike
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