I'm 20 years old. I don't have $7000 for a ls1 swap ... And my engine runs perfect. I just want better mpg.

 

You deserve the medal of honor for that reply, you must be on tranquilizers.

 

 

you don't know what combo u have. there are likely bad for mpg things in your combo that won't be cured by efi.
so you need money, and lot's of it.
Just get a ~Geo metro for work; c3 on weekends.

 

Wishful thinking.
Take Gordon. He loves his efi.
But things didnt go as planned.
He expected it would work with his big cam.
It would not run closed loop.
So he got a smaller cam.
Better, but still won't run closed loop. He uses it in open loop while he waits for his smaller, but roller this time, new smaller cam. Maybe it will run fine, but, whenever he gets it docile enough to work, GUESS WHAT, a 4165-6210 will do the same job w/dual plane and get very close mpg.

 

Haven't heard of Gordon's issue... Is it a factory computer or aftermarket? Narrow band O2 or wideband? There is no reason an aftermarket computer with wideband wouldn't run closed loop, no matter how big the cam.

 

How do you know it will not run in a closed loop. I still would not call it a small cam, it is just better suited to fuel injection. I seriously doubt it will ever be docile. Running a street motor is a comprimise. I want the best of both worldsbut carb or EFI you have to make decisions on what you want. When I originally selected thecam I had no thoughts of going to fuel injection. I knew pretty much from the start it was not going to provide what I wanted but I thought I'd try. Getting an EFI to work is just selecting the right parts combo and setting up the computer to work with them.

 

The two best options are take or send your demon carb to a carb shop that has a test mule dyno motor. The air bleeds are all wrong and you need holes drilled in the primary blades...........

Or sell the demon and get a carb in the 600 - 650 cfm range and tune it up.

 

Zwede, Gordo, I never really believed in the old saying "you can't teach an old dog new tricks" since I am in the old dog category. But, listening to all this, I think I may have underestimated.
There is no way in hell a carb can adapt to all the environmental and physical variations today's applications demand. Muli-Port EFI is worth every penny it cost for the enhancements it provides for drive-ability, economy, ease of tuning, and for me most important, performance. and...That Includes WOT.
But, I know you guys already know this.

You young guys, don't be mislead, take the time to learn.

Bullshark

 

good topic.
there is no way in hell that some "cheap affordable" efi is going to adapt to all the crazy combos in this club.
.
i almost bought a c6. there was a 3000 page manual just for codes. another book for the rest of the car.
.
efi is job security for mechanics.
.
i lived in Vorhees in 1978-80. i drove a 76 vette about 30k miles. never touched the qjet. always started right up, got 17.6 mph on the highway, 15 or so local.
The dealers didnt have a carb guy. they werent needed. For a rare problem, the carb would be swapped out.
.
Just bought a HD car radio reduced frm $150 to $23. I knew it had to be a lemon. but for $23 why not? So it is a great radio, but the software some young kid wrote it that never used a 70's car radio. No way to switch stations quickly like on a 70's car. No "previous" button. So beware of todays "improvements". .
Buy efi if u like.
Visa card and charge them back if it doesn't work right.
I'm keeping the HD radio, worth 23 bucks to play my favorite station in HD.

 

Hey Matt, is my cam too big for efi? 261/268 @.050 and .650 lift on a small block? The motor makes 600hp and runs in the 10's normally aspriated right now. Oh also has a tunnel ram, that's a hard combination for carbs or fuel injection.


It runs like a kitten in closed loop and self tuned itself with the build in wideband. It starts with the bump of the key everytime. I've drove it 70 miles round trip and raced it at the track,too. I know of almost 400 of these efi systems on the rode right now getting good mileage and improved drivability, not to mention in all conditions. I've used carbs my whole life and no one can say their carb runs, idles, starts, and calibrates itself to all temperature and environmental changes like EFI does. It might do some of those, but they CAN'T do all of them.
Heres Hotrods video documentary: http://forums.corvetteforum.com/c3-t...stal-vids.html

 

I understand that you want to switch to EFI and I almost did the exact same thing. I bought a 350 with a TPI system on it with the intentions of making a TPI 383. What I found when researching is the combination is a torque monster that flattens out around 4,000 RPM. I decided to sell the injection system and go carb because my car will sit in the garage more than I will drive it. From the info I have gathered, the TPI system is a great system that is designed for torque. If you are going to do it, you need to get the complete system off of a donor car. There is a good website that provides wiring diagrams to set it up on your car and you will need to have the PROM chip reprogramed. These things are not too difficult if you take your time. You will also have to get a new fuel pump and most likely exchange your fuel lines because injection systems require more PSI than carbs. This means getting an external fuel pump. People will tell you that you need a new fuel tank but it is untrue, you just need to change the fuel lines to handle more pressure and get a new pump. You will need the biggest injectors to hand the 383 and should get the bigger throttle body and intake runners. These things are all added costs but I don't think you will enjoy the drivability of the car without them. For a daily driver, you are right on with the TPI system, just make sure you get a complete system off the same donor car because although most the TPI parts are interchangable, you will have less headaches with one that is complete. There are several computer systems you can get and the differences are relatively minimal but there are differences. Check out this website, it should help with some decisions. Overall, you should decide exactly what system you are looking for and then start looking, TPI systems are everywhere and the challenge is finding the complete system because parts are available everywhere. I sold my complete system cam and lifters included for $415 on ebay so they are out there. Good luck
http://chevythunder.com/fuel%20injec...ance%20pg1.htm

 

Ron
that is a NICE car
Do they offer a money back guarantee on the efi? Does it have a knock sensor and instantly adjust timing and mixture for a tank of low octane gas? EFI has been out 25 years so i expect this stuff by now.
Have u checked your mpg? Not expecting too much, just curious.
What would your whole motor cost to duplicate?
I get 18-19.3 mpg around town on a $395(new to replace) holley. Bought it at a swap meet in 1975 for $25, Spent about $180 on it over 34 years. Do you think i could go 34+ years on your efi and never be stranded? What would a rebuild cost and how often?
Can it tolerate a rusting gas tank?(carbs dont like rust)
Inquiring minds want to know.
Thanks for chiming in. I have an open mind.

 

Money back guarantee? Does GM or the gas station you buy your gas at? No one offers that, but as for 6 days a week phone tech support, and an online forum, yes. I'm not trying to sell anything here, I'm just offering suggestions. This is actually our lower level system. The XFI is running in everything from street cars to 5,000 hp cars on the track now.

If I drive calmly, I get 13 mpg right now. Remember cubic inches uses x amount of fuel to maintain a certain ratio of air to fuel. So a larger motor always pulls in more air per stroke and needs more fuel to keep the correct ratio. My motor is 434 inches. A little 350 would do better. If you watched the video or read the latest Hot Rod mag on the shelf they made 5 mpg better than the carb on that vehicle and they didn't even lean it out like I told them. They could have gotten more than the 18mpg they got.

My car used to run great on the 2 carbs, too. If you go to Colorado Springs, CO from here, your carb would lose about 10 mpg if you didn't completely change jets, squirters, and power valve. I did it, I know. Then you drive back and the carb will see so lean here at sea level it will burn itself up. There are guys that live in Utah that can drive 1 hour and be 8,000 feet higher in altitude. Again huge tuning issue with a carb, not EFI.

A rusting gas tank???? Everyone uses a fuel filter don't they? If it gets clogged you change it. Or the one that comes in this kit you can open and clean it, too. A carb won't tolorate a rusting gas tank with out one either. I have had a tiny little piece of fuel hose get lodged in my needle and seat and the carb overflowed all over my hot engine. This is actually pretty common and very scary. I've seen this one at the track, too.

Bottom line, carbs are cheaper that EFI. No ones going to argue that. Hold on, this is a CORVETTE forum! CHEAPER! If you race you can pay $700 - $900 for a high end carb. Double that if you run duals.

Bottom line, EFI (if tuned correctly) runs, starts, and over all temperature changes and conditions will give better gas mileage. It is constantly adjusting the fuel with a Wide Band O2 sensor. The good ones anyways.

As for power, if you are racing and both systems are tuned to exactly the same A/F ratio I don't think you would see much difference. The times that people say EFI made a big increase, just didn't have their carb tuned right or it was the wrong size. From experience though the conditions at the track start changing and you see everyone changing jets and adjusting their mixture to keep their times right and I never opened my hood. It takes care of its self.

 

Get over it. EFI > carb.

 

Ditto GordonM.
I have a TPI from a 90 Vette on my Lingenfelter 383 and, with larger runners, 23 lb injectors and a massaged throttle body, it makes aroud 400 HP and 450 lb-ft TRQ. It runs out of air about 6k RPM.
And, if I ever sell it, it can be diagnosed and maintained by a GM dealer.

 

What do you mean it runs out of air?

 

The TPI tubes are not big enough to flow enough air into the motor. As the rpms increase the motor need more air. It is like trying to suck air through a straw. In a 305 it will go to about 5000 rpm. A 350 will run out at about 4500 rom so a 383 will start to fall off in power around 4000 rpm. The runners are just not big enough. Some of the aftermarket ones have bigger tubes to flow more air.

 

Ok. So would it hurt the motor? Or just not make as much hp after say, 4,000 rmp?

Thanks guys for all the info
Will

 

I live in pensacola also and can give you the name of a corvette guy from way back. He owns a small auto repair shop on the northeast side of town and works on all models but he does all of the work on vettes himself. I know he would be more than happy to talk to you. He has always been very reasonable on repairs and I have never been dissapointed with his work.