Tuning EFI vs. carb conversion

[stdyhand]

Well as the title states I am unsure what to do. Tax season is coming up and I hvae a lot of work planned for my 91 GT including H/C/I among some other smaller goodies.

My problem is I read a lot about need a "tune" after this is done. Some say it costs upwards of several hundred dollars to get a tune and then if you ever change anything later you might need to get another tune.

I will be honest, there isn't a snowball chance I am going to pay that much money when I can convert it over to carb and tune the carb myself.

I have been considering whether to do that very thing. We don't have to worry about emissions around here and this car is only used on the weekends for a little fun. I would keep the EFI if I could but not if it means paying hundreds of dollars to make it run right.

I can eliminate all that wiring and sensors and go Carbed, tune it myself, and make power a lot cheaper.

I know the EFI has its advantages and may even have more of a power curve through the low to mid lift range but I've heard that on the top end the carbs tend to do better. However I rarely see that top end very much so I know EFI would probably be more efficient and so would retain it if I could.

My plans coming up:

I am changing to a 351 and rebuilding the block. (Not stroking it to 408 just yet as I can't afford to do this and everything I'm planning at the same time.)

I'll be getting a H/C/I along with a bunch of other stuff, not counting I have a lot of body work to do.

I am only aiming for 400-450 HP so I figure a 351 can get me there without too much trouble. I am looking at AFR or trick flow heads (leaning more towards AFR). I am not sure on my cam choice but it'll be chosen to match the heads and my overall power band of course.

My question is, how may people have done all these types of mods and gotten away without a tune? Do you think I'd be better off going carb?

 

[2000xp8]

With the proper meter and injectors, the car will run just fine efi, no custom tune needed. These guys seem to like to tune their cars, but i believe they do it more as a hobby than a necessity.
Remember, the efi foxbody was around long before dyno tuning and guys did just fine.
Having friends in the business i know for a fact you can easily run 500rwhp+ no programming needed.

As for the carb, i'll be straight with you, it's a terrible idea no matter how you slice it. devalues the car, likely it will run worse not better, and is not exactly cheap.

 

[Cobra912]

while I have owned several supercharged efi set-ups and now a carbed set-up I agree with the above. Unless it's a track car like mine I'd stick with the EFI for an everyday driver / cruiser. While the carb is a helluva lot easier to work on than efi in terms of parts and parts costs, you will deappreciate the value of your car real quick if you ditch the fuel injection - IMO. If driveability becomes an issue with your new set-up, getting a chip tuned isn't really that expensive after all is said and done. If you can afford to the put parts in the car you should be able to afford to make them stay together.

 

[2vNotch]

Save yourself time, money, and hassle....Buy a Demon carb and convert it! Bigger is not always better tho, remember demons flow way more as compared to an edelbroke...i ran a jetted 625 from them on my 347!

 

[LarsD]

Save yourself time, money, and hassle....Buy a Demon carb and convert it! Bigger is not always better tho, remember demons flow way more as compared to an edelbroke...i ran a jetted 625 from them on my 347!

I'd be wary of a Demon. I have one that I have run on my Dodge for the last ten years and it has been great. I needed a new carb for my truck, and despite reading rumblings about the recent Demons having problems I bought one anyway. I ended up having to send it back for a Holley because it was garbage.

That being said I would stick with the EFI if it were my car.

 

[stdyhand]

Well let me ask this. If I decide to run EFI on the 351w I will be putting in, what will I need beside the following:

H/C/I which I'll be getting anyway
Fox oil pan, pump, and pickup for 351
Power steering bracket
harmonic balancer & maybe a spacer for belt alignment
flywheel
Possibly a new Hood for clearance issues.
Injectors
Matching MAF for injectors
Larger throttle body
New CAI
Headers

What is the max HP stock 19lb injectors and stock MAF can handle?

I was thinking about getting 30lb injectors for this 351 if I go with EFI. Is that too much of an injector?

Am I missing anything on that list?




I

 

[stdyhand]

If driveability becomes an issue with your new set-up, getting a chip tuned isn't really that expensive after all is said and done. If you can afford to the put parts in the car you should be able to afford to make them stay together.

The thing is most of us are on a budget. We aim to make as much power with as much money as can spend. I will be making a complete engine change plus doing a lot of body work so I will already have quite a bit of money tied up from the start of this next project. This is not counting I am hoping to rebuild my T5 to Z spec so I'm probably looking at another grand or more right there.

I would agree that in the long run it would make sense to get a tune, but that just isn't possible right away. My concern is keeping the car together and running until I can afford to get a tune. I'm just another working stiff so money for projects takes time, particularly with kids and all.

When you mention getting a chip tuned, are you referring to a dyno-tune or purchasing a chip with a tune already on it? The reason I ask is because the later is about 350 by itself tuned to what you say your mods are, but it would probably never free up as much HP as a dyno tune.

 

[2vNotch]

List looks good! I totally understand a budget thats why i say buy u agood intake and carb and cut out the $2-25oo costs to run fuel injection! Not sure about the stock injectors and MAF but i would imagine they wouldnt b efficient in much more than a 300hp application. As far as the 30# go thats a good injector for stroked and boosted 302 based engines, i believe you are gnna have to step up to prob arnd a 42# if u go 408

 

[stdyhand]

List looks good! I totally understand a budget thats why i say buy u agood intake and carb and cut out the $2-25oo costs to run fuel injection! Not sure about the stock injectors and MAF but i would imagine they wouldnt b efficient in much more than a 300hp application. As far as the 30# go thats a good injector for stroked and boosted 302 based engines, i believe you are gnna have to step up to prob arnd a 42# if u go 408

Well the carb conversion is not out of the question yet. It is still being higly considered. One concern is the fuel tank issue. I keep hearing it is best to get a sump tank or weld one onto a new stock tank. Well the sump tanks cost around $500 and I'm not about to do that. I can buy a baffled sump for $50 but I only have a mig welder so I don't think that is going to weld an aluminum tank so well.

Most of the welding shops around here do not like to weld fuel tanks, even though I explained I would buy a new fuel tank and sump so they don't have to worry about fuel vapors in the old tank.

I know I can use the stock tank and just run a pick up tube, but my concern is vapor lock. I have to run an inline electric pump outside the tank and they only like to push the fuel so my concern is it wont keep a steady pressure of fuel to the carb at higher RPMs.

 

[2vNotch]

Use the stock setup with a pick up and install a regulator between the carb and distribution block ??

 

[foxbodymike87]

I'd be wary of a Demon. I have one that I have run on my Dodge for the last ten years and it has been great. I needed a new carb for my truck, and despite reading rumblings about the recent Demons having problems I bought one anyway. I ended up having to send it back for a Holley because it was garbage.

That being said I would stick with the EFI if it were my car.

The holley on my truck sucks ass idk what the cfm's are but its a big ass 4-barrel and its pretty crappy lol.

 

[Three50won]

stdyhand, just to add...you still have to tune a carb setup. You're not just gonna slap a carb on there and off you go. You're gonna need an AFR gauge just like the EFI guys do. In fact you're gonna need an AFR gauge even more so because the EFI computers will self-adjust to to a certain degree. However if money is an issue then go with a carb set-up...

 

[LarsD]

The holley on my truck sucks ass idk what the cfm's are but its a big ass 4-barrel and its pretty crappy lol.

Yeah the junk carb I pulled off the truck was a Holley as well. lol

 

[Bryan83taco]

List looks good! I totally understand a budget thats why i say buy u agood intake and carb and cut out the $2-25oo costs to run fuel injection!

Where do you get this from? 2000-2500 just to maintain a EFI system? I don't see bigger injectors, 255 lph fuel pump, adjustable FPR, AFR guage, and a tune getting anywhere close to that. The stock 19 lb injectors are good up to 300 hp.

 

[NIKwoaC]

What is the max HP stock 19lb injectors and stock MAF can handle?

I was thinking about getting 30lb injectors for this 351 if I go with EFI. Is that too much of an injector?

The stock MAF really doesn't even support the power a stock 5.0 makes. It is a major choke point on a stock 5.0, so I would suggest you don't even consider it for your 351.

30lb injectors are going to be too small for your application. People ask this question a lot, and Google is your friend. There are lots of websites with calculators to determine the injector size you need. Here is one of my favorites. If I put in 450hp, a BSFC of .5, a max duty cycle of 80%, and a fuel pressure of 39 psi (which is about what a stock 5.0 is), I get ~37 lb/hr injectors. It's usually a good idea to round up to the next available size, so I would think a 39lb injector or so would be a good idea for you.

List looks good! I totally understand a budget thats why i say buy u agood intake and carb and cut out the $2-25oo costs to run fuel injection! Not sure about the stock injectors and MAF but i would imagine they wouldnt b efficient in much more than a 300hp application. As far as the 30# go thats a good injector for stroked and boosted 302 based engines, i believe you are gnna have to step up to prob arnd a 42# if u go 408

No way does it cost that much to run fuel injection! If he is putting this engine in a car that was previously an EFI V8, all he really has to buy is injectors, a MAF meter, and a fuel pump. Can't really count the cost of a fuel pump, because he'll have to get a new one, regardless of which direction he takes, EFI or carb.

Injectors: ~$300
MAF meter: ~$300 (I got my 97mm Abaco from AFM for about that price, and it is fully programmable, right out of the box. So, if he goes with an Abaco, he'll already have some amount of tunability.)

So, he's in maybe $600, MAYBE $700 with new EFI parts, and this is all plug and play, no headaches of converting to carb.

For full tunability he can pick up a quartehorse, which is $250. Software is around $100.

So, in the end, he's about $1000 into EFI parts with full plug-and-play, data logging and tunability.

 

[2vNotch]

I was figuring on him buying an aftermarket upper and lower, fuel rails, injectors, TB, mass air, fuel pump and the whole nine....keep in mind hes wanting to make 600hp, hes not gnna b reusing any stock parts to get there!

 

[2vNotch]

I was figuring on him buying an aftermarket upper and lower, fuel rails, injectors, TB, mass air, fuel pump and the whole nine....keep in mind hes wanting to make 600hp, hes not gnna b reusing any stock parts to get there!

nevermind lol i got him mixed up with another thread...sorry guys

 

[90mustangGT]

Although I have always had EFI vehicles, I will say that carb is much cheaper. Carbs are easy to tune, and cheap to tune.

Devaluing the car, like the cars are worth that much, as thought these are good investments, but it will be unsellable to someone where there is smog testing, but once you do big cams and such, it's off the charts anyways.

MAF sensors are expensive, injectors are expensive, the fuel pumps and systems cost more. Having a "chip burned" , well that is really limited. The cost effective way, but yet extremely expensive is when you start messing with stand alone aftermarket EFI's. Look at the "Tuning" section and see all the issues and cost. Really? I know plenty of guys that know carbs really well. God's gift is the wideband O2 sensor/gauge. Carbs are simple, but it doesn't mean anyone can tune them. It takes some skill, but it can be learned. However, nobody can just write a tune for you.

 

[Three50won]

NikwoaC, you know your stuff. But I just wanted to mention that a stock Mustang MAF might not support the potential of a 5.0, however in stock form it is very well capable of handling the power output. Remember, Ford has never been the type to overkill anything. So they def were not gonna give a 225 hp engine a MAF that's capable of supporting 400 hp. And even if they did you'd still have to take into consideration the rest of the induction system. They'd find a way to choke it off somewhere else anyway.

2vNotch, yes if you bought all brand new components then you would get close to that mark. However you wouldn't be too far behind when you consider the price of a brand new carb intake, the carb itself, the fuel pump, and other components needed for a carb conversion.

90mustangGT, I agree with your post. However I never felt that it was extremely difficult to tune an EFI. If anything it's a little challenging and exciting at the same time. It's kinda fun...and the reward when you accomplish getting the engine running perfectly is worth all the effort.

 

[stdyhand]

Injectors: ~$300
MAF meter: ~$300 (I got my 97mm Abaco from AFM for about that price, and it is fully programmable, right out of the box. So, if he goes with an Abaco, he'll already have some amount of tunability.)

So, he's in maybe $600, MAYBE $700 with new EFI parts, and this is all plug and play, no headaches of converting to carb.

For full tunability he can pick up a quartehorse, which is $250. Software is around $100.

So, in the end, he's about $1000 into EFI parts with full plug-and-play, data logging and tunability.

I have no idea what quarterhorse is. Is that like the Bama chips you buy that are already burnt according to the information you supply them regarding your injector size, MAF, etc? Your talking 350 dollars and its something that will allow me to tune it myself, correct? I wouldn't mind paying that one time if I can use it over and over in the future. Do you hook it up to a lap top like they use on the dyno's? Does this quarterhorse say how much HP/torque your putting out or is that limited to an actual dyno?