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Old 09-05-2019, 02:30 PM
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Default Opinions on EFI system

Okay, so I’m getting some miles on my Cobra now and am still fiddling around with letting and accelerator pump tuning on the Brawler carburetor. I got to thinking, why am I wasting my time? Why not go EFI? So I’m looking for anyone’s opinion, from their experiences, not hearsay, on what bolt on self learning system with timing control you would recommend. I’ve got a .040” over 351W with aluminum Edelbrock heads, and intake, and a healthy cam that’ll run with 13 inHg at idle, and probably about 400hp.

Holley Sniper?
Fast EFI?
Atomic EFI?
Any other?

Also, can these systems learn okay with the open headers we use?
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Old 09-05-2019, 05:31 PM
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Lots of discussions on this subject. Try using SEARCH.
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Old 09-05-2019, 11:54 PM
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Add the MegaSquirt 99-04 Mustang Plug and Play MS3Pro system to your list. It is like a poor man's Haltech or Motec that uses an OEM factory wiring harness and if you are interested in factory instruments (can't imagine but...) it drives all of them!

The really cool part is the pricing ($1,349) and the use of the OEM Ford wiring harness and the OEM Ford sensors. The 99-04 Mustangs used a camshaft sensor to pick up #1 TDC firing. You can do the same thing with a modified distributor. The MS3Pro supports all types of dumb coils and smart coils (dumb ones are cheaper) in their COP or coil near plug implementations.

The beauty of the OEM harness is you don't have to build it! Its construction will last longer than your car and the connectors (which usually bankrupt the project budget) are already attached to the harness by Ford.

Check out all the other stuff the MS3Pro PnP system offers, like traction control, knock detection and control, engine failsafes etc. click here => 99-04 Mustang PnP and don't forget that they are the only manufacturer to offer a lifetime warranty on the system. Did I mention they are really inexpensive?


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Old 09-05-2019, 11:58 PM
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Old 09-06-2019, 09:48 AM
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I have a FiTech. I made the change because the vacuum issues created by the big cam caused sputtering and bucking below 1800 rpm. I works great, but it is not self learning, you have to program it with the included handheld module. 400 hp system would be about $1000-1200 plus a 177 lph in tank fuel pump and a return fuel line is all you need. The computer and fuel pressure system are all inside the EFI.
Another consideration, is where to put the O2 sensor. If you have collectors in your headers, that is ideal vs tapping into the sidepipe. If the sensor is too far downstream, you may have issues.
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Old 09-06-2019, 10:16 PM
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I've used a megasquirt on two extremely different vehicles. Worked very well, and fairly easy to learn.

Most current systems are "self learning". What that really means is that you can get most of the basic tune done simply by driving around under various conditions. The key here is "most". That last 10% or so requires some work on your part to get it where you want it.
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Old 09-07-2019, 09:29 AM
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SLP, I have a Megasquirt II that connects to the A9L connector if you are interested. Send me a PM.
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Old 09-07-2019, 12:29 PM
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Quote:
Originally Posted by bobcowan View Post
I've used a megasquirt on two extremely different vehicles. Worked very well, and fairly easy to learn.

Most current systems are "self learning". What that really means is that you can get most of the basic tune done simply by driving around under various conditions. The key here is "most". That last 10% or so requires some work on your part to get it where you want it.
How well do these new systems deal with high altitude? My Accel system ran great at sea level but was never taught (before self-learning) about living above 5000 feet and couldn't get out of its own way at 10000 until the tuner closed that remaining 10%
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Old 09-07-2019, 10:48 PM
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carbs are easier to tune efi takes computers and expensive sensors to many things to go wrong after market not as good as factory lots of folks can tune carbs not many can tune efi
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Old 09-07-2019, 11:05 PM
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Most ECU's handle altitude changes really well. It's a fairly simple mathematical calculation based on the air pressure reading from the sensor. A good ECU will have a dual sensor, so it measures manifold pressure and ambient air pressure as you drive.

Cheaper set ups will have a single sensor. It measures ambient air pressure at start up, and sets the fuel map based on that. If you're climbing Loveland pass, it will run great when you start the engine at the bottom, but will gradually get richer as you ascend.

There's always an Old Guy who will insist that a carb is better than EFI.
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Old 09-08-2019, 09:25 AM
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Quote:
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carbs are easier to tune efi takes computers and expensive sensors to many things to go wrong after market not as good as factory lots of folks can tune carbs not many can tune efi
"Easier" is a variable factor based on what you are familiar with.

As for computers and expensive sensors, any professional today is tuning a carb or efi on a chassis dyno using a wide band O2 sensor. Leaded fuel and reading spark plugs are long gone.

Factory EFI systems can be used to very high Hp levels.

A new car with a Carb has not been sold since, what, mid 1980's. Well over 30 years. Most certified master mechanics today have little experience with a carb. Some have never seen a carb on a car, short of going to an antique car show. I think you meant you personally know lots of people who can tune a carb, but few who know what an EFI system is.

Bottom line: if you use all modern expensive computers and sensors on a chassis dyno and tune your carb as close as you can get it, which close is the best you can do, it is only good for that day, assuming the weather does not change. The more the weather changes and time moves on the further from close that reliable old carb will be. Drive up a mountain and all bets are off. EFI will be much closer to spot on at all of these conditions. This is fact.

However a carb typically fails much more slowly and rarely in a catastrophic engine stops kind of way. Not sure if they allow EFI on single engine air craft, but likely not. I think they may still be running points in a distributor, but I have no idea what they really do.
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Old 09-08-2019, 07:55 PM
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On a recent outing, (Thanks again, Bob Cowan) we ran our cars to the top of Pikes Peak. Some carb'd, some factory ECU's and a couple aftermarket ECU's.

My system uses a Performance Electronics PE3-8400 ECU and incorporates both a MAP sensor and a separate barometer sensor. It was tuned for local altitudes (Saint Louis area, 500' ASL) (EightStack system on an FE)

We ran to the top, 14,115 ASL. The carb guys had issues. They made it but their engines were not happy. The other Factory ECU guys made it fine, but Ford has invested a lot of money into tuning and they benefited from it. My car ran to the top, stopped, started, cruised, pulled, etc without issue, performing as well at 14,000 ft as at 500'

The injection learning curve is kind of steep, but once you've learned and set the system properly, it really makes huge difference, compensating all the time for Air Density. Cold start, hot start, high altitude, doesn't matter, it just works.

Don't think you can just put an injection system on and it will run great from day one - it needs tuning, and with the infinite adjustment, it takes a fair amount of work. Most systems 'self learn', but that only covers the fuel tables, you still have to manually tweak cold start, hot start, acceleration and de-accel. But once you get it set, you'll be one happy camper.

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Old 09-09-2019, 09:23 AM
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Quote:
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The injection learning curve is kind of steep, but once you've learned and set the system properly, it really makes huge difference, compensating all the time for Air Density. Cold start, hot start, high altitude, doesn't matter, it just works.

Don't think you can just put an injection system on and it will run great from day one - it needs tuning, and with the infinite adjustment, it takes a fair amount of work. Most systems 'self learn', but that only covers the fuel tables, you still have to manually tweak cold start, hot start, acceleration and de-accel. But once you get it set, you'll be one happy camper.

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Old 09-11-2019, 08:15 AM
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Easier = kind to your wallet and I do not agree with your master mech not knowing how to work on carbs.
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Old 09-11-2019, 11:18 AM
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I had someone install my Holley Sniper and the dual sync distributor

I love it...I hadn't had any issues with it over the last year or so (but haven't driven it more than 1,000 miles).

As far as tuning, I haven't had to do much to it other than explore it and mess with the crank time (which fixed my hot starter issues).

I'm decent with tuning carbs; FI is just much better. If you can get 100 octane gas than maybe carb is fine; but 93 octane at the pump, FI vastly outperforms...not even close.
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Old 09-22-2019, 10:39 AM
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Quote:
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Easier = kind to your wallet and I do not agree with your master mech not knowing how to work on carbs.

if you are worried about your wallet, buy a corvette.
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Old 09-22-2019, 11:42 AM
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Quote:
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Easier = kind to your wallet and I do not agree with your master mech not knowing how to work on carbs.
Hauss I agree a carb is cheaper. I agree it takes less technical knowledge to fiddle with it until it works. I agree that a clueless person is not likely to be able to fiddle with EFI until it works. I am assuming those are the types of points you are trying to make and not trying to put words in your mouth.

I thought I knew my way around a carb, when I was a puppy. After learning how EFI works, you start seeing why you failed, back when it took a ten story building to do what the cheapest calculator will do today. You tune a carb in your garage and then take it to chassis dyno tuner, who will put a wide band O2 sensor on it. After you see see how far off you are, you will start to understand the appeal of measuring what the AFR actually is, real time. Then you will start to see why EFI is so nice to have.

Around here in Ohio, every dyno tuner I contacted is ready to handle many EFI systems. Many will work with carbs, but not all. I never found one who could only deal with carbs and does not work with EFI. Think about it. If one existed, how long could they stay in business?

Just because you do not understand something, it doesn't mean it isn't the best option. However it certainly is hard to trust what you do not understand.
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Old 09-22-2019, 12:37 PM
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I'll make another point. About the only things you can adjust, on a car engine, carb, by an external adjustment, is the accelerator pump, choke, idle speed, and idle jets. Anything to do with normal driving and WOT AFR is pretty much changing parts. In particular, jet sizes, power valves, and air bleeds. Tuning the AFR at WOT, which is where the hidden Hp is, requires draining fuel, disassembly, changing parts, and reassembly. If you are doing this on a chassis dyno, you are getting charged by the hour. So now you are playing with fuel on a hot engine in a car with a glass body encased in a flammable plastic. Or you are paying extra costs to allow the engine to cool.

If I am tuning an EFI car, I type some numbers into a look up table and press enter. I do not even have to turn the engine off.

Timing is the same way, I type in some numbers and press enter. You may be pulling a distributor and changing springs. You are locked into changing parts, while I am typing numbers and pressing enter. I have tremendous flexibility to shape my timing curve to any shape I want, you are limited to mechanical linear slopes. I can shape my AFR table to give any AFR I want at a multitude of operating conditions. You are limited to the physical parts available. I can try countless variations in minutes while it takes you a half hour to try one.

Which is easier to tune?
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Old 09-22-2019, 11:25 PM
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You win I can only say I can adjust my carb with basic hand tools and I have very little experience with efi . I have heard that certain efi systems will have learning problems when trailord, to different altitudes from friends . That is what I was referring too. Not all efi"s are equal. Aftermarket not as good as car manufactors programs . many components to fail mass air flow ,water temp,oxy sensors, and so on.
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Old 09-23-2019, 08:11 AM
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my experience has been that most "pros" don't do a very good job at tuning...they change the jets once and "it's tuned".

having my own O2 sensor has been essential in tuning my carbs.

so nice just to have it perfect all the time with my EFI setup though. it fixed all of my drivability problems: fuel boil, hard start, slow cranking when hot, leaness/richness...such a relief to finally have it all right.
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