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  • 1 Post By eschaider

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  #1 (permalink)  
Old 11-29-2022, 07:26 AM
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Default Holley EFI

Revisiting going EFI from a Holley 650. It appears that there are two choices from Holley for a 347 with a lopey cam that likes 2000rpm and up for throttle response. Is vaccum a major factor in determining which EFI manufacturer to use or stay with what i have. Too much info and not enough knowledge to sift thru what works without days on dyno. Just trying to make up my mind. Our travels are between sea level to 7,000'. Thanks for advice, Gary
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Old 11-29-2022, 10:31 AM
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Most folks these days are headed towards the Holley Sniper EFI systems.

Bill S.
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Old 11-29-2022, 10:44 AM
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Gary,

Lopey idles and vacuum considerations are meaningful considerations for carburetted engines. They make no difference for EFI. In fact the EFI will somewhat smooth out your loopy idle and improve low speed throttle response — although that may not be what you want.

What you want to do before spending money on EFI is to purchase some reading books on EFI systems, which means you will probably spend around $50 on various candidates. Get familiar with the capabilities of EFI systems and decide which capabilities are important to you. Next thing you want to do is hunt down EFI providers that offer those capabilities. Rank them according to cost and capability. Decide how much money you want to spend on the conversion. Pick the system that matches you list of important features and meets your budgetary goals.

One of the most important capabilities you will want is a Mass Air Flow (MAF) capability. There are three fueling models for EFI. Alpha-N, Speed Density, and Mass Air Flow. the only one that will allow you to move 7000 feet vertically and still properly fuel your engine, without retuning, is the MAF based system.

Most aftermarket systems are speed density. If you experience a 1500 foot or more change in altitude, a speed density system will benefit from being retuned. Speed density system providers will either suggest the difference is not worth retuning for or suggest the speed density logic can accommodate it. Both suggestions are wrong.

By the time you get to 3000 feet your engine will feel like it has lost considerable horsepower, partly because of thinner air and partly because of incorrect fueling at that altitude. At 7000 feet you will think you need a tow truck.

The other thing to be sensitive to is sensors. Most aftermarket suppliers like GM sensors. In fact they like them so much they repackage them in their own proprietary bubble packs and boxes and reprice them significantly above the over the counter equivalent GM sensor price point. You want to avoid these types of providers.

If you are electrically handy you will enjoy building you own wiring harness for an aftermarket system. If you are not this will be a royal PITA. Some EFI manufacturers will work with an OEM engine wiring harness saving you all the build effort. By work with, I mean they will plug right into the OEM under dash connector on the under dash harness that connects to the engine harness.

Holley does offer some EFI systems that can make use of selected OEM harnesses. You should look at them. You should also look at the DIY Autotune Plug and Play systems that plug into a stock Ford Mustang harness. DIY Autotune will be less expensive and come with a base tune to get you started. BTW they also support MAF based fueling and use Ford OEM sensors which you can buy directly from Ford.

Here s a link =>MS3Pro Plug and Play. Pick the Mustang ECU closest to what you are doing and the ECU for the year and engine harness you decide to use.

I forgot to mention if dashboard support is important to you they support many aftermarket dashes/displays such as Racepak, Race Technologies, AiM Sports, AEM, Dakota Digital, Autosports Labs, Perfect Tuning, and OEM Ford New Edge dashboards.
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Last edited by eschaider; 11-29-2022 at 11:27 AM..
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Old 11-29-2022, 11:25 AM
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Quote:
Originally Posted by eschaider View Post

One of the most important capabilities you will want is a Mass Air Flow (MAF) capability. There are three fueling models for EFI. Alpha-N, Speed Density, and Mass Air Flow. the only one that will allow you to move 7000 feet vertically and still properly fuel your engine, without retuning, is the MAF based system.
To expand on a MAF system. If you don't use a MAF, and at least one O2 sensor, what you have done is changed the system to an electronic instead of mechanical carburetor. You have a huge expense at no gain over the mechanical system since the benefit of EFI is that it automatically compensates for atmospheric pressure. Yes, even local weather conditions but more importantly altitude changes. If you live at a constant altitude and don't have a MAF then the EFI system will perform no better than a propertly tuned carb and you will have spent a lot more money that you would have used to tune our carbs.

You'll also probably have additional expenses in fuel return lines and more likely than not upgraded fuel lines and fuel pump.

The truth is that unless you go from Phoenix to the mountains, and go there to race, the carbs adjusted for your altitude will perform well enough. Plus, unless you stop, it won't matter, since the MAF takes its initial altitude reading before the engine runs (it can't measure altitude once air flow starts.)

Chances are that if your carbs are properly tuned now, after the EFI conversion you'll wonder if it was worth the expense. Of course, if you've given up on badly tuned carbs a well adjusted EFI system will be a gain.

Lastly, if you are a tinkerer and this is a project to keep your hands busy then by all means go for it

This topic is probably the second-most new thread that has already had many many discussions already in the forum. In fact, you will find the same participants giving the same advice. Search can be your friend.
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Last edited by twobjshelbys; 11-29-2022 at 11:31 AM..
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Old 11-29-2022, 02:23 PM
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If your EFI system has pre and post temperature and pressure sensors then the fueling depends on whether or not the sensors are continuously read or only initially read, as Tony has already said.

A Mass Air Flow sensor reads air mass continuously as the engine operates which gives you a huge advantage over speed density technology and allows you the freedom to go to high altitude like Denver or low altitude like Death Valley without the need to retune your engine. There is typically also an IAT1 (Intake Air Temperature pre-compressor) and sometimes an IAT2 sensor (Intake Air Temperature post-compressor) to map how much the blower heats the air (for proper fueling) but also for detonation control.

Hot intake charges are more susceptible to detonation than cool intake charges. If the ECU's software is smart enough to track the IAT2 temps it can be used to pull timing when IAT2 temps get too frisky. This becomes a big deal for blown gas engines. One of the most detonation sensitive fuels is nitromethane. For the proletariat enthusiast it is always good to know that gasoline is equally detonation sensitive in, yes, supercharged applications.

By now it should have popped up on most folks radar screens that blown gas needs good detonation detection and prevention system. Many but not all EFI systems provide some level of detonation detection. For the ones that do not (or do a poor job) there is an excellent detonation detection and prevention device available from J&S Electronics. It is called The Safeguard and it is available in three different configurations to handle distributor ignitions, smart coils (near or on plug) and dumb coils (near or on plug).

The J&S device will detect knock and then pull timing from just the cylinder than knocked and do it in real time before the next ignition event! there is absolutely nothing available from anywhere else that can do this today. The technology is relatively mature but because of complexity has never been commercially duplicated. It was developed over 40 years ago for turbo charged V6 Buick Regals. Even embedded EFI knock control logic does not perform this well!

This is a link to the J&S website where you can dig little deeper if you are so inclined, click here => J&S Electronics.

Do not get detonation detection and prevention confused with the blinking lights that flash when they think they see detonation. By the time you see the light and before you can react, the damage has already been done. The earliest detonation events are imperceptable to the human ear. You need technology to 'hear' them. Even more daunting the sonic signature of detonation can be elusive.

The J&S Safeguard System consistently catches all of it at inception and pulls timing before the next ignition event occurs. After the event the J&S technology begins to increase the timing at each ignition event until it 'hears' detonation again. When it does, it steps back from the brink and runs that one cylinder just shy of detonating. It does this in real time as the engine is running and for all eight cylinders independently.
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Last edited by eschaider; 11-30-2022 at 12:53 AM.. Reason: Spelling & Grammar
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Old 11-29-2022, 06:21 PM
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Thanks for the info all. This is why i asked for advice. I am most likely staying with my carb. Stumbles a little under 2000 rpm at times but goes strong. No choke contributes.
Great info Ed, Bill and Tony. What eye candy i would like is an 8 stack of webers.
Gary
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Old 11-29-2022, 06:22 PM
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Thanks for the info all. This is why i asked for advice. I am most likely staying with my carb. Stumbles a little under 2000 rpm at times but goes strong. No choke contributes.
Great info Ed, Bill and Tony. What eye candy i would like is an 8 stack of webers.
Gary
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Old 11-29-2022, 06:22 PM
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I think the biggest issue when moving towards Holley EFI is getting it. I ordered mine in February of last year, and still haven't received it, was "apparently" in stock when I ordered it, but low and behold it ended up backordered. Each month they extend the back order to the next.
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Old 11-29-2022, 08:40 PM
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Quote:
Originally Posted by Roylerumble View Post
I think the biggest issue when moving towards Holley EFI is getting it. I ordered mine in February of last year, and still haven't received it, was "apparently" in stock when I ordered it, but low and behold it ended up backordered. Each month they extend the back order to the next.

Which Holley EFI do you have on order?
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