No, not at all. Was stating 'most people' consider aftermarket EFI too complex. Its very simple, if fitech was around a few years back then it would have been a no brainer for me. My carb runs great, and I actually drive my car (just drove 300 miles last weekend). I would love to test out the MPFI setup from them, I may in the future.

I have a first Gen Edelbrock ProFlo system in my 72 Roadrunner. It's not exactly stock, 505 stroker with a decent cam. I love the way it runs. The ProFlo 2 kit is very similar, but offers more tuning capability. The EFI makes the car very reliable, easy to star in any weather, and idles well in all temperature conditions, even with the AC on. I saw a slight increase in mpg, but not much. After I installed an overdrive tranny, I saw a great improvement in fuel economy. With the EFI and the overdrive tranny, the car is a pleasure to drive anywhere.

After the run from Dallas to Green Bay I'd had enough of the blow through carb and bad manners. The EFI went on shortly afterwards.

I used an old Electromotive TEC II system and a port injection intake of my own design. The distributorless ignition was kinda nice but the system operated backwards from everything else out there.
You had to set the absolute maximum amount of fuel then it was divided by all the other factors to get the proper fueling. While effective, it was mind boggling for most people (even those with efi experience). I was largely on my own. Electromotive offered to dyno tune for a fee but their Virginia office is a bit distant for me.

This time around I want a system that is as hands free as possible. While I can figure out an EFI system I don't care to do that again. Too many things compete for my time.

I find it incredible that people are bad mouthing TBI systems when there is millions upon millions of them on the road being driven seamlessly by people every day and there is another group defending carburetors as "all you need".

TBI systems atomize and control fuel much finer than any antique fuel mixer could ever hope to do.

While a PFI system is ideal I doubt few people on this board know much about designing a PFI intake manifold that takes maximum advantage of runner length and plenum volume for a given engine displacement and operating range.

Myself included.

why design when you can buy.

Thanks for proving my point.

A carb intake with fuel injection bungs does not maximize PFI use.

And what point would that be? We're talking adapting a 50 year old design for MPI use. So choices would be limited. But infinitely better then running a carb. Cheers.

Which isn't much better than TBI in that configuration.



Only if your choices are limited to what you can buy over the counter.

A proper PFI intake has the runners and plenum sized for a specific engine displacement, expected RPM range, torque peak(s) etc that take advantage of several well known tuning principles.

I remember one Chrysler study and seminar discussion of an aftermarket intake for the Viper engines. The engineers were laughing as pretty as the intake was the secondary tuning peak of the intake occurred long after the engines internals would have been scattered on the ground.

I'll have to disagree with you friend. PFi is vastly superior no matter what engine designed is used. Even 70 years ago when those German DB series V-12 aircraft engines were using DFI vs the British Merlin's using pressure carburetors.

Except for the wet flow problems like fuel puddling and poor fuel distribution that occur with TBI, albeit these problems are mostly noted during warm-up and cold starting. Either system is an upgrade over carb, but come on, even in the 50's chrysler engineers saw the superiority of an electronic port fuel injection system, ie the 1958 electrojector system.

Apples to Oranges.

Talking the difference of a 33 liter engine vs a 27 liter. The fuel injected engine had a handling advantage as it didn't lean out under certain maneuvers.

One was also supercharged.

Ironically the carburated unit made more power per liter due to being supercharged.

How much wet puddling are you going to get moving the injector 5-6" up the intake tract? Not a hell of a lot.

Again, TBI and PFI are lightyears better than carbs.

Modified carb intakes with fuel injector bungs are far from an ideal PFI solution and ignore the fact that dry and wet intakes have different runner and volume requirements.

Look it up, there are several excellent online resources that discuss optimal intake designs.

Another reason I prefer the FiTech throttle body over the other TBI systems is the fact that they use annular discharge. That will help keep the fuel in suspension better than injectors firing directly at the floor of the plenum.


Intake manifolds have a big impact on port injected systems. That's why the factory manifolds are so complicated. Tumble flaps, multiple port routings, and all that stuff they use helps the efficiency of the engines.

I did what I could when laying out my intake. The runner length was a toss up but I dug into plenum theories and came up with a 390 cubic inch design.

It worked for me. The hot rod was a torque monster. I'm sure someone who had access to all the fluid dynamics software would laugh at my work.

Some people have been discussing an eddy efi kit with intake that is designed for port injection over in the race section. Not sure the cost, but certain it's more than the fitech tbi.

That's what I'm talking about. Very nice adaptation! I have a friend fabricating something similar with a Ford flathead, he'll be using the coil packs, wiring, fuel pump , other odds and ends & PCM from a 11 Camaro. All going into a deuce. Again very nice.

From their FAQ's:

Q: Are these systems E85 compatible?

A: Yes, but please reduce the output claims of the system by 25-30%.

The Edelbrock XT PFI intake is a nice intake, only avaliable for RB engines with standard port size. The XT computer that comes in the kit is quite lacking (no wideband O2, no self tuning, no A/C idle compensation, no cooling fan outputs. The kit is also expensive, around $4,000. They do have an upgrade for the stock computer, but I think it is an additional cost, I think around $500?

If you have a 440 and want to use this intake, don't buy the kit, just the intake, TB, fuel rails/hardware, and maybe the injectors (depending on cost and injector size needed.) The EFI sensors, MAP, Air Temp, coolant temp, are all common GM sourced stuff.

Then you can get a computer and wiring harness from Holley, FAST, or Megasquart. All these can handle a variety of ignition/trigger position sources.

On the FiTech E85 question above, The answer needs more information.
I think they are they saying the peak advertised HP level will be 25-30% lower because the injectors size? Not that the engine will make less power on E-85 (upto the injector size limitation?)

Forgot to mention, the fuel tank mounted fuel pump is a better design than feeding the remote sump with the stock low pressure engine mounted pump. The low pressure pump is still susceptible to vapor lock because the suction side of the pump can lower the pressure the fuel is under lowering the temperature the fuel will start to turn to vapor. The Vapor20-Liquid temperature (20 parts vapor to 1 part liquid) at standard atmosphere temp varies around 95 degrees to 140 degrees depending on winter/summer blends of gas according to this Chevron Tech review:
https://www.chevron.com/~/media/chevron/operations/documents/MotorGasTechReview

Interesting article because gasoline is many hydrocarbons mixed, different parts of it vaporize at different temperatures.

Heard back from FiTech about E85, here is the response:

Hi Mark
yes you can run E 85 with our system, just deduct 30% from the
advertised horsepower on our throttlebody's.
Anything else let me know

E-85 carries fewer BTU's per gallon so it takes more of it to support the same amount of HP. For E-85 applications its always recommended to upsize injectors at least 30% for this reason.

This is true for any system.

FYI not all injection systems are E-85 compatible as it is corrosive to some degree. Chrysler use to sell Flex Fuel Spirits and everything in the fuel system was stainless steel for this reason. Even the valve guide seals were unique as the fuel would attack the regular seals.

Anyone know what the conversion to compare Gasoline to E-85 per unit of air?
I think E-85 has about the same BTU / gallon as propane 84250, and gasoline is 116090 btu/gallon, but Gasoline (ideal) Air Fuel ratio is 14.7:1 where E-85 is 9.7:1, so you can burn more E-85 fuel with less air to make up the difference in BTU, but I don't know how to compare the two.

Just trying to see which has the greatest BTU for a given amount of air, even though you will still be using more E-85 fuel.