Corvair Fuel Injection
Frequently asked questions

Is it cheaper than a rebuilt carburetor?
No. Not even close.

Is this a fully calibrated "Turnkey" system?

No. These are throttle bodies that fit Corvair engines directly to make it easier for you to build a do-it-yourself system.

Is this the cheapest way to add fuel injection?

No. Probably the cheapest way is to use the original equipment parts from a junk yard engine of a similar size and configuration.

Why not use the original equipment controller from another car?

This is possible if you can find an engine of very similar capacity and power output. You also need to be able to use all of the sensors that the controller requires. Since almost all other cars are water cooled instead of air-cooled, the coolant temperature sensor may be the largest problem. See examples built by Ted Brown and Craig Nicol.

Is this the cheapest way to increase fuel economy?

No. Pump up your tires. Buy a wide band oxygen sensor ($300) and tune what you have to the edge of leanness. Then buy a SafeGuard ignition system from American PI to limit the pinging caused by the lean mixtures.

What does a fuel injection conversion cost?

The parts can cost as much as $15,000 (cylinder head modifications $3000, engine assembly $2000, manifolds $1000, throttle bodies $2700, fuel injection controller $5000, fuel injectors $300, high-pressure fuel pump $400, fuel pressure regulator $150, fuel filter $150, wide band oxygen sensor $300).

Or as little as a few dollars to buy a junk car to strip the fuel injection components and make all the adapter parts yourself.

The Black Hawk Engineering turbo system comes in the middle with a parts cost of about $2,850 for the turbo system with all new parts (throttle body $1,250, fuel injection controller, relay box and wiring $600, sensors $100, fuel injectors $200, high-pressure fuel pump, fuel pressure regulator and fuel filter $250, wide band oxygen sensor $200, plus return line, hoses, clamps, etc.).

The Black Hawk Engineering non-turbo system costs about $2,350 for the 2 throttle body system with all new parts (throttle bodies $900, fuel injection controller, relay box and wiring $600, sensors $100, fuel injectors $100, high-pressure fuel pump, fuel pressure regulator and fuel filter $250, wide band oxygen sensor $200, plus return line, hoses, clamps, etc.).

You will also need about 20 hours of labor to fabricate a wiring harness and fuel lines and to install the the fuel return line, high-pressure fuel pump, fuel pressure regulator and throttle bodies. That will add about $1,500 to the cost if you pay someone else.

The you will need to tune the system. This will probably take another 10 hours or $750. If you pay an experienced technician to tune the system on a dynamometer, it will take less time but you will also have to pay for the dynamometer time so the cost will be about the same.

What MPG can I expect with EFI?

This depends a lot on driving style, but here are some representative figures for a modified 95 HP engine with the turbocharger & carburetor from a 1966 180 HP engine (Otto cam, vacuum advance, MSD ignition with boost retard, K&N air filter, etc.) in an early model coupe in mostly highway commuting:

Worst mileage recorded (30% rich cruise step) 13 MPG
Stock 180 carburetor 16 MPG
Optimized jet & metering rod combination 18 MPG
The same engine with electronic fuel injection (using the extra power) 21 MPG
The same engine without the turbo (95 HP setup) 22 MPG
The same engine without the turbo and with electronic fuel injection TBD

Will the fuel-injection conversion pay for itself in reduced fuel costs?

Eventually. The payback mileage is about 58,000 miles with $3.25/gallon gas prices. When gas prices rise to $4.00/gallon, the payback mileage is about 47,000 miles. At $5.00/gallon, the payback mileage is about 37,600 miles. At $10.00/gallon, the payback mileage is about 18,800 miles.

What do throttle-body injection and port injection mean?

Throttle body injection uses a few fuel injectors mounted on a central throttle body like a carburetor. Port injection uses a separate fuel injector for each cylinder. Since Corvair cylinder heads do not have fuel injector bungs, the cylinder heads would have to be modified by welding and machining to add fuel injector pockets.

What do high-pressure and low pressure mean?

High pressure fuel injectors usually require about 40 PSI fuel pressure. The low-pressure fuel injectors used on most throttle body injection systems usually require about 12 to 15 PSI fuel pressure. Carburetors use 2 to 6 PSI fuel pressure. The Black Hawk Engineering fuel injection systems use the more widely available high pressure fuel injectors mounted on throttle bodies.

Why throttle body instead of port injection?

Port injection is slightly more efficient, produces slightly more power and slightly lower emissions. Throttle body injection is much easier to install and does not require disassembly of the engine to weld fuel injector bungs to the cylinder heads. My goal was to create a bolt-on system that could be reversed if desired.

The next turbo project will have port injection and a larger throttle body.

Why does Black Hawk Engineering make fuel injection components for Corvair engines?

I wanted to experiment with fuel injection and I have 2 vehicles with Corvair engines that are project vehicles (not daily drivers). This made them logical candidates for experimentation. My goal was to create engines with better performance and better drivability that could survive in normal driving for a long time.

High-pressure fuel injectors are available in a much wider range of flow rates than low pressure fuel injectors and high pressure fuel injectors are required for port injection with turbochargers, so I chose to use high pressure fuel injectors for my experiments.

Should I build a turbocharged or normally aspirated Corvair engine?

Normally aspirated (non-turbocharged) engines make more power by generating more air flow at higher RPM. Turbocharged engines make more power through increasing boost at normal RPM. It is generally more expensive to build an engine that will withstand high RPM than to build an engine that can handle more boost.

Corvair engines have difficulty breathing because of the restrictive cast intake manifold and small diameter exhaust stacks with a large dent in the side for pushrod tube clearance. A stock "140 HP" engine only made about 110 net HP and 146 ft-lb of torque. In order to get more than about 135 HP, you need to convert the heads to slant exhaust tubes with exhaust headers. To get more than about 170 HP you need to remove the cast intake log manifolds and use two 3 runner manifolds with Weber carburetors or a 6 runner manifold with a 4 barrel carburetor. This is all quite expensive. A set of heads modified by an expert costs at least $3000 plus the intake (another $3000 for Webers and manifolds) and headers (a minimum of $500 for Clark's headers, much more for equal length headers).

A stock "180 HP" turbocharged engine makes 148 net HP and 210 ft-lb torque. The stock YH carburetor and muffler are very restrictive. Large increases in power are possible by reducing the intake and exhaust restriction. Turbocharged engines have 3 potential problem areas. The first is detonation, the second is insufficient cooling and the third is piston failure from high boost. The first problem can be solved with a SafeGuard ignition system from Ray Sedman (about $600). The ability to cool the engine will then limit the amount of power that can be produced. If the cylinder heads are carefully deflashed (excess metal removed from between the cooling fins) and the sheet metal carefully sealed, the engines can produce significant power. The "Engine Analyzer" software program predicts 193 HP and 278 ft-lb of torque for my turbo fuel injection system with a wastegate limiting boost to 12 PSI to prevent collapse of the pistons.

I favor turbocharged engines for high performance street use. For autocrossing, a normally aspirated engine may necessary for quicker throttle response.

Why MegaSquirt?

MegaSquirt is a fuel injection controller developed for educational purposes. It is supported by a community of several thousand people. Many of these people have developed add-on software and equipment. Others answer questions on the forums. Since education rather than profit is the primary goal of the group, the cost of the controller is much less than other fuel injection controllers. The systems are tuned using free software on a laptop computer.

Will other fuel injection controllers work with Black Hawk Engineering throttle bodies?

Yes. Most aftermarket systems can be adjusted to match the number of injectors used and the flow rates required. Be sure to check if the coolant temperature range for air-cooled engines can be accommodated.

Will Black Hawk Engineering tune the system after I install it?

That is not included in the purchase price. Email and phone support are available, but you will have to tune your own system (or pay someone else to tune it).

Will Black Hawk Engineering give me a free fuel injection system so that I can test it for you?

No, If you are too lazy to work for the money to buy an EFI system, you are probably too lazy to install and tune even a free system.

Are group buy prices available?

Yes. Email for details.

There have been a lot of negative comments about EFI in the Corvair forums lately. What do you think?

There are many people who never build anything so they have a lot of spare time that they use to belittle those who do build anything new.

I take the advice of Mark Twain: "Keep away from people who belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great."

If you want to continue to live in the sixties, that is OK with me, but I would rather continue to learn new things.

$5,000 for an ADMITTED 4hp gain on a 140? What the heck am I missing here????


The actual price is $3,138.

I guess that you are also willing to ignore the 20% improvement in fuel economy and the huge improvement in drivability.

4 carburetor Corvair engines are not limited by carburetor flow capacity like the 2 carburetor and turbo engines. The 4 carburetor engines are limited by tiny exhaust stacks, restrictive exhaust manifolds, restrictive intake passages, an outdated camshaft design and limited cooling capacity.

If you do the math, a 164 cubic inch Corvair engine at 5,500 RPM and 85% volumetric efficiency consumes 221 CFM (cubic feet per minute) of air. The estimated airflow of 4 Rochester H carburetors with 1.25" throttle plates is 308 CFM at 1-1/2" water pressure drop. The original 4 carburetors have more than adequate airflow for stock engines. The estimated airflow of only 2 Rochester H carburetors with 1.25" throttle plates is 154 CFM at 1-1/2" water pressure drop so using only 2 carburetors does limit airflow.

The estimated airflow of 4 Black Hawk Engineering RH throttle bodies is 399 CFM so there is even more extra capacity in case you improve the airflow through the engine.

399 CFM is 80 percent more than 221 CFM. So you could still use Black Hawk Engineering RH throttle bodies if you increased the airflow by 80%. This could give you an 80% increase in horsepower or about 200 HP. All you would need is ported slant-tube cylinder heads, an optimized camshaft, tuned exhaust headers and a whole lot of development time. That will cost a whole lot more than the fuel injection system.

Horsepower costs money. How much are you willing to spend?

Corvair owners are frugal. Why don't you sell fuel injection systems at a huge loss so that more Corvair owners will be willing to buy them?

This is a part-time business, not a charity. The parts are fairly priced for the number of hours of machining time required to manufacture them.

Still have questions? Send an email to: sales at blackhawkengr dot com

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