FAQ - EFI - Black Hawk Engineering

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.

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?

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.

The Black Hawk Engineering turbo system comes in the middle at about $2,850 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 with all new parts (throttle body $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.).

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 3 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 the boost limited 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?

Yes. Just buy 20 fuel injection systems at the regular price and the 21st system will be free.

Are group buy prices available?

Yes. email for details.

Is this a fully calibrated "Turnkey" system?

No.

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. I am not even asking for repayment for the 2 man-years of my time plus all of the material that I invested in developing these parts.

All of these parts are not usable due to machining errors or design changes.

Still have questions? Send an email to: sales@blackhawkengr.com