Fuel Injection Overview

The Corvair fuel injection overview will guide you through the transition and answer some of your questions.

This kit was designed and built with 3 major objectives:

• Increase performancedependability, and driveability of the Corvair.
• Completely reversible
• Cost-effective

Features:  

  • GM Type Sensors and Parts
  • Electronic Distributor
  • User-adjustable with Laptop if needed
  • Off-the-shelf GM/Bosch parts
  • TBIs that use carb bases and fit like the originals
  • Simple to install and reduced connections
  • Wideband O2 support/Auto-Tune

This is a DIY Self-Install kit that takes the hard work of resourcing parts and electronics to make a complete EFI kit.  You will need to ensure that all the parts are suitable for the installation and  This will require some time and effort to make it run perfectly as each engine is different.

Background: Fuel injection has always been costly for Corvairs mainly because the Port injection requires costly welding and the manufacture of low-production parts. The Throttle body was chosen for its dependability and simplicity and uses mostly GM main-line production parts to keep the price low. The dual throttle body has been used before but was fragmented and used a costly computer to run.  EFI Temp input was always a problem for The Corvair due to the wild temperature fluctuations of the Air-Cooled engine. We make our own engine temp sensors that are unique to the Corvair engine so the ECM can properly control and trim the engine’s operation. We hope you find this one of the most well-thought-out, economical, and dependable kits ever produced for Corvair, and should provide years of trouble-free service. This EFI system is a DIY system with many pre-made/adapted parts to aid you in the successful installation of your system, but it relies on your skill and knowledge of the Corvair and EFI. If you doubt your abilities, hire an authorized installer or friend/club member to help you with this installation.

Theory: Carbs and points on the Corvair and all engines of that era are a compromise. The Carbs give the best fuel mixture at only certain times due to the design. Distributors can’t compensate for Temp and use flying weights to control the timing… good, but again a compromise. Fuel Injection along with electronic timing applies the best fuel mixture and timing for RPM, Load, and Temp. Other sensors also trim the fuel and timing, but those are the basics.  EFI will increase the life of your engine, reduce maintenance costs, and provide years of trouble-free service.

What should I expect?  Ease of starting, good all-around performance, and better fuel economy. This will not make your worn-out engine new.  It does not fix burned valves, leaking heads, cracked pistons, etc…. its fuel injection. It maximizes the amount of fuel and spark for the best all-around performance and economy based on external factors that a traditional Carb and points can’t do. During the initial cold starting, the engine will run rich (emulating a choke) to aid in the cold start and run.  Your engine will perform better and last longer due to the elimination of cylinder wash and heavy rich cycles that foul spark plugs.  Since you will not be checking your spark plugs as often, your plug wires will last a lot longer.

Will my engine run perfectly?   Out of the box, No, but your engine should run well enough to drive but you will need to make some adjustments using the free software Tunerstudio MS.  If you want to perfectly tune your engine you may want to invest in the paid version of MS Tunerstudio.  This “paid version” will allow you to tune the engine as you drive using the “Autotune” feature will reduce your tuning time. Adjustments to startup, timing, idle, and parameters may also need to be made, but the paid version of the software is not required for those changes.

What is the difference between Gen1 and Gen2/Gen3 EFI?  The first generation EFI used remanufactured GM ECM and throttle bodies but after 100 kits were produced an affordable supply quickly dried up.  The GM ECM was hacked to allow it to run the Corvair engine but it was difficult for most end-users to adjust the ECM.  The Memcal chips that were used to adjust the GM ECM are no longer manufactured and those that are, are fakes from China and will not work.  It also used a throttle body that had a very large bore and was precisely tuned to avoid a stutter at tip-in but gave maximum airflow.  The 2nd Generation uses an easy-to-configure ECM using free software (MS Tunerstudio) and there are many forums explaining the different functions and adjustments. We have reduced the number of connections and included more pre-made parts, Wideband support, and less wiring for a quick install.  The 3rd generation is an accumulation of everything we have learned over 15 years of building EFI.  It features a bolt-on aluminum top and uses a factory-type coil.

How does it compare to other Corvair EFI systems?  Fuel Rails, Lines, Electronic Ignition, Rev Limiter, Wideband, Nitrous and boost control, and dual fueling tables (controls each Corvair head separately) are part of this system at no extra cost.    The throttle bodies have the venturi removed for maximum airflow which = POWER.  You can also order the TBI bored to 1-3/16″ inches to achieve maximum airflow for an additional fee.  Other EFI installs are usually $1000-$1500 more than the purchase price when you add all the things you must buy to install a generic system not designed for the Corvair.  There is a 4 barrel system on the market that touts, just bolt it on and it will self-tune.  Even though we find those claims pretty amazing, they still require a lot of plumbing and an intake manifold that add significant cost to a system that was never designed for an engine as small as the Corvair.  We even supply the fuel pressure regulator to ensure you have a successful EFI install.

Just because you can does not mean you should: Electronic Fuel Injection will allow you to start the engine and drive immediately after starting, even in cold weather. Today’s engines have close tolerances which allow them to run cold without damage. The Corvair engine was never designed to meet designed clearances until after it was warmed. You can drive your vehicle immediately after cranking, but it is NOT advisable to do so until the engine has warmed and proper clearances have been obtained.

Commonly Asked Questions:

What do I need to purchase that does not come with the kit?

  • Fuel pump (Sending unit with a pump available as a kit)  (Approx $249.00)
  • Wideband O2 Sensor (approx $150-250) based on manufacturer
  • High-pressure rubber hose/Steel tube (between the car body and engine and fuel return) $30.00
  • Misc Bolts/Screws to meet customer desire

What is the difference between Narrowband and Wideband O2 Sensors?

  • A Narrowband O2 (NBO2) sensor is calibrated to know three things. Rich, Stoichiometric, and lean. This sensor can tell the ECM when it’s Stoichiometric 14.7:1 AFR (Stoich) but is not used under heavy throttle or idle conditions.  If it’s not Stoich, the ECU will command the fuel to be reduced or added based on the sensor information to achieve Stoich.  The NBO2 sensor only provides information to the ECM under light, coasting, and cruising conditions.  If tuning with a Narrowband O2 sensor, you can only tune 14.7:1 in those areas and others such as WOT are a guess.  These sensors are very cheap compared to Wideband O2 sensors, but are very accurate and have a long service life.  Narrowband O2 systems are NOT recommended unless you understand all the settings and how the engine will interpret the signals.
  • A Wideband O2 (WBO2) sensor is much more sophisticated than a narrowband sensor and can be used as a tuning tool during setup and AFR correction during normal use. Wideband sensors can tell your ECM the exact AFR (example 13.2 AFR) of the engine so the ECM will adjust (add or take away) the value in the VE Table to reach the commanded AFR.  Wideband sensors provide the ECM with the exact AFR values to a tenth of a decimal.  These sensors are more expensive and the service life is shorter than the NBO2 sensor, but should last the life of your Corvair engine.  The Wideband O2 system is highly recommended for tuning and normal operation. 

Automatic vs Manual Transmission:  When using EFI with the Corvair Powerglide (automatic transmission), you will face some of the same issues of drive idle that the engines equipped with carbs,  You can manipulate the EFI system to be more responsive to those RPM changes, but you need to make sure throttle plate openings are the same on both side and adjust both sides together after you get a good idle.  The Automatic will work but will take a little more time than a manual transmission due to the “in gear” idle caused by the drag of the torque converter.  Every torque converter has different drag characteristics, so there is not tune to for all automatics.  It will take a little time and finesse, but it works great.

Should I use Single or Dual O2 Sensors? A single O2 sensor (Narrowband or Wideband) is perfect for the conventional 2-to-1 exhaust as both exhaust streams enter into 1 pipe before entering the muffler.  The O2 sensor is placed ahead of the muffler to gain an accurate reading and should be placed according to the installation instructions.  If you have Dual Exhaust, you can still use a single O2 sensor, but would only read the Passenger’s side, and adjust both throttle bodies.  If dual O2 sensors are chosen, each O2 sensor will trim the throttle body fuel for that side.  Each side of the engine (Drivers/Passengers) is independently controlled based on ECMs dual fuel tables.  These fuel tables will need to be activated within the software and an extra (2nd O2 sensor) wire may have to be installed on early EFI versions.  We recommend that you use wideband O2 sensors for all setups, but particularly for dual O2 sensors as you are not gaining that much control using Narrowband O2.  The provision for the second O2 sensor is not included in the wiring harness and will need to be added separately.  Dual wideband sensors are not available on the 4-TBI stagged injection model.

Should I use the Crank Wheel or the Brown EFI Distributor?  The crank trigger is mounted directly to the crank no “slop” is present and provides precise timing information.  The Brown EFI Distributor has a trigger pickup inside which gives the engine RPM and timing information but is geared from the crank gear and may not give as accurate information as a crank trigger.  It was mainly designed for the racing community which can’t use crank-fired triggers and the engines that use the air conditioning or smog pulley.

Early Model (EM) vs Late Model (LM): 61-63 EM and low HP 64’s did not come with a Harmonic Balancer (HB). When a harmonic balancer is used, you must also switch the rear engine mount to a 64 model for the belt to have sufficient space for a fan belt change.   The late-model control panel is mounted in place of the removed voltage regulator.  The EM/Wagon control panel is mounted sideways in the blank area under the voltage regulator area.  FC has a completely different control panel and is fitted to the shape of the FC engine bay.  The location of each is specified on the installation page of the website.

FC/Wagon:  The FC has little space below the lid….there is not much so most people select the standard early low-profile air cleaner system.  There are a couple of “really talented” metals workers who made air cleaners for the 140, but we recommend if you’re running a 140, use the 2 TBI kit with block-off plates and standard air cleaners.

140 Engine 2-TBI:  The 2-TBI system with 1-3/16″  bores and removed venturi make it a higher flowing TBI and will easily provide enough airflow and fuel to make the 140 engine produce plenty of power with fair fuel mileage (using block-offs).    For the normal driver, we recommend the Bored or Unboard 2 TBI kit with block-off plates or fake throttle bodies.

140 Engine 4-TBI Stagged Injection:  The 4-TBI is all about power and mileage is not a concern as you are just a 140 monster.  We highly recommend a wideband on all models but is a must for the 140-4 TBI setup and you must have a good concept of the computer and EFI.

How do you make the Carb a Throttle Body Injector?  When we get your carb, we disassemble it to the core and remove the throttle shaft and other unnecessary parts.  We then sandblast and media-tumble the base to make it clean and smooth. We installed a new throttle shaft and sealed the venturi holes.  A TBI top is added to the base and injectors and other pieces are added depending on their function (TPS/ICS/4-TBI).

What about Air Cleaners:   The factory air cleaners fit the Brown EFI system.  The early/FC setup will require that you drill and thread with a #10-32 and install hex head bolts.  The backside has a dimple pre-marked to drill and should be accomplished off the engine.  This will allow the spring to be loaded and unloaded without interfering with the injector. You may have to fashion/bend your J-hook to secure it properly on later-model air cleaners.

Brown EFI will work on all Corvair engines that use a bolt-on carburetor.  The ignition system uses the distributor and coil configuration for all engines  The ECM is easily adjustable using a laptop and provided cable to match users’ performance objectives.  Autotune (using a wideband sensor) is a great tuning aid and is available in the MS Tunerstudio software for a $59.00 upgrade fee to the software vendor.

Our TBIs are Corvair Carb-based converted to TBIs with the venture removed and can be bored to 1-3/16″ for maximum airflow.

Wagon EFI using fake fuel pump

2 Throttle body w/Coil Ignition

4 Throttle Body w/Coil Ignition

Legal Stuff:
The E.P.A, Federal Regulations, California (CARB), other states and governing authorities prohibit the sale or use of some aftermarket parts, including those that tamper with, modify, or defeat emissions systems in any 1974 or newer vehicles.  Brown Injection Systems, LLC prohibits the use of its products on emission controlled vehicles.  All parts are sold for OFF ROAD< RACE-ONLY. ground-vehicles use purposes only.