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Fitting Fuel Injection to a Carb Car

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WestonE:
I was recently asked about how to fit Modern FI and mapped 3D (load sensing) Ignition to a Carb car without it being too obvious. This is not a simple task and decisions have to be made on how far the associated engine is tuned.

Basic facts
if a single throttle body is used both chokes opening together is better. Think Retrojet DGAS from Webcon fitted to a modified and gasflowed OE Carb manifold
1 choke per cylinder gives better power and economy for given engine speed
Side Draft gives more power than down draft BUT needs a modified radiator set up and great care to get cold air to the intakes. Think Heritage DCOE look alike throttle bodies from Jenvey
The straighter the airflow the better BUT
Hot air loses power and risks engine wrecking uncontrolled combustion called detonation
Long trumpets and long inlet length aids mid range torque on the TC. I know I have built enough of these to know. Check out the Group 4 pictures
Longer Duration cams or inlet only cam need higher compression pistons i.e. 10:1 minimum with 11:1 better and a 4 into 2 into 1 exhaust with matched lengths
Downdraft carb pattern Throttle bodies. Think Jenvey DCNF style Throttle bodies give more scope to keep the existing radiator. BUT they MUST have an insulated air box fed with cold air to give the best result. This is an opportunity to hide them for that stealth look.
You need a modern ECU modern sensors and trigger wheels so forget bits of old Beta IE FI
A 36 - 1 tooth trigger wheel is essential (engine speed) as is load sensing Throttle Position Sensor or Manifold Air Pressure Sensor
Air Temperature and Water Temperature sensors are essential
A wide Band Lambda sensor can tune the system for you in real time BUT rolling road mapping is still essential
Coil per plug ignition only works with Sequential injection
Sequential Injection needs a cam position sensor ( adapted from an Integrale distributor on a Beta IE cam distributor drive)
Batch Injection 1&4 2&3 and Wasted Spark Coil pack will do all most people need
FI needs high pressure filtered fuel supply and does NOT tolerate fuel surge. Twin 8mm fuel lines shielded from exhaust heat feed & return are essential. A swirlpot and high pressure pump like the webcon integrated pump and swirl pot lets you use your carb tank
No body has an existing ECU map for your car that is worth using and trying to drive to a rolling road on a start up map is a very stupid idea. Get it transported or load a trailer.
A good rolling road can map you car in 2 hours with a morning check on cold starting if you have a good ECU.   
ECU's have to be wired into your car and will need a relay and fuse box creating as part of this. It is easier than you think with a written or typed connection plan.

Why Bother?
Pass every emission test HMG will present.
Instant starting & perfect running in cold weather or hot weather
More power AND better fuel economy
Nicer to drive
More reliable - Provided you installed it properly

Enjoy!!

Eric     
300BHP Fuel Injected and Supercharged Montecarlo with a Link G4+ Fury ECU and Drive by Wire

squiglyzigly:
Eric
Thank you for taking time to make this valuable post.  I’m sure there are several of us wanting to make such upgrades to our cars sooner or later, myself included, and you’re patience to keep helping with endless questions on this topic is appreciated.

All the best for the new year
Ian

WestonE:
Hi Ian

Thank you. It is good to know someone noticed. Over time I will try to add some pictures of things like the trigger wheel and sensor install. The only bits of IE I could have mentioned using are the fuel tank. The manifold and throttle body could be used but you would be fitting a new Throttle Position sensor and a new fuel rail to suit modern injectors.

Happy Christmas

Eric

mangocrazy:
Nothing you post goes unnoticed by me, Eric...  ;D

At present I'm intending to continue with my plans to use twin DCOE 45 Webers with my newly rebuilt engine, but am certainly interested to see what would be needed to convert to FI in future. I guess it all deoends how well the car runs on the DCOEs; that will determine whether I decide to convert to FI. Is there anything I can do now to prepare for a future conversion to FI that I can install/bolt on that won't affect carb operation but will make future conversion to FI simpler and easier?

WestonE:
Hi Graham

Aside from collecting the bits to install the sensors and fuel pump. Having twin 8mm fuel hard lines installed is essential. For twin carbs the second line can be capped off.

Enjoy

Eric
Practical Performance Car September 2020 shows how to fit a Land Rover High Pressure Pump and swirl pot to a classic tank. 

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