Advice on EFI conversion please

[ds15]

I’m writing to ask for advice on my approach for a not-quite-usual EFI conversion on my 74 TR6 (CF22072U).

I’ve just purchased a collection of parts that looks like two near complete PI sets including early type manifolds, linkages, cam, metering units, distributor, pipes, plenum and so on.

My thought is to convert to EFI using the 6 injector PI system as basic architecture.

I’ve got a good local LBC mechanic who says he’s comfortable with the mechanical aspects of this project, but he’s not done an EFI conversion. I'd like to get him in touch with a tuning shop which is familiar with ECUs like Haltech and Megasquirt. Between the two of them I should get workable recommendations for an ECU and software, distributor and fuel pump plus the skills to make all the pieces work together.

What do you think? Will this approach work? Many thanks for your comments and suggestions.

David Soknacki

[Elwood]

I have a friend in my TR club who says that the PI manifolds can easily be converted to electronic injectors, and since he runs a fuel injection biz, he probably knows what he is talking about. Hope this helps some.

[HuhReally]

Eminently feasible. In my limited experience, a lot of decisions flow from this one, Are you going to use the PI individual throttles for throttle control?

Yes. It will be difficult to get a clean Manifold Absolute Pressure (MAP) signal. Which means fuel computations will be based on throttle position and RPM (AlphaN). That may drive computer choice. Additionally, ignition timing will be based on RPM only. Timing drives torque output at any given RPM which gives you that particular HP. This means you would be optimized at wide open throttle (WOT), but not so much at lower loads.

No. That would require a common plenum and a single throttle body. A good plenum is about 1.5 times the engine displacement in volume and won’t collapse with 14PSI differential. A single throttle body should be sized to not throttle the engine at WOT max RPM but not so big as to make tip in response a problem. In this case there would be a great MAP signal. With ignition control based on load and RPM, torque could be optimized throughout the range of operation.

Either way, both require high pressure fuel (3BAR), filter, supply line, pressure regulator, possibly return line. You may need a swirl pot to prevent cavitation. An oxygen sensor would be great, Bosch LSU ADV would be my minimum.

[baws]

Eminently feasible. In my limited experience, a lot of decisions flow from this one, Are you going to use the PI individual throttles for throttle control?

Yes. It will be difficult to get a clean Manifold Absolute Pressure (MAP) signal. Which means fuel computations will be based on throttle position and RPM (AlphaN). That may drive computer choice. Additionally, ignition timing will be based on RPM only. Timing drives torque output at any given RPM which gives you that particular HP. This means you would be optimized at wide open throttle (WOT), but not so much at lower loads.

No. That would require a common plenum and a single throttle body. A good plenum is about 1.5 times the engine displacement in volume and won’t collapse with 14PSI differential. A single throttle body should be sized to not throttle the engine at WOT max RPM but not so big as to make tip in response a problem. In this case there would be a great MAP signal. With ignition control based on load and RPM, torque could be optimized throughout the range of operation.

Either way, both require high pressure fuel (3BAR), filter, supply line, pressure regulator, possibly return line. You may need a swirl pot to prevent cavitation. An oxygen sensor would be great, Bosch LSU ADV would be my minimum.

Have I said "I love my ZS's"?

[Steve]

I recall a number of cars I saw in the UK had their systems updated to electronic PI, the original bodies were fitted with Bosch injectors. Would be a neat project.

[lfmTR4]

PI cars had a different cam and other bits that US market cars did not so I’m not sure that just bolting on the PI to a US market car is a good idea no matter what injectors and pump you use. The bits have to work together efficiently to run smoothly and generate horsepower. Stock motors are over carbureted with the ZS cabs so imagine what you would get with PI.

[darock]

If you don't want to tinker around you better go with a "sorted" setup like a Haltech. Costs more in the first place but will be a lot easier later. Megasqirt despite being a lot easier nowadays is still more a DIY approach.

Bernhard

[kiwican]

This site might be of help

www.eficonversons.co.uk

[stitchit]

I don't know these guys are still in business, the best company to talk to is EMERALD3D http://www.emeraldm3d.com they have bolt on preconfigured system. This can be linked to a tablet tune as you go package, it also offers you 3 switchable curves. It uses a webber manifold and throttle bodies.

[JochemsTR]

Hello David,
I bought ECUMASTER EMU Black. Very good features and good software. Pricing is just a little above MS3. Yes, some may think its overkill, but that is upto the buyer.
I got myself CR Bodies, converted with bearings and bored up for more airflow (like CP).

@ HuhReally: Speed Density even with 280 Cam works just fine. No need for AlphaN.

Jochem

[JochemsTR]

With any EFI system, the hardware isn't the problem. Getting your car to run in all conditions takes tuning adjusting your VE/AFR Tables over and over and over....this take time, patience.

[JochemsTR]

Just to show clear picture of those CR Bodies with Bosch Injectors....this was on my test bench.
The car runs with everything besides...good clear view of how the injectors work...
Jochem

[stitchit]

Are you using the individual throttles? Are they on a single shaft of seperate SHAFT?

[JochemsTR]

Hi Stitchit,

hope these pictures help

[JochemsTR]

The 3 Bodies have their own shafts, but are connected. Nothing changed from the Original. The shafts have bearings, since common failure with CR or CP Bodies are the worn housings.
Still need to synchronize and this is being done like the original PI....
My goal was to keep the original look as much as possible....
Jochem

[JochemsTR]

Compared to my carburator, I just turn the key, no choke, nothing and just watch the system regulate itself. EFI reacts more aggresive than carburator. But the overall 6 cylinder character remains.
As you can see, not much change from an PI except for the fuelrail and the wires on the injectors.

[ds15]

Hi Joechem
1. Thanks for the inspirational photos!
2. My plenum looks somewhat battered and I'm missing an air cleaner assembly. Rimmer shows that the two parts are not available.

Where did you get yours?

Many thanks for your help.

D