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Converting to EFI


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How complicated will it be to convert a carbureted Esprit Turbo to fuel injection if you have access to an injected Esprit engine with a damaged block. Is it a direct bolt on or injected engine blocks have differences?

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I guess that depends which fuel injection system, assuming you mean the GM Delco system.

You need to be able to mount the flywheel sensor, and have a suitable flywheel.

I think all the sensors which bolt into the block are not an issue.

You need a wheel speed sensor.

Tacho take off might need conversion to run off the ECU pulse rather than a dissy system. There may be some other gauge issues, but don't thank so.

Fuel system would need a suitable pump, or swap over fuel tanks and use the later pump.

Put the oxygen sensor into the exhaust system.

Other than that it should be quite simple with the correct wiring harness, sensors etc.

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  • 3 weeks later...

I've got some questions related with EFI conversion;

1) Considering that my speedometer is already working in its current condition, will I need the wheel sensor?

2) According to Hugh Kemp some dimensional changes were made in the efi engines' block, material strengths were altered and an extra boss was inserted on one cylinder to install the knock sensor.

So does this mean that there is no boss in carbureted engine blocks to install a knock sensor?

3) Are these engines internally balanced? What is the possibility creating balance problems after changing the flywheel?

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  • 2 weeks later...

I've also done what Mark has done, and fitted all the lotus parts as much as possible (manifolds, fuel pipes, etc), but fitted an Emerald M3D system.

with regards the block.. You are talking about the later 'zeus' block. this did have the position to mount the knock sensor.

However, the earlier blocks do have a boss in the casting in the correct place for a knock sensor. If you dare, then you can drill and tap this. But, you need to be careful obviousley not to drill through completely or you'll cause yourself some right headaches!!

I drilled and tapped mine.. but in fact my Emerald ecu doesn't use the knock sensor afterall!

I'll be upgrading to the latest version though, so that may well use a knock sensor.

the car will still need the wheel sensor fitted if you go for the Lotus ECU, as it needs a digital speed pulse. You could still use your cable driven speedo though, if you don't want to change it.. but you will need the speed sensor, which I think will require a new driveshaft with the pickup ring on it. You may be able to fabricate a mount for the pickup itself, rather than fit a new rear suspension arm that has the mount for the pickup.

You'll need to do loads of wiring no matter what you do... I don't envy you having done it once!

Make sure you have all the wiring manuals to hand.

I decided that overall it was easier to fit an aftermarket ECU.. although then you have mapping headaches to worry about. It'll need a good few sessions on a rolling road.

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  • 1 year later...


Hilly did this to his Esprit before adding an Audi V8 instead. Here is a description from Lotus Esprit World:

I have to admit, I'm very tempted to do this myself as well. I know Lotusbits sells an almost complete set for approx 2000 pounds. Check their website.


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I spoke to some one about this a few months ago and they were working on the Epsrit kit, don't know where it's up to.

Life is like a sewer, what you get out of it, depends on what you put into it. (Tom Leahrer)

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