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fuel injection & crank-fired ignition on 907 engine


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I have been working on converting the 2.0L 907 engine in my Jensen-Healey to crank-fired distributor-less ignition and fuel injection.

I got the car running first on the crank-fired ignition to make it easier to debug one specific thing at a time. Once I had that done and

got the car completely reliable with just that change then I came back around and removed the Zenith-Stromberg carbs in order to

replace them with multi-port fuel injection.

I have a 14 page PDF article I wrote on the crank-fired ignition conversion process. This article includes various wiring diagrams and

photos of the critical bits of the conversion. I have E-mailed this pdf file out on request to various folks.

Just today I got the fuel injected car over to a friend's house where he took a video of me talking about the EFI conversion and

showing the motor running quite well.

If anyone is interested the video can be found on youtube at:

This is a first prototype with very rough wiring and some functional but crude looking air filters. Eventually I plan on writing a similar

article covering the addition of the Electronic Fuel Injection.

Edited by StevenD57
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I have been working on converting the 2.0L 907 engine in my Jensen-Healey to crank-fired distributor-less ignition and fuel injection. I got the car running first on the crank-fired ignition to make

Hi Steven Is there any chance you could email me your pdf article on the FI conversion you did on your Jensen Healey? I am about to start a project on my 1973 JH. Regards SImon

This is something I'd like to do on my Esprit. I made and fitted a megajolt to a ford xflow powered seven and that worked very well. I'm always interested to see how others have mounted the trigger wheel and sensor as that's the hardest bit really (from my ignition only experience - I daresay the fuel mapping takes a fair bit of effort) I'm just on the lookout for a set of throttle bodies suitable to swap my dellortos out for that don't cost a fortune - I may be waiting some time!

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This is something I'd like to do on my Esprit. I made and fitted a megajolt to a ford xflow powered seven and that worked very well. I'm always interested to see how others have mounted the trigger wheel and sensor as that's the hardest bit really (from my ignition only experience - I daresay the fuel mapping takes a fair bit of effort) I'm just on the lookout for a set of throttle bodies suitable to swap my dellortos out for that don't cost a fortune - I may be waiting some time!

I did this conversion on a Jensen-Healey so I think mounting the VR sensor & trigger wheel might be a little easier than on an Esprit. Particularly an Esprit with AC compressor as I believe I mounted my VR sensor bracket where the compressor would normally go on a car fitted with AC.

As far as the throttle bodies, I really believe trying to find the throttle bodies to fit a Dellorto intake manifold is not really necessary. I think the inatke manifold fitted to the US cars with the ZS carbs is MUCH easier and cheaper to use for an EFI conversion. I used two single throat throttle bodies I found at a junk-yard on two V6 Nissan Maxima cars (one throttle body installed per car). These have throttle plates that are 2.125" in diameter. After making adapter plates to replace the normal ZS adapter plates and porting the plates and manifold to blend to the 2.125" throttle body size, I don't think the dual throat throttle bodies to replace the Dellortos is needed at all. Besides if you never intend to go back to the carbs, you can probably sell the Dellorto setup and recoup a good part of the cost of the EFI conversion.

You can check out pictures of my bits & pieces here:

http://s685.photobuc...H%20EFI%20work/

Edited by StevenD57
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  • 1 month later...

I fitted EFI using an aftermarket ECU and 4 throttle bodies to my red 1984 Esprit Turbo.

I am still using the dizzy and therefore have batch fuel injection.

Due to the 4 throttle bodies we have very low vacuum to feed the MAP on the ECU. Still working on that problem but I did not want to go with a single throttle body as I wanted to keep the existing plenum.

The low vacuum is also due to the low compression ratio of the 910 engine.

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What aftermarket ECU did you use?

Where do your injectors mount? In the throttle bodies or closer to the intake port in the manifold itself?

Do you have any pictures or videos of the install?

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I will take some photos and post shortly.

The throttle bodies were made to fit where the carbs went so that the plenum chamber is still used. In fact it looks much like the carb insatllation, but cleaner.

The injectors are mounted in the throttle bodies and I have used 4 x 450 ones.

The ECU is made in South Africa by a company called Dicktator www.dicktator.co.za and the system is running purely on MAP. I do feel that the better option would have been to use a 50/50 unit working on TPS and Turbo pressure. The problem with the Turbo engine is its lack of vacuum due to its very low compression ratio.

The Dicktator on my 89 Excel HE with its high compression would work much better.

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BTW, the Megasquirt ECU I used on my 907 motor in my Jensen-Healey is able to do a blend of speed density (MAP only) and Alpha-N (TPS based load signal).

The newest code release also includes a new special mode that uses an improved version of this to make independent throttle bodies like your setup work better.

and the Megasquirt is around $400USD for a brand new unit.

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Attached are the pics taken today, basically showing the fuel rail and the injectors of the rear 2 cylinders. As I said, it looks much cleaner than the carbs.

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  • 2 weeks later...

Hello Steven.

I have delivered the Esprit with the throttle bodies and the ECU to the tuners who are 140 kilometres away. Lovely drive even with the poor fueling pre turbo boost.

They are now going to remove the ECU and send it back to the manufacturer to re program to take TPS and Turbo (50/50) The lack of vacuum and the pulsing were just to hard to tune. I will keep you updated on its return in a week or two's time.

I somehow think that going the same route with the Jensen Healey Lotus engine may give the same problems even though you have a higher compression ratio. The problem is with sharing the vacuum with the three ports not in induction mode causing a low vacuum reading and the other is the violent pulsing present from a single port. With the Jensen Healey, I would just go with TPS. I think that would be great..

Would love to find a Jensen Healey roadster for myself and I have been looking in the "for sale" pages locally, but nothing as yet. The other car I just love the look of and that is the Marcos GT of 1964 era. WOW. I want one.

Regards Roger

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I have been driving the Jensen-Healey for quite a few weeks now and it drives just fine with the current tune that is using the manifold air pressure readings as the primary load sensing mechanism. Remember I am using the US spec manifold for the twin single throat ZS 1.75inch carbs that has been ported out to work with two 2.125inch single throat Nissan throttle bodies. The US manifold has a largish balance tube between the two manifold sections just behind there the carb bodies bolt up. I am using a vacuum signal off of this as well as the individual ones off of each of the twin manifold runners so I have three vacuum ports all tied together feeding the brake booster as well as the Magesquirt MAP sensor and the fuel pressure regulator.

Maybe the fuel injection control system you are using just isn't up to the job of working well with this sort of setup. How much is this tuner and shop charging you? I bet for the money you are paying you could easily afford a Megasquirt ECU instead. Another friend of mine in South Africa is very experienced with the Megasquirt ECUs as he has switched three Jaguar V12 engines over to Megasquirt with the EDIS crank fired ignition with wasted spark coil packs. I bet he would be interested in assisting you with the setup. The Megasquirt setup has been used with hundreds of turbocharged and supercharged positive boost systems.

BTW, are you interested in reading a VERY good on-line article about a BMW 2002 motor with a similar throttle body setup to yours? The guy who wrote & published it has some excellent information in his multi-page article that includes a lot of nicely done photos.

Edited by StevenD57
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  • 9 years later...

Hi Steven

Is there any chance you could email me your pdf article on the FI conversion you did on your Jensen Healey? I am about to start a project on my 1973 JH.

Regards

SImon

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Yes, I’d be interested also!

My car has a 912 engine with a DTA ECU And fuel injection using twin Jenvey throttle bodies. This conversion was fitted by Lotusbits, and I have been very pleased with it.

Richard

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