MFI to EFI

[jpnovak]

I am building a new engine and wanted EFI and ITBs. I had some MFI stacks around and thought I would just adapt these. So I made some EFI adapters that screw into the heads in place of the MFI injectors.




I like the Siemens Deka injectors that were originally used on BMW applications. They have 21mm tips and almost protrude into the intake tract. Very much like the MFI injector.



I made some fuel rails but did not like them. I decided to make a flex line system similar to the RSRs. I just got my parts back from the plating company. They came out great.





Now I just have to finish building the new motor...

Oh, these will likely be offered in the catalog very soon by our sponsor.

[Dave Colangelo]

Swanky! What kind of ECU are you running?

Regards
Dave

[Jim Richards]

Jamie, you mad scientist! I can't wait to see how this turns out.

[Quickstep192]

I can't wait for you to turn it into a turnkey offering!

I have a car that was originally MFI and was converted to Webers by the PO.
Fooling with the Webers was fun the first hundred times, then started to get old.
I have the original MFI stacks and would love to convert to EFI.
I like the RSR look flex line system too; better than fuel rails.
Please keep us up to date on your progress.

[jpnovak]

Dave, I have been installing Megasquirt based systems for the past many years with great success.

Jim. you are too funny. Good to hear from you.

I have a nearly turn-key kit right now. That is what our host will have in the catalog. The challenge is offering final fuel line fittings and ECUs as everyone has their own idea and each install is a little bit different.

Send me an email and I can help you put together a system. If you already have the stacks and linkage the rest is very easy to convert. Just need to figure out what fuel connections are remaining after the weber conversion. Do you still have the return line?

[sjf911]

Nifty looking, I like the retro look. How are the injectors anchored to the heads? Also, do you have thermal isolators or is there any concern about head temperatures and the injectors?

[zelrik911]

Very neat solution.
Where do the connectors ( & clips) between the black lines and the injectors come from?

I was thinking you could make a 'figure 8' shaped keeper to hold the injectors in and bolt one end onto the manifold stack stud. This is how the injectors are secured in DJet EFI Mercedes from the early 1970s.

PS: This would solve some problems that hold back EFI conversions on Lucas petrol injection on the Triumph TR6 (UK Euro & Australia, not USA ) by not needing a fabricated fuel rail. Also looks very close to original - as classic cars in Europe cannot be modified in any way (that's noticeable ha ha!!)

[jpnovak]

Steve, These are currently friction fit just like the CIS systems. With the long tip injectors they are very tight and you have to pry them out of the holder to remove. I would not be worried about them coming out. Even an intake backfire would not have enough pressure the push them out. I am not concerned about the heat. Once properly tuned the CHT should be within an acceptable range.

Zelnik, The clips are standard injection clips. Nothing special there. Yes, it would be possible to have a lower clip but it is not really needed.

I am happy to discuss other applications and installations. I am not familiar with the Lucas systems.

[Jonny042]

I've been working on a similar setup - mostly gathering parts so far but I now have enough MFI throttle bodies and stacks to keep me going for a while.

I have an SC Based 3.2SS that I am converting from CIS to EFI, but using MFI - my initial thought was to machine the heads for MFI (just in case I get bored and need a challenge, down the road!) and then use your adapters to fit the deka injectors. I had seen them on your website.

Lately I have been thinking I may as well just machine the heads for the EFI injectors. SInce the thread for the MFI injectors is 12mm and typical EFI injectors are 14mm, there is probably just enough meat in the head for this approach, and the tiip of the injector would be that much closer to the surface of the port.


Like you, I have been put off a bit by the fuel rails I have seen. The extruded aluminum ones are the easy way out, and effective, but simply don't have the right vibe in the engine compartment of these cars IMO.

I really like the injector top adapter idea - I've only seen these a few places and always assumed they would require "normal" fuel hose, but this looks really slick - is that 5/16 nylon fuel tubing?

[al lkosmal]

Jamie,
Looking good. Very cool w/retro-vibe. This offering, combined with your EFI/ECU tuning skills, should be a winner.

regards,
Al

[Quickstep192]

Originally Posted by jpnovak

Dave, I have been installing Megasquirt based systems for the past many years with great success.

Jim. you are too funny. Good to hear from you.

I have a nearly turn-key kit right now. That is what our host will have in the catalog. The challenge is offering final fuel line fittings and ECUs as everyone has their own idea and each install is a little bit different.

Send me an email and I can help you put together a system. If you already have the stacks and linkage the rest is very easy to convert. Just need to figure out what fuel connections are remaining after the weber conversion. Do you still have the return line?

I'll drop you an email. My car still has the original fuel pump and return and uses the PMO setup with the restrictor on the return to establish fuel pressure, so yes, I still has the return.

Curious to know how you're feeding fuel to the flex lines. Did you build some type of distribution manifold?

[jpnovak]

Jonny,

I started with a fuel rail setup on the adapters. The problem is clearance on the driver side with the MFI linkage. It does not like WOT unless you use short injectors. The flex lines eliminate this problem and maintain a look.

IMO there is not enough room to accurately drill an SC/Carrera head for EFI injectors. The flat that is centered on the outside of the intake mount is considerably smaller than the early head castings. I suppose that if the counterbore is not flat and concentric you would be fine but at the risk of cutting the o-ring upon installation.

The fuel lines are made with Cohline Polyamide tubing. The same as used in Factory CIS systems.


@quickstep. The original MFI pump does not put out enough pressure for EFI installations. Since you have the plumbing it is relatively easy to put a new pump inline and take advantage of existing lines. You will need a regulator on the downstream side of the fuel system.

Yes, these have a distribution manifold that mounts in the center of the engine bay. I am mounting mine on the shock tower.

[jpnovak]

Thanks Al,

I am not sure how I missed your comment this weekend. This means a lot considering how nice your ITB triple speed project is.

Jamie

[Dodge Man]

With the OEM $$$$ value of MFI parts, the modern commercial EFI parts available that look like MFI were not an option? Just asking?

[Maxhouse97]

Any update on the kit? Were you planning a 3.2 application?

[jpnovak]

Hi Tony,

I do not really have any updates.There are a few systems out there working well.

I have not really planned to do a system for a 3.2. You could install the injector lines on a 3.2 and replace the factory fuel rail setup. Though there is really no need for this and there would be clearance issues with the AFM around Cylinders 5 and 6.

The adapters are listed in our host's catalog. Here is the link.

Porsche 911 (1965-1973) - Fuel Injection - Page 1

[Maxhouse97]

Thanks Jamie. I was actually looking for a full ITB system. I thought this kit was intended to provide that with stock MFI HW.

I'm doing my research now ... and may start a ITBs for dummies thread since it seems to be quite complicated!

[jpnovak]

Tony, This is designed to allow those with existing MFI systems to convert to EFI retaining the ITBs. There are several reasons for a conversion but the most prevalent are aging MFI pump that is out of spec or in most cases, building an engine that no longer matches the MFI space cam fuel delivery profile.

There are a few sources for ITBs for your 3.2. PMO, Borla (Formerly TWM), Jenvey, Rothsport, etc all offer a system that would bolt up to your Carrera. The additional components would be the ECU system to drive it and a competent tuner to help set it all up. This last part is the most important factor. If the tuner is you or a local shop, find a system that is easy to use and familiar to all parties.

[Nux]

ahh the search function is really a bliss! I want to do this exact conversion on a 2.0S MFI engine.

Jamie: How did this setup end up doing in the end? Did you use a TPS or just MAP?

And how exactly did you screw those things in the heads?

[jpnovak]

It works very well. Here is my latest build.

EFI based on Factory MFI stacks and throttle bodies. This is a hot rod 2.8.





This system runs Speed Density (MAP only). There is no clean way I have found to connect a TPS to the factory stacks. Its not really needed. The MAP sensor responds much faster than TPS anyway.

Fantastic throttle response. It just goes fast and runs great everywhere.

The outside of my adapters are knurled allowing them to be turned easily into the heads.