911S 1971 Standalone EMS conversion

[JJ 911SC]

Originally Posted by Quickstep192

If I were doing this in the US, what injectors could I use?
What ECU would be best?
What's a US source for the crank trigger and other sensors?

Clewett Engineering

[Tiago/Tecnomec]

Hi Quickstep192, I lost my first drawings of the adapters, but did a rough resketch, here it goes (please don´t mind it looking so bad):



I fabricated the fuel rails "on the fly", I just measured the spacing between the center of the holes on the heads (on my 2.2 it was 119.5mm, but it depends on cyl. diameter, so each case should be different), then used some SS tube and sheet I had laying around, and with the help of some friends (welder and machinist brothers), we made them.

The coil stands were even more hand-made, I cut 6 "slices" of SS tube that was a snug fit on the coils and rounded off the edges. Then I scribed an outline on sheet, rough cut 6 pieces on the plasma cutter, drilled then filed them down to size, and then litterally hammered them on the bench vise to make that z bend and clear the valve cover corners.

Since my intention was only making the build on this car and the fact that I am a very small shop with limited equipment, there is a lot of hand work involved using simple tools like drills, files, etc. I also tried to use as much of simple and affordable materials as I could. I just like fabricating simple and functional parts a lot more than I like buying fancy expensive parts (that are not always functional)...

Here are some more details of the conversion:

I made a stand from aluminum bar to mount on the microswitch fixing studs, and adapted the TPS to it, centered on the original bellcrank. I made a special nut with a flat driver on the end, this goes in place of the OEM nut, the milled flat on the end fit inside the TPS and rotate it. I also made an SS arm so the original wouldn´t hit. I have drawings for the nut and the arm, not the support sorry:



Here is a little trick I did to read the ECT, instead of plugging the original mechanical pump´s existing lubrication line, I tried a gamble and fabricated a little SS adaptor and mounted the engine temperature sensor on it, the oil bathes the sensor tip inside, it is working perfectly (I think it looks kind of ugly but it works):



I used a Bosch fuel pump that is not expensive but flows very well and is very reliable. I made a simple mount and attached it to the floor of the car, near the tank outlet:



I put the MFI electrical pump on storage since it is so expensive.

Here is the fuel pressure regulator:



I mounted it on the MFI´s fuel pump original placement, hidden on the left rear banana arm (out of sight), so the fuel return line goes back from here (used the OEM hard lines on the central tunnel, large one to feed, and smaller one to return). This way there is only one fuel line that goes up to the engine bay that is already pressure-regulated, so the installation looks cleaner from the top.

I hope it helps anyone, please post any questions and comments.

See ya all!

Tiago

[Quickstep192]

I'm completely fascinated by this conversion. I have a few more questions. They may be uninformed, so I'll apologize in advance. My car started out with MFI, but it was converted to Webers before I got it, so I'm completely unfamiliar with the MFI setup.

I see blocking plugs in the cylinders at the base of the Weber intake manifolds; I assume they're closing the holes where the original injectors went? So, in Tiago's setup, the new injectors go in those holes using the adaptors Tiago made? This is obviously different than throttle body injection where the atomized fuel gets injected into the airstream going through the throttle body. This leads me to believe that injectors designed for use with EFI throttle bodies like PMO's might not work in this application. Is that a reasonable assumption? Also, if the injector goes into the adaptor, wouldn't the injector's spray pattern be impacted by passing through the adapter?

[Tiago/Tecnomec]

Originally Posted by Quickstep192

I'm completely fascinated by this conversion. I have a few more questions. They may be uninformed, so I'll apologize in advance. My car started out with MFI, but it was converted to Webers before I got it, so I'm completely unfamiliar with the MFI setup.

I see blocking plugs in the cylinders at the base of the Weber intake manifolds; I assume they're closing the holes where the original injectors went? So, in Tiago's setup, the new injectors go in those holes using the adaptors Tiago made? This is obviously different than throttle body injection where the atomized fuel gets injected into the airstream going through the throttle body. This leads me to believe that injectors designed for use with EFI throttle bodies like PMO's might not work in this application. Is that a reasonable assumption? Also, if the injector goes into the adaptor, wouldn't the injector's spray pattern be impacted by passing through the adapter?

Hi again, I am glad to see your interested!

Are you sure these blocking plugs are threaded on the intake manifolds (and not on the heads)? If your car still has the original heads, the original threaded holes on the heads should be there, and blocked in some way...

I believe any multipoint injector with the correct flow could be adapted. Not so sure about a single-point or TBI injector if that´s what you are reffering to (if it is, I would definitely NOT try that).

About the injectors different spray patterns between injectors types, and the adaptors impacting the spray, I am sure it all does happen, and it does affect the results in more than one way. BUT, sometimes we just have to do it to really see what happens (there are inumerous tests and simulations that can be done to try and predict what is going to happen, but sometimes just doing it is faster, cheaper and show results that are real and practical. Of course I believe we should always respect physics and good work technique, but the goal is to BUILD IT! If it doesn´t work, let´s try something different.

I had not had time or enough mileage yet to do some reliable fuel consumption tests, but I believe any strong negative impact of the adapters will show on the mpg...

There is also another trade here: The fuel pressure is a lot lower now (45 psi) compared to the MFI´s over 100 psi... That is a sure loss in fuel atomization, but now I have more precise AFR (and spark timing) control and tunability in relation to engine temperature, intake air temperature, RPM, throttle position, and exhaust O2 content than before.

If the end result on fuel consumption is a gain or a loss, we will find out soon.

In relation to drivability, throttle response, ease of starting, and power, I am very happy to inform that it is all good so far!

See ya all, best regards from Brazil!

Tiago

[rick2]

Outstanding Tiago!!! I love the can do and build it attitude. Especially with the fact you have not ruined the value of the car and now its drivable. Plus your still using the MFI stacks. I agree with the fancy off the shelf stuff not working, I have run into it several times. I recently went to adjust the valves on a turbo with the Billy Boat shiny stainless exhaust and had to remove the entire exhaust and turbo just to adjust the valves. Arrrr.
Keep up the great work and Thank You for sharing your information.

[Tiago/Tecnomec]

Hi rick2, thanks a lot for the compliments, I am very happy to be using the car more frequently now, it is such a joy to have it running good again!

I would also like to correct a mistake I made on the last post, where I said "MFI´s over 100 psi" is wrong. The correct statement is "MFI´s over 1000 psi".

I am cleaning the car over to a local car show on November 15th, and hope to have some good pictures to share soon.

Best regards from Brazil,

Tiago

[Tiago/Tecnomec]

Hello everyone!

I just did a 300 mile road trip this weekend with the car, and I am very happy to say it behaved great! No problems at all, the engine was a doll! There was a slight "pop" on occasion when lifting off the gas after cruising at about 80-90 mph, but got rid of it with some tweaking of the fuel maps.

The fuel consumption was actually ok, took some miles to dial the car in, but after all it did roughly 22 mpg. That included a lot of start-maneuver-stop, and a little town driving.

Well enough talk, let me show you some pictures:



I am a very lucky man, not only I own a Porsche, but I also have a beautiful and loving wife Lia, who put up with me and even helps me with all this car stuff:



A little cleaning:



Check out the cool made in Brazil 550 spyder replicas in the background!

I was also very surprised with the fact that the car won "Best Aircooled car" prize on the show!

See ya all!

Best regards

Tiago

[Tiago/Tecnomec]

A few more pics from the meeting, now from a professional photographer:

[Flat6Heaven]

Hello Tiago,

You have done a very nice job setting up your "S". Congratulations on receiving the prize!

Can you tell us more about how the coils on plugs (COPs) are driven? Do they just receive 12v and a signal from the ecu?

How has the car been behaving since you last posted two months ago? Still nice?

Thanks in advance,
Ben.

[GaryR]

I really like the COP setup, would try and go that route when I dump the electromotive setup and use the MSII to control spark.

[Eric_Shea]

Oi amigo,

Minha esposa é Brasileira. Ela cresceu em São Paulo.

Conversão muito legal!

[ShakinJoe]

Great thread

[jpnovak]

FYI,

I had a small run of adapters made such that I could have a set for my car. I am currently building a 2.5 that will be EFI running MFI stacks.


If anyone is interested please send me PM or email. I can also supply fuel rails.

[Tiago/Tecnomec]

Hello everyone!

Flat6Heaven (Ben), thank you very much!

Yes, this ECM has up to four configurable ignition outputs (I am using only 3 since I set it up in DIS, firing the coil in pairs (cylinders 1-4, 6-3, 2-5). Since these coils have built-in ignitors, thats basically all that´s to it. But it is possible to use coils without built-in ignitors, you would just need to hook up an extra ignitor module "box" from the same manufacturer of the ECM to fire the coils...

This is the EFI/ignition electronic control module I am using (it´s attached to a moulding I made to hold it):





The car is still behaving great! I had a misfire about 15 days ago, and one of the COPS was dead... I had bought them all used, so don´t know what happened, maybe it was just old... Replaced just that one and everything is fine... I have a few more small issues with the car, but not related to the conversion, like an oil leak from the gearbox speedo gear and stuff like that... It´s being hard to find the time to get to it...

Hey GaryR, I would deffinitely reccomend it, it is a very simple hookup, and has worked great so far!

Oi Eric, que coincidência legal! Obrigado pelo elogio. Um abraço!

Here is a little clip I made testing the car around my shop. Sorry for the low res and short duration... the battery died...



See ya all!

[GaryR]

Love the way you run it from 5000-7500! Is the tach accurate?

[Tiago/Tecnomec]

Originally Posted by GaryR

Love the way you run it from 5000-7500! Is the tach accurate?

Yes it is! Check it out, directly from the crank trigger:



The dyno pulls showed the power peak at 7300 rpm, tepering off at around 7500, so...

Let´s put those cams and intake to work!

I am also VERY addicted to that roar!

[Craig_D]

Awesome!!

[prebordao]

Hi Tiago, Brilliant video !
I suppose the ECU you're running is brazilian. Can you point me to a link to their site ?

Obrigado

[Tiago/Tecnomec]

Thanks guys!

prebordao, yes it is brazillian, their website is ::[ Pandoo ]:: Performance parts

They are about to launch a new ECM model, so mine is just about to get "obsolete"... Oh the eletronics!

[aquazulu2]

Yes nice job. I found the page looking for the kit.. I expect kit not yet available. bet it will soon be though, now that the trail has been mapped..