CSI to EFI, what's the best practices

[martin2day]

Hello,

first some information about me and my car.... :-)
I am Martin from germany and I have build and setup some cars before... I have also build a Cobra Kitcar from England with an V8 and full sequential Megasquirt MS3 ITB.
So I think some basics are available. :-)

Now I have buy an old 911 SC 3,0 from 82 and I am very happy with the car.
I want to keep the car for a very long time. I just don't like CSI and the lambda control that much... there are many parts, that are very expensive and it is very hard to maintain it...

So I want to upgrade the CSI to an modern EFI system.
I have buy an manifold and throttle body from the 3,2... this is very cheap and good part I think.

For the Ignition and the ECU I want to here your opinion and experience.
I think about a "cheap and simple" setup with an Microsquirt (MS2Extra) or an "komplex and expensive" MaxxECU street...

The CIS inject every cylinder at the same time... very simple but it is okay. This the MicroSquirt I have only 2 Injector outputs and 2 Spark Outputs... it is like the CSI...
With the MaxxECU I can run more complex algo... but is this necessary...??? :-)

For ignition I want to use COP... easy and I dont need any extra Spark Module...
What is here the best brattice :-) Denso 02240 or 02243

My way is to get an simple and effective System that generate some extra Power with the SSI exhaust... :-)

Thank you for your help and answer.
Have a nice day
Martin

[AndrewCologne]

Now I have buy an old 911 SC 3,0 from 82 and I am very happy with the car.
I want to keep the car for a very long time. I just don't like CSI and the lambda control that much... there are many parts, that are very expensive and it is very hard to maintain it...

Many people will give you good answers regarding EFI, but my comments below refer to your exact choosen words from above.

a) You dont wanna now how much more expensive a complete change to EFI incl. COP is, compared to check and fix a present CIS. :-)
b) What on your present Lambda CIS is actually hard to maintain, what are the current problems?
c) The CIS with lambda control is also an electronic regulated mixture control system for optimal combustion. If all works "as it should", means as it left the factory you benefit here from a very good performance as well.
Maybe you check your system in advance and at the end, if all works properly and then, if you are still not satisfied, you can change to EFI/COP etc.
Instructions/Set up for 930/16 engines you can find here:
https://nineelevenheaven.wordpress.com/the-911-sc-3-0-engine-with-catalyst-and-lambda-control/
https://nineelevenheaven.wordpress.com/english/

[TwoBluPorsches]

I would agree with Andrew that a working CIS system shouldn’t be hard to maintain and will work well for drivability and reliability.

However, pretty good horsepower gains can be realized by using a 3.2 manifold and an air/density EFI setup.
The CIS runners, fuel distributor and throttle restricts airflow in comparison to a 3.2 manifold. The EFI setup with a vacuum sensor instead of airflow sensor removes that airflow sensor restriction.

I’ve got an aftermarket EFI on my 3.0 that uses the 3.2 manifold. My 3.0 engine is big port so the 3.2 manifold doesn’t have much of a port size mismatch, it uses a stock distributor with advance locked. The EFI provides batch injection instead of sequential, and therefore works fine with older injectors of the type used on a 3.2. The EFI adjusts timing.

Comparing against other cars with CIS engines that had similar exhaust, the EFI conversion is worth about 25 horsepower on a stock engine.

I’m not sure what would be gained by going to coil on plug, it really wasn’t an option back when I converted mine. I suspect it would not be much.

If you read threads about carburetor conversions you’ll find that they provide good HP increase on stock 3.0. I can’t imagine the carburetors giving better fuel mixture than CIS but they will certainly flow better.

I think the takeaway is that the CIS is too restrictive for the potential of an otherwise stock 3.0

[TopTuning]

Save up and get good components that let you take advantage of all the modern tech if you're going to do it.

MoTec, drive by wire ITBS (like mine, more affordable than you think!)

Dual wideband fuel correction, Knock sensors, coil on plug, flex fuel if you have e85 available etc.


It's not *that much* more than the cheaper ECUs, and lightyears better than megasquirt or MaxxECU stuff. I've used those and every other system you've heard of, MoTec M1 series is by far the best ECU with only maybe Emtron coming close.

On a 2.7 Non S engine I made about 40 whp over stock CIS, with huge torque gains everywhere. Not to mention the fuel milage went way up, starting and drivability problems gone. Lots of engine protection and safety stuff protect your engine from what could be a catastrophic failure (like loosing oil pressure or overheating)

You also get incredible diagnostic ability far better than even a modern OBD2 car.

It's really the only way to go in my opinion, having done this professionally for decades.

[gsmith660]

For an 80s SC you can get a kit from bitzracing that is not very expensive and fairly easy to install and Tony gives you all the tech support you would ever need. Considering the cost and availability of CIS parts for my 2.7 I went megasquirt and never looked back.

[silverlock]

In the throes of a CIS -> EFI conversion as part of the 3.2SS build on my ‘78 SC as we speak. My CIS system was in very good condition — rebuilt WUR from Tony, FD not too long ago, etc. Car ran great.

Big reasons for the swap are power, tunability, and overall reliability. I put > 10k miles per year on this car across rallies & lots of spirited weekends, across different temps & altitudes.

Swapping to a 3.2 Motronic w/ a custom SW chip. Going MoTeC, CoP, a GT3-style plenum, etc - is easily another $15k on top of this. Tuning, parts, etc all factored in. Given infinite $$ and a less adventurous driving schedule, it might have made more sense. Gotta draw the line somewhere.

But a chipped Motronic is approachable by any shop (no matter where I might move), parts are easy (yes, even injectors - e.g. Sal’s) and I’m not trying to squeeze every ounce of HP out of the car. Still way up over keeping CIS.

[Dr J]

If you do go efi, I recommend:

1) a good wiring harness
2) a tuner familiar with your chosen ECU to program it and
3) knock sensors

Might as well go COP rather than batch fire.

[montauk]

Earlier today, I got 1980 Porsche 911 started for the first time with my ITB conversion. It's been quite the journey. I went with PMO ITBs, a Haltech R3 ECU featuring built-in power distribution, Clewett cam and crank sensors, Denso coil-on-plug ignition, and rebuilt Bosch fuel injectors. For the drive-by-wire setup, I sourced a used BMW throttle motor along with a BMW pedal.

It’s still early days, but I’ve genuinely enjoyed the process—even with the inevitable mistakes, all of which were fixable. I estimate my total investment is around $10,000, though I’ve never actually tallied it up.

Last year, I put in a ton of work and had the car running perfectly—until the airbox cracked. That was the final straw for me when it came to the CIS system. Sure, I could’ve replaced the airbox, but that would’ve meant sticking with outdated technology. At that point, I figured I’d rather have carburetors than CIS—there are simply too many valves, hoses, and other components required to keep CIS reliably functioning.

[martin2day]

Hello,

thank you all for your help.
First, I don't want to start a discussion about the CSI and the costs or the maintenance of this system. You are right, there is no need to change this system if it is in good shape...

I like the new stuff and build and setup the new ECU, and what I say about the CSI is a nice to have... if I remove the old system.

This is I picture of my MS3 full sequential setup in my cobra.


The Porsche Setup:
- I have the 3,2 Manifold, so I need no Kit for the 3,0. I can build and setup the system myself, no problem.
- DBW is very nice... a 997 pedal + throttle is also very cheap... and I get e clean look... no need for a idle valve :-) And there are many more features... but: I want and feel the old car... so I will not get DBW
- i want to keep the system as simple as possible, so I think about only a trigger wheel, no cam sync... so I have to use wasted spark and 2 Squirts per cycle... on at the right time and one not....
But: the CSI inject every cylinder at the same time.... and that goes very well... so my setup is much more better and accurate than the CSI....

What do you think about a setup without a cam sync... ?

Ingnition is also a part I think about. I will control the ignition per ECU!
I can:
- fixest the disturbitor and use the coil and old wires (looking old)
- use external wasted spark coilpacks... and the wires
- use COP's

What do you think about this part?

The only part I did not have any experience is Knock Sensor and Knock detection.
I reed many about it but in my option it is not very easy to setup such a system correctly... what are your opinion?

Have a nice day
Martin

[montauk]

Regarding the cam sensor, I wondered about that too. I was very nervous about drilling a hole in the end of the cam shaft. It turns out that the only thing I had difficulty with was getting the cam cover off the engine. Once that's done, the rest is easy. Being able to use COP makes the wiring neater and a simpler.