Pelican Parts Forums

Pelican Parts Forums (
-   Porsche 911 Technical Forum (
-   -   CIS to EFI kit (

tbitz 12-12-2003 11:07 AM

CIS to EFI kit
2006 update:

This thread was started back in 2003 and is fairly long. For those that don't have a few hours to read it here is an executive summary.

I had converted my Porsche 911 to EFI back in 2002. Lot's of folks were also interested in such a conversion. In 2003 I was without a job for a while so decided to make a kit that was more production oriented and simply a bolt on for others. I had parts CNC fabricated and documented the installation with a very detailed installation guide with lot's of color photos.

This thread goes through the adventure.

A dedicated Yahoo Group has been created for folks to discuss the details of there CIS to EFI installation. You can join the group here:

Back to the start of the thread....

With the recent slump in the high tech market, I find myself without a job and looking to do something different.

Some of you may know that I have converted my 1978 911SC from the stock CIS fuel system to an electronic fuel injection system. (look at the link below) and do a search in the archives for details.

I am wondering if there is any interest in producing a kit for people the looking to go down this route?

The kit would include everything you need to dump the CIS and to go to EFI.

The kit would include:

-Custom made fuel rails for the 911
-all fuel lines and connectos
-special plugs to fit EFI injectors in the stock Porsche runners
-wire harness
-adaptor for TPS sensor for stock porsche CIS throttle body
-engine temp sensor
-intake air temp sensor
-manifold pressure sensor
-braket to install ECU under passenger seat
-fuel map table for the 911 engine
-instruction manual
-two options for the air box. For those looking for weight reduction the current airbox can be cut down to reduce weight. The other option is leave the airbox almost as is using existing air filter. All fuel lines disconnected and metering plate removed.

-and here is the deal on the ECU

The ECU would be Megasquirt which is a proven design in hundreds of vehicles. You would have two options for the ECU since I did not design it and would be unethical for me to profit from selling the ECU.

1) What you would have to do is buy all the parts yourself and assemble and solder everything and test the megasquirt ECU (About $150US in parts). This was the orginal intent of the designers.


2) I buy the PCB fom the designers and parts and charge a fee for assembly and the cost of parts. (Note: Posts by the original designers on the Megasuirt yahoo group have OK this arrangement in the past). I would make sure they had no problem with this arrangement before making this as an option.

Software for tuning is available on the net for free. Directions on where to find it and installation would be provided.

Note this is a "speed density" system (not mass airflow) which lends itself perfect for turbo/supercharging the engine.

Let me know the following:
1) Would you be interested in such a kit?
2) I'd also like to know if you would never buy such a kit unless the fully assembled ECU was included
3) how much you'd be willing to pay for such a kit?



MotoSook 12-12-2003 11:38 AM

What would be the cost? How many maps would you get? Will the maps be developed or will a trip to the dyno ultimately be needed by the user?

How does your car drive on the street? How does it idle? Is there a power advantage? If so how much (over Stock CIS)?

It's a good don't take the above the wrong way.

911ctS 12-12-2003 11:57 AM

Sounds like a good kit that would work for many people. Will the megasquirt ECU work with a mass airflow system if you had the proper intake manifold (3.2 or custom)? What do you do with the Metering plate and fuel distributor on the current system? Do you just put the TPS on the existing CIS plate?


turbo6bar 12-12-2003 11:58 AM

Tony, I have procured 10 kits worth of Megasquirt parts for a college student in Texas. He assembles the kits and resells them at roughly twice parts cost, and he has the permission of the Megasquirt gurus.

I would be interested in a kit, but like many things the price must be right. In fact, I will email you offline. I love to tinker, but as my investments grow, I find less time to play.

For the best market, I think you need to sell the kit as complete as possible. You need to add value and credibility, otherwise guys can just DIY.

Good luck whatever you decide.


turbo6bar 12-12-2003 12:00 PM

Tony, I just saw Clint's post. I think the ideal solution is MAF. The person who can accomplish this will be sitting on a mine, because this removes a great step in the installation: TUNING. That one step places much fear in my mind, perhaps unecessarily.

Just my opinion.

RickM 12-12-2003 12:01 PM

Would you consider packaging a version that will control ingnition as well.

project935 12-12-2003 12:06 PM

Excellent idea! I've been watching your progress with your conversion and I hoped to follow in your footsteps with my project eventhough I was going to go a slightly different way (non-CIS donor). I think there are a lot of others doing the same too.

To answer your questions;
1. Hell yes! Put some modern and EFI based hardware/software on my engine anyday. Many, many EFI donors out there ...
2. A packaged ECU would be nice, but to keep it cheap I would keep it DIY. If the demand is high enough it should be cheap to have the MS kits built in quantity - even low quantity (<50 at a time).
3. Should sell well for $12-1400 I would think (should be a nice profit). $1000 or less and it would sell like crazy IMO. Just depends on how much you want to get out of it since you did the initial development. The whole point is to keep it low-cost EFI - IMO anything more than $2K is getting close to other alternatives. Costs depend on how you have your parts made too ... to sell a lot of them, above average quality and repeatability would be needed.

I'd be happy to work with you on the development of other 911 applications as well.

Souk - the more people that apply this idea to more vehicles with different combos, the more base maps there will be to choose from. I would think the initial different engine combos might need some dyno time to really fine tune the setups.

Cool ... cool ... cool

JTO 12-12-2003 12:18 PM

Funny how this came up today. I was fighting CIS problems all morning. If the price is right and the upgrade is not too tough for those of us with hams for hands, I'd probably buy the thing.

autoxracer31 12-12-2003 12:24 PM

will this EFI kit be able to be better performing than the CIS? I hate how we cant tune it for squat

Rouxzy 12-12-2003 02:15 PM

I have been pondering the idea of antiquating the CIS and installing EFI. Let me know.

911ctS 12-12-2003 04:53 PM

This all sounds great, i think there is certainly a market for this. I often thought of taking an old pair of Zeniths and turning them into a pair of throttle boddies by pluging up all the holes and gutting the jets and what not. (just simple stright through barrells with butterflies). Then welding injector blocks to the short manifolds below, put some fuel rails on and maybe a TPS. Then've got a set of poor mans TWM's. I will do this someday... I promise.

red-beard 12-12-2003 05:12 PM

I would love to apply this to my recently rebult 914/6. I'd love to do it to the SC, but I think it may have problems at SMOG time. It won't be exempt for another 7 years....

tbitz 12-12-2003 06:14 PM

Some answers to questions:

How many maps would you get?
Right now I have a map for a 1978 911SC. As mentioned above as people pick up the kit a database of maps would be developed. I only own a 1978 911SC, so that is the only map I can generate for now. Tuning really isn't that hard.

How does your car drive on the street? How does it idle?
Car runs great from -10C to +35C (15F to 85F). Idles fine, no wild hunting common with CIS cars. I still use the stock AAR for idle up.

Is there a power advantage? If so how much (over Stock CIS)?:
Most likely there is a power increase. I haven't dyno it so I can't back that up with numbers. The biggest improvement has been the responsiveness of the engine. No more lag common with CIS. Fuel is instantly dumped to engine when pedal is pressed with programmable acceleration enrichement which is not available via CIS system. No screws to turn to adjust mixture. Everything is easily done via a laptop.

Will the megasquirt ECU work with a mass airflow?
No. Megasquirt is a speed density system. It uses a Manifold Pressure Sensor (MAP). I don't want to get into a debate over MAF vs MAP. Both need tuning. I think MAP is the only way to go if you plan to boost the engine (which I will be doing). MAP would only be offered.

Do you just put the TPS on the existing CIS plate?
TPS goes on a slightly modified CIS throttle body (not fuel metering plate).

Would you consider packaging a version that will control ingnition as well?
Ignition maybe possible as well. There are versions of MS firmware that do this. I haven't tried them yet. They basically allow you to retard timing based on RPM and manifold pressure (perfect for a boosted engine). You decide how much and when.

What would be the cost?
Not sure at this point. I'm thinking in the $1200 range. Big variable is machining of certain parts. I will work on a more accurate price target.

Seems like alot of people fear the tuning aspect of this conversion. It really isn't that hard. In fact there is software out there that will automatically tune the engine for you if you have a rough starting point. All you do is run the engine through each of points of the 8x8 table (8 RPM and 8 MAP values) and it figures out the VE for you. It uses the O2 sensor to determine the proper fuel mixture. This can be done on a dyno, or just by driving around.



project935 12-12-2003 07:16 PM

911ctS - my thoughts exactly ... that was what I was going to do. I think this type of setup will look very 935ish if you turbo'd/intercooled.

tbiz - I also like the idea of boosting a EFI-CIS intake engine. How much boost do you think the CIS intake box will take? With or w/o popoff (w/o I would think)? Very 934ish ...

The Megaspark/Megajolt (uses another Megasquirt ECU to control ignition) also looks interesting. It seems to use a separate crank or cam timing wheel/hall effect sensor. I'm wondering if a Pertronix equipped dizzy could also be used to drive the Megaspark - I believe that's just another form of hall effect sensor right?

I've also been casually watching the development of the Megasquirtnspark - the all-in-one DIY fuel/ignition controller. Looks like progress is being made, but it'll be some time before it's complete.

1fastredsc 12-12-2003 07:50 PM

If the mega squirt excepts wide band o2 sensors then tuning would be much easier.
My only fear is programming, i can't program worth a crap. But tuning, as tony says, is fairly easy.

tbitz 12-12-2003 09:40 PM

Megasquirt does accept a wideband O2, if you have the proper controller feeding the O2 sensor. In fact I am running wideband O2 on my setup.

Wideband O2 setup is pricey though. The sensor alone is over $200, plus the controller.

With wideband O2, you can get AFR (Air Fuel Ratios) in real time :) Now if that doesn't wet your pants I don't know what will ;)

makaio 12-12-2003 09:56 PM

If it was idiot proof ( install & tuning), and $1200 or less I would do it in a heart beat.

Alan Cottrill 12-12-2003 10:03 PM

I've looked at the tuning interface. If you can post on this forum you can tune this FI.

if you don't have the cubic dollars to do it on a dyno, use a laptop and a buddy in the passenger seat and drive it till you get it.


I'm rebuilding my engine now and I am VERY interested in this.

the MS site recomends if you are going to break in a new engine that you should do it with a known functional fuel system. for me that would mean breaking my engine in with cis then droping the engine to convert.

do you think it's possible to get MS set up well enough to start the engine and break it in with out too much trouble.

i just worry about that first 20 minnutes. I'd hate to not be able to get the idle up over 2k at start up.

Chuck Moreland 12-13-2003 08:48 AM

I think it is a great product idea. If you can execute it well and find distribution it may do okay.

But I sure don't understand your comment "I did not design it and would be unethical for me to profit from selling the ECU".

Pelican parts didn't design anything they sell. Is that unethical? Shops sell the parts they install, and they didn't design them. Is that unethical? Of course not.

What you want to do is deliver a complete soluton that is easy for your customers, and that includes the assembled ECU. Contact the megasquirt guys and tell that what you want to do. I'm sure they'll be fine with it.

Otherwise you are providing half a solution.

Elombard 12-13-2003 09:41 AM

I would probably buy too. I would want a complete turn key for my 78 SC. All assembled and read to bolt on and tune. I agree if you can work in spread sheet soft ware, should be able to tune it. I think the machining will be cheap if you do it in batches.

All times are GMT -8. The time now is 05:13 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.