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How I did EFI on a 931 - somewhat dial-up friendly!
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-nick  



Joined: 16 Nov 2002
Posts: 2700
Location: Cambridge, MA

PostPosted: Fri Jan 05, 2007 8:17 am    Post subject: How I did EFI on a 931 - somewhat dial-up friendly! Reply with quote

This is as much for my records as it is for anyone else Keep in mind, this is sans spell & grammar check, so be easy on me! Also, this is by no means the _only_ way to do it, nor does it include everything done (see my abbreviated "wiring" section!). I figure it would help anyone thinking about it though. I'll try and get some accompanying pics up too.

Enjoy.


MegaSquirt-II + EDIS

also see: www.msefi.com


(early version of the engine bay)
-----------------
Fuel Tank to Fuel Rail

Everything can stay stock from the fuel tank all the way up to
where the metal fuel lines come up near the bottom of the brake
booster.

Remove the metal lines that bolt together from the brake booster
and snake around under the windshield. Also remove the flexible
rubber lines that bolt between the fuel distributor and the metal
lines that you just pulled.

On the end of the flexible lines that screw onto the fuel dizzy -
split the rubber and metal crimp and you'll find a barbed end.
Now screw these barbed "adapters" onto the metal lines near the
brake booster.

The 5/16" barbed line is the fuel feed and traces directly back
to the fuel pump & accumulators.

The 1/4" barbed line is the fuel return back to the tank.

- Fuel rail plumbing / parts.

I picked up my perfect-fit rail from board member Endwrench. The
5/16" fuel line feeds the rail.

Use a barb&hose at the end of the rail into a fuel pressure regulator.
The Mallory/Bosch adjustable and reference sensing FPR is perfect and
reliable. The outlet of the FPR goes to the 1/4" return line to the
fuel tank.

I have a cheap in-line fuel pressure gauge to make sure the pressure
is set correctly with the adjustable FPR. This is obviously optional.

*Note- aeroquip fittings & lines would make all this much tidier.
Swapping my rubber lines to aeroquip is on my to-do list. It just
didn't make it in this time around.


-----------
Injectors

I'm using 42lb/hr Bosch high-impedance injectors. Low-imp injectors
require a little more hardware work to the MegaSquirt board.

Endwrench supplied injector cups that screw in place of the stock
CIS injector cups. The injectors & fuel rail snapped right in with
no leaks or problems.


-----------
Intake manifold


This is where things got a little crazy. I cut the stock intake
manifold to where the intake manifold runners were 180mm long.
This cut had to be at an angle across the runners to keep them
all the same length since the front runners aren't straight.

The total new runner length (including 20mm in the head) is: 200mm
The total old runner length way: 328mm

I had a new plenum welded up then welded to the stock runners. The
dimensions are:

Main body = 30cm long x 10cm OD x 3.5mm thick
Plenum volume = ~2142cc

Which is slightly larger than the stock plenum.

Next, I tapped the firewall end of the plenum for two 1/4" vacuum
barbs, one 1/2" barb, and for the intake air temp (IAT) sensor.
The 1/2" barb supplied the brake booster vacuum. The 1/4" barbs
supply the blow-off valve, MAP sensor, boost gauge, wastegate line,
and fuel pressure regulator. The IAT is the generic GM sensor
which screws in and uses a GM weather-pak connector.

*Note- my Frankenstein intake was mostly an attempt to shorten the
plumbing for the intercooler (which worked perfectly). You might
not want to go to such lengths! Finding a competent aluminum welder
was not an easy task. Hint - go to a radiator repair shop.


------------------
Throttle-Body


(944 TB on left, Ford TB on right)
I mounted a flange for a 65mm Ford 5.0L throttle body off a '86-'93
Mustang/Explorer to the new intake plenum. This TB is as simply as
you can get - a single butterfly, a variable throttle position
sensor, and a bolt-on idle air valve (aka, aux. air valve).

I cut up a 5.0L wiring harness for the TPS connector and the idle valve
connector.

The TPS has three wires, follow the MS manual to figure out which is
which with a multimeter. It's easy.

The idle valve only has +12V and ground. I don't believe it is polarity
sensitive. It's either open to raise the idle when cold, or closed. Simple.

I cut about 6" off of the stock throttle cable and put together an
excellent-working throttle cable with some hardware store parts.

*Note - the butterfly in the throttle body has a ~1/8" hole that you
should plug up or else you won't get the idle below ~2000rpm! I used
a tiny nut & bolt & washers and some loc-tite to make sure it never
comes loose and gets sucked into the engine!

The manifold bolted on just fine, however the dipstick and the dipstick
mount had to be "modified". When I assemble, I bolt the manifold to the
head, then push in the dipstick tube, then tighten the dipstick tube
mount down to hold it in place. See pics (coming)

Also, the TB and inlet hoses were too tight a fit for the stock pressure
switches on the brake master cylinder. I removed those switches and
plugged the MC and wired a pedal activated brake light switch - a la '81+
cars.


-------------
EDIS Ignition


I bought the EDIS parts online via a MS board vendor. It totaled to
around $120 or so. This includes the EDIS-4 brain, coil pack, ignition
wires, 60-1 trigger wheel, and the trigger wheel's VR sensor.


The trigger wheel was tricky. I had a machine shop make an adapter on
a lathe. The adapter fit into the crank pulley and used the same bolt
to pull itself down with. Use the 944 crankshaft bolt as it's longer.
The trigger wheel was then pressed onto and tack-welded in place to the
adapter.

The advantage to this is that I could spin the "missing tooth" of the
trigger wheel to any position I wanted since the adapter was just
secured in the middle by the crankshaft pulley bolt.

For the VR sensor mount, I made a very simple mount out of 1/4" aluminum.
Next I removed the rubber-stud mount for the metal radiator hose on
the big alternator/AC mount. I used the threads in the alt/AC mount
to screw my VR sensor mount on. It took some measuring to get the
VR sensor at just the right distance from the trigger wheel teeth.

Once the gap between the trigger wheel & VR sensor is set, just rotate
the trigger wheel until the missing tooth is 9 teeth forward of the VR
sensor when the engine is at TDC. Then torque down the crankshaft bolt.

The EDIS ignition wires are great quality and have nice ends on them.
However, they're _really_ long. I mounted my coil pack right on the
intake runners which is pretty nearby the spark plugs. You can push
the ignition wires through the coil-side ends, then pry open the copper
ends and shorten the wires. Check the Magnecor website for an excellent
how-to on plug wire crimping.

Be sure to use some shielding for the VR sensor wiring. I have mine
shielded up to the relay box, and then out from the relay box to the
MS box.

Finally, Endwrench made up a steel block-off plate for where the
stock ignition distributor used to be. I drilled and tapped the center
of the plate for an extra crankcase breather line.


-------------
Sensors

Intake air temp (IAT) sensor is generic GM screwed into the rear of the
intake plenum.

Manifold air pressure (MAP) sensor is internal to the MegaSquirt

Coolant temp sensor (CLT) is generic GM. For this one, you can remove
the stock thermotime switch/sensor. Now pick up a male-female brass
adapter from your hardware store and screw it in the thermotime
switch's place. Then screw the GM CLT sensor into the adapter. Now
you get accurate coolant temp numbers and you can leave your stock
VDO sender in place for your stock coolant temp gauge. Amazingly, the
temps of the two agree quite well...

Wideband Oxygen Sensor (WB-o2). I consider this a requirement. I use
the Zeitronix kit. It works great and interfaces with the MS software
for real-time air/fuel ratio numbers.

I've also got an exhaust gas temp (EGT) probe. I just drilled & tapped
the exhaust manifold on the flat-spot near the turbo mount for the probe.


-------------
MS Wiring

You're on your own here. I started by pulling everything related to the
stock CIS, stock o2 lambda system, and stock ignition system. I pulled
all the wires related to those components from the fusebox outward.

I used the MS relay board which I would _highly_ recommend. On top of
everything else, it gives you a fuel pump relay so you can get rid of
stock $80 relay that usually flakes out anyway.

I bought several packs of the black heat-shrink that JC Whitney sells.
It's really good quality stuff and makes wiring MUCH nicer of a
prospect.

In addition to the heat-shrink, you'll need lots of small butt-end crimps, various
spade and eyelet terminals. I bought a wiring harness from a MS vendor that
was printed with the component every ~4". Such as "CLT CLT CLT" or "INJ1
INJ1 INJ1" etc. You get the idea. It makes wiring - and tracing wires, a
thousand times easier. The same vendor also attached the connectors for
the Bosch fuel injectors and gave pigtails on the GM weather-pak connections.
Otherwise, you need special crimping tools for these connections.

I mounted the MS relay board and the EDIS brain where the stock fuel
filter resides. It's a good common spot. You also have big holes near
there where the metal fuel lines used to run through into the engine
compartment that you can use to route wiring through. Keeps things
relatively clean. Just be sure to mount the brain & board off the
surface and out of the flow of water drainage!

I mounted the MS brain under the driver side dash. There is an
excellent space left open by the stock o2/lambda brain that you can
use freely.


-------------
Crankcase Breather

I made this very simple - I drilled & tapped the dizzy block-off
plate then ran a hose from it to the crankcase breather in the
block. There is a plastic tee in the middle of the hose with an
inline crankcase breather filter.

As long as the rings are in good shape, there shouldn't be any
blow-by out of the breather filter. I saw a little oil around the
filter while running in new rings for the first 20 miles, and
nothing afterward.

The stock air/oil separator can go. And the line from it to the
oil pan (which always seems to be leaking) can be pulled. I found
a magnetic oil pan bolt to screw into the oil pan where the air/oil
return line used to be.



-------------
Additional


I swapped the compressor housing on my stock 1980 K26 turbo to an early
Audi K26 housing (including the compressor wheel). The wheel and
housing have the same specs as stock, but I got rid of that enormous
stock pop-off valve plumbing.


Forge Motorsports makes a recirculating pop-off valve that works
great just venting to atmosphere. I put a breather filter on the
vent side and packed it with some blue paper towel/shop towels to quiet
the noise. I can barely hear a "psshhh" when it blows. Perfect.

There is a big empty space in the engine bay where the CIS airbox once
was. A 951 intercooler fits in there just right. I had to move the IC
inlet from the front of the side of the IC to make it work. Some more
artful aluminum welding.

Here is the induction plumbing:
K&N cone filter
2" OD aluminum pipe
2" 45* silicone elbow - clamped onto compressor inlet
45* 2" silicone elbow - turbo compressor out
2" OD by ~5" length aluminum pipe
90* 2"-2.25" silicone elbow - intercooler in
2.31" silione tee coupling - intercooler out with BOV connection
2.25" by ~4" aluminum pipe - flared on IC side for 2.31" coupler
90* 2.25"-3" silione reducing hose - to throttle body


-----------------
Engine specs



88mm hypereutectic VW flat-top pistons with coated skirts
Compression rings gapped at 0.027"
Piston-cylinder gap at 0.002-0.003" (you could make this 3-4 thou)


Head combustion chamber opened up to 23cc volume and polished

Static compression showing ~155psi per cylinder
Compression ratio ~8.5:1

Raceware head studs

Intake manifold and head ports gasket-matched
_________________
1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet


Last edited by -nick on Sat Jan 06, 2007 5:01 am; edited 4 times in total
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Joes924Racer  



Joined: 03 Nov 2002
Posts: 11966
Location: Oregon, Denver Colorado native!

PostPosted: Fri Jan 05, 2007 8:25 am    Post subject: Reply with quote

great stuff nick, thanks for the post
pics would put it through the roof.
_________________
1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.
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Peter_in_AU  



Joined: 29 Jul 2001
Posts: 2740
Location: Sydney, Australia

PostPosted: Fri Jan 05, 2007 12:32 pm    Post subject: Reply with quote

You're a legend mate!!
_________________
1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)

Learn to love your multimeter and may the search be with you
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endwrench  



Joined: 07 Dec 2002
Posts: 1629
Location: Victor, Montana

PostPosted: Fri Jan 05, 2007 4:11 pm    Post subject: Reply with quote

Great write-up and actually very dial-up friendly!!

One thing though, is the MS-II more friendly with low imp injectors? The MS-I needs a flyback daughter board. It was my understanding the MS-II could be easily modified for the low imp injectors but still worked without modification on high impedence injectors.

Todd
_________________
'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....
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-nick  



Joined: 16 Nov 2002
Posts: 2700
Location: Cambridge, MA

PostPosted: Sat Jan 06, 2007 4:44 am    Post subject: Reply with quote

Thanks guys!

edit - I swapped low & hi imp injectors above, fixed now!

I honestly didn't look into using low-imp injectors. I just stuck with high-imp since they were essentially plug-and-play. There seem to be more choices with low-imp injectors though. If I need to move up in flow rate again, I'll check it out.
_________________
1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet
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bass gt  



Joined: 02 Dec 2004
Posts: 971
Location: Johannesburg for now!!

PostPosted: Sat Jan 06, 2007 10:09 am    Post subject: Reply with quote

Nick,

Nice work!!!! Interesting factoid about the plenum chamber. I wonder if this makes a difference in a ITB set up such as mine???

Steve
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flosho  



Joined: 01 Jul 2004
Posts: 3158
Location: Eau Claire, Wisconsin

PostPosted: Sat Jan 06, 2007 11:09 am    Post subject: Reply with quote

That's an awesome write up! It will be very helpful... Now for the hardest part.. the wiring! I think thats the part I'm most afraid of...
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macBdog  



Joined: 16 Aug 2004
Posts: 1100
Location: Brisbane, Australia

PostPosted: Sun Jan 07, 2007 1:06 am    Post subject: Reply with quote

Very nice!

So do you take your temperature reading from the termo switch socket in the corner of the radiator? Its not too far from the head to get a good reading? And MS turns the thermo fans on and off fine?

Cheers.
_________________
1979 931 with a 350 chev
1973 911E with EFI
p-talk wrote:
I'm still convinced the word 'Porsche' makes people crazy in all kinds of ways
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-nick  



Joined: 16 Nov 2002
Posts: 2700
Location: Cambridge, MA

PostPosted: Sun Jan 07, 2007 6:17 am    Post subject: Reply with quote

Thermo-time switch - at the back of the head, as opposed to the thermo-fan switch on the radiator. Although I do think you can use MS to turn on the radiator fan(s) if you wanted!
_________________
1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet
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tom2turbo  



Joined: 16 Jan 2007
Posts: 33
Location: Portland, Oregon

PostPosted: Mon Jan 22, 2007 4:23 pm    Post subject: Reply with quote

Nice write up. I am thinking about this project on a 931 as well. What is getting into my mind is the injector mounting and the fuel rail.

I have a Volvo B-21ft that is being converted from K-Jet to MS&S. A Volvo B-230ft supplied the low impedance injectors, relays and wiring, fuel rail and intake manifold, all ready to go without modifications. The only mod was the TPS and mounting plate. Here is a link to a similar project, not my own. http://www.sonic.net/~kyle/242/work/

Do you have a photo of your fuel rail and injector mounting?
--Tom
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endwrench  



Joined: 07 Dec 2002
Posts: 1629
Location: Victor, Montana

PostPosted: Wed Jan 24, 2007 2:59 pm    Post subject: Reply with quote

Shameless self promotion

http://www.924board.org/viewtopic.php?t=20991

This is what nick used.

I think this will be last one I build.

Todd
_________________
'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....
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flosho  



Joined: 01 Jul 2004
Posts: 3158
Location: Eau Claire, Wisconsin

PostPosted: Wed May 09, 2007 1:46 pm    Post subject: Reply with quote

nick, do you have a part number or a specific make/model the FPR came off of?
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-nick  



Joined: 16 Nov 2002
Posts: 2700
Location: Cambridge, MA

PostPosted: Thu May 10, 2007 6:30 am    Post subject: Reply with quote

I think the part number was MSD-2222. It's an MSD-modified Bosch regulator. racerspartswholesale and the like carry them.
_________________
1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet
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Min  



Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada

PostPosted: Thu May 10, 2007 11:01 am    Post subject: Reply with quote

-nick wrote:
I think the part number was MSD-2222. It's an MSD-modified Bosch regulator. racerspartswholesale and the like carry them.


Apparently these particular regulators are extremely reliable. If I didn't need a wider range of adjustability, I'd purchase one of these for sure.

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.
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flosho  



Joined: 01 Jul 2004
Posts: 3158
Location: Eau Claire, Wisconsin

PostPosted: Mon Jul 16, 2007 8:48 am    Post subject: Reply with quote

Nick, you removed the lines coming from under the brake booster, did you reinstall the fuel filter inline below the brake booster, or what are you using in place of the original one?
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