924Board.org

[Paul]

I agree with Smoothie, but here's a couple of things to consider:

Porsche recommends 0W-40 Mobil 1 in all Porsches (old and new).

If your motor is already leaking oil it will get worse with Mobil 1

Running rich will dilute Mobil 1 quickly causing low oil pressure

Mobil 1 has a much higher burning point, so it allows turbo bearings to be lubricated at higher temps.

Running anything higher than 0W-40 even in very hot climates will cause more startup wear.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[Chrenan]

Glad to here Ideola is giving Eurorace (European Motorworks) some business, I like what they did with my NA head...
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1987 951 - M193 Version for Japan

[FRporscheman]

How rude of me, I forgot to thank you all for the welcome and all the great input - thanks!

What is it about the CIS system that makes it so unlikely to work if it's been sitting for a long time?

Is it really that hard to clean up / revitalize CIS?

I was thinking if the 931's engine was going to be such a pain to get going again, I could just grab a 944 or 951 engine and put it in, but I just read some threads on this and learned about the whole difference in engine mounting designs. Bummer.

Would it be cheaper to rebuild a 931 engine and turbo, and convert it to EFI, or would it be cheaper to stick in an alien engine? Half-rhetorical question. I need to read all that stuff in the engine swap forum.
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'93 968
'84 944
82 MB 300td

[Lizard]

I understand why ideola and chrenan dont agree with switching to EFI right off the bat.

I will expand alittle more on my info.

you have CIS parts which have sat for a long time, you will have to pull the tank and clean it out, you will probably have to replace the fuel pumps, you will have to blow the lines clear, as well and clean most of the CIS componants.
You can get it run on CIS, there is no question about that, but when you combine the hassle of doing this as well as the possible issues you could have with the DITC ign system it will not be a fun experiance.
Now we have a very frequenting board member here -nick who has a 931 already running on EFI, you can contact him or probably search the board to find all his info, and if you find out what sensors he uses, what injectors he uses, and get all the same parts, you can buy used EDIS parts online that are guarenteed to work no problem.
If you use all the same parts as him you could technically beg borrow cheat or steal the fuel and ign map he is using on his car, but judging by other things nick has said I dont think he would mind helping you out.
This would make the MS system pretty much plug and play with alittle wiring, at least upto a point where the engine would start and you could further tune it to your liking.
you can get MS for a very reasonable amount along with a good wiring harness and you can do it reasonably cheap. You will probably have to replace the fuel pump at this time anyways and a standard 45PSI pump is ALOT cheaper than a CIS capable pump.

So you CAN use the CIS after a massive cleaning task (some will still need to be done) but you eliminate a massive headache later by doing this, as well you can then remove the fuel accumulator from the car. Which is a massive bonus as you will have to replace this to get the CIS to a useable point.
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3 928s,

[Chrenan]

Lizard does speak the truth, and has the skill and knowledge to setup EFI, somthing I lack so I am more intimidated by going that route.

Another major problem with CIS is when the fuel distributor gets gummed with old fuel, it is very hard to clean. It can be seperated into two halves, but from what I've read on the board, not many (none?) people have been able to properly seal the distributor after splitting it.

Long term, you, me, and everyone else who would like to keep a 924 into its thirtieth, fourtieth and fiftieth years will have to convert the fuel system as the rest of the car will likely outlast the CIS.
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1987 951 - M193 Version for Japan

[Min]

[Min]

[FRporscheman]

Wow. I hate CIS even more after reading all that stuff. Lol.

I really wouldn't mind all the work. I am after all looking for a project, and I've had a couple successful project cars already. I'm not really experienced when it comes to custom stuff like retrofitting some EFI into a 924, but if others have done it, I wouldn't hesitate to do it with their help.

I bet if there was a bit more demand for 924 EFI, a few of the experts here could collaborate and put together a DIY retro kit. Keep the 924s alive while turning a bit of profit. Money to keep their own 924s happy.
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'93 968
'84 944
82 MB 300td

[Chrenan]

I'd love an EFI kit that only requires me to turn wrenches to install and comes with absolutely everything. The problem is, I don't think many guys would pay for one (other than me). Most 924 owners complain about the cost of basic maintenance items, never mind an actual upgrade.
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1987 951 - M193 Version for Japan

[Min]

[Lizard]

I have to agree with Chrenan on this one FR
the 924 owner can tend to be alittle on the cheapish side of things, and a direct bolt up EFI kit would be impractical as whoever were to build it would need to get some return back for the investment of time and $$$ output, which most owners would not be willing to cough up the money for that, I think that you could only sell about 10 kits of it and it would probably require some more tuning, which if you arent willing to learn how to do costs alot.
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3 928s,

[john h]

You guys must have some pretty shitty fuel in the US. I haven't used on of my 931's for two years and just put a battery in it – let the fuel pumps turn over for a few minutes to build up system pressure and then hit the key - engine fired almost start away and runs sweetly. The only precaution taken when I stored the car was remove the battery and DITC ignition module so if anyone broke into it's garage they couldn't start it.
With my GT replica I swapped it's motor over a few years ago (2004) and installed a 931 motor that had been pulled out of a wrecked car in 1989, as the CIS was still connected up on the spare motor I just used that as it was easier to connect two lines than swap over the whole CSI metering unit - again this engine started straight away.

In the 20 or so years I've been running and racing 924 and 931's I've found the CIS extremely reliable - more so than the EFI on the 944 I used to own. I've never had any problems with the CIS so I'm sticking with it - not point in fixing it if it aint broke.
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Remember a Porsche is not just for Christmas,

if you take it to pieces slowly it can provide anguish all year long!

[924guy]

the fuel quality in the us has degraded over the past several years IMO, seem the more we pay, the worse the quality of fuel we get. But these are only my own observations.

as for the topic at hand, I wouldnt sweat the cis too much. its a good set up. run some fuel stabilizer through it every so often (far better than even techron at cleaning the lines out, and slows the fuel degrading when sitting) and its not to bad. stand alone fuel management is popular, but unless your going with a full custom setup, its usually optional.

the 931 is a great car to have, there can be headaches, but far easier to work on than a 968, no pesky balance shafts or variocam, and comparitively, much cheaper to play with.
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Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
Performance by Pasha

[Glen931]

I dont have much experiance with 931's compared to many of the people posting but I bought mine with 80k miles and it had been sitting for 4 years under a car canopy. started it up, test drove it and then payed the guy 800 bucks and drove it home. it was completly lacking power at first but getting rid of the cat, some Mobile 1 10w30 synthetic and carb cleaner sprayed in the cis and it ran great for a year and a half and 15k miles untill due to neglect the timing belt broke . It does have the warm start problem sometimes but let her sit for 5-10 mins and starts right up. Im not saying im a fan of CIS, but synthetic oil is a must on turbo cars in my oppinon. Oh and for the record I went 9k miles before changing the Mobile 1 and when i drained it I didnt notice much thinning from contamination. maybe i was just lucky?
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"Nitrous is like a hot chick with an STD, you know you want to hit it, but you are afraid of the consequences"

1980 porsche 931 beige
1987 Porsche 951 red, 51kmiles.. prefect cond.
1978 ford fairmont wagon 2.3 turbo engine

[FRporscheman]

Yeah that's why I want a 931 - easier to work on, and cheaper.

How can 924 owners complain about the prices of basic parts?! They're dirt cheap compared to the prices of 968 parts. To buy 968 parts, you need to be the secretary of a country's treasury. A new Variocam unit was quoted at about $1600. Wtf...

Yeah I know nobody in their right mind will ever make a EFI kit, I was just saying "oh, it would be great if..."

I want to learn / read more about juicing HP out of a 931 engine. I read somewhere (I think 924.org) that without changing anything in the bottom end, one can get around 220hp. Then there's pistons, then there's more crazy stuff. Can someone clear this up for me or just link me to where I can find info.

I don't want a restoration project per se, I want a go-fast project, even if it doesn't go "fast" by today's standards.
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'93 968
'84 944
82 MB 300td