968 Dead on Road

OK.... Hopefully you guys can help with some direction on this. As I was on my way to work this evening (night shift at a prison) I pulled off the freeway to exit. The car died.... Just died... No idiot lights nothing. It started downshifting (tiptronic) until it stopped and then died. I popped the hood and checked to make sure everything looked kosher (praying it wasn't the balance belt) and everything looked OK. I checked the transmission oil, no obvious problem there. I said a quick prayer and turned it over.... She started right up again. Has anyone here seen or heard anything about this happening before? :(

Happened to me in my conquest. When i tried to restart it it snapped a rod and put a hole in the block. Lost oil pressure, but didn't register it. Obviously not your problem if it started up fine. Just be careful.

Also, maybe some sort of electrical problem. Fuel delivery backing off=downshift=kills engine??? Only guess I have and it's a long shot, but sometimes bad wiring can cause strange issues like that, and in a european car it wouldn't surprise me.

DME fuel relay, can come and go as it pleases, buy one for next time it does it, always good to have a spare one, once they start, there never the same again.

Thanks guys, I'll get the relay, that's a pretty common fault. I'm also planning to do a tune up in a couple of weeks, so I'll take a close look at the fuel delivery system over all.... I just hope it doesn't turn out to be anyhting too serious.

Otay... New update. Took a closer look at the tranny this afternoon, and I noticed the sight glass shows that the ATF is a bit low. I wonder if the trans might have gotten hot due to reduced fluid or just detected low fluid, and shut down. Maybe safety to keep idiots from burning up the transmission? I want to add ATF, and then watch for a few days to make sure there isn't a leak, but the owners manual doesn't do any good at all. I'm about to google for a way to add fluid, but I hope someone else has a little input. Is this even possible? I'm still planning on replacing the DME relay, but I don't want to run it at all until I know it is OK. Kill the Tiptronic, and replacing it will be a nightmare. Thoughts???

Is the DME fuel relay the same in most of these cars ../44/24/68/.... interchangeable

I beleive that tehy are the same for the 944, 968 and 993. Probably the 924S as well, but I don't know about the regular 924. BTW, replaced the DME relay, and it hasn't been a problem again. 32 bucks from my local independant Porsche shop.

To turbo your motor your looking at a big chunk of change man. I wouldn't supercharge it!

I priced out custom turbocharging a 968/S2 engine about three years ago, and my estimated cost was about $6K USD, with all mechanical and fabrication work done by myself.

I talked with Kokeln, and what I gathered from them is that they build the engines using the stock pistons, which I was skeptical of at first, except with custom made Carrillo connecting rods, which are slightly shorter and decrease the compression ratio. I would strongly advise checking with Kokeln about this, this is just what I recall from years ago, for all I know they may have meant using forged pistons which are identical to stock. I know there is a problem with getting aftermarket pistons in that they must have the special coating, so that is something you would have to look into.

I was quoted $2000 USD for the rods, they were one of the big ticket items, as was the turbocharger, I priced out a ball bearing Garrett unit at $1700 USD, and an Autronic ECU which would have been around $800 USD. The projected cost came out to around $5000, so I estimated an additional $1000 for little things that would be unforeseen.

Then again, I found numerous ways to save money through resourcefulness, such as using injectors from a turbocharged RX7. The RX7 uses only two injectors, so they're over 600ccs a minute in some applications, and slightly more if you increase fuel pressure. Having the means and experience to fabricate a turbo header and exhaust is a big money saver too, as well as the intake For most people this is out of their league, although I'm sure Powerhaus or Kokeln would be willing to sell the necessary custom parts, for a hefty premium.

That being said, if you can penny pinch and bargain hunt, $10K should be enough to build a 500hp 968 engine. Last time I checked, Powerhaus wanted $20K for a complete conversion. Considering the time, money and custom parts involved, that's not entirely unreasonable.

Hope this info helps!

Connor

Thanks for the input Conner. Right now it isn't economically feasable for me to throw the cash down for the complete conversion. I am looking at a couple of changes this winter though. As it is, I plan to upgrade to M030 brakes, and suspension work. I have heard good things about Leeda from the guys at 968.net and rennlist, what are your thoughts?
I also plan to do a thorough tune up of it shortly after christmas, I will post and keep everyone informed of the proceedings. After that I can start shopping for the parts to convert to turbo.
I have been keeping abreast of the developments in superchargers for it as well. The good news is that 9M racing in the UK has theirs down pat. The bad news is that they shared the research with Speedforce Racing in California. Apparently there are some differences between the ECU in US spec and ROW cars. They haven't gotten the software tweaked to work as it should as far as I know. The worst part is with the relative rarity of these cars, there isn't much of a market for it either. Without selling kits, they can't front the money for development. Without development, they can't work the bugs out to sell more kits.... It's a vicious cycle no matter how you dice it. I'll just have to see what is more feasable when I have the nickels to rub together.

Again thanks for your thoughts guys.... I'm sure once the conversion starts it will be an interesting and well documented saga.