Porsche Enthusiasts Club Forum

Just dropped the new dizzy in my car, connected up as per 123ignition set up, the car will only start by leaving on the original +ve wires on and the -ve wire off the coil, however the car immediately stalls. If I remove both old +ve and -ve or leave both wires on the coil the car will not start.

Help?

The 123 setup???

Not sure how this is supposed to be set up, is there instructions with it?

As the distributor is programable, I would say that it probably needs to be installed/static timed completely differently to a conventional distributor.

The Mittelmotor dizzy is based on the 123tune ignition. I have followed the instructions as far as they go. It has been basic timed up, software loaded on the dizzy and laptop. All looks fine. Engine starts on first turn of the key but stops within a few seconds as if the ignition or fuelling is cut off. The map installed on the dizzy is one selected and pre loaded by Mittelmotor so it should work out of the box

If it is starting and then cutting out, it sounds like as soon as it see's a vacuum the ignition timing is going out of range, this is all I can think of which would allow it to start and then cut it out.. try retarding the timing on the dizzy a few degrees and see if that starts it and keeps it running.

I have tried disconnecting the vacuum from the dizzy and no difference.

It still starts on the button, I even get a blip or two on the throttle before cutting out circa 2-3 seconds after starting. I emailed Mittelmotor last night but they clearly don't work Saturdays

Ah well, I'm pulling it out and waiting for Monday's response

Hmmm.. sounds like it might be getting upset by your coil resistance being too low or possibly your ignition leads and plug combination, modern electronic ignition components are much less tolerant especially of the coil resistance.

Do they specify a coil to use? does it use an external ignition amp, or direct connection to the coil... are you using an ignition amp such as a standard 924 item? If so, I wonder if your amp is a bit marginal and the wider dwell that the new dizzy might be using at lower engine speeds might be too much for the amp.

Sure it will not be a serious issue, just a shame you have to wait a bit for the new toy to sing for you.

nothing is ever simple! be good to see the results from this once its up and running properly.

on a side note, where is the best place to source pistons and rods for these engines? also I heard some parts are no longer available for the engine when rebuilding, is this true? if so which parts cant be sourced and how do you get around this when rebuilding an engine.

after considering building my 944 turbo into a full blown track car, it seems the 924 engine is possibly the better engine to push further with decent power. couple that with the fact I have a pretty much full race prepped 924t running perfectly sat in the workshop, I am now considering building the 924t into something with a bit of poke.

the car only weighs around a ton, and there is plenty more weight to come out of the car, and so I think anything above 300bhp will make for a very quick car. I was contemplating removing all the cis and running modern management and a modern turbocharger.

the 924 is now my current winter project, and I spent yesterday removing the running gear from the car for a full check and refresh, if im going to build the car into something a bit more special, nows the time to make the decision and start making plans.

I would love to build a Carrera gtr rep, but I cant seem to find panels anywhere, so I would likely go down a Carrera gt look with fuch wheels etc.

I would love to see more information on the car that was just purchased from prepfab, hopefully a build thread will shed more light on that car as it looks very interesting!

Reversing back through this thread will answer many of your engine questions. But in summary

Pistons - OEM turbo = Mahle cast, OEM CGT/GTS = Kolbenschmitt forged, or JE etc custom pistons. Or try Mittelmotor http://www.ebay.co.uk/itm/Satz-Rennspor ... 2a33bb58ee

Rods - OEM rods are fine in stock form or lightened and shot peened. Or go to Mittelmotor again http://www.ebay.co.uk/itm/Satz-Rennspor ... 2a33af510a

Rod bolts are NLA. Its OK to reuse them on light use road engines but anything spicier then ARP make them on 10 set minimums for circa £200 set.

Main bearings are NLA and extremely hard to source. Rod bearings are that much easier. If you find a source of KS or Vandervelt then several of us would be pleased to buy a set or two.

Oil pumps are NLA so hope existing is in tolerance, usually are.

No experience on EFI/standalone engine management, but Wes does. Again re read his posts here.

Mark has Steve Bassingtons old and new turbo shells and engine block. If you google his name and/or Bass GT you will find build threads on 924board.org to see his previous direction

Lots can be done to these engines to release the 'monster'. Again both Wes and John have written within this thread.

Other parts sources
http://www.mittelmotor.de/webshop/englisch/mm.htm
http://garage.ideola.com/

924 Carrera GT to GTS engine build. This car is now running 340bhp on CIS!
http://www.youtube.com/watch?v=STVYcsej ... tg&index=3

Carrera GT GRP bodywork is available and a pig to install and make look good. There is a good build thread on 924owners club forum but its within the members only section

thanks for all the info! your right I need to read the whole thread through from the start and make some notes!

the parts availability is my main worry! imagine putting all the time/money/effort into building a motor, then for whatever reason having an engine failure, or oil starvation etc to lunch the bearings, and be left will a useless pile of parts as you cant rebuild the bottom end! its not even like getting another 924t engine would be easy, and then what state might it be in when its 30 years old!

what did you do with your engine when it was rebuilt? did you replace the bearings or re use the old ones?

my engine seems to be very good. it has had a rebuild in its history, and has done limited miles since. it also runs perfectly, and has very good oil pressure etc. but that doesn't mean to say when building it for more power it might not have any issues??

I started to rebuild a spare engine prior to my original deciding to blow oil through no.4 bore. I now have three engines including the rebuilt one in the car. I will rebuild my matching number engine at some point once all the parts have been sought.

I'd recommend leaving your existing engine internals alone and enjoy it as is. Source a spare engine and rebuild parts in the meantime. Once you have gotten into your current car/engine then you will know whether rebuilding a monster engine is worth it. I've spent over 2 years on this journey so far and I'm still not finished. My expectations have moved considerably since the start, as has the spend involved.

Do some homework on this before going in too far only to be stalled by an NLA part or a long wait for it. And take this comment the right way, your attention span on recent projects have taken more twists and turns than a politicians career! I'd hate to see a 'breaking a 924t track car' advert due to bolt or bearing sourcing problem

Your right. Prob best to just refresh the car and get it driving again without going mad.

I have always wanted to build a mad 944 or 924 but there seems to be many things holding me back. I am used to tuning jap stuff in which things can be done very easily and cars can run big power without any issues and off thr shelf parts are plentyful.

Your right in that my mind changes like the wind! It does frustrate me, my problem is I want to do many different things and I dont have the time to do them all. Also bear in mind I have many other projects, which im glad to say have now been completed so I now have more time to concentrate on one of my porsches which I have decided will be this one.

I think for the time being I will concentrate on putting this back together without gettin to carried away on the search for power!

Its a shame parts are hard to find and tuning these cars in the uk is such a small market. But then I suppose it is a rare 30 year old car and so cant expect much else.

Cheers

It lives!

I was missing the tacho wire off the -ve coil side. With the -ve signal? wire and TUI disconnected it all starts and runs. Had to time the dizzy to the 8deg seen in the software, now all should be good for a test drive later.

Phew! Good one - Rob

Just been for a hoon. Alls well. Feels stronger, smoother and absolutely no knock at 1.0 bar or so.

Now I need to speak to Jon regarding any fuelling tweeks we need to do. Although I have been studying the GTS' 928 fuel metering set up. Hmmmmm!!

Sounds as though the dizzy has already paid for itself