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There are plenty of 928s and 944s running Megasquirt ECU's with no problem because it is cheap and easy. I used a Microsquirt which is limited to batch fire and wasted spark but still more advanced than the ECU's the 928GTS used! My total installation would have been cheaper than 4 new Webers. Webers are fine and sound good and the fueling would be good occasionally separated by a series of flat spots. Also, there is no adjustment for different altitudes. There are several threads on Rennlist for Megasquirts and Microsquirts. Here is one https://rennlist.com/forums/928-foru...onversion.html
No need for a dyno unless you feel the need. I used the auto tune to set the fuel maps and on my race car which also has a Microsquirt I just flog it about the circuit and tune that way.
The major improvement with EFI is losing the distributor. You have probably heard the saying all the horsepower is in the ignition! The 928 really responds to a good ignition map and it's the ignition that greatly improves the drivability and better fuel economy. The 928 is easy to convert because the early Golf's and Mercedes from the same period used the same injector screw in bases. I use Audi 1.8TT injectors and Ford coil packs but the Golf coil packs are widely used.
In Australia, finding a dyno that will tune carburettors is getting very hard!
I do wonder if DIY Autotune would think about putting out a "kit" specifically for the 928. I run an MS3 in my track Miata and it's honestly excellent. They do many different "plug and play" setups for quite a wide swath of platforms. I've never converted anything from mechanical to EFI, but if anything, this would be the path I'd look at first. EFI is not wizardry, it's fairly simple, and in a lot of cases you do NOT need a dyno to dial anything in.
I do wonder if DIY Autotune would think about putting out a "kit" specifically for the 928. I run an MS3 in my track Miata and it's honestly excellent. They do many different "plug and play" setups for quite a wide swath of platforms. I've never converted anything from mechanical to EFI, but if anything, this would be the path I'd look at first. EFI is not wizardry, it's fairly simple, and in a lot of cases you do NOT need a dyno to dial anything in.
I don't think there were enough sold to warrant a plug and play Megasquirt. It is probably not really needed if you buy the ECU with the labelled cable kit and just use GM sensors. The 928 engine is quite a simple OHC engine and I started with computer-generated timing and fuel maps and the car started up and ran straight away. I started the auto-tune function and the car was running smoothly and with an excellent response after driving about a kilometre! If I had used an MS3 I would have used Chev coils and gone sequential.
I used to have a track Miata. I bought it and used it while I finished off my supercharged Fiat race car [903cc]. This car also uses a Microsquirt and this conversion from an engine that dates back to 1955 was a bit more difficult EFI conversion than the 928. The Fiat does faster hillclimb times now than the Miata and the 928!
A little update on my project. I tested the pressure on each cylinder and found one to be 6/6.5 ish bar, the rest between 8 and 10. Or 90/95 and 115 - 145 psi for the imperial people. At first tests I got some weird numbers (one even got up to 16 bar) and the rest was dropping. So did a second run where after a test I would hook up the battery charger whilst I was working the steps to the second cylinder etc. Also added a few drops of oil in the spark plug hole each time, so hopefully these results are a bit more meaningful. What do you guys think of those numbers? Unfortunately I also found some glitter in the oil coming from the spark plugs. I'm in trouble am I not?
seems low numbers ... i did a compression test recently , all were between 11.5 and 12.5 bar.
Is that "glitter" metal ? sure not a good sign .....
PS i once ruined the ignition coil doing a compression test ( = 8 x some revs on starter motor) due not disconnect it. Seems the coil must be able to get rid of energy via the spark plugs ? Could have been coincidence but i don't think so.
seems low numbers ... i did a compression test recently , all were between 11.5 and 12.5 bar.
Is that "glitter" metal ? sure not a good sign .....
PS i once ruined the ignition coil doing a compression test ( = 8 x some revs on starter motor) due not disconnect it. Seems the coil must be able to get rid of energy via the spark plugs ? Could have been coincidence but i don't think so.
It does sure look like metal. I will check with a magnet soon if it is steel. I did keep it plugged at my initial tests, but since values were weird and some cylinders fired despite fuel pump being disconnected I decided to unplug it. Hope I did not do any damage though. Will check later.
In the barn forgotten cars have a tendency for substancial damage. Reminds me of my "good" S2 spare engine bought 15 years ago with deep scores in two bores after disassembling.
It does sure look like metal. I will check with a magnet soon if it is steel. I did keep it plugged at my initial tests, but since values were weird and some cylinders fired despite fuel pump being disconnected I decided to unplug it. Hope I did not do any damage though. Will check later.
for compression test you remove all 8 plugs ( more easy rev's with starter motor ) and wire the throttle wide open. Could explain your low numbers ... if you only did remove 1 plug at a time with 7 making compression ???
08-04-2024, 03:50 PM
