First post here, I was reading you from time to time (as I do on many US based BMW forums, not too much info on boot bimmer in France). I am posting on behalf of a friend who owns a Z3 1.9l roadster fitted with DASC. I personnaly own a Z3 coupe 2.8l and an E36 M3 3.0L (euro spec)
so set up is as follow:
90k miles engine on a Z3 1.9L
DASC kit, 15k miles on it.
fitted during the week:
NickG tune stage 3
pulley 3.4"
snow performance stage 1
The first issue we had:
that was with the snow performance kit, we did not order the solenoid valve and find out about the requirment for this with DASC (due to the injection being after the throttle body and subsequent risk of siphoning) set-up while fitting it. Upon realising this we decided not to run with the sno performance on the road.
Yesterday the car was driven down to the road track, 200 rouble free miles. Before that 2 or 3 run down the road were done with no problems.
once at the track:
reconnected snow performance before going in. All went ok for 8 miles when the low level alarm for methanol/water tank went off. Seing that and in order to protect the pump, my friend shut off the injection (in car switch) right away.
Immediatly a very strong smoke came though the air vents and smoke out of the exhaust so he decided to proceed to the next fire man pit. on the way he felt the car was sluggish (more on that later). the fire was quickly put out and only located on the exhaust just after the header.
the car was brought back to the pits and the findings were:
-snow performance tank level was in fact low, so around 1 gallon was injected in 8 miles
-blown filler cap seal (seal couldn't be found but was there the day before, re ), so that explained the oil everywhere in the engine bay area and was probably the source of the fire
-flexy hose between MAF and throttle body was partially disconnected, no idea how did that happen
-we tried to restart the car, sounds like there is no compression
-looking at pistons through the spark plug holes, they look like brand new pistons (shiny)
-engine turns freely by hand
-oil pressure and temp, water temp were ok on the way to the fire man pit.
what we don't know (amougst other things):
-AFR: no meter, will be fitted for the rebuilt
-boost pressure: gauge wasn't looked at
Basically looking for opinions on what went wrong before rebuilding. My feeling is that the injection rate of methanol/water was much too high, almost as much as petrol. When I thought of the siphoning effect before I only thought of it at idle, now in insight, it also takes place everytime the throttle is closed.
I still can't understand how the filler cap seal could be blown like that though
Car is still at the track, we will collect it during the week, and open the engine after to have a good look at the pistons, after having done a compression test.
Original theorie of mine was:
the methanol injection was cut off in th middle of the straight at 7000rpm. Very high revs and closed throttle butterfly lead to partial vaccum being created in the intake manifold, correct? if so, the siphoning of the methanol/water goes on but as the pump is not running, it is not under pressure anymore so no atomisation of it, just dripping. Than goes into the piston chamber and probably vaporised immediatly => Hence the white exhaust fumes that could be seen as soon as the methanol injection system was shut-off. That might also have washed the bores and blown the piston rings.
Looking at pictures my friend just sent me, I think that my original bore wash theory is out the window, definitely looks like pinging to me.
Car was running on 98 RON fuel (I think it's 93 of your octane number which is an average of RON and MON). Should we be running higher octane fuel at 10psi?
I am getting my friend to check that the pulley size is correct and that the MAF he fitted was the correct one too. If these two check out, then I am a bit at loss so once again, any suggestion welcomed.
the headgasket was found to be ok during diassembly.
Pistons appeared to have melted on the exhaust side, too high EGT?
anothr Q: what octane petrol is run by those running 10psi on stock engine? we wre running a 98 RON (93 for US octane rating I think)