M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Swaps, Turbos, Buildups => Topic started by: ludoz3 on November 29, 2009, 01:42:19 AM
-
First post here, I was reading you from time to time. 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 therie 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.
(http://img690.imageshack.us/img690/8960/img3725c.jpg) (http://img690.imageshack.us/i/img3725c.jpg/)
(http://img522.imageshack.us/img522/7940/img3726v.jpg) (http://img522.imageshack.us/i/img3726v.jpg/)
(http://img163.imageshack.us/img163/5996/img3727r.jpg) (http://img163.imageshack.us/i/img3727r.jpg/)
(http://img130.imageshack.us/img130/7046/img3746u.jpg) (http://img130.imageshack.us/i/img3746u.jpg/)
(http://img33.imageshack.us/img33/2791/img3745cz.jpg) (http://img33.imageshack.us/i/img3745cz.jpg/)
(http://img682.imageshack.us/img682/5585/img3744r.jpg) (http://img682.imageshack.us/i/img3744r.jpg/)
(http://img263.imageshack.us/img263/1127/img3743.jpg) (http://img263.imageshack.us/i/img3743.jpg/)
(http://img29.imageshack.us/img29/2281/img3727c.jpg) (http://img29.imageshack.us/i/img3727c.jpg/)
-
Classic water inlet the water raises compression and goes superheated and cuts through the piston, happens a lot with head gasket failures.
Dave
-
Classic water inlet the water raises compression and goes superheated and cuts through the piston, happens a lot with head gasket failures.
Dave
Thanks or the input dave. so could it be the fact that he lift off at high revs, siphoning the methanol injection system?
Also when he came back to the pits we noticed that the flexible hose between MAF and Throttle had slipped off partially, so that could cause the car to run lean and eventually the high temp?
-
the hose probably came off because of the massive blowby
-
I think you've hit it right on the head,,, Both times I blew a head gasket in an engine and it let go to the cylinder it melted the piston. I've seen it in numerous race cars as well.
Yea, I'm not a big fan of water/methanol injection as a aid to protect an engine, I'd rather make the engine management do its job and if I need that much boost, CHANGE THE PISTONS!
I've seen too many toasted engines from water injection run amok. And if you buy a nice enough unit to really be metered, and stable its about as cheap to rebuild the engine for the boost your trying to run.
Its about 2 grand to rebuild the engine B&B and some mild head tweaks. If you start there, add the boost your likely going to get 100 extra HP and not have to mess with it.
Just my .02 bucks worth... I HATE having to screw around to keep anything running, it interupts my fun and cost too much.
Dave
-
Nick,
by blowby you mean the engine overhead breathing back to the hose? It would make sense.
Dave,
Forged internals will go back in. Looking at VAC motorsport they have a kit giving a compression ratio of about 10 and that they are good for mild boost applications like in our case (10psi). I'll have to look into available options.
Head gasket is not damaged.
-
:) Forged good.
Curious, why not drop to 8.5:1 and really run boost? I guess it would depend on if your running the BMW computer, or the WAR chip, or a standalone?
Cheers.
Dave
-
running stock ECU remapped by NickG.
as for the boost level, I read that the roots type blower used in the DASC kit are not really efficient above 10psi.