m20 Turbo Headgasket pushing Issue

[.FUDD.]

probably just the tune, I bet its timing map is too aggressive, or fuel quality is too low.

popping at 10psi means serious tuning issues. Even the stock head bolts can handle 12psi on a decent tune.

send me your timing map and I'll see what i can do as far as comparing it to a few of my known safe tunes.

I believe the issue was a faulty CPS!

Car used to hesitate and cut out under boost. With the new crank position sensor she is running cherry!

[Q5Quint]

So the cool thing about megasquirt- is that it logs all the sensor data- so you can see if a sensor is faulty or not.

If you are missing timing and injection events because of a bad cps.... there would be a major huge earthquake stutter as no fuel or spark would suddenly slam the engine, then it finds the sensor again and fires back up. I would get some hesitation and missing under boost but a new set of plugs would fix it.... but they would torch themselves in about 6 months since I was running a bit rich up top. It was a hesitation, not a every-cylinder and every-injector cutting off situation. If it was the cps- there would be a huge dip when it loses the sensor in your megasquirt log.

Happend to me because a wire was loose, and at high rpms it would vibrate enough to loosen a bit... but then make a good connection again at low rpm.

I would shave the head and deck the block if it was out of straight,
swap injectors around and put #3 on cyl 1 to see if that moves the problem,
use new plugs gapped short (mine would blow out stock gap at 7psi) although your plugs look fine,
check your timing map against other timing maps- conservative is better.
check the block timing itself with a timing light, there are megasquirt settings to compensate for this. If they are wrong a conservative 'looking tune' could actually be too advanced. ie 20 degrees advance in the ms tune file could actually be 25 degrees in the real world if your settings are off.
watch the sensor readings in megatune to make sure the coolant temp or cps etc are not being all weird and jumpy- a bad ground can make them jump around a bit-
make sure your tune is conservative enough that it will not destroy your car if somebody 'smart' at a gas station accidentally put some 87 in the 93 tank.

They have bluetooth and android apps for that thing man- check that tune!

It seems like you are the kind of spray and pray gearhead I used to be- the PO could have had a high quality gas station nearby and a bad tune (well technically a good agressive tune) that was barely detonating and he never knew it. Some bad gas and some wot runs to heat things up a little too fast and warp the head jusssst a little bit and poof- headgasket gone. X 4.

You are lucky it is the gasket and not the piston.

Post that tune!

[Q5Quint]

stock timing map for the curious or ants

[justinv]

Sorry guys been busy, I do want to mention a few things.

To save my self the embarresment and to make my initial post short and sweet, to be correct this is the 4 HG ive blown SMH :( one time was due to not re-torquing headstuds properly after intitial start and i went out and ripped it, (nothing like doing 2 HG in two days! so fun haha) The car has popped twice now around 120mph under heavy boost.

I just finished putting the car all back together and will be starting it up this weekend.
I ran a victor rienz one time and have used felpro all the others,
I am torquing ARP to 70 ftlb with arp assembly lube and retorqing after a good heat cycle which is usually bleeding the cooling system, I run some cheap oil through during this first start up then drain and run 10-40 castrol synthetic. I will post up more info from the megasquirt setup once the car is running and i can gain accsess, and flowing my injectors wouldnt be a bad ideal.

I was getting alot of heat/ steam (maybe oil/coolant) coming from the valve cover port which i have a hose running it to the ground to dump to atmosphere, my plugs looked like shit and i fear my valve seals may be failing, i will post a pic of plugs this evening.

I am going to keep the car parked until i tune it but before that is done i need to put the clutch in due to it slips under load in high gear so no tuning until that is taking care of.

what are CT?
and again i will post up as much info as possible once car is running and i connect to the megasquirt.

Thanks again guys

When you run it again,You should smell the steam under your :)oil cap
for signs of fuel vapors. You always have blow by with turbo engines.
If your crankcase isn't vented properly,
This could cause overheating and premature oil wear.
I vent mine under boost instead of vacuum.
I drilled the euro distributor hole plug
and welded an aluminum tube 6" long with a filter
And draw straight from the valve cover to the turbo inlet.
I still have low summer intake temps.
This will help a lot with engine temps also.