Thread: Help me diagnose a VET with blown headgasket

So I blew my head gasket, it was blowing compression into the cooling system, spraying all the water out of the reservoir tank. We already took the head off, the failure was on cylinder #4, since the water wasn't getting there, the cyl 4 overheated a lil and it has a few scratches .

I already have the brand new metal headgasket, will send the head to the machine shop to have it resurfaced, and since I was running OEM studs (brand new), I also got a set of Mazworx ARP head studs.

I have spent a lot of money into this project, and its a bit disappointing to have problems like this. What I'm doing now, while the engine gets fixed, is try to find the reason of failure!! Maybe you guys can help me out.

Things to consider:

#1 The engine ran like a champ for almost a year, it spent most of the time at only 10psi though
#2 Daily driven car
#3 Built internals: JE pistons 86.5mm CR is about 9:1, Eagle rods, VE metal HG.
#4 Head and block surfaces were checked OK before the build.
#5 It started blowing out water after like a year while tuning, here is what happened that day:

Since I finally had the water injection installed on the car, the idea was to try it out by triggering the water injection from 10psi using the small noozle (AEM kit), I wanted to leave it at 15psi that day, I have a wideband and a MSD knock detector permanently on the car, the timing was conservative and the fuel mas was on the rich side (11.0 afr), I increase the boost controller percentage, and made 12psi, the 2psi increase felt brutal, and then I started leaning out the AFR's to something close to 11.8 AFR, when I got it there, I parked to change the boost controller settings so I can boost 15psi, after I got done with that, when I left, I didn't build boost on 1st gear, just revved it without boost, shifted into second, and then BOOOM!! a gigantic backfire!!! I was running open cutout, and I could see the explosion under my car lol and actually felt it on the car floor, so I pulled over, revved the engine a couple of times, no weird noises, left again, revving fine, AFR's fine, vacuum fine, it built boost ok and pulled strong..! but 5 minutes later the temp got a lil bit high (not much), pulled over, opened the hood only to see the reservoir tank spraying water, so I let it cool down, and then opened the radiator cap, there was no water on the radiator at all, but the oil on the engine was clean.

What I was running that day was, NGK BKR7, 70% alcohol 30% water on the AEM kit triggering at 10psi, boost controller set at 12psi. All my friends insist that the problem is the water injection, since the engine never gave any trouble before that day. There are no signs of detonation on the block and head, also, at 12psi is ridiculous to have a failure like this, considering I plan on boosting +20psi (thats the real reason I got the meth injection), my friends say that some drops of water on the combustion chamber can kill an engine, but the water is supposed to be atomized at like 170psi, no drops there!.

I'm fixing this mofo, but I can't afford more problems like this, please give me your inputs on this issue, because I don't want to back off on the 20-24psi plan.

Thanks in advance!!

The only thing I can think of at all is that it might have been preignition (not detonation). How much power would you say you were making at 12 psi?

You'd probably have a hole through the piston though if it were preignition. =/

Preignition? What's that? How big of a hole in the piston do you mean?

Google images for preignition:









I've also seen them melt into basically a small potato shape of aluminum.


What's preignition? It's when the air/fuel mix gets ignited before the spark plug initiates the ignition process (usually well before). Best explanation I've found is here:
Engine Basics: Detonation and Pre-Ignition: Streetrod Stuff

It felt like low 300whp, based on other SE-Rs that I have driven. Cylinder 4 is the only one affected, the piston is fine, the combustion chamber is fine, but the cylinder wall has a couple of scratches on one side...

I was asking to see if the spark plugs were the right temp range and it seems like they were for your power levels.

How did the spark plug look on cylinder #4?
Have you checked the compressor/exducer blades on the turbo? Any pieces missing?
How bad did the gasket look?

Turbo looks on great condition, all the spark plugs looked the same (a bit black). Now, could really some drops of water cause a problem like that?? I'm asking because of what my friends say, also, cyl #4 is the one closest to the TB, thing is, the AEM kit comes with a check valve so that won't happen.

Also I will have those stupid DW injectors flow tested. Just to discard another option.

How was the tune on your setup?Sorry to hear about your engine.
I should consider myself lucky for being able to run 2.0 bar of boost for soo long.

I doubt it. Anything is possible but that sounds totally crazy to me.

FYI: YouTube - Water injection plenum view through sightglass

Since the cylinder is scratched is it also possible you melted the ring land of piston #4. Which would possibly not be visible from the top. You could replace the head gasket and then find out #4 still has no compression.