Thread: Help me diagnose a VET with blown headgasket

Before taking the engine apart I did a compression test. Cylinder #4 was at 150psi, the rest at 180psi, I tought that fixing the HG would bring it close to the others, I have seen engines with piston ringlands broken and the compression test is more like 90-100psi, should I take the pistons out also and check?

the scratches are barely noticeable, you can only feel it only if you pass the finger thru the cylinder wall.

The tune was around 11.8 afr, conservative timing.

yeah its hard to say, ive had cracked ring lands on an old motor of mine and it still came up 150 while the others were about 175. It will just blow smoke out the breather but still run fairly good. Detonation is a nasty thing.

Who knows, Maybe you just lifted the head but seems kinda weird for that power level unless you used old head bolts or something. Then its possible. I hope you get it all figured out.

I guess I will take out the pistons and check, that sucks. I used brand new OEM bolts, I dont think the head lifted at only 12psi, that would be weak lol

its not only that it could be because of the water/meth injection if you were spraying too much, That stuff cant compress so when you work compressed air and then too much water/meth into the mix that could be what the big backfire was for.

This happened with that installed and operating correct?

If so you might look at retuning the nozzles or pressure on the system. Cuz too much could be a bad thing definetly.

I'm using the smallest nozzle of the kit, for 200-300hp I think. That's what my buddies say, that stuff cant compress, so if somehow drops (not atomized) get into the combustion chamber, that could happen. The nozzle is installed 3" from the TB. The gigantic backfire happened after I was parked, and left, 1st gear didnt boost, shifted at like 4000rpm to 2nd and BOOM!. Maybe some water got on the TB while parked, and when I left got into cyl 4 since its the closest to the TB???? dunno..

possibly, that would cause the head to lift if enough got in there at once.

Usually with detonation or preignition you will have signs of damage to either the tops of the pistons, top edges of the block where the firing ring seals, or the head itself or all or multiple.

If you have no signs of pitting caused by that, it was probably just that case of something like that happening caused by the water/meth kit. Sucky either way. Not much you could do hopefully doing the headgasket and studs will bring the motor back to tip top shape so you can get it all figured out.

The block needs to be resurfaced, I have to take the whole engine out now. Thanks for everybody who has posted. I would like more input from some of the water injection nuts. I really need to find what happened so I make sure it won't happen again.

I vaguely recall recommendations to place the nozzle either as far away from the TB as possible. I don't remember if before or after the intercooler is a concern.

I believe water injection has the same problem as fuel when injected before the plenum. Because of the mass of the gasoline or water in this case, you won't get even distribution into the runners even though you might get an even distribution of air. Like you said, cylinder 4 is fed first from the plenum, and that would see the least water.

I still don't know if that would be enough to cause your problem. I would think you could run 15 psi without even worrying about water injection. =/

Yeah, I got the W/I mostly for high boost +20psi, but I wanted to give it a try and see if I feel any difference at 15psi... I have tuned cars here at 14-15psi on pump gas without problems.

I'll do a research about nozzle placement.