Water injection and cylinder pressure
 

Does water injection increase cylinder pressure ( doesnt compress) or lower it because of the cooling factor? Just wondering as my last head gasket failed from cylinder pressure ( pushed the gasket but didnt blow ) It also bent a rod with 700cc/min in a 450hp 3.3L 6 cylinder turbo. Cheers

Re: Water injection and cylinder pressure
 

Cylinder pressure has more to do with ignition timing than the effect of water injection.

If the rod was bent, it is more likely due to hydrolocking. What type of water injection system were you using?

Re: Water injection and cylinder pressure
 

Home built setup. Never once hydrolocked, the engine only ever saw water above 4000rpm or 7 psi. Made great power with, my other problem in other thread was a bad cdi. It may be the cause of the bent rod, one minute it would ping or be advanced the next it was retarted. So it may have bent a rod. Can detonation bend a rod? I cant imagine 700ccmin bending a rod. Would the water make less cylinder pressure than detonation? Obviuosly detonation is a spike though. Cheers

Re: Water injection and cylinder pressure
 

I cannot how else a rod can be bent. How many rob are bent. If there was only one, it might be distribution problem.

Describe how your home made system works.

Re: Water injection and cylinder pressure
 

Its got a 40psi pump activated by a kill switch at the moment, a homemade valve I machined up out of brass and stainless to open at a set psi (not just a one way valve). The valve has a needle and seat out of a carburettor in it with a separate chamber for boost only to open it. The water tank is pressurized 1:1 to boost. So the nozzle will always have 40psi ( good spray pattern). All the plugs look identical with the water on. It made great power once it was setup properly ( well once the cdi was removed ). It is only 1 rod. The only thing I can think of is the bad CDI has detonated that one rod really bad. Cheers

Re: Water injection and cylinder pressure
 

It looks a well thought out system with very little to go wrong. What psi is the checkvalve set to open? It is a blown through system.

1. Are there any sign of detonation on the piston top or bent rings?
2. Ring land OK for that piston?
3. Does the spark plug look the same as others?

It has to be a sever knock to bed a rod. IO can only guessing at this stage.

Re: Water injection and cylinder pressure
 

Funny thing was every bore had scuff marks and piston crowns except the bent rod cylinder. It also had a blown gasket on that cylinder and the one beside it. But never had any hydrolock on startup. It did let off a HUGE backfire on startup with the bad cdi. Whether thats caused it I dont know. Has anyone bent a rod or blown a gasket from too much water injection at running speed? I had it triggering at 7psi.

Re: Water injection and cylinder pressure
 

Could the hydrolock be the result of the leaky head gasket? This is toi assume the leak was there for some time.

Re: Water injection and cylinder pressure
 

I have bent rods before until one finally snapped. Detonation did it. Back then, I did not use water/meth.

Re: Water injection and cylinder pressure
 

yeah I think I figured out what my problem was ( I think lol ). The head lifted and pushed coolant into the cylinder on the intake stroke. Cheers