I'm in the process of stripping down my Sr, and I have just noticed some small cracks in the head round the spark plug holes, does this mean I need a new head?
I'm in the process of stripping down my Sr, and I have just noticed some small cracks in the head round the spark plug holes, does this mean I need a new head?
I'm not sure if this is the same for everyone but the bottom three photos are showing correctly and are mostly greyOriginally Posted by MadManMeasures
I'm in the process of stripping down my Sr, and I have just noticed some small cracks in the head round the spark plug holes, does this mean I need a new head?
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I'm getting only one pic and the others are not fully loading/mostly grey
but can see one hefty crack and worse looks like lots of detonation pitting between both inlets,
the crack alone renders it as needs a repair or/its scrap/ get another head and start over ,will need find why its showing the det damage
is the car running a chipped ecu or stock,how much boost pressure etc
I have a cracked SR head for spare rockers/shims and the car it came from suffered an overheated/melted ignition amp
and I guess it went into super spark mode and just randomly fired I think and cracked all four plug holes at least 3 cracks per plug hole
but there is no det damage to my head so I think something was wrong with yours before the head cracked
like it was detonating for some time and then the crack appeared
Looks like my photo bucket isn't working too well. I am surprised by how bad the head looks. The car was running perfectly fine just compression was a bit low so I decided to do a full rebuild. One of the coil packs did fail a few years back which could have caused the det. But that would have only been. One cylinder and they all look rather similar. It's been running a custom mapped H-dev chip and 18psi of boost on a stock t28 for the past 5 years. I have now bought another head. But have no idea what caused the current one to crack. I did notice a very slight drop in power on the last track day but I was assuming that was the turbo starting to fail. The ignition amp looks fine. I am converting to r8 coil packs before the car comes out again.
suspect low comp readings from scorched/super hot exhaust valves and seats pitted
nothing really stands out as why its lasted so long and then gone into what looks like pretty bad det damage,
carry on with the rebuild and get it running on a low boost and have it checked/mapped
if you don't have one get a wideband and exhaust gas temp gauge maybe with a warning light for track work
Glad you've got a new head, would be worth considering having it pressure tested before you do any work on it. Most engine centres can do it and it isn't expensive.
Yeah that could be the cause of the low compression. It did come back up to 166psi over all 4 cylinders when I did a leak down test though. Definitely glad I decided to do the rebuild now I've seen the condition of the head. I have got an AEM UEGO to go in once the engine is done. I am planning on running it on the current ecu on very low boost, then I'm going Link G4+ plug in. The new head should be good I ordered it from H-dev. Its been cleaned, skimmed and had the valves lapped in which saves me another job.
that reads as a good plan and list of parts,the head will save a lot of time getting it back together,
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