Gixxer Squid Posted February 13, 2009 Author Share Posted February 13, 2009 Pull the head. Looks like a valve came apart or something, but the piston coming apart could have interfered with the valve. Regardless, you have head damage Your right, the seat obviously did not want to stay were it was supposed too. Obviously the damage could have been much worse than the little scuff on top of the piston. Blown head gasket as well. Quote Link to comment Share on other sites More sharing options...
Careless Posted February 13, 2009 Share Posted February 13, 2009 man, that is the luckiest form of destruction one could possibly hope for, short of a blown head gasket and a few other minor things. Don't feel dismayed, even though you have to get the head re-checked and that guide probably needs to be pushed out and replace. It could have been far far worse. Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted February 13, 2009 Share Posted February 13, 2009 Wow, yeah I'll say you got lucky on that one. unfortunately it's hard to say exactly what happened. just be glad there's no apparent block damage. you might still drop the pan and pop that piston out to inspect the rings and rod. Its entirely possible they might have cracks, or have metal lodged in them which could score your cylinder walls. The piston itself, aside from the valve mar still looks good. I think you're a lucky ducky it wasn't worse. good luck. Phar Quote Link to comment Share on other sites More sharing options...
Overkill Z Posted February 13, 2009 Share Posted February 13, 2009 agreed...you are a really lucky guy...iv seen similar things happen to high boosted sr20's and normally when this happens the whole head gets crushed around the valves. as for the California gas... Ya its lame...only use Cheveron seriously... you can go online and look up what each manufacturer puts into their gas... Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted February 13, 2009 Share Posted February 13, 2009 Look at the last picture - the seal has dug into the chamber. And if you drove it home like that the exhaust valve must have been hitting the displaced seal... Also if you are running a flat top piston and thats a P90, a stock head gasket would give you a 8.5:1 CR but a 1mm would put it at 8.7:1 *according to LEngine* You might have a different setup from stock sizes though. *edit* I just saw the engine was overbored so my comment doesnt apply Sorry about that, I hope you get it fixed soon. good luck Quote Link to comment Share on other sites More sharing options...
Gixxer Squid Posted February 13, 2009 Author Share Posted February 13, 2009 Yeah, I am pretty lucky or so I thought. Since this is a high performance engine a re-knowned engine builder is suggesting I pull the engine and replace all the pistons and check rods etc, etc. This obviously adds another 3k if not more and I did a compression check on the 5 other cylanders (after this occured) and they were all 115-117 psi, including some previous damage to a throttle body screw getting into piston one and two. I keep getting so much different infomation and not sure what to do cause I surely don't have another 3k+ floating around in this economy but on the other hand, I would hate to have other failure due to the tops of 1 and 2 potentially giving away and since I practically have the engine already apart, bite the bullet and pay the piper. The throttle body screw already caused me to pull the engine once and get a new turbo but that engine builder said it was not a real problem having the piston scarred like this. I put about 400 miles on the thing before the seat failed running 18psi and #1 and #2 seem to be fine. The screw did ZERO damage to the cylander walls so why not just fix the head and and put it back on. Thoughts?? Quote Link to comment Share on other sites More sharing options...
Gixxer Squid Posted February 13, 2009 Author Share Posted February 13, 2009 Wow, yeah I'll say you got lucky on that one. unfortunately it's hard to say exactly what happened. just be glad there's no apparent block damage. you might still drop the pan and pop that piston out to inspect the rings and rod. Its entirely possible they might have cracks, or have metal lodged in them which could score your cylinder walls. The piston itself, aside from the valve mar still looks good. I think you're a lucky ducky it wasn't worse. good luck. Phar errrr......... drove the car home about 3 miles after this happened so cylander walls probably survived:nono: Quote Link to comment Share on other sites More sharing options...
ozconnection Posted February 13, 2009 Share Posted February 13, 2009 Looks like the head is defective IMO. Valve seat became unseated? I've not seen this although it's entirely possible I guess. Talk nicely to the head builder to see if they can fix it for you. That piston with the throttle plate screw marks......were there marks like that on the P90? I'm assuming there were! What is your gut telling you to do? With as much that has gone on with your engine and all the money that you've already spent on it, you need to get it fixed right this time. I would pull the engine down completely and inspect everything, especially the pistons. You owe it to yourself. Peace of mind is something that'll not haunt you like suspicion. And get that 2mm gasket too if that's what you need OR rework the chambers so that you don't need a 2 mm gasket!! Good luck! Quote Link to comment Share on other sites More sharing options...
510six Posted February 14, 2009 Share Posted February 14, 2009 Myself, I would have the head repaired and when tuning on California 91, shoot for 11.2 -11.5 AFR . Quote Link to comment Share on other sites More sharing options...
Gixxer Squid Posted February 14, 2009 Author Share Posted February 14, 2009 Looks like the head is defective IMO. Valve seat became unseated? I've not seen this although it's entirely possible I guess. Talk nicely to the head builder to see if they can fix it for you. That piston with the throttle plate screw marks......were there marks like that on the P90? I'm assuming there were! What is your gut telling you to do? With as much that has gone on with your engine and all the money that you've already spent on it, you need to get it fixed right this time. I would pull the engine down completely and inspect everything, especially the pistons. You owe it to yourself. Peace of mind is something that'll not haunt you like suspicion. And get that 2mm gasket too if that's what you need OR rework the chambers so that you don't need a 2 mm gasket!! Good luck! LOL, gut says to open the bank, wife says otherwise:biggrin: I will have the chambers opened up and won't need the 2mm headgasket if thats the route I go. The head will be repaired at a minimum, pulling the block and pistons though at another 2k plus to the equation minimum:? Quote Link to comment Share on other sites More sharing options...
Careless Posted February 15, 2009 Share Posted February 15, 2009 you must pull the block and at least check the bearings. and if they're out, replace them... it's like 100 bucks for a set of new big end and crank bearings. you don't need anything fancy shmancy like the 300 dollar Calico Coatings CT-1 ACL Bearings I have for my build. There are 1200 hp engines running standard nissan bearings with the RB's. Some people recommended above all others. A friend of mine just bought new edelbrock heads and intake for his 350 sbc, and then he bought a bottom end that was built by someone who worked at a GM facility of sorts. The 7th cylinder piston had a smiley on it from valve to piston contact. But he thought nothing of it as the engine turned over by hand fine. The car lost oil pressure on the highway on the way to a Camaro show about 10 days after driving it because the bearing moved a touch when the previous owners valve/piston made contact. The starter would back the bolts out with Red Loctite, the car started to get harder and harder to crank over. And it just made a lot of rumbling noise from the rear of the engine. Turns out that bearing was crushed and spun, threw a rod into the oil pan. You do not want the same thing to happen, so at the least, pull the crank, get it checked for scarring. have it micropolished if needed. replace it with bearings similar to what you had in there just now, get the head checked. And locate a set of oversized aftermarket replacement pistons of the cheaper kind. That way you can drive it conservatively at least or on less boost. They should still be able to take a pounding, and if you pull everything and just refit the block yourself, you'll looking at half the price, with the polishing and straightening of the crank and having the head rebuilt if the builder owns up to doing something wrong with the seats (if he did). You can install pistons and rods and bearings yourself. If you have the balls to drive a car at 16psi and know enough to pull the head, this may be the chance for you to refresh your skills (if you've done it before) or learn some new tricks and acquire some new tools. Plus, you get to say you took it down to the last bolt... even if it's something that you don't wanna get into right now. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted February 15, 2009 Share Posted February 15, 2009 Seat definately fell out. Ferdinand porsche had that happen on the first volkswagen beetle during an endurance test when he was descending a hill and shock cooling caused a seat to fall out. They took a feeler gauge, put it between the seat and the head, hammered the seat in, and then broke off the feeler gauge and drove the car a few thousand miles with no troubles. Is your thermostat sticking open? I'll guess somebody knife edged the throttle body and that's what caused the screw to fall out in the earlier mishap? Quote Link to comment Share on other sites More sharing options...
islanddozer Posted February 15, 2009 Share Posted February 15, 2009 Ouch man ! I would not trust anyone else to put your investment back together. Take the time and have piece of mind. Sorry to hear about your troubles. These are great engines and built right they take a kicking. Quote Link to comment Share on other sites More sharing options...
Daeron Posted February 15, 2009 Share Posted February 15, 2009 I would say, save yourself some worry, and spend a *little* bit of the cost of having a machine shop doing everything on a few tools (engine stand hoist, etc harbor freight FTW) and tear this engine down, inspect as advised above, and re assemble it all yourself. If the compression calculation earlier (8.7:1?) is close to right, 18psi seems alot of boost to be running with 91 octane max. I tried to look over what you said the specs for the engine were.. 144 mm rods, 280 stroke, zero deck height add up to ~25mm pin height??? thats a TIGHT PACK unless something else is amiss, but the compression plus the boost on the octane might be a tad much.... The standard wisdom with a high quench design head like the P90 is to have the flat top of the piston coming i *believe* ~.0022 inch from the quench pad of the head (1 fast z/Brian is the person who I quote on that subject, I don't have the link handy) IF you need to dish the piston out a little to lower the compression a smidgin, then you would want to grind a peanut/trapezoidal type shaped dish into the face of a piston that will push close enough to the head in your bottom end when assembled. This little depression should mirror the combustion chamber in the head in all ways possible/practical. (It won't be nearly as large in volume or in outer "circumference") This will give you a nice even rounded-flatttish pancaked chamber for all that air/fuel to get squished into from the quench-pad area at the last moment, which should be the best shape you can get for your chamber. Obviously, pistons with sufficient meat are required to machine this depression into. The EXTREMELY close approach of the piston crown to the quench pad is critical; the number used should be researched and decided based on more than just my posting here. This is honestly just a tad beyond my ken, but I can kind of see where you need to go (I think) and dropping the compression, achieving proper clearance (WHICH your builders may well have already done) and giving those pistons that little scallop should be the magic bullet that dips your compression while increasing your engines tolerance for high compression, nipping your bud on both ends. Quote Link to comment Share on other sites More sharing options...
Xander Posted February 15, 2009 Share Posted February 15, 2009 I have had a similar experience. I had some fancy 87mm forged flattops in there and due to detonation a sparkplug broke. It's not healthy to have a hard piece of ceramic bounce around in an engine with about 1mm of space between the piston and the squish pad. It hammered the piston to bits. I looked a lot like you piston with the screw damage only worse. The problem was that I had the wideband O2 sensor in the stock location inside the turbo housing (I used a z31 turbo). Having the O2 sensor this close to the cylinderhead caused it to overheat. This in turned made my Megasquirt think the engine was running rich so it started injecting less fuel. Running lean at 15 psi of boost at 6000 rpm is not a good thing as you can imagine. So what's the position of your 02 sensor? Quote Link to comment Share on other sites More sharing options...
Gixxer Squid Posted February 15, 2009 Author Share Posted February 15, 2009 I have had a similar experience. I had some fancy So what's the position of your 02 sensor? 12" past the turbo downpipe Quote Link to comment Share on other sites More sharing options...
Gixxer Squid Posted February 15, 2009 Author Share Posted February 15, 2009 Awesome feedback guys. As much as I would like to do this myself, I am mechanically challenged and want to run the piss out of the car. E85 station is being built close by and thats what she is going to run 100% of the time if I can help it. Rebello racing has the head and Dave is crunching some package numbers for me. They are getting the block next weekend. I want a track car I can run the crap out of but she has to be built right and reliable and everything points to Rebello to have this done right. Probably got to get a 2nd job but we all know the importance of having it done right the first time which I don't think happened. pixr of me running the crap out of my GSXR-750. Speed is in my blood, need the car to hold up to this punishment. Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted February 17, 2009 Share Posted February 17, 2009 errrr......... drove the car home about 3 miles after this happened so cylander walls probably survived:nono: You can still drive with scored walls especially if the cylinder is dead, as noted with bad valve seat no compression. I didn't say it was frozen, lodged, just that where could be metal particles in by the rings. Scoring would only bring down compression, but could lead to other issues. As I said before, if you didnt' want to pay to have it all taken apart, you could just jack it up, drop the pan, pop out that piston, inspect it. replace anything that needed replacing. and pop it back in, button up the pan, then get your head fixed and you're probably okay. I don't think there's block damage looking at the picts, but you don't know if that damaged (cracked/bowed) the rod, or flattened a bearing. It's easy to do since the head is already off. Phar Quote Link to comment Share on other sites More sharing options...
Gixxer Squid Posted February 18, 2009 Author Share Posted February 18, 2009 You can still drive with scored walls especially if the cylinder is dead, as noted with bad valve seat no compression. I didn't say it was frozen, lodged, just that where could be metal particles in by the rings. Scoring would only bring down compression, but could lead to other issues. As I said before, if you didnt' want to pay to have it all taken apart, you could just jack it up, drop the pan, pop out that piston, inspect it. replace anything that needed replacing. and pop it back in, button up the pan, then get your head fixed and you're probably okay. I don't think there's block damage looking at the picts, but you don't know if that damaged (cracked/bowed) the rod, or flattened a bearing. It's easy to do since the head is already off. Phar I think I am going to bite the bullet and get it done right so I have some piece of mind. I am going to have a hard time putting the right foot down knowing that I could cause potential damage. I want to change the cam anyhow to a better profile. It just sucks but I guess those are the costs of having a high performance engine. Quote Link to comment Share on other sites More sharing options...
Gixxer Squid Posted July 11, 2009 Author Share Posted July 11, 2009 Car finally done, info here if you want it. http://forums.hybridz.org/showthread.php?p=1044191#post1044191 Quote Link to comment Share on other sites More sharing options...
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