Ok. So it seems I heavily detonated a few weeks back (as some of you may recall) and I screwed the cylinders. My mechanic tells me they are 4mils of a an inch out of shape. The cylinder walls have been honed and supposedly are ok, a part of course from the shape issue. The pistons supposedly are ok also, although a bit scratched.
So now I have 3 options:1. Re-ring my old pistons (Ross 8.5 .02 over) with new rings and pray2. Overbore the cylinders to .03 or .04 over but, although it would be the better option, it means I would have to buy new pistons.3. Get a donor block and bore to .02 as my current block and use new rings with the old pistons.
What do you guys think? Right now, since I'm practically broke and owe a lot to the credit card company, I'm leaning towards just using new rings and praying that I don't burn oil or have bad comp in the cylinders. Is .004 of an inch that much? Can I still take this motor to my previous goal of 18PSI?
All observations and recommendations are welcomed.
Bad news - continued
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Structure240sx
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I don't know if I really want an entire KA... shipping it to CR could be a hassle. But it is a possibility.
18PSI is still my goal, it has been since I started about a year and a half ago. It's just that my car broke down on a very bad moment. If my current block won't get me there then I'll find another one or another motor. I'm in no hurry to get there... I'm taking it step by step.
18PSI is still my goal, it has been since I started about a year and a half ago. It's just that my car broke down on a very bad moment. If my current block won't get me there then I'll find another one or another motor. I'm in no hurry to get there... I'm taking it step by step.
look in the classifieds section, ebay, FA, http://www.car-part.com
What does he mean by "out of shape"? They aren't round anymore? They are oversized by .004" at the worst case? .004" is a lot when you talk about engine tolerances. The factory spec for cylinder runout and taper for your engine is less than .001", so .004" is over 4x what is allowed by the factory. Ask your mechanic how he measured the cylinder. Human error can be big in this case....004" is the thickness of a sheet of paper. Why would he hone a cylinder that was so far out of spec? Why are your pistons scratched? Doesn't detonation cause dents? If your cylinders really are out of round by .004, then I don't think you can use the block without cleaning it up first.
DAEDALUS wrote:What does he mean by "out of shape"? They aren't round anymore? They are oversized by .004" at the worst case? .004" is a lot when you talk about engine tolerances. The factory spec for cylinder runout and taper for your engine is less than .001", so .004" is over 4x what is allowed by the factory. Ask your mechanic how he measured the cylinder. Human error can be big in this case....004" is the thickness of a sheet of paper. Why would he hone a cylinder that was so far out of spec? Why are your pistons scratched? Doesn't detonation cause dents? If your cylinders really are out of round by .004, then I don't think you can use the block without cleaning it up first.
He used a micrometer. And yes they are .004" ovaled (trans?). And yes he said that it was 4x off factory spec. He honed the cylinder cause they where scratched also. Then he measured. The pistons are probably scratched because of the amount of water that went through my oil system instead of oil. Cylinders, pistons and rings where all covered with the orange stuff (rust?) which means water.
What do you mean by cleaning it? The cylinders, at least, have already been cleaned and honed to eliminate the scratch marks. The pistons are still to be measured to see if they could also be out of spec.
I'm probably gonna find a stock ka block and use that. How much should I pay for one? I have no idea being from out of the US how much do engine blocks, ka specifically, go for.
As long as the pistons are ok I'll go this route. If they are not then I'll look for options.
BTW, when you said he used a micrometer, I hope you meant an inside micrometer. Even then, I think a bore gauge would have been better.
I still think it's worth a second opinion on the cylinder profile before dropping much money on anything else. Can't cost much to have the block measured. The only reason I say this is because of the human error that's possible when measuring by hand. Unless of course he used some kind of bore jig to hold the micrometer properly inside the bore.
I still think it's worth a second opinion on the cylinder profile before dropping much money on anything else. Can't cost much to have the block measured. The only reason I say this is because of the human error that's possible when measuring by hand. Unless of course he used some kind of bore jig to hold the micrometer properly inside the bore.
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im two techno
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