hks piston trade need help!!!???

[chillmieste]

AS some of you may know my engine came with bad pistons and I am rebuilding my block. I have HKS 86mm pistons, they are a direct drop in. The performance shop that is working on my car (http://www.streetlegalimports.com) said that since the pistons are shot the cylinder wall might have been scratched. He said he would have to bore it to fix the problem and thus I would need bigger pistons. He said i should get 87mm pistons. The thing is, I got these as a gift from my friend who could not finish his sr20 because he is moving out of his moms house (that bum) and he needs the money. So I was wondering if any shops out there could trade me for larger forged pistons? These hks pistons are brand new, never installed, complete kit with rings and everything needed. They retail at $950.00 at hksusa.comAnyones help would be greatly appreciated.

Thanks,

Charlie

[GraySilvia]

Why can't you just hone the block and then let the rings take up the extra clearance? There's no reason you should have to BORE the block unless there are some rediculous scratches in there.

[chillmieste]

Would I lose horsepower from having 1mm more of clearance? Would it really make a big difference on the safe side, meaning like would it last just as long as its suppose too?

[GraySilvia]

Well, the problem with 87mm pistons is if you want to bore the block to 1mm over, you take the nikasil cylinder liner off with it. So you need to beg and plead and do all you can to keep the nikasil liner or you can sleeve the block OR have it recoated with nikasil. Neither one of those last two options are cheap. I think the service limit on the nikasil liner is .008", or .2mm? If memory serves me correctly anyway. So, have a reputable engine shop (machine/build shop) take a look at it and see if a hone of <.008" will be sufficient to clean up the cylinders. Hopefully you can just hone it and be done.

Also, nikasil should be DIAMOND honed, not carbide honed. Carbide honing makes for inferior oil retention properties. Just FYI. I hope some of this helps.

[Nathan]

If you do end up boring it though, look into a shop that deals with a lot of small 2 stroke engines such as snowmobiles and motorcycles. They make much more common use of nikasil and will either know where to have the cylinders re-coated or can do it themselves. I'm not saying to get the machine work done there, just after it's bored and honed get it re-coated (I dont know if a honing is necessary after coating the walls with nikasil or not). And then as GraySilvia said, there is the option of sleeving the block which might be a more intrusive and expensive option than you are looking for. Has the performance shop actually cracked the engine open to see what the walls look like?

[chillmieste]

They havent opened it up yet until I start paying them for the labor to put in the pistons. I am taking it on Saturday to get the work done. I will tell him to call me when the block is open and ill tell him to recoat the walls with nikasil. I think that would be my best bet. Ill also tell him to diamond hone it with nikasil. I really appreciate all your guys help. I will post again on Saturday to let you guys know whats going on. Im not in the mood to get screwed over again. Thanks again for al your help!!!!

thanks,

Charlie