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I bought a 93 GS that already had the ZE swapped into it, but I burned oil like crazy. I'm in the process of rebuilding it (new oil and water pump, timing belt, tensioner, pulleys, head bolts, and gasket set) but have run into an issue. I got the pistons out of the block, and compared them to the ones that came in my rebuild kit, but it looks like DE pistons. I have searched here, mx6, and probe forums plus google. Every topic that has to do with pistons mainly turns into a DE vs ZE argument. So, I pose my question: If I cannot get the company to send the correct pistons, if I install the DE tops....what will happen? I'm fairly certain my compression ratio will drop and I'll lose power, but how much? Is there anything else that will go bad? I've dropped $3200 on the car, $400 something for the rebuild kit, and I don't remember how much on other parts. Getting ANOTHER set of pistons is out of the question unless the wife sells a kidney.

Bottom line, the KLZE has a 10:1 compression ratio, and the pistons are flat on top with recesses for the valves. The KLDE had a lower compression ratio of around 9.2:1 and the pistons had a dish shape top with the same recesses for the valves.

You will not hurt anything mechanically by using DE pistons in a ZE. You will however lose some power. How much? Don't know. Maybe 10-15hp, maybe more like 20hp... no way to know unless you dyno'd the engine with and without the higher compression pistons.

I am assuming as part of the engine rebuild you had to bore the cylinders oversize, which is why you got new oversize pistons and rings. I have seen on the forums that you can get stock ZE pistons in oversize'd sizes, but only in Japan. Other option is to go with custom forged pistons, but like you said, not cheap, ~ 550USD a set.

If you did not have to rebore the cylinders you could have just done a re-ring job and lightly rehoned the cylinders, but I am assuming that was not an option.

Hope this answers your question.

Take it easy,
Tim

I have a set of 5 high compression "ZE" pistons up for sale. A few of the skirts have slight marring, but the piston crowns and ring grooves are in great shape. I would let the set go for $50 + flat-rate USPS shipping.

Thanks for the replies! I'm going to try and salvage my ZE's. I don't believe they are damaged, but I'll inspect and measure the ever living crap out of them once I can get all the junk off. I've never had to determine piston condition before. Is there anything I should keep an eye out for? Or is it just a "looks good so it's good" thing? At work for our Rotax engines, the only inspection criteria we have for our piston tops just says if there is ANY damage to ship the motor back to the factory. I was burning/losing 1-2 quarts a week, and I found it all on 1, 4, and 6.

You may want to inspect/replace valve guides and seals too...

As soon as some cash frees up I'll be running them to a local shop to have them cleaned and checked. I could do diassembly and cleaning here at work but it's a little...frowned upon. Most of the shops here look shady and run down, but I'm not going to judge them by their appearance, only their price tag.

If you were burning that much oil that engine was also low on compression. Even with the DE pistons you'll likely end up with higher compression compared to before you broke this engine down.

I'm assume you did not break that engine down because you were simply losing oil (leaks). If you were burning oil then there are only 2 possibilities:
1. Oil entering the cylinder through the top (valve guides / seals)
2. Oil entering the cylinder through the bottom (piston rings not sealing)

Most of the time you'd be boring the cylinders to a larger size and getting matching pistons and rings. The block and heads would be decked - machined flat. You'd get a valve job and the heads would get new valve guides.

Bottom line: Don't sweat the piston design. If you rebuild this engine right it will be way better than what you had.

Planing down the heads will increase compression, they just have to make sure there are no piston to say,,spark plug or valve clearance issues. Go to a few garages and ask them who they use, that I think is your best course of action.