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Old 04-28-2016, 03:42 PM   #1
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Question Oversized OEM pistons OR Forged Pistons - Budget build recommendation?

Hi Guys,

I'm at a fork in the road right now. I am in the middle of a budget rebuild for a turbo application. Machine shops says I need to bore the block over 0.20 due to water damage on the cylinder walls. I initially was just going to shot peen my rods and reuse my pistons but now I need to replace my pistons. To keep things under budget, I am looking at running Ebay forged rods now and based on my search, these should suffice. My goal is to achieve 300-350HP (or at least the potential of my GT2560R can provide). I have all the supporting mods leaving the bottom end of my engine the weakest link.

With my power goals in mind and keeping it budget friendly, what does the Miataturbo community recommend? Go with oversized Mazda OEM pistons OR go with forged pistons? Pros/cons? Any advice is greatly appreciated.

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Old 04-28-2016, 03:59 PM   #2
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A 2560 *might* do 300 at the wheels if you tune everything right or use an optimistic dyno. No way is it going to see 350.

OEM pistons are probably fine for the 270-ish that a 2560 will probably max out at, if you really want 350 you need forged, IMHO.

Of course, forged Supertechs are probably cheaper than OEM oversized pistons.

--Ian
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Old 04-28-2016, 04:35 PM   #3
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Cast pistons will do the job if you tune the engine perfectly and never detonate it. Do you trust yourself to do that?

Forged pistons will do the job without any trouble, even if you ping it a couple of times during tuning. A good 4032 piston is silent on start-up and doesn't burn oil.

Every motor I open gets Supertech pistons unless otherwise restricted by race class.
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Old 04-28-2016, 04:52 PM   #4
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Get forged pistons
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Old 04-28-2016, 07:53 PM   #5
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I sincerely appreciate the feedback and confirmation. Forged pistons does offer added buffer and potentially room for growth if I decide to upgrade the turbo. I think I'll look into Supertech pistons and hopefully they will mate up well with Ebay rods. You guys rock!
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Old 04-28-2016, 07:56 PM   #6
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Don't forget to use wiseco rings with the supertechs

Aside from my mildly tuned car, the engine itself runs great. No ragrets with supertech & wiseco ring combo.

Example: Supertech Pistons Miata

Quote:
Why mix and match pistons and rings?
Over the years we have tried just about every piston and ring pack available. We are looking for the same thing you are. Long wear, perfect oil control and of course good power. OEM ring tension is about 15lbs. The NPR rings that Supertech supplies are less than half the ring tension of OEM. That's great for power and lower oil temps but leads to greater oil consumption than OEM. We have found the best overall compromise between power, service life, oil consumption, and oil temps in an OTS (off the shelf) piston and ring is to combine these two brands into one kit. Take advantage of our endurance racing experience. The Wiseco rings cost a few bucks more than the NPR's but they are worth it.
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Old 04-28-2016, 09:41 PM   #7
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Also running supertech wiseco rings
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Old 04-29-2016, 10:37 AM   #8
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Dunno why someone on a budget would choose OEM over supertech. I went with wiseco, but I got a great deal on them (ie, less than supertechs).
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Old 04-29-2016, 11:13 AM   #9
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The OEM are great, <300rwftlb and Ive seen no trouble at all.
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Old 04-29-2016, 05:18 PM   #10
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+1 for the Supertech/Wiseco combo, also w/ Ebay rods.

Do it and don't look back.
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Old 05-01-2016, 06:47 PM   #11
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My engine build is all motor, but longevity was a goal and I knew if have a solid tune, so I went with OEM. I built the engine 10 years ago, it's still running strong.
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