Oversized OEM pistons OR Forged Pistons - Budget build recommendation?
04-28-2016, 02:42 PM
#1
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.
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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04-28-2016, 02:59 PM
#2
Elite Member
Join Date: Mar 2007
Location: Santa Clara, CA
Posts: 5,166
Total Cats: 855
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
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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04-28-2016, 03:35 PM
#3
Former Vendor
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Join Date: Nov 2006
Location: Sunnyvale, CA
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Total Cats: 2,099
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.
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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04-28-2016, 06:56 PM
#6
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
Aside from my mildly tuned car, the engine itself runs great. No ragrets with supertech & wiseco ring combo.
Example: Supertech Pistons Miata
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.
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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