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Old 09-17-2010, 09:48 AM   #1
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Default higher compression pistons

Anyone make higher compression near 10:1 pistons. I saw some forged supertech? 10.6:1
any forged stock 9.4:1?
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Old 09-17-2010, 12:33 PM   #2
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Arais could probably make you a set to whatever compression you fancy. Wiesco can do 10.3.
There are others, some Japanese makers have stuff closer to 11 I'm sure.

Also Google.
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Old 09-17-2010, 12:55 PM   #3
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Are you trying to do a high compression lower boost set up? I think JGTC cars do this. They run like 13 psi and 12:1 on race fuel.
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Old 09-17-2010, 02:19 PM   #4
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My 8.8:1 supertechs will end up being around 9.8:1 with all the head and block shaving that will be done. If you want higher than 11:1 just let your engine builder know that and they can adjust with deck height and head gasket thickness along with a few other things. Just because the pistons "says" it will be X compression dosen't mean your engine will be that compression when it's fully assembled.

You can also use the 10.6:1 an have some head work done to smooth out the combustion chamber and run a thicker head gasket like 1.2mm instead of the standard 1mm to make it around 10:1.
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Old 09-17-2010, 02:28 PM   #5
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just figuring out what higher compression pistons are out there for the motor. Orginally was looking at dropping compression, now I may just try to find forged pistons at the same compression as stock or higher.
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Old 09-17-2010, 02:29 PM   #6
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I would go with the 8.8:1 Supertech's and have your head/block shaved to bring it up to stock 9.5:1.
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Old 09-17-2010, 02:40 PM   #7
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The next time I have to say that any major forged piston manufacturer can make you a piston in whatever CR you want people are going to start to get banned.
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Old 09-20-2010, 10:20 AM   #8
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The next time I have to say that any major forged piston manufacturer can make you a piston in whatever CR you want people are going to start to get banned.
But they can!

If you put up the $75,000 in tooling for the forging die and engineering time to get the machining done.
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Old 09-20-2010, 10:25 AM   #9
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not really, if you call say weisco, you can pretty much get whatever you want if you're just willing to wait...no 75,000 buy in.
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Old 09-20-2010, 12:09 PM   #10
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not really, if you call say weisco, you can pretty much get whatever you want if you're just willing to wait...no 75,000 buy in.
My 12:1 stock bore BP pistons from Weisco tool six days from order to arrival. Not that you'd want THAT much compression.

When we needed custom pistons for the vintage two-stroke SAAB rally car, Weisco had one set in stock from a previous run and sent them right out. Next time we needed some, it took about six weeks and I think they made around six sets (18 pistons).
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Old 09-20-2010, 12:15 PM   #11
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Y8s knows not of what he speaks. There is no tool and die, just a forged billet of aluminum and a 5-6 axis cnc machine. You tell them what CR you want, and they make it. A week or two later you get it. Most of the manufacturers don't even carry stock, they just make large batches that other places stock, thus the illusion of a shelf piston.
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Old 09-20-2010, 12:17 PM   #12
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Originally Posted by neogenesis2004 View Post
The next time I have to say that any major forged piston manufacturer can make you a piston in whatever CR you want people are going to start to get banned.
oh Im very much aware of this, I was just wondering if anyone knoew off the top of their head if there was some around 10:1. I have looked around but I hadn't seen any yet, still looking.
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Old 09-20-2010, 12:34 PM   #13
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....why?
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Old 09-20-2010, 12:37 PM   #14
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Waiting for Hustlers to see this one....
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Old 09-20-2010, 01:23 PM   #15
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Quote:
Originally Posted by neogenesis2004 View Post
Y8s knows not of what he speaks. There is no tool and die, just a forged billet of aluminum and a 5-6 axis cnc machine. You tell them what CR you want, and they make it. A week or two later you get it. Most of the manufacturers don't even carry stock, they just make large batches that other places stock, thus the illusion of a shelf piston.
a forged billet in the shape of a piston.

They can vary the shape and size a little bit, but the bulk shape from which they start machining is pretty piston-like already. I've watched "how stuff works", I have seen the bideoz.

the goodness starts at about 1:20.





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Old 09-20-2010, 01:49 PM   #16
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Eh, one mold would probably work for 50% of Japanese motors.

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Old 09-20-2010, 02:03 PM   #17
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I had JE make my pistons in the CR I requested. Pretty close to the same price as an off the shelf. For my latest motor, they requested a mold of the combustion chamber. That will cost a little more, but it is not out of reach for Joe Shmo that wants something special.

Good piston manufacturers can make any bore, any pin location, any ring grove, and any combustion shape you desire.

And by the way, do not get to hung up on CR specs. Those numbers are estimates, and are affected by many variables like stroke, bore size, and valve timing.

The actual cylinder preasure I have when the engine is assembled, is what I would base on how I would force fed it.
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Old 09-20-2010, 02:05 PM   #18
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For the average Joe Shmoe build, those are all known variables.
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Old 09-20-2010, 02:28 PM   #19
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Quote:
Originally Posted by neogenesis2004 View Post
For the average Joe Shmoe build, those are all known variables.
I get it, but some Joe Shmoe's out there want to take it to the next level. Piston manufacterer's can accomodate them without busting the bank.
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Old 09-25-2010, 04:55 PM   #20
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Originally Posted by chicksdigmiatas View Post
Are you trying to do a high compression lower boost set up?
x2

High boost, high compression= zoom zoom boom
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