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Is it 12:0:1, 12:5:1 etc? Need to know.
 

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wiseco has a piston set out that does 13.7:1... im sure SOMEONE is running it, but im sure Skunk2's Drag RSX and other drag cars could be running higher compression, custom one-off domes that we will never know about

but for off the shelf, the highest is 13.7, its actually on wiseco's site

its under application for K24 with K20A2 head, but im fairly certain it will work with the TSX combustion chamber... not sure how it would throw off compression

also, it says on their site the block has to be sleeved, anyone know anything about this? is it because of the material used for stock sleeves?
 

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The absolute max you can get without totally reworking the Combustion chamber is about 14/1 on a head that has been opened up to a 90mm bore(which I now have, JE is the shit when i comes to custom pistons plus they are sponsoring my K Series Race Car!). In my street motor I will be running these..............Mahle Pistons..............the new hottnes!!! Try
www.nolimitmotorsport.com for these.................there soon to be a new K20a.org Vendor!


There's my dog making a cameo appearance!!!!
 

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11248c said:
Is it 12:0:1, 12:5:1 etc? Need to know.
On my current pistons I have a 19.5 dome volume and with the stroke of the K24 I will be using this season...I would be at 16.7:1 with a 50cc chamber and an .030 gasket. I will be modifying the piston to get around somewhere betweeen 15 and 15.5
 

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19.5cc Dome Volume???I would hate to know how much that cylinder head has been reworked to get that kind of dome to fit in that head. It is pretty hard to get anymore then 14/1 static compression on a Stock K20a or k20a2 with a stock rod length, stock combustion chamber. You can have 16/1 is you want and I would love to be able to see inside your cylinder head so I could watch the flame front fizzle away and not burn any fuel, unless of course your running Methanol. Take a look at the piston I posted and take a good look at the Dome and see how sharp the peak is on it and then figure that by making more compression you have to widen that dome or peak so it will force the fuel to run away from the top of that peak and pool up in the exhaust and Intake reliefs and you will have one hell of a crappy fuel burn.....but hey that's just a theory that everyone that has any clue about physics would know.


That Mahle piston has a 12CC Dome Volume on it and that's a 12.5/1 Compression Piston. The math on that Import Builder Piston at 14cc's doesn't add up to 14.5-15/1 Compression. That would more be like 13.64-13.7/1(rough mental math) and if I am correct that is just a off the shelf Wiseco Piston.
 

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jtuner77 said:
19.5cc Dome Volume???I would hate to know how much that cylinder head has been reworked to get that kind of dome to fit in that head. It is pretty hard to get anymore then 14/1 static compression on a Stock K20a or k20a2 with a stock rod length, stock combustion chamber. You can have 16/1 is you want and I would love to be able to see inside your cylinder head so I could watch the flame front fizzle away and not burn any fuel, unless of course your running Methanol. Take a look at the piston I posted and take a good look at the Dome and see how sharp the peak is on it and then figure that by making more compression you have to widen that dome or peak so it will force the fuel to run away from the top of that peak and pool up in the exhaust and Intake reliefs and you will have one hell of a crappy fuel burn.....but hey that's just a theory that everyone that has any clue about physics would know.
Yeah, its kind of funny you mention all of that...you should contact the company that originally put my car together and explain it to their "tuner" cause he as no clue.

As fas as the physics and thermodynamics behind the internal combustion engine goes...yeah...i know a little I guess being that I am working on an ME/Physics double major. Which is exactly why the piston dome is being re-worked for this season. But the question in the original post was "what is the highest compression." I just gave an answer.
 

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Not trying to start a arguement at all but when i was doin some math in my head and thinking about how that dome has to look a BIG red flag went up. I think you need to CC the combustion chamber and the motor fully assembled and then find out what it really is............I mean it may be but I would hate to know how much knock per millisecond(detonation) your getting trying to burn the fuel up with that dome design or what rating plugs you are using to burn that fuel.

the funniest thing is that i wish i took more physics in College. Most of it I just learned from building a few hundred motors. It would have been so much better if I took more physics classes. Good luck with your Masters.

So in lew of tha statement the compression can be what ever you want it to be depending on how deep your pockets are and how much time you are willing to spend in R&D.
 

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Combustion chamber is 53cc, .030 gasket. With the bore and stroke of the k20, and a 19.5cc dome volume the CR was just over 14:1. Or couse with and increase 13mm in stroke the ratio goes to near 17:1. The K24 pistons will likely have a dome volume of 13.75 or 14cc. That should put me right around 15:1.
 

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H2nr said:
so if the 20a2 head is 53cc then is the 24a2 head the same?
No, my head has had extensive work done. I have not checked the chamber volume on the k24, although I have one sitting here...i probably should.
 

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So you have done some chamber work then?? How far is the piston in the hole at tdc??? .030 Compressed thickness???Because the stock k20a2 head is 50.7cc's and the type R is the same. The k20a3 and the k24 had a 53.5cc combustion chamber.

You also have to remember just because there has been modifications done to the head that allows you to make more compression doesn't mean the car is going to be able to make more horsepower. I have seen some heads in my day then have been reworked like mad and allowed some mad compression that ran piss poor do to fuel burn problems. Sometimes simplicity is the key to making power. I love to see people over-engineer stuff and it make as much as the guy next to him that has half of the money invested in his build.
 

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jtuner77 said:
So you have done some chamber work then?? How far is the piston in the hole at tdc??? .030 Compressed thickness???Because the stock k20a2 head is 50.7cc's and the type R is the same. The k20a3 and the k24 had a 53.5cc combustion chamber.

You also have to remember just because there has been modifications done to the head that allows you to make more compression doesn't mean the car is going to be able to make more horsepower. I have seen some heads in my day then have been reworked like mad and allowed some mad compression that ran piss poor do to fuel burn problems. Sometimes simplicity is the key to making power. I love to see people over-engineer stuff and it make as much as the guy next to him that has half of the money invested in his build.
With the same piston I mentioned earlier the compression ratio in the K20 was only 14:1...you can almost get that with shelf pistons. The head was reworked for airflow, not compression. It flowed 308 cfm @ 28 inches of H20. From what I understand that is a pretty decent number.
 

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All major piston manufacturers can make you anything you want, i have built very high compression k's with arias, wiseco and je. All of the pistons were done differently but all done very nice.
 
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