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PISTONS, Low Compression for the Twin Cam - TC-310A

At 02:33 PM 9/26/2011 +0000, Mark Hester wrote:
"With all the great work several of us have done with Arias Pistons an others, modern squish patterns, modern materials, etc, surely we could drop the use of these old pistons 8.8:1 by now. I just see all those BHP's someone does not get to enjoy".

On 9/26/2011, James Alcorn wrote:
"Auto Vintagery has been using Arias pistons now for 30 years, and most of our engines have them installed. As heads and block surfaces are skimmed over time the compression ratio goes up along with the reduced volume of the chamber. The clearance between the piston and valve is very small, and I have no worry using the low compression NOS set up, for one of my own cars. I have found little difference driving on the street between the high and low piston set ups.
    That being said, I am getting 119bhp from a low compression standard bore engine equipped with Weber carburetors. Also interesting is 125bhp using +.100 over low compression pistons. There is nothing like cubic inches to increase torque and bhp.
    Arias has been a good manufacturer for us, but we have found, the wall clearances of .0025 recommendations have resulted in scored piston skirts, and we have gone to .0045 or more, with fine results".

At 11:28 AM 9/26/2011 -0400, Bill Spohb wrote:
"You can run 91 octane on the 9.9 pistons without any problems".

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