400 Pistons- FYI

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Dec 22, 2004 | 11:57 PM

TMI

Thread Starter

Laughing Gas

Joined: Nov 2002

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From: Fairmont

400 Pistons- FYI

Pictured from left to right:
Hypereutectic Custom piston,
Hyper. Piston machine for Aussie Heads 9.5:1,
Badger Flat Top Piston,
Hyper. Piston machine for stock 400 heads 9.5:1,
Stock OEM piston.

You can see the difference in the heights. On the left, Hypereutectic Custom pistons. The Badger 40010F piston in the middle is .015" shorter than the stock OEM piston on the right.

Dec 23, 2004 | 03:09 AM

Torque1st

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Thanks for the pictures.

Can you give compression heights and dish (+valve relief) volumes for all of those pistons?

Is the piston diameter above the rings always about 0.030" under nominal bore? In other words on a piston for a nominal 4.030" bore is the ring land 4.000" dia?

Dec 23, 2004 | 06:28 PM

TMI

Thread Starter

Laughing Gas

Joined: Nov 2002

Posts: 1,198

Likes: 9

From: Fairmont

The "crown" of the piston is usually about .030" The dish volumn of the pistons shown are about 30cc and 12cc. This is the volumn of everything above the first ring land.

Compression height: +/- .001"

Hyper's 1.722'
OEM 1.655"
Badger 1.637"

After measuring them it's interesting to see how far off they are from the "spec"

Dec 23, 2004 | 11:50 PM

Torque1st

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That is why it is good to have the pistons in hand before machining the block. Of course sometimes you miss on the overbore cleanup size...

Thanks for the info. It will help guys running those dyno programs.

If somebody gets time maybe they can separate out the individual element volumes and post them.