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  #1  
Old 12-30-2004, 12:12 AM
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Killer_Mopar Killer_Mopar is offline
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Default Dome vs Flat top

I'm going to be buying pistons for my 400 stroker soon and am wondering which piston would be a better choice. The engine will have ported 452 heads with 1.81/2.14 valves and I plan on using a 150-250hp shot of nitrous. So with that being said, what piston would be better for my combo......Flat top or Dome??? and what advantages do each offer? Thanks
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Old 12-30-2004, 02:54 AM
DartGT66 DartGT66 is offline
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Depends of what compression ratio you are aiming at. Generally flat top is more efficient, but depending of the heads you use they may not be enough to achieve the CR desired. In your case, if your 452 heads have been typically rebuilt they may be at around 84cc's with nailhead valves high in the chamber. But you must measure them to know first, assuming something is just a guess that can be either right, or usually wrong. You must also know the deck height, how close to the deck your pistons are at TDC, and then you can count your CR.
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Old 12-30-2004, 08:16 PM
moeflo moeflo is offline
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If I could machine my way to the desired CR, I'd use flat-tops due to the OEM head's spark plug location.
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Old 12-30-2004, 09:05 PM
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How about the reverse domes in the open chamber heads?
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Old 12-31-2004, 04:03 AM
DartGT66 DartGT66 is offline
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Reverse dome is another thing, it doesn't affect the flame travel like a regular dome.
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Old 12-31-2004, 09:04 AM
eric414 eric414 is offline
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i would go with a flat top
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  #7  
Old 12-31-2004, 10:35 AM
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Fordged flat tops.
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Old 01-02-2005, 08:41 AM
heigleracing heigleracing is offline
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Default pistons

flat tops for your combo.

compression # is important when picking out the cam u will use.
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  #9  
Old 01-02-2005, 10:46 AM
Billydelrio Billydelrio is offline
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Default small cubes require big dome!

If I could I would use a flat top, but when the engine is of little cubic inches, like my 273, domes are needed to get the compression up. I am currently looking at a 15.2 cc dome to get 11:1 with my current project.

The following attatchment is a photo of a nearly finished domed piston I am machining for my 273.
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File Type: jpg 273 finished piston.jpg (32.3 KB, 33 views)
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  #10  
Old 01-03-2005, 05:14 AM
DartGT66 DartGT66 is offline
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Looks good, cuold still be rounder shape. Those "commando" pistons are not available new as far as I know, where did you find yours?
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  #11  
Old 01-03-2005, 10:04 PM
Billydelrio Billydelrio is offline
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That piston is a 40 year old +.030" Jahns cast piston that I found in a $100 junk yard 273 which I raced from 1996 to last year. The compression distance was short, so even with a large dome, the CR too low. I had to mill the block .050" and the heads near .040" in order to get 11:1 CR. The bore in that block was pretty well used up back in 1996 and when I took it apart last summer, it was worse off.

I happened to have a little stroker crank and a standard bore block, so I decided to mate them with the Jahns pistons. The pistons then stuck out of the block a wee too far and the dome was too high in the chamber, so I zero decked them, deepened the valve notch, and reduced the dome to net 15.2cc. Depending on the head I use, I could have up to 11:1 CR.

I did not mean to high-jack this post with my projects.
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File Type: jpg 273 modified pistons1.jpg (32.3 KB, 13 views)
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  #12  
Old 01-05-2005, 10:17 PM
408daytona 408daytona is offline
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BIG CUBES, LOWER COMPESSION, AND PUMP GAS. A COST EFFECTIVE WAY TO MAKE IT WORK.
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  #13  
Old 01-06-2005, 08:49 AM
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Nitrous, to put simply, is like a supercharger in a bottle. If you plan to run pump gas, and be streetable, a lower more efficient c:r is desired. ie flat tops or reverse dome, preferrably forged with nitrous.
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