Congrats Mike! Those are great numbers on your ‘pure’ stock SD455! It’s really cool that your engine has the stock internals including the relatively heavy +.030 TRW SD pistons and the original factory exhaust manifolds. Speaking of which, the factory outlet diameters are only 2.06”/2.125” on the RAIV/455HO manifolds, so I’m wondering if they are the same on the SD manifolds??? We have found that using the Pypes 2.5” mandrel bent headpipes with their captured flanges are necked down to roughly 2.20” at that point, then open up to 2.5” once you get past that. Even though, the 2.5” mandrel 90 degree turn seems to be less restrictive than anything smaller, so you could find a few hp and lbft throughout the pull range.
Did you calculate your finished static compression ratio to actually be 8.4 to 1?
Dennis
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12-31-2024, 10:43 AM
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