onegreedy

i opened up the 351 trying to see what i am looking at,

everything inside looks brand new except the tops of the pistons(carbon build up)

down side looks like allready bored 40 over, and the weird thing is i have never seen a piston shaped like this see pic

is this a standard cutout for a 351 piston?


see how shiney new the side looks, like it just came out of casting is this normal for a 5000 mile motor?

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70stangguy

that looks like the top of the pistons that came with my 351w out of a 84 f250. i replaced them with flat top pistons.

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70 coupe
dark blue black interior
351w
edelbrock rpm heads
rpm air gap intake
holley 650dp
3"ss magnaflow exhaust
t5 tranny
8"w/3.80gear

06 GT coupe
vista blue w/flat black 10" stripes
cold air intake
slp loudmouth

mustanglover66

Those are dished pistons used to lower compression. The sides should stay shinney for the whole life of the motor.

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66 Fastback, 68 302, MSD with 6AL, 600 Holley, Grab-a-trac performance package, 6 banger to V8 converted

onegreedy

but basically low compression naturally aspirated means loss in power correct? versus if i have just notched or flat top pistons,

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racin66coupe

yes

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1966 coupe

67mustang302

Higher compression can make more power from better thermal efficiency, you can also run a larger cam. You need to have an engine that'll run with the fuel you have available though. Many of the newer n/a EFI engines are running 10.0-11.0:1, some as high as 11.5....but I'm sure the knock sensor triggers frequently at low rpm.

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Who cares how much horsepower it has, all that matters is how fast it goes!

Best run 13.23 at 106.97mph with a 2.183 60'
Times from before tune and driver mod.

onegreedy

i will probobally get some flat 9.6-1 pistons these are a 7.6-1 cr

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67mustang302

7.6:1 is great compresion......for running 18psi of boost on pump fuel.[&:]

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Who cares how much horsepower it has, all that matters is how fast it goes!

Best run 13.23 at 106.97mph with a 2.183 60'
Times from before tune and driver mod.

JMD

You must consider the heads you are going to run in conjunction with your pistons.

We are running dished pistons (-15cc) with 60cc chamber heads on the 408 to come up with a little more than 11 to 1 CR..

Head gasket thickness and piston deck heightare CR factors as well,,,, these will both tend to lower it a little..

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39 Ford Coupe, 30 Year "Project Car" to be done by mid May 2009
408 Windsor, Tremec TKO 600, E85 Fueled
Custom "ground up" TCI Chassis
9" Track Loc.

If you are not quite as smart as you think, are you smart enough to know?