Pistons

[ss3011]

Depends on which way the offset is. Factory offset is to quiet piston noise.

[Larry Hill]

Is the piston balanced in the center or on the center line of the off set pin placement? Just wondering about inertia.

[Dwight Southerland]

Depends on the piston. A lot of piston configurations so not lend themselves to equal balance around the centerline of the pin. For example, BBC 396 high compression piston is unbalanced no matter what you do that is reasonable. You can add a lot of weight to the flat side of the piston to balance it, but is the extra overall weight infringing on the advnatge of minimum reciprocating weight? You can offset the pin, but it will take .150" to .210" offset to acheive balance.


Note: The above numbers were calculated using minimum weight Stock Eliminator pistons. You numbers will vary according to your restrictions.


When I built the engine for the Corvette (SS) I worked to achieve a better balance relative to the pin centerline. Did it help? Who knows?!? A-B-A was not attempted, it just sounded good and trick to converse about in techno-savvy circles.


I have seen pistons out of a very fast 283 SS engine that had the pin offset by .090"

[Jim Hanig]

Originally Posted by Dwight Southerland

Depends on the piston. A lot of piston configurations so not lend themselves to equal balance around the centerline of the pin. For example, BBC 396 high compression piston is unbalanced no matter what you do that is reasonable. You can add a lot of weight to the flat side of the piston to balance it, but is the extra overall weight infringing on the advnatge of minimum reciprocating weight? You can offset the pin, but it will take .150" to .210" offset to acheive balance.


Note: The above numbers were calculated using minimum weight Stock Eliminator pistons. You numbers will vary according to your restrictions.


When I built the engine for the Corvette (SS) I worked to achieve a better balance relative to the pin centerline. Did it help? Who knows?!? A-B-A was not attempted, it just sounded good and trick to converse about in techno-savvy circles.


I have seen pistons out of a very fast 283 SS engine that had the pin offset by .090"

Dwight would the off set be to right or to the center?

[Dwight Southerland]

[Billy Nees]

Originally Posted by Dwight Southerland

Assuming that we are looking at the front of the engine in your picture, then on a V8 engine the drivers side pistons would be offset toward the intake side of the engine and the passenger side pistons would be offset toward the exhaust.

[Jim Hanig]

That's what I thought, thanks.

[fordteacherguy]

Originally Posted by Dwight Southerland

Depends on the piston. A lot of piston configurations so not lend themselves to equal balance around the centerline of the pin. For example, BBC 396 high compression piston is unbalanced no matter what you do that is reasonable. You can add a lot of weight to the flat side of the piston to balance it, but is the extra overall weight infringing on the advnatge of minimum reciprocating weight? You can offset the pin, but it will take .150" to .210" offset to acheive balance.


Note: The above numbers were calculated using minimum weight Stock Eliminator pistons. You numbers will vary according to your restrictions.


When I built the engine for the Corvette (SS) I worked to achieve a better balance relative to the pin centerline. Did it help? Who knows?!? A-B-A was not attempted, it just sounded good and trick to converse about in techno-savvy circles.


I have seen pistons out of a very fast 283 SS engine that had the pin offset by .090"

Here is a link to JE's new line of asymmetrical pistons that are built offset with attaching article and video..

Most are import applications but you get the point.

http://www.jepistons.com/Articles/10...d-Pistons.aspx

[Jeff Stout]

Anyone care to put a HP gain by doing this?

[FED 387]

HP Minimal---- if anything---RPM capabilities / rate of acceleration probably more due to to lighter piston weight but HP negligible