Pistons
 

Anyone running off set pins in their pistons,and how much.?Do you feel that theirs any power in it.

Re: Pistons
 

Jim I didn't see any difference. Used whatever offset Patterson sent. It was a PITA when I had to replace a couple of pistons.

Re: Pistons
 

Depends upon how thick the cylinder walls are....if its friction your trying to reduce I think the coatings available take care of that.


If you have a thinwall block (like most fords) that you got carried away with, with the boring bar, you can take some pressure off the major side by offsetting the piston pin to the minor side


and, some say its easier to "rotate" the crank


as with all non standard mods...your mileage may very

Re: Pistons
 

If the pin is offset, would it cause the piston rock and break ring seal due pivot point placement?

Re: Pistons
 

Well I am not sure about that Larry some pretty well known engine guys say to run them

Re: Pistons
 

Offset pistons-----small amount of power there--- because of less power need to overcome rod load and easier crank rotation--- it makes engine RPM quicker---FED 387

Re: Pistons
 

Piston rock is actually worse with centered pins.

Re: Pistons
 

Dwight is correct.

Piston offset reduces friction and cylinder wall loading; it also improves geometry.

https://cdn.rideapart.com/wp-content...Cylinders1.jpg

F1 and NASCAR has been doing it and also using guided pistons.
Would not be surprised if Pro Stock is doing the same, especially with the use of short deck blocks.

Re: Pistons
 

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

Re: Pistons
 

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

Re: Pistons
 

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"

Re: Pistons
 

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

Re: Pistons
 

Re: Pistons
 

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.

Re: Pistons
 

That's what I thought, thanks.

Re: Pistons
 

people use to turn mopar piston around backwards in old days was supposed to make them faster, the diagram posted is for quieter operation,isn't offset the opposite for power?
I would guess the taller the compression height of the piston,the more difference this would make?
MikeTaylor 3601

Re: Pistons
 

Back in the 1960s "reverse offset" was the hot setup for Jr. Stockers. LOL

Re: Pistons
 

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

Re: Pistons
 

Anyone care to put a HP gain by doing this?

Re: Pistons
 

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

Re: Pistons
 

Yes, I'm quite sure I used to put the offset on the side of the rotation. When I ran my shop I had dozens of 72-75 440 cast pistons laying around from customer builds as well as many 383 blocks so I would bore the 383s .070 and use the 72 440 pistons to put together budget street and bracket motors for the locals. The 72 440 has the same compression height as the 68-69 383/335 and the extra 30 grams or so could be removed from the pin. Got rid of a lot of junk laying around the shop and would make a nice high 11 low 12 second street motor for the low buck guys.

Re: Pistons
 

Looks like multiple ways to achieve this. Move bore towards center of motor ( as pictured), offset wrist pin hole in piston. How about re-bushing small end of rod to move rod over? Can anyone of these or all ways be used on a stocker motor.

Re: Pistons
 

Think about what you said here. How is that going to change anything? It would not matter if the rod were 'S' shaped; the relative connection between the big end and small end would not change.