acceptable rod ratio

[BigBro74]

Really is a rod ratio of 1.41:1 just unacceptable?

My question is would you sacrifice c.i. for a better rod ratio?

this isn't like a restricted intake class circle car or something is it

for most applications- nope and nope

Jason

[wyrmrider]

no- to a point

[piston guy]

Custom rod length and it is what it is for rod to stroke ratio. The pin can only be so far up before the ring runs into the edge of the valve relief. Thin , narrow rings help but it is still a compromised piston. Don't even look at how ar the piston comes out of the bottom of the bore. It's scarry.

A long rod enables the total length of the piston to be shorter, and usually incorporates a shorter compression distance - therefore a more compact ring package through the use of thinner rings. However, at the bottom of the stroke the pistons are FURTHER up in the cylinder, hence not much chance of "the piston comes out of the bottom of the bore".

Bill if you can keep the piston in the bottom of the bore with a 9.8 block and a 4.500 stroke you're a better man than me and I have been doing custom pistons for 20 years. It is NOT happening! BTW the "piston" is NOT further up in the bore because of rod length, (the 4.500 stroke dictates that) , the piston is shorter in overall length due to the higher pin placement and because of that less comes out the bottom of the bore.

[engineguyBill]

Custom rod length and it is what it is for rod to stroke ratio. The pin can only be so far up before the ring runs into the edge of the valve relief. Thin , narrow rings help but it is still a compromised piston. Don't even look at how ar the piston comes out of the bottom of the bore. It's scarry.

A long rod enables the total length of the piston to be shorter, and usually incorporates a shorter compression distance - therefore a more compact ring package through the use of thinner rings. However, at the bottom of the stroke the pistons are FURTHER up in the cylinder, hence not much chance of "the piston comes out of the bottom of the bore".

Bill if you can keep the piston in the bottom of the bore with a 9.8 block and a 4.500 stroke you're a better man than me and I have been doing custom pistons for 20 years. It is NOT happening! BTW the "piston" is NOT further up in the bore because of rod length, (the 4.500 stroke dictates that) , the piston is shorter in overall length due to the higher pin placement and because of that less comes out the bottom of the bore.

PistonGuy,
Your post didn't say anything about stroke, 4.500" or otherwise . . . . . . . Sorry if I misunderstood your point. However a long rod will not result in the piston coming out the bottom of the bore, regardless of stroke. Yeah, I have been doing this stuff for over 50 years myself.

[piston guy]

How do guys deal with rod-ratio's in standard deck height, BBC's that have a 4.5" stroked crank??

Say, a 4.6" b x 4.5" s = 598" engine...

You know the ultimate stealth BBC engine....

pdq67

Bill ,
I should have quoted this in my response that you quoted. It's all good. I've been at this for 50 years too. The "School of Hard Knocks" doesn't hand out diplomas or I'd have some. LOL

[Warp Speed]

Engines and all of their parts are a stack of compromises. Is a 1.4 rod ratio a good thing? Heck no. But in some combinations, architecture dictates it to be the lesser of compromise for what your trying to do.