Crankshaft vs. cubic inches clarification

[Ttype6]

How did you achieve 281 cu. in. ?

Claude.

He did this by over boring the cylinders of his 4.1 Liter stage 2 block to 4.061". You can't over bore a production block to this size. You must have a stage 2 block.

 

[toofastforyou]

He did this by over boring the cylinders of his 4.1 Liter stage 2 block to 4.061". You can't over bore a production block to this size. You must have a stage 2 block.

Yeah, or maybe a T/A block ? I already have a Stage 2 block (#153).

thanks,

Claude.

 

[earlbrown]

He did this by over boring the cylinders of his 4.1 Liter stage 2 block to 4.061". You can't over bore a production block to this size. You must have a stage 2 block.

It is a stage block. Extra meat and a little extra deck height. That's how that long ass rod manage to BARELY fit with a stroker crank.

 

[750H.P.V6]

Yeah, or maybe a T/A block ? I already have a Stage 2 block (#153).

thanks,

Claude.

You can't go that big on bore size with a TA block.

Neal

 

[Ttype6]

It is a stage block. Extra meat and a little extra deck height. That's how that long ass rod manage to BARELY fit with a stroker crank.

I did notice that he was using 6.5" long rods.

 

[ttypewhite]

Claude, I wouldn't be concerned about cubic inch if you have a virgin block. I started with a new block from DLS and just cleaned it up a little to give me 268 cubic inches. Don't bore it out big if you don't have to. There is no benefit in boring it out big out of the gate. You give yourself little room for error if ever you have a problem and need to go bigger. The difference of a few cubic inches is not going to mean anything in a street car. Leave yourself room for growth.

 

[Ttype6]

Don't bore it out big if you don't have to.

I agree with this,but I would start with a 4" bore to unshroud the valves.

 

[750H.P.V6]

I built an engine a few years back from a new 4.1 Off center block and I purposely bored it 3.965" to start just because they are so hard to come by.

Neal

 

[turbobitt]

It is a stage block. Extra meat and a little extra deck height. That's how that long ass rod manage to BARELY fit with a stroker crank.

The deck height and long rod length is not the limiting factor on the stroke. Its more like the cam to connecting rod clearance.

 

[earlbrown]

The deck height and long rod length is not the limiting factor on the stroke. Its more like the cam to connecting rod clearance.

In this case it was the limiting factor because you have to make room for rings. You can get away with encroaching on the oil ring with a support rail but the wrist pin can't get in the 2nd rings area.

Deck height,rod length, and stroke flat out tell you how much room you have for a ring pack. If there's no room, there's no room.

 

[bison]

In this case it was the limiting factor because you have to make room for rings. You can get away with encroaching on the oil ring with a support rail but the wrist pin can't get in the 2nd rings area.

Deck height,rod length, and stroke flat out tell you how much room you have for a ring pack. If there's no room, there's no room.

Hehe. You're telling this to someone who has been running 6.5" rods with a 3.59" stroke for like 15 years. Two different sets of pistons. No ring problems. I know he doesn't have a unicorn either.


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[blklt1z28]

Bore x bore x stroke x number of cylinder x .7854= CI of any engine.

 

[achalmersman]

Bore x bore x stroke x number of cylinder x .7854= CI of any engine.

Never heard that but it works. I guess the engineering side of me just always wanted to just use pi * bore * stroke * cylinders. Lol

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[earlbrown]

Hehe. You're telling this to someone who has been running 6.5" rods with a 3.59" stroke for like 15 years. Two different sets of pistons. No ring problems. I know he doesn't have a unicorn either.

k

I was talking about a specific engine with more stroke than that.


I stand by my math though. The deck height sets the stage and when you subtract the rod, the CH and 1/2 the stroke, there has to be room for a ring pack. Unicorn or not, stuff still has to fit.

 

[earlbrown]

Never heard that but it works. I guess the engineering side of me just always wanted to just use pi * bore * stroke * cylinders. Lol

You forgot to cut the bore in half and square it.


I'm with you though. It's easier for me to just do the standard math than remember constants and shortcuts.

 

[NY Twin Turbo]

Yeah, or maybe a T/A block ? I already have a Stage 2 block (#153).

thanks,

Claude.

Maybe it's time you move to a Monte Carlo with a V8?

I heard those things are fast!

 

[dank GN]

lol I have a unicorn

 

[achalmersman]

You forgot to cut the bore in half and square it.


I'm with you though. It's easier for me to just do the standard math than remember constants and shortcuts.

Yea I'm an idiot. What I get for late night texts. 2pi * r or d * pi is for circumference not area lmao

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[TURBOELKY]

In this case it was the limiting factor because you have to make room for rings. You can get away with encroaching on the oil ring with a support rail but the wrist pin can't get in the 2nd rings area.

Deck height,rod length, and stroke flat out tell you how much room you have for a ring pack. If there's no room, there's no room.

I know this thread is a little old, but there’s room.

 

[rag231]

Just to add more fuel to the cubic inch fire, there are some 3.70 and 3.750 stroke cranks out there, odd fire and even fire!!