Engine stroke

[horsepower addiction]

I have a crankshaft and the manufacturer says that it’s 3.650 stroke but requires a 5.850 rod. This is what they sent me If anyone understands.

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[Optimum Performance]

So all the specs are standard Coyote except it is clearanced for an 0.080" shorter rod. With a standard compression height piston it would place it 0.080" further down in the block. Did you ask the company you purchased it from? Looks to me that it was clearanced for an aluminum rod( growth) and/or a custom piston combination. Did you measure it and make sure it was not a typo? Not much info about why you have it, sounds like something you picked up second hand?

And to be clear, you could run a standard 5.93 rod in it. That value has no bearing on stroke.

 

[horsepower addiction]

So all the specs are standard Coyote except it is to Jo for an 0.080" shorter rod. With a standard compression height piston it would place it 0.080" further down in the block. Did you ask the company you purchased it from? Looks to me that it was clearanced for an aluminum rod( growth) and/or a custom piston combination. Did you measure it and make sure it was not a typo? Not much info about why you have it, sounds like something you picked up second hand?

And to be clear, you could run a standard 5.93 rod in it. That value has no bearing on stroke.

All the specs are stock so I don’t understand why it would need 5.850 rods. And pistons.
The specs I posted were what Callie’s gave me.

 

[Optimum Performance]

All the specs are stock so I don’t understand why it would need 5.850 rods. And pistons.
The specs I posted were what Callie’s gave me.

Again, that does not say anything about needing 5.850 rods. Stroke is stroke, your crank takes a standard length rod.

 

[horsepower addiction]

Again, that does not say anything about needing 5.850 rods. Stroke is stroke, your crank takes a standard length rod.

Here

 

[horsepower addiction]

If they modify the crankshaft so it takes 5.850 rod then it no longer has a Stock stroke, right. What am I missing? I don’t understand how it has stock stroke but needs shorter rods.

 

[Optimum Performance]

If they modify the crankshaft so it takes 5.850 rod then it no longer has a Stock stroke, right. What am I missing? I don’t understand how it has stock stroke but needs shorter rods.

I'm out, not enough information to comment further. The Math's do not add up.

 

[horsepower addiction]

I'm out, not enough information to comment further. The Math's do not add up.

That is exactly what I’m saying.
From the numbers that the manufacturer sent me. The stock rod and piston should be good to go.
So I don’t understand why they told me I need 5.850 rods and pistons.
ether they made a mistake or they machined it somehow that i have never heard of

 

[horsepower addiction]

I guess I’ll test assemble one cylinder and see if the top of the piston exits the cylinder.
everything that I was getting from the manufacture, didn’t make sense to me, so I was hoping it would make sense to someone here

 

[RagmopInKona]

Sounds like it might be a nitrous set up. to move the piston pin location and add material to the piston face.
Finding it hard to believe the company that produced the part to not be able to tell you what it was designed for other than take it to a builder that knows this set up.
No matter it doesn't change the stroke unless the crank was offset ground.

 

[Optimum Performance]

I guess I’ll test assemble one cylinder and see if the top of the piston exits the cylinder.
everything that I was getting from the manufacture, didn’t make sense to me, so I was hoping it would make sense to someone here

Curiosity got the best of me so I just called them. You can run all the stock parts on it. You can go with the 0.080" longer OE rod length, or you can run the shorter rod to run a lower pin height and a structurally stronger piston. Balancing with longer rod may require more metal depending on what your rotating mass forces are. If it's an high rpm N/A build it may equal or be less than the shorter heavier parts.

So as originally suspected, it's clearanced for the shorter rod so that option is open.

 

[Linkster1666]

First Post says:

"CAM CUT FOR 5.850 ROD"

Leads me to believe that the valves open MORE than the Stock Cams since the Stock Rod Length is 5.933 in.

Summit Specs

But once again, I don't know anything.

 

[VictorH]

Curiosity got the best of me so I just called them. You can run all the stock parts on it. You can go with the 0.080" longer OE rod length, or you can run the shorter rod to run a lower pin height and a structurally stronger piston. Balancing with longer rod may require more metal depending on what your rotating mass forces are. If it's an high rpm N/A build it may equal or be less than the shorter heavier parts.

So as originally suspected, it's clearanced for the shorter rod so that option is open.

What an incredible resource on this forum. Not only the wisdom and advice that sure seems to be based on experience and knowledge but also his shop is an excellent source of high-quality parts for our cars. Cheers to you!
Regards,
Victor

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