8.1 inch rod in stock block/stroke 350 and -----

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mekilljoydammit
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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by mekilljoydammit » Thu Sep 28, 2017 3:50 pm

Stan Weiss wrote:
CamKing wrote:
Stan Weiss wrote:I do not know what DV's thinking is on this. I know people say the rod just connects the piston to the crank. But for me this is a rather large change in cylinder volume change verse crank rotation.

Stan
Thanks to an unlimited budget, my Dad did a ton of testing on this. The results showed, that after you get to about a 2:1 rod to stroke ratio, the added weight of the rod costs you more, then the slower max piston speed of the higher R2S ratio provides you.
Mike,
Thanks.

8.1 / 3.48 = 2.32759:1

From some numbers that I have (correct?) a late '90's Ferrari F1 v10-3.0l engine had over 2.4:1 R/S ratio.

I know that there are a number of produce motorcycles in the mid 2.2:1 R/S range.

Is this just the result of them being big bore, short stroke, very high RPM engines or is there some other reason?

Stan
It's a consequence of the big bore short stroke package - there's actually a cutaway available of the 2000 vintage Ferrari V10 on http://www.grandprixengines.co.uk/ if you go poking around, and if you sorta squint, a lot of stuff is getting pretty close together around BDC.

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Post by dwilliams » Thu Sep 28, 2017 3:59 pm

Mark O'Neal wrote:That's really not that amusing. The amusing part is all the goobers that took the 6.000 rods out for their 406 Chevies...because Smokey said they wouldn't fit.
Smokey liked BBC-diameter wristpins and wanted all three rings above the pin. Gets a bit tight if you insist on doing it that way...

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by Mark O'Neal » Thu Sep 28, 2017 6:14 pm

Maybe. But what he said was "You cannot put a 6.000 rod in a 406 Chevrolet."

I think it was them new leather britches......

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by GARY C » Thu Sep 28, 2017 10:48 pm

Mark O'Neal wrote:Maybe. But what he said was "You cannot put a 6.000 rod in a 406 Chevrolet."

I think it was them new leather britches......
Knowing Smokey's love for misdirection it would not surprise me if he was doing it while telling other you can't do it. Wasn't he the one that always pushed the longer rod is better concept?

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by digger » Thu Sep 28, 2017 10:58 pm

It's wise to pick the low hanging fruit first

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by SchmidtMotorWorks » Thu Sep 28, 2017 11:30 pm

Warp Speed wrote:Its hard to believe it is being discussed! LOL
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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by Racerrick » Fri Sep 29, 2017 12:49 am

Talk about bait and click. I put in 6.8" rods in sbc once, when I was cleaning parts I put them in the oil pan to dry. LOL

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by kimosabi » Fri Sep 29, 2017 7:15 am

Well the opening poster of this thread makes a living through releasing public material. So yes to me it is a publicity move, bait click etc etc etc.

How about we make it really short stroke, like 2.5" stroke?

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by CamKing » Fri Sep 29, 2017 11:34 am

Stan Weiss wrote:
Thu Sep 28, 2017 3:30 pm
CamKing wrote:
Stan Weiss wrote:I do not know what DV's thinking is on this. I know people say the rod just connects the piston to the crank. But for me this is a rather large change in cylinder volume change verse crank rotation.

Stan
Thanks to an unlimited budget, my Dad did a ton of testing on this. The results showed, that after you get to about a 2:1 rod to stroke ratio, the added weight of the rod costs you more, then the slower max piston speed of the higher R2S ratio provides you.
Mike,
Thanks.

8.1 / 3.48 = 2.32759:1

From some numbers that I have (correct?) a late '90's Ferrari F1 v10-3.0l engine had over 2.4:1 R/S ratio.

I know that there are a number of produce motorcycles in the mid 2.2:1 R/S range.

Is this just the result of them being big bore, short stroke, very high RPM engines or is there some other reason?

Stan
In a lot of cases, they go with the rod length that works with the deck height they need to run.
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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by peejay » Fri Sep 29, 2017 12:55 pm

mekilljoydammit wrote:
Thu Sep 28, 2017 3:50 pm
It's a consequence of the big bore short stroke package - there's actually a cutaway available of the 2000 vintage Ferrari V10 on http://www.grandprixengines.co.uk/ if you go poking around, and if you sorta squint, a lot of stuff is getting pretty close together around BDC.
Yup... the only way they could make the rods shorter would be to open up the bank angle, which (when it was allowed) would make the engine wider, which would hurt aero, and probably also screw up airbox plenum volume.

'Course the only way to know for sure would be to build engines at 72, 90, 135, etc and see what works! Hey it's only other peoples' money...

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by piston guy » Fri Sep 29, 2017 3:43 pm

Who cares where the rings are . The bottom of the pin is .351 ABOVE the deck of the block. How do you install a wrist pin and not suffer compression loss when the pin is IN THE HEAD? No amount of pin offset or head gasket stack can cover that! 6.300 rod ? yes 8.1 BULL$%&T. He admitted it's a trick question. Tricks come in a box and you pour milk on them. Brain teaser for the brainless.

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by peejay » Fri Sep 29, 2017 5:29 pm

As mentioned upthread, all you need are negative clearance height pistons and you're good to go!

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by Mark O'Neal » Fri Sep 29, 2017 9:13 pm

GARY C wrote:
Thu Sep 28, 2017 10:48 pm
Mark O'Neal wrote:Maybe. But what he said was "You cannot put a 6.000 rod in a 406 Chevrolet."

I think it was them new leather britches......
Knowing Smokey's love for misdirection it would not surprise me if he was doing it while telling other you can't do it. Wasn't he the one that always pushed the longer rod is better concept?

A few years later, he did.

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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by gvx » Fri Sep 29, 2017 9:59 pm

I have seen some of the components of this mystery project and it is a small block Chevy.
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Re: 8.1 inch rod in stock block/stroke 350 and -----

Post by Joe-71 » Fri Sep 29, 2017 10:12 pm

The only way to physically install a complete set of 8.1" rods in a 350 Chev block and have them part of the rotating assembly would be either a static display, or he will have to have a pair of spacers with liners to extend the deck height to make it all work. Spacers for intake manifold, etc. Just saying. Joe-71

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