36hp Destroke 64mm carnk

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Ok folks what are you thoughts about destoking a 36hp 64mm crank to say 57mm or 61mm .....could I still use the 36hp rods or would I have to use shorter rods ??? Any thoughts ???

[gimmesomeshelter]

Why do you want a shorter stroke?

Cheers,

P-
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"I would rather have questions that can't be answered than answers that can't be questioned."

Richard Feynman

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Just trying to see how i can keep a 1.1 performance engine ..and I wanna use okrasa/ww heads ...original 1.1 is 64x75 =1130cc if I were to go 61x77=1136cc or 60x78=1146cc or 57×80=1146cc all would be in the 1.1 class it would be easier to use the 77 and up pistons for the okrasa/ww heads but would have to destroke the crank ...i was/am just curious maybe bored in life lol

[Mr. OGPaint]

A crankshaft shop such as DPR can easily do this for you. Stock rods should work. Cylinders will likely need to be machined to custom length to keep compression from being too low.

I replied to your earlier cylinder head question. Are you trying to fit into a racing class with a displacement limit?
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Patrick Hall

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[WickedWagens]

Unless you are limited by racing rules, there would be not cost worthy reason to destroke a crank in a already small engine. It is already hard enough to get enough compression to get these to make any power. DPR could do it for you, but why spend money for less power?
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1968 Ghia Land Speed Car
G/CFALT 106.643 MPH
G/CGALT 113.131 MPH
G/CBGALT 134.606 MPH
G/CBFALT 146.715 MPH
G/CBGC 158.242 MPH
H/CPRO 93.383 MPH
H/CBGC 94.33 MPH
H/CBGALT 101.282 MPH
H/CBFALT 120.591 MPH

[JeeWee]

there is a guy in germany running in the 1200 challenge with (if I am correct) 50mm crank so he can use large P+C so there is more room for larger valves (not so easy with 77mm bore)
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1192CC WW okrasa
48,2 DIN PS (58SAE HP)@4430rpm - 83Nm@3610rpm

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For him to use a 50mm crank he would have to use a bore of 86mm or 87mm to Be a 1200cc I wonder what heads he's using if I recall okrasa/36hp heads would already be risky with 85mm ...unless he's using the 40hp/1600cc case than there's no problem

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Was looking around and went on dpr machine shop Facebook and seen them working on a 50.5 😯😮 crankshaft ...i tried posting the link here but it didn't allow me to ..but if you Google dpr 50.5 crank its Facebook will pop up in search/All and you guys can see them Machining it there's 2 videos....

[bugguy1967]

I don’t frequent in the vintage speed area, but destroking also will make the crank stronger because there’s more journal overlap. You should use separate pushrods, shorter, custom rods, or rods from another kind of engine, and a reduced compression height on the pistons, instead of trying to keep it stock width. You’ll have trouble fitting tins and exhaust, but that stuff is minor.
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"