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Old 04-23-2018, 01:14 PM
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bob58o bob58o is offline
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If a Hemi Predator has its pitson sitting 0.025" below the deck and I swap the 55mm Predator crankshaft for a 54mm gx200 crankshaft, my piston would be another 0.020" in the hole. [55mm -54mm = 1mm; 1mm / 2 = 0.5mm; 0.5mm = 0.020"].
Starting at 0.025" in the hole, crank swap puts me at 0.045" in the hole.

But a gx200 crankshaft needs a gx200 connecting rod.
Predator standard length is 3.308. GX200 standard length is 3.303. ARC offers a gx200/clone connecting rod that is -0.020" (3.283"), which would be 0.025" shorter than the Predator Rod.
https://www.arcracing.com/6267-honda...09-billet-rod/
RC -.020" short length billet rod for the GX200 & GX160 or the BSP196cc(Clone). Machined from domestic 7075-T651 air craft grade aluminum.
3.283" center-to-center for a 1.180 rod journal and .709" wrist pin. Uses ARC's custom manufactured bearing inserts and ARP rod bolts manufactured specifically for ARC. ARC has the only forced oiling scoop dipper rods available for these engines providing superior lubrication at the bearing journal.

54mm crank with -0.025" Rod puts me around 0.070" in the hole.

The gx/clone uses the same 0.709" wrist pin that the predator does, so you can put a Honda crank in the Predator block if you use a Honda rod and a Predator piston.

So I would have a 70mm bore, 54mm stroke - Hello 208cc Engine.
With the piston sitting ~0.070" Below the Deck Surface.
With a 22cc Hemi Head...
And a 70mm Head Gasket (0.045" thick)...

7.25 :1 SCR.....



Clone Crank
http://www.nrracing.com/product-p/bsp-1275.htm

Honda Crank
http://www.nrracing.com/product-p/13310-zl0-602.htm

I would probably want a forged piston which would probably mean I would need a 0.490" wrist pin connecting rod. Haven't looked into the compression height of the forged pistons and connecting rod lengths available for them. I imagine I would need the piston cut, as opposed to the above drop in option with the stock hemi piston.

Smaller SCR means I can run more boost!
How do we feel about running 20% Nitromethane RC fuel through a roots blower with an effective compression ratio 15:1?
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