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LiveForMud -> RE: THUNDERCAT BBK (7/18/2008 7:51:47 AM)
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you guys have to remember cat's idea for designing their engines... they don't build them to be high-strung, high-rpm power houses, rather they like to make more power at lower rpm with a more broad power band in those rpm. meaning they use slightly smaller intake/exhaust ports and smaller cams to beef up the low-mid rpm power. you can't have optimum power in both high and low rpm at the same time with non-super/turbocharged engine... you gotta compromise one for the other.
look at the can-am 800: at 800cc and 62hp, that's 77.5hp/liter
thundercat: 67hp at 952cc is 70.4hp/liter... thundercat is more mildly tuned
if cat were to "un-detune" the thunder cat to make 77.5hp/liter like the can-am, it would come off the factory floor with 74hp, which is a little bit much for most people. if you're familiar with the street scene, 85hp/liter isn't uncommon with a well-tuned, good mannered engine... so some small mods like a decent port job on the head and some hotter cams (~20 degrees more duration and a little more lobe lift) and the cat 950 is a 80-85hp engine without having to go bigger in displacement (bbk or stroker). really push the limits with a max-effort port job and as big of cams as it can take (~30-40 degrees more than stock), spin it to 9,000rpm or better (which should be right at hp peak with large cams), and this engine will be making well over 90hp... and over 100hp with more displacement. dragstrip and circle track engines regularly make over 100hp/liter. heck, nascar engines (cup cars) make 900hp from 5.8 liter engines (limited to 358 cubic inches), which is 155hp/liter and they only turn around 9,000rpm (about the same rpm as atv engines). formula 1 cars make 900hp from 2.5 liter engines turning 18-20,000rpm and that's a hideous 360hp/liter (but those aren't your normal piston engines... very specialized valvetrains).
moral of the story: know what's possible, and what you're dealing with.
did anyone figure out if the 700H1 cylinders will work with on the 950 block yet? the H1's 102mm bore with the 950's 71.6mm stroke gives 1,170cc. you better hope arctic cat's new bevel gears are strong to handle that kind of beast, with the above mods, this engine could make 120hp or more. that'll cost a TON of money since it'll all be custom work at this point, but still...
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