deckheight Posted January 27, 2009 Report Share Posted January 27, 2009 Aftermarket head w/changable domes. Below is what most people consider safe for stock bore and stroke Banshee... 21cc domes = 92 octane = apx. 7.0:1 CCR 19cc domes = 100 octane = apx. 8.0:1 CCR 18cc domes = 110 octane = apx. 8.5:1 CCR If you decide to go with a big bore or stroker the above changes. Where do you live that high octane fuel is not available? Must be pretty rural? At any rate, there is no free ride. If you want to substantially increase engine efficiency beyond cylinder porting and tuned exhaust you will have to bump the compression. I personally do not recommend "octane boosters in a bottle" as a replacement for high octane gasoline. Good luck Quote Link to comment Share on other sites More sharing options...
michaud321 Posted January 28, 2009 Author Report Share Posted January 28, 2009 thanks for the numbers, i didnt know what cc of domes i would need is it worth spending the money on a head to run a 21cc at 92 octane?on a stock motor just ported ,will that boost my power enough to notice? im almost done with my questions so if i port my motor, run a higher octane fuel and get a +4 timing plate i should be satisfied with the power and money i spent, i thought i would have to spend a little more $ on performance. Quote Link to comment Share on other sites More sharing options...
deckheight Posted January 28, 2009 Report Share Posted January 28, 2009 I am not trying to talk you out of a stroker or big bore, most people that have those mods like them. Just pointing out the diminishing horesepower to $$$ spent ratio once you go past a certain point. Assuming an efficient tuned exhaust, cylinder porting, decent air filters, etc... 87 octane (stock compression) is about 48hp at the crank. 92 octane set-up is worth about 57hp at the crank. 100 octane is about 73hp at crank. Scrub maybe 10hp off any of the above for a rear wheel hp comparison. And add maybe 5hp or so for either the stroker or the big bore... An apx. 2.25cc reduction in trapped volume and an additional 9hp going from a stock head to a 92 octane head has always noticable to me LOL. If it's worth the $$$ to you I do not know? Plan on an extended swing arm for any of the 100 octane packages BTW... Quote Link to comment Share on other sites More sharing options...
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