EvilBanshee Posted April 29, 2012 Report Share Posted April 29, 2012 Hey guys, the weathers finally warming up here in CANADa. Looking to get a set of shearer pipes and bump up the compression more on my 421cc from VITO's. They sell a "13" degree angle dome and a "9" degree angle dome. I plan on going from 22cc to 20cc dome. But im not sure which angle would be better. I run straight 100LL av gas. Timing is at +5. Im at sea level. Cranking compression with the 22cc domes is 155psi. I think i can bump up the compression more and still be ok with 100LL. If not a Can get 110 or 112 octane. But if i will have to go 110-112 octane i would more then likely maximize to that and run 18 or 19cc domes. Your opinions are appreciated, From what iv been told the greater the angle, the faster the flame speed, the more horse power? correct? Quote Link to comment Share on other sites More sharing options...
PassionRE Posted April 29, 2012 Report Share Posted April 29, 2012 Hey guys, the weathers finally warming up here in CANADa. Looking to get a set of shearer pipes and bump up the compression more on my 421cc from VITO's. They sell a "13" degree angle dome and a "9" degree angle dome. I plan on going from 22cc to 20cc dome. But im not sure which angle would be better. I run straight 100LL av gas. Timing is at +5. Im at sea level. Cranking compression with the 22cc domes is 155psi. I think i can bump up the compression more and still be ok with 100LL. If not a Can get 110 or 112 octane. But if i will have to go 110-112 octane i would more then likely maximize to that and run 18 or 19cc domes. Your opinions are appreciated, From what iv been told the greater the angle, the faster the flame speed, the more horse power? correct? Incorrect, youll have to know the angle of the crown on the pistons your using and then base the dome angle offset from that..Jim Quote Link to comment Share on other sites More sharing options...
registered user Posted April 29, 2012 Report Share Posted April 29, 2012 website says 9* domes is for blaster pistons only. aparently those pistons have different radius than regular pistons. do you know what pistons you have ? might want to figure that out. just my unprofessional observation Quote Link to comment Share on other sites More sharing options...
EvilBanshee Posted April 29, 2012 Author Report Share Posted April 29, 2012 i do believe the pistons in my shee are blaster pistons. 68mm bore. And my current domes are the 9 degree. I was just curious on people opinions on which angle made more horepower. I know for my snowmobile i bought a aftermarket head with interchangable domes that bumped up the compression and had a different dome configuration that increased performance by combusting more efficiently. I figured VIto's had the "OPTION" of differnt dome angles . Quote Link to comment Share on other sites More sharing options...
BANSHEE HP Posted April 29, 2012 Report Share Posted April 29, 2012 do you know if you have a 4mm 110mm or 115mm rod? or check the piston number Quote Link to comment Share on other sites More sharing options...
EvilBanshee Posted April 30, 2012 Author Report Share Posted April 30, 2012 (edited) do you know if you have a 4mm 110mm or 115mm rod? or check the piston number 115mm long rod crank Edited April 30, 2012 by EvilBanshee Quote Link to comment Share on other sites More sharing options...
registered user Posted April 30, 2012 Report Share Posted April 30, 2012 i do believe the pistons in my shee are blaster pistons. 68mm bore. And my current domes are the 9 degree. I was just curious on people opinions on which angle made more horepower. I know for my snowmobile i bought a aftermarket head with interchangable domes that bumped up the compression and had a different dome configuration that increased performance by combusting more efficiently. I figured VIto's had the "OPTION" of differnt dome angles . i dont know much about vito but its seems they been around a while. you can only assume they would have the domes figured out by now, so there would be no need to offer a bunch of "options". then again ive seen people in this business 30years and still dont know anything. if you want something different than what they offer you can buy a blank dome and have it cut to your own specs Quote Link to comment Share on other sites More sharing options...
BANSHEE HP Posted April 30, 2012 Report Share Posted April 30, 2012 vitos carries 9* and 13* domes for the different pistons that are out there in those dome angles. a wsm 68mm stock stroke piston has a 13* angle some of the older stock stroke vitos 68mm pistons were 13* also now they have 3 newer pistons all with 9* angles, a stock stroke 68mm 9*, a 2mm offset pin height 68mm piston with 9* angle for 4mm 110mm rod cranks, and a 6mm offset piston(just like a blaster 573mo6800) with a 9* angle for the 115mm rod. haveing a 115mm rod narrows it down, you have either a 573mo6800 wiseco or a vitos 6mm offset piston in 68mm. Quote Link to comment Share on other sites More sharing options...
EvilBanshee Posted May 1, 2012 Author Report Share Posted May 1, 2012 Ya ill have to get ahold of vito's. I was just curious to which Dome would be better. But if i only have 1 choice then my question is answered. Does anybody have a rough idea of how much more compression 100LL could handle? Like i said kicking compression im at 155psi. Compression ratio is 14:1. Timing is at +5 The domes i have are 22cc. I think i could easily be safe with 20cc domes. Im at sea level. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted May 1, 2012 Report Share Posted May 1, 2012 Wsm should have 5mm pin offset, not 6mm. Quote Link to comment Share on other sites More sharing options...
registered user Posted May 2, 2012 Report Share Posted May 2, 2012 i believe a 2cc decrease in head volume would eqaul 1 number higher for your ratio. assuming you calculated correct to get 14:1, you would have about 15:1 with 20cc Quote Link to comment Share on other sites More sharing options...
EvilBanshee Posted May 2, 2012 Author Report Share Posted May 2, 2012 with a 22cc dome, 8.88 20cc you get 9.68 roughly. 9.68:1? Are you sure? I CC'd this motor before i installed it in the banshee. Me and my buddy came up with 14."?":1 (roughly 14:1) Static compression ratio i do believe? not dynamic. I forget which one we did. Maybe we fucked up lol Quote Link to comment Share on other sites More sharing options...
EvilBanshee Posted May 2, 2012 Author Report Share Posted May 2, 2012 that was for a stock engine, my bad 10.6 with 22cc 11.5 with 20cc this is without taking into account head gasket thickness. it will be less depending on the side of the HG. this is using the formula No idea what the head gasket thickness is. Its just 2 orings... I that the interchangeable billet head from VITO's. And dont we need to know exhaust port hight and all that shit? i cant remember what all that is... Quote Link to comment Share on other sites More sharing options...
EvilBanshee Posted May 2, 2012 Author Report Share Posted May 2, 2012 the numbers i gave will be the highest CR you can get with your engine. WEll in that case i should have no problem running 20cc domes with straight 100LL. Maybe i can even go down to a 19cc dome. ?? Quote Link to comment Share on other sites More sharing options...
registered user Posted May 2, 2012 Report Share Posted May 2, 2012 read this http://www.sacoriver.net/~red/uccr.html also a stock banshee has a CR of 6.4:1 thats from above the exh port. different ball of wax than measuring from the full stroke. i dont see why people get so stumped on this comrpession ratio shit. put piston at TDC, pour oil through the plug hole until it gets to the threads, record how much oil you poured in. total cylinder volume+ amount of oil you poured in the plug hole divided by the amount of oil your poured in the plug hole. if you want to know the japanese method then pour oil in from where the piston is at the top of the exh port Quote Link to comment Share on other sites More sharing options...
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