ITALIABANSHEE Posted June 4, 2008 Report Posted June 4, 2008 From the description you can see that I'm not an engine guy. I've read tons of threads on Cool heads and domes raging in different CC's. Correct me if I'm wrong but it seems that if the higher compression the higher octane is needed to operate properly?? Does a higher or lower compression have anything to do perfromance wise? Whats a good rule of thumb to go by if the average Joe wants to upgrade there heads with a cool head and what CC's to use. I'm planning on doing this mod on a basically stock shee soon to bolt on some t5's with an open lid k&n. I currently use VP because I thought running race gas would improve performance. I've been using this gas from day 1 with no issues. I'm at sea level at 100% humidity. What's the professional opinion in here on this topic? thx G. Quote
LS1Inferno Posted June 4, 2008 Report Posted June 4, 2008 Yes higher compression = higher octane needed = more power. But too much you risk burining it up easier, and or bending/breaking rods. Race gas on a stock bike is really useless, just wasted money. Quote
lowbuckracing Posted June 4, 2008 Report Posted June 4, 2008 Save your money on the VP....If your stock and 130 psi run pumped gas all day!IF your looking to get performance out of race gas ,you need a little more motor..Cool head and some pipes with the right jetting makes a nice difference..Do some porting and some carbs,lil timing advance and you'll be riping...All in the funds!Good luck! Lowbuckracing................................................................... ................................................................................. ................................................................... Quote
LS1Inferno Posted June 4, 2008 Report Posted June 4, 2008 Save your money on the VP....If your stock and 130 psi run pumped gas all day!IF your looking to get performance out of race gas ,you need a little more motor..Cool head and some pipes with the right jetting makes a nice difference..Do some porting and some carbs,lil timing advance and you'll be riping...All in the funds!Good luck! Lowbuckracing................................................................................................................................................... . ................................................................... You know insted of all the periods you cound just say PERIOD lol yeah basic bolt ons make for some fast bikes and porting is the BEST mod for stock cylinders. for the price. Quote
dajogejr Posted June 4, 2008 Report Posted June 4, 2008 Higher compression will give you more low end and midrange, something a banshee is not known for, at the slight exchange for some top end...something they have plenty of. With higher compression, you get more heat. With that heat, depending on how much (based on how much compression) you might have to run a higher octane gas so it doesn't pre-ignite. I've always been more of a fan of more timing and not so extreme on the compression.... Quote
ITALIABANSHEE Posted June 4, 2008 Author Report Posted June 4, 2008 Thanks for the info fellas, you guys always come through!!! So what is the acceptable compression range when going with coolheads and domes without blowing off the heads based on my specs. Again, I'm at sea level with no mods other than pipes, open lid filter setup and +4 timing. Gas and VP configs would be helpful. thx G. Quote
okbeast Posted June 4, 2008 Report Posted June 4, 2008 If you wanna run pump gas keep it below 155ish or so. That's what most people will say but I"ve had buddies run alot higher w/ pump gas and be fine, but no one will tell you that on here. As for timing +5 or +6 is fine IMO. If you wanna run race gas you could go all the way up to 200 or so, that's a tad high and unreasonable but you could. I'd say 175-185 is normal. 19cc or 18cc domes would get you there at sealevel. Quote
dajogejr Posted June 4, 2008 Report Posted June 4, 2008 Compression RATIO is actually the key to figuring out if you need race or pump fuel, cranking PSI is a start...but you could have a nasty drag port and only have 150 cranking PSI but still need race fuel...just an example. Once you start to get to high in compression, the cylinders will fight themselves...not what you want for long runs. But for short runs, it's ok.... More compression puts stress on the rotating assembly as a whole, timing...not so much. You also should have the crank trued and welded before you think about really putting the compression to it. I've seen plenty stockers separate...on stock compression and timing. Once it separates, UGLY things happen real quick. Quote
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