jjfizzle51 Posted January 4, 2006 Report Posted January 4, 2006 hey all i finally got a noss machine cool head it is great i love it but i have a question. could i still ajust my timing +4 and run 91 octain i think my elevation is around 4200 feet if not higher im in utah and i ride big sand mountain so if anyone has this set up and runs 91 octain plz tell me. also im not going to try this but was just wondering what would happen if you ran lower octain then your suppose to and is it even possible to run a to high octain. thanks for any help and thanks dlnoss for a great item easy to install to Quote
Wallrat Posted January 4, 2006 Report Posted January 4, 2006 What size domes did you get and what's your compression? You could probably stay on 91 octane down to a 21 or maybe even a 20cc dome w/ a +4 advance. Lower than that and you'll need higher octane. Quote
2003LimitedBanshee Posted January 4, 2006 Report Posted January 4, 2006 It is going to completely depend on the dome size you chose as far as octane goes. Most consider approx 150 psi to be the cutoff for needing to run higher octane. Thus, if you're running a 19cc or smaller dome, you probably will need to run a mix of higher octane (based on Nossmachine.com cylinder psi approximations). Running too low of octane should never be done, you run a serious risk of pre-ignition or worse, detenation. The later of which will usually leave you broke down in a hurry. In my experience running more octane than is required, is really only damaging to the wallet, but I usually run a little more, as opposed to a little less for the obvious reason. I also prefer to cut a little Trick 116, as a result of advancing the timing 4 degrees, but most will tell you it isn't necessary, again just some relatively cheap insurance. DLNoss is usually on from time to time, and is good at responding to items, especially those involving his products, and he would be the definitive source, obviously. Quote
it's stolen Posted January 4, 2006 Report Posted January 4, 2006 I think you will be ok with +4 timing and 91 octane if you are running 20cc or larger domes. I run a stock head that was milled and rechambered to 17cc, it was ok on 91 octane until i advanced the timing. after I advanced the timing the topend lasted about 10 min. do not ever run less then premium pump gas. Quote
jjfizzle51 Posted January 4, 2006 Author Report Posted January 4, 2006 ya i got the 19's so i dont think ill do the mod cuz my dad pays for gas and dont want him paying that much for it but thanks anyawayz for all the help. i am also considering getting my flywheel lighend can you guys post some names of trust worthy guys that would do it thanks Quote
it's stolen Posted January 4, 2006 Report Posted January 4, 2006 i am also considering getting my flywheel lighend can you guys post some names of trust worthy guys that would do it thanks 455112[/snapback] pm boonman Quote
locogato11283 Posted January 4, 2006 Report Posted January 4, 2006 i dont think id run 19cc domes and +4 timing on 91 octane... Quote
dlnoss Posted January 4, 2006 Report Posted January 4, 2006 I agree with what the other guys are saying. It sounds kind of risky. Have you checked your compression with the 19cc domes? Quote
2003LimitedBanshee Posted January 4, 2006 Report Posted January 4, 2006 Told you dlnoss was good about checking into the boards.... Oh yeah, check with Boonman, everyone recommended him to me, I've got mine on the way to him right now. Quote
FIRST BANSHEE Posted January 4, 2006 Report Posted January 4, 2006 you need to check your cylinder pressure, I run the 19cc domes at about 1000ft i think, and have 192 psi. I have to run race fuel. at 4200 ft you might be ok. under 155 psi and you should be ok. use a quality comp tester and hold the throttle wide open when you do the test. Quote
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