grpark20 Posted October 20, 2008 Report Share Posted October 20, 2008 Just curious to see what every one with the 4 mil long rod and port work to match is running for compression, or what you are trying to shoot for? Basically what would you consider the optimum compression when you factor in the expense to ride with your octane requirement. I know everyone will be different for various reasons and conditioins you built your shee for (dune, drag, trail). If you could add your octane, dome size, and timing if any will help too. Thanks. Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted October 20, 2008 Report Share Posted October 20, 2008 What kind of fuel are you trying to run? I have set them up for between 145 and 185 depending on application and fuel intended Quote Link to comment Share on other sites More sharing options...
grpark20 Posted October 20, 2008 Author Report Share Posted October 20, 2008 What kind of fuel are you trying to run? I have set them up for between 145 and 185 depending on application and fuel intended I'd like to be able to run 93 pump gas...but if the gains for higher compression meaning running race fuel are worth it, then I'll go that route. Just want to here whats making everyone happy. Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted October 20, 2008 Report Share Posted October 20, 2008 Well, like I said...It also depends on application. For example, I like to set trail or Mx motors at 180 if the customers budget allows race fuel. Those engines will benefit more from the added compression=more low end grunt. But I like to set my duners and drag motors up with less compression so they will rev out easier. I would go 145-150 for pump gas. I like to set up engines for about 165 to run alcohol. A nice compromise seems to be about 160-165 on 100 octane. Quote Link to comment Share on other sites More sharing options...
gregrob Posted October 20, 2008 Report Share Posted October 20, 2008 155-160lbs I mix in a little race gas if I go to lower elevations. I usually ride at 6000+ feet though and haven't had any detonation issues on 91 octane. Went to St Anthony's and mixed race gas about 30% just be safe. Quote Link to comment Share on other sites More sharing options...
gregrob Posted October 20, 2008 Report Share Posted October 20, 2008 I will also add that if you're going to set yourself up to have to run race fuel, just skip it and go to methanol. Yes there are all the negatives of which I'm well aware but the gains in power and running cool are worth it for me. Quote Link to comment Share on other sites More sharing options...
spike Posted October 20, 2008 Report Share Posted October 20, 2008 Passion 12port stroker, 21cc domes sea level@ 165psi +8 timing. strait 100LL avgas. Quote Link to comment Share on other sites More sharing options...
grpark20 Posted October 20, 2008 Author Report Share Posted October 20, 2008 I will also add that if you're going to set yourself up to have to run race fuel, just skip it and go to methanol. Yes there are all the negatives of which I'm well aware but the gains in power and running cool are worth it for me. Point well taken.....I was running 100LL AV Gas on the old set up I had. Never checked the compression but was widing @ sea level with 20cc domes. I could ride the trails and logging roads for 6 hours and burn 3/4 of a tank. Going to be a lot different with new set up. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted October 22, 2008 Report Share Posted October 22, 2008 180 psi, +6 deg of timing on Sunoco 110, Citgo 110, or VP 110 Quote Link to comment Share on other sites More sharing options...
91tsiawd Posted October 22, 2008 Report Share Posted October 22, 2008 185psi, +7timing, 112 leaded Quote Link to comment Share on other sites More sharing options...
screamin_banshee_2003 Posted October 22, 2008 Report Share Posted October 22, 2008 (edited) I run 4 mill hot rod crank with stock ported cylinders to match +4 timing 22 doomes 158-165 PSI with 97 octane gas no detonation at all Edited October 22, 2008 by screamin_banshee_2003 Quote Link to comment Share on other sites More sharing options...
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