Here in Phoenix the best pump gas we can get is 91 octane. I'm wondering what a 50/50 mix of 91 pump gas and 110 octane racing fuel would yield in terms of octane rating. Or how to figure it out based on other combinations. Anyone know?
I know people that have tried this for circle track racing and had very poor results. It's nearly impossible to keep a consistent mix. You will bounce around 3 or 4 points all the time unless you blend it and keep a separate supply. Plus, it's a huge hassle. What's your compression and are you using any power adders? You might find it easier to run the 91 on the street with a slight de-tune (if it's also street driven), pump it out and switch to race gas on race day and put your full tune back in it. Way more consistent. Keep a barrel for race gas and a barrel for the 91 you pump out, that way you know exactly what you have. Talk to a fuel supplier, not a salesman, and get the whole story on mixing different fuels together, It's not as simple as it would seem with all the additives involved and you can actually create some lousy gas at times if not carful. SPark
some guys actually have two separate tanks in there car one for race gas and one for pump gas. the race gas tank is usually around 5-10 gallons and the street tank is the regular tank that came in there car
i seen that as well..stock tank mounted and a small cell in the trunk..just using a valve & different fuel pump. i think you could also plumb it to use the same pump though, easy enough. was in a 68ish mustang if anyone cares lol. honestly though before you go through all that..maybe drain your tank and run 110 to make sure you like it before you decide to go through all that work & a bit of money.
Hi Gene. I know plenty of guys that do it by ratio mixing to achieve the difference between the two fuels. In fact.. I blend e-85 at the pump on my cars and work vans. A 50/50 mix of 91 and 110 would be about half the octane split between the two fuels.. so figure close to 100 octane. That should be more than you'll ever need to enable that little motor to run more aggressive tunes and still also allow for some extra safety margin while running them. The motor will also make slightly more power with the racing blend on its own even without an additional tuning. You might also consider running a dry ice filled "cool can" for your fuel supply as well. Just insulate the lines leading from the cool can all the way to the carb and you can run an extra bit of ignition lead too. Every little bit helps and that should be worth another .005 -.01 off you times. Maybe even slightly more in hot weather if you tune for it.
Help me out here, why run two tanks? I mean if the car's not detonating. have you tried 87 octane pump gas.
I could be wrong here.. but I believe they were just pointing out what they've seen others do in the past.. and not necessarily recommending it for Gene's setup. The only guys I ever see running 2 tanks anymore these days are shooting meth into turbo motors.. or running computers and auxiliary fuel systems loaded with race fuel into same turbo setups with higher boost levels. I saw a twin-turbo LSX(71' Chevelle SS clone) last year at the Car Craft summer nat's that had 2 separate fuel tanks and that motor made around 1,100 with conservative boost in the teens.. and almost 1,700 when he flipped a couple of switch's(over 25 psi, IIRC). I made my boys stand back another 40 feet when he ran it on the dyno because I've seen twin turbo motors come apart before. Awesome steet legal car. For this setup.. you wouldn;t want to negate the potential gains with the added weight of the additional components(smaller N/A 6'ers aren't known to have an over abundance of torque to spare anyways, right?) and I'd say just mix the fuel ahead of time(in tank and out for reserve) and be done with it. Then go have fun.
I found this online calculator... http://www.motorsportsracingfuels.com/OctaneCalculator.html Our local Sunoco is now selling 110 octane. I mixed a 60% of 89 octane with 40% of 110 octane solution to see if I could tell any differences with the butt-0-meter. I ended up backing 200 revs off the idle...runs better/stronger and it smells good too!
