In my car, I am shooting for low 8's in the 1/8th which would probably put me in the high 12's in the 1/4. Unfortunately, I have only run it once and it had a loose battery cable connection at the starter and would break up at anything over 3500rpm and I could only get a 9.3 out of it ( I think that's mid 14's). I fixed that the next week and then proceeded to drop a washer down the intake with the engine running and had to tear it down. I also changed the cam, rear gearing and rockers as well as the carb at that time and the car is down for paint now, so, to make a long story short, I am dying to know what it runs now and how much more I need to do to run the numbers I am after. Anyhow, to convert 1/8 to 1/4, the generally accepted factor is 1.57. So, multiply your 1/8 mile by 1.57 to get the 1/4. In my example, 9.3(1.57)=14.6. Not bad for an open diff and no ability to rev. However, traction is not taken into account as the effect of the 60 foot time on overall ET is somewhat diminished over the longer track since you have more time to "fix" it with a better top end. So, if my engine was running right and I ran that same crappy 9.3 in the 1/8 with a 2.2 sec 60 foot ( what I ran!) it may have actually run a 14.2 or 14.1 because of the greater traction in the higher gears. It's not an exact science because of the vehicle dynamics involved and how they change over a given period of time. It is why a car can have a bad leave relative to another car, but given enough track can run it down by the end.