Agreed.... However, if the guy's car is set up as an 1/8 mile car, it probably has really steep gears that are ideal for 1/8 mile blasts. If he were to 1/4 mile race it, he may need to change the rear gear and the car would probably slow down somewhat in the 1/8th.8.70s-8.80s
typical way to calc 1/8 mile to 1/4 mile is 1/8 mile ET x 1.57 or 1.58 depending on the car.
not sure how accurate this is but this site: http://www.wallaceracing.com/8th-quarter-conversion.php says 8.89.