Ok Guys, I looked through all the calculators, but I still cannot figure this out. My car runs a 6.82- 1/8th mile on a 28/10.5 tire. This is with a 4.10 gear ratio @ about 6k through the traps. I want to be able to run the 1/4 mile also, just by switching the tires and not the gears. What size tire would allow me to do this and go through the traps near max RPM? Thanks in advance
Too little information provide. We need vehicle weight, estimated HP for better results. But, honestly, I'm afraid you probably can't run that tall of a tire or you will just be running through the 1/4 mile trap bouncing off your rev limiter. But, for the sake of argument, with that tire and rear gear, 6000 RPM shows 122 MPH unless you have a really, really loose converter. A 30" tall tire would make 6,000 130 MPH. I'm not sure you can get a bigger tire or if that one will fit.
For a car that's set-up for the 1/4 mile, is there an general number used to estmate rpm difference from 660 to 1320? (ie...5000 rpm@660' and 6000 @ 1320)
Those numbers dont add up to me. My Regal, while 800lb lighter, ran 6.40 in the 1/8 and 10.20 in the 1/4 with pretty much the same combo going through the traps @ 5800. / 128 mph. My guess is your converter is to loose.
RPM = 336/tire diameter X gear X MPH. That is WITHOUT converter slip. What is your trap speed through the 1/8 mile? Tire height affects final drive. For our purposes, stock tire height is 26.6" Final Drive = stock tire height/new tire height X gear So with your 28" tire height, 26.6/28 X 4.10 =3.89 For a 30" tire, 26.6/30 X 4.10 =3.63
Sorry it was a 6.88 et. 1.54 60ft 4.44 @ 330 6.88 @660 99.60 mph Coasted to 11.70 1320 On this run I noted that my 1-2 shift was early. I left ar 1500rpm foot-braking. My
OK, so with a 28" tire, 4.10 gear, and 99.60 MPH, 336/28 X 4.10 X 99.60 = 4900 RPM without converter slip. You are turning 6000 RPM, so your converter is slipping quite a bit.
I'd talk to Jim Weise, https://www.v8buick.com/index.php?threads/updated-torque-converter-program.278923/
