At what speed do we simply "run out of gear" - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

*LanceS13* · 04-04-2002, 01:01 AM

ok...I just rationalized/derived this formula and it gave me a reasonal number, but if isn't right someone can correct me <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt='

'>
SPEED=[(RPM)/(GR*FD)]*0.00595*TR
where
GR=gear ratio
FD=final drive ratio
TR=tire radius in inches
RPM=duh!

This gives 159.1mph at 6900RPM, .759 5th gear, 4.08 final, and 12" TR (24" tire)

Find your TR with xxx/yy/zz being the tire size:
TR={[(2*0.yy*xxx)/24.5]+zz}/2

04-04-2002, 01:01 AM	#4
LanceS13 AutoX Junkie Join Date: Jun 2001 Location: MS Age: 43 Posts: 2,044 Trader Rating: (0) Feedback Score: 0 reviews	ok...I just rationalized/derived this formula and it gave me a reasonal number, but if isn't right someone can correct me <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=''> SPEED=[(RPM)/(GRFD)]0.00595TR where GR=gear ratio FD=final drive ratio TR=tire radius in inches RPM=duh! This gives 159.1mph at 6900RPM, .759 5th gear, 4.08 final, and 12" TR (24" tire) Find your TR with xxx/yy/zz being the tire size: TR={[(20.yy*xxx)/24.5]+zz}/2 __________________ 1992 240SX Fastback #47 DSP MS SCCA RX-7 ITS Project FOR SALE