Kinda following up on what boB says..... (and I hope you mean a race track
when you say "road racing")..... there is no finite answer toyour question.
30 years ago, we would have said the best gear ratio is the one that has you
at max RPM in high gear (direct drive at that time) just before you have to
apply brake at the end of the longest straight. With the equipment that is
available now, and the money willing to be spent, the equation has grown to
many, many more steps than what we have been use to.

The ideal situation has us being able to keep our RPM in the area where our
peak torque is being developed in acceleration conditions and where peak HP
is being developed during sustained high speed conditions. The ideal
situation also has us in "direct"... that gear that gives us a 1:1 ratio to
avoid gea losses.

The question you have offered is difficult to answer.... add the query
regarding 'economy' and all bets are off.

Decide on your priorities and then ask te question again stating what you
expect *within reason*. .....


"SharkMan" > wrote in message
oups.com...
> Hello,
>
> I have a Mustang with a 347 putting out 475hp. I plan on road racing
> this car, no drag racing ever. I am a driver, not a mechanic, so I
> looking for a second opinion. The shop doing the work on the car wants
> to put in a 3.73 gearing. I was thinking 3.27 would be better for
> economy and top end performance. I was hoping someone out there could
> help me with this.
>
> Thanks!
>
> David
>