Appears to be a "Laurel" racer - third one back on left row.
Another photo from that track...
This is from the following website.
There are a number of interesting photo's of Model T's on that site- and the stories to go with them!
The grandstand in that picture is still being used today. I have been to many a "Maxwell Street Days" flea market in the infield of that race track, and was there last summer for the Ozaukee County Fair.
Always wondered, why two occupants?
The riding mechanic has to operate the hand operated fuel pump.
Much earlier cars needed a rider to keep the sight glass oilers ful and dripping.