Kevin,
I can't give you any figures, but I don't think that the acceleration phase from lift-off to Vcl would take more than 5 sec.
Lifting off in my RV-7 or my mates RV-8 at around 60KT would see 80KT on the clock by the time you had pitched up to the climb attitude; less than 5 sec. You should be able to establish a reasonable distance from that.
Rafael,
I see you are doing research into RVs.
It might be easier to ask the question from the opposite direction. ie. Can an RV-7A with an IO-360 and CS prop, take-off from runway at 3700 'AMSL that is #,000 ft long. How long is the runway?
I am sure that a bitumen runway in your capital city Brasilia (assume that is where the runway is, Brasilia being around 3,300 ft AMSL) is at least 4,000' long. If this is the case an RV-7A will have no trouble operating out of this runway.
The RV-7 will easily out perform a Beech Bonanza and according to the charts a Bonanza will clear a 50' obstacle at 3,700' Pressure Altitude, 30?C, nil wind, bitumen in 2,400'. AN RV-7 WILL DO BETTER THAN THAT.
Hope this helps a fellow Southern Hemisphere man.
Pete.