As long as the ESC and motor are 4S rated sure. Build or buy a series adapter like this.

Be careful with run time / low voltage cutoff, if there is any difference in the packs one will drop lower than the other. Use a higher LVC if possible, don't run real long until you get a feel for it, check cell voltages, etc.

If trying this in a normal 2S RC (just guessing from your signature) be careful with gearing, check temps frequently at least at first.