MD/PhD here and just matched to a research track. Research tracks offer 3 yrs of protected research time with guaranteed salary. In order to do this without the track, you would have to secure your own funding by successfully obtaining a research grant, which is easier said than done these days.
ABIM has strict guidelines on how this research time will be split as to fulfill the full clinical fellowship training (80% research and 20% clinical). Most traditional 3 yr fellowships, esp heme/onc, will allow you up to a year of research but more than that is generally not protected and a fellowship in your FOC is not guaranteed. If your institution is not ABIM research track certified, unfortunately it would not be possible for your institution to financially support you during your research time.
I'd say do as many blocks of research elective as you can and apply for a fellowship elsewhere in a program that emphasizes research and is SUCCESSFUL at obtaining grants. Not all academic institutions can do this. NIH RePORTer website can help you with this as well as doximitys fellowship search. Most programs that offer research pathways think of it as an investment in a future faculty member hence the limited number of spots.
I would approach your PD and just ask how you could maximize your research time during residency which may get you close to 2 yrs of research including the time during fellowship. Most PDs would love to hear that a resident is interested in research. It brings money into the institution.
Hope this helps!