"if i wanted could i convert my traxxas trx 2.5 to a diesel"
Yes -------- BUT!!
the converted motor (any diesel ) in your car will need a bigger flywheel( heavier clutch assy), or starting will be very difficult and the idle will need to be much higher , this is due to the higher compression of a diesel. It will also need the gear ratio of the driveline changeing to get the advantages of a diesel.
This is no big deal with aircraft as simply useing a larger dia prop will acheive this, a larger prop also makes better use of a diesels higher torque.
This is not to say a diesel cant be run at the higher RPMs like a glow. The MVVS 15 is a good excample, to quote some No's :- " According to Aeromodeller review, Aug, 1997, peak HP 0.56 at 20,000 RPM,
Peak torque at 17,000.
Recommended prop 8 x 4 or 7 x 6. Without silencer, 8 x 4 APC turns 16,200,
APC 7 x 6, 16,500. 9 x 4 APC 13,100."
Also one of my favourite small diesels is an 1970's 1cc Barbini, this was designed for both aircraft and tether car use, it swings a 7X5 wood zinger prop at or above 11,300 RPM But max HP is at 18,000RPM and Max RPM's are 28,000, both good examples of a diesels flexability.
Stewart