Your Next Jupiter Engine?

[PJGD]

Gerald Palmer originally designed a 1200 cc engine for the Javelin (what a dog that would have been) but quickly saw the error of his ways and settled on 1486 cc capacity.

For all those who are looking to build a bitza Jupiter or Javelin Special, here is a 1200 cc turbo engine that will get you some respect on road or track. Just look for a time-expired one of these to graft into your chassis: http://www.rotaxservice.com/rotax_engin ... 914ULs.htm

[robert lintott]

As it stands , respect on road or track may be difficult . An Aero engine runs at constant speed --at various rpm --usually with a VP propellor . Look at the rpm at max torque 4900, almost up to max power 5500. Getting off from a standing start in a Javelin or Jupiter could be very exciting /frustrating . The Rotax must be a good engine but kitting it up for road use would be very costly , a Subaru looks a good bet ! Bob

[PJGD]

Robert: Well, my post was very tongue-in-cheek; I would not expect anyone to attempt such an engine swap unless they happened upon a free Rotax engine!

As for the torque curve; peak torque is high in the speed range because that is a better match to the propeller-law curve, but for automotive use one would advance the cam timing by a few degrees so that the inlet valve opens a little earlier, but more importantly it closes earlier which due to the gas dynamics will drop the peak torque speed to lower in the range. Note that this is the opposite of what Jowett did for the R4 Jupiter where they retarded the cam timing by 4° crank to get more power at the top end relative to the standard Jupiter but at the cost of lower torque in the mid-to-lower speed range. Nevertheless, at 3000 rev/min, the torque value of the Rotax engine in turbocharged aero form is only a little lower than the Jupiter's peak torque value and one can only imagine what a slug an in-period 1,200 cc Jupiter would have been. I would guess that if the Javelin had been released with the 1,200 cc engine, ERA would never have considered building a sports car from it. . .

I would agree that a complete Subaru powertrain swap would be a much easier and more practical undertaking.

Philip