The exhaust pulse has very little thrust energy since it expands quickly as it leaves the engine. Exhaust position back in the day was something that some designers felt could keep dirt out of the exhaust by having it point up on profile ships.

Best,   DennisT

And I suspect everybody decided to get on the down exit bandwagon because everyone was burning their fingers getting to the NV?? Do you know if Fox was always down?

    Before you get fixated on the position, keep in mind that the Torpedo engines came out when almost all models were full fuselage, and engines were just naturally mounted upright to make them easier to access. Look at all the old plans and engines are either upright for the most part or inverted on occasion. It's my guess that the engineers that designed the Torpedo may simply have wanted the exhaust pointed away from the person starting the engine. Most people are right handed, and if flying C/L models fly counter clockwise, so they are positioned on the outside of the circle to start the engine, and thus the exhaust points away. As far as I know, Torpedo/early K&B Green Heads are the most common with the left handed exhaust set up. Some Some sparkers ares et up that way but a lot of those can have the cylinder rotated to face either way. I have some Super Cyclones like that. When profile C/L models came into prominence, I would guess that is when most all of the other engine manufacturers went with the right side exhaust for obvious reason. This is all just my guess from a life time of reading old books and magazines. I doubt that there is anything anywhere written by the designers at the time. It is an interesting topic, and part of the history of the hobby.
   Type at you later,
    Dan McEntee

  That was probably the Adrian Duncan review of the engine? That sounds like an answer that was just pulled out of thin air!! I've flown my share of models with no landing gear and when either landing on dirt ball fields or grass, there is as much stuff ends up on top of the airplane and there is on the bottom and you still probably have the fuselage bottom to keep it actually out of the dirt. With the exhaust pointing up, what gets in there, stays in there!  With it pointing down, what goes up must come down!! A slightly better change of not getting anything in the engine. Either way, it's gonna happen. Now, with that having been said, if they would have mentioned that this position was used to keep fuel and oil in the cylinder to help with compression and cold starting, I would have found that to be more likely. That would be more practical for a diesel, but doesn't explain why the Green Heads and Torpedoes were like that. Like I mentioned before, there were a lot of sparkers that had left handed exhausts, or they were side ports or has slits around the cylinder. And most of those were aimed at free flight use. I looked a little bit but didn't find any other contemporary engines with left hand exhausts. Another old modeling mystery!
  Type at you later,
   Dan McEntee

Made the mold backwards and didn't want to admit it.

I'd wager that most buyers of K&B Series '61 > '67 (?) engines reversed the case. I sure did, but that was pretty much before any decent tachometers were available at reasonable prices. They'd still haul azz until they broke, which was often.  Steve