Advice for speed - Jett 40 Sport
 

I purchased a "quickie" with a Jett 40 sport engine. I do not know the actual make of the plane. First should I be running a 10X6 prop for max performance? Second, for max speed with this engine should I purchase a different plane? I only want the plane for nothing more than straight passes that provide a thrill.

Thanks in advance.

RE: Advice for speed - Jett 40 Sport
 

Your plane and engine are a good match. I would use a 9x7 or 9x8 prop. The SJ 40 would also be great on a Dust and Shrike..

RE: Advice for speed - Jett 40 Sport
 

Just want to check here...... do you have a Jett .40 Super Sport (sport racing engine). Identified by a muffler with a bulge in the middle section, and a red carb with no idle mixture adjustment. Two version heads were available - one is a standard glow plug, and in Ohio/Midwest the CAPS version used the Nelson plugs.

http://www.jettengineering.com/engines/ss403.jpg

If image shown here is your engine, do not use a 10x6 prop. The muffler is tuned for higher rpm than the SS40 can reach with a 10x6. You want to hit above 17,000 peak ground rpm. Start the engine, find peak rpm, back off 500-600 rpm from that, and launch it there. Higher rpm (smaller prop) is better on this one.

Standard blade APC 9x7, 9x8 are suitable. For speed on a Q-500 plane, Use the APC 8.75x8W, 8.75x7.75, 8.8x8.5, 8.5x7.0 (no this last one is not too small - and the plane will really haul the mail).

If your muffler does not look like this one (constant diameter barrel section) it is a standard Sport Jett engine - in which case any of the above props are still suggested, although that one is capable of turning a 10x6 for sport use.

For the time being, stick with the Q-500 design you have. If you want to go faster, build another (current design) Q-500. Its about the fastest thing you can bolt that engine into, and it will make a great flying sport ship.

I hope this is helpful

Bob Brassell

RE: Advice for speed - Jett 40 Sport
 

The SS Jett 40 is a very strong engine. With a nelson Q 500 muffler it will out run the sport Jett 50 by over 1200 rpm. It will turn an 8x8 9.25 19400 on a good day. Strong engine considering it only a 40.

RE: Advice for speed - Jett 40 Sport
 

Now why would you put a Nelson muffler on a Jett when Jett has there own Q-500 muffler? [sm=confused.gif]

RE: Advice for speed - Jett 40 Sport
 

Because the SS Jett 40 came with an SS muffler and a Nelson muffler was the only short muffler I had on hand. Worked fine.

RE: Advice for speed - Jett 40 Sport
 

I got a rebuilt JETT SS 40 in trade and it hauled but! I was on a SIG Kobra with robart mechanical retracts. The blind nuts failed, engine got loose, plane wrecked. It is now on a Sonic 500.

Try someof the Props Bob27 suggested you will have some fun with it.

RE: Advice for speed - Jett 40 Sport
 

Something just don't seem right mating parts from rival companies. :D
I am sure it worked fine and no offense meant.

RE: Advice for speed - Jett 40 Sport
 

One has to look at the Genesis of these engines a bit more. When Nelson first did his .40 for Formula One (RIRE), he had been making piston and sleeve assemblies for several years for the ST X-40 engine. So the bore/stroke of his first F1 40 was the same as the Tigre. In fact, when he build the first prototypes, he used an OS rear end for the rotor and induction. I think that Dubby was also making P/S assemblies as well long before he started making engines. Turns out, he also used the same bore/stoke, as well as the same exhaust spacing for the muffler, as did Nelson use the existing ST exhaust measurements. I have even heard of some pylon guys mixing Nelson and Jett parts in the same case, but don't remember the particulars.

There is a long history of mixing engine parts in some speed and carrier events.