dfq2581

Would a .40L Jett engine be a good choice for a scrath built .40 size hots (from original plans). I am talking about the engine that turns the lower RPM's
Thanks

bob27s

My Feedback: (19)

Thanks for writing....

Short answer is YES.

Longer answer...

When the Hots first came out, the popular engines for it were the OS 40 FSR, 45 FSR, Enya .40, HP gold cup, K&B .40 Many folks also flew with Rossi and YS power. These are all standard "40" size engines of that era. The weight and balance of the plane is looking for that 15 - 17 oz engine up front.

The Jett 40L engine is a "32" size engine. Same size as the OS 28, 32, 35, Webra 28, 32, 33 and similar. However the 40L will turn a 9x6 or 10x6 as well or better than other .40 size engines on the market today. So from that perspective, if you keep the aft end light and it balance properly, you save a bunch of all-up aircraft weight, you get the engine performance, and result is super aircraft performance. The engine is not significantly lower rpm compared to the SJ-46, you still want to prop the engine for peak ground rpm around 15,000 - 16,000 range. Engine runs great, well behaved, and the idle is wonderful.

Alternate...

The standard SJ-46 engine (or SJ-50) would be my choice for the plane. These are the current standard "small block" .46 size engines. Very user friendly engines, great throttle, excellent idle, unmatch for reliability.
For this application, a standard 10x6 prop would be ideal turning around 16,500 rpm, and once the engine has some time on it, worth playing with an 11x4 or 11x5 to control airspeed a bit better. You might consider with these using a backplate engine mount - saves a little on weight, and makes for a nice installation.

I hope this is helpful

dfq2581

Thanks Bob! I actually had a Sport Jett .50 back in 1996 and it was awesome! had it on a plane similar to the Hots but it was rather heavy and it would still do knige edge loops with a little more than 1/2 throttle! I was considering the .40L for weight purposes as I am a big fan of lighter aircraft, they just fly better and that is why I like to scratch build. Thanks again but I do have one more question does the .40L drink less fuel than the .50 or are they about the same?

bob27s

My Feedback: (19)

fuel burn is a bit less

more rpm = more fuel burned per minute

The 40L has a smaller carb (slightly) than the SJ-46

Fuel draw is very good too.

Light weight is always a good approach, especially when you do not have to miss out on the power.