js3

My Feedback: (3)

Bob,

I just received an email message from Dub with a little info on the new Jett Q40 LS. What can you tell us all about this new motor?

Also, what seems to be the state of the art regarding BSE vs Cast Case technology? Dub said that he chooses BSE tech for quickie motors and Cast Case for Q40. What's the difference in performance?

Thanks,

bob27s

My Feedback: (19)

I have not run the LS engine yet myself. But Dub has been working on it for pretty much the entire year.

So far... so good....best I can tell you there. The case is basically the same. Just a differnt rod, crank, pistion, sleeve. Design is rather basic... fabricating this beast is not quite so basic.

Also... worth noting for others..... its not really a 'long stroke' engine. This one is basically a square engine (closer matched bore and stroke). The racing engines have historically been under-square (big bore) engines.

As for the crankcases....

It is somewhat of a black art there... we are not 100% sure why the Q40 engines run better in the casting... parts are the same... ground rpm is generally the same..... its just something "that happens" that Dub stumbed on setting up a practice engine. Clearly it is an interaction of a number of things (fluid dyanmics, thermodynamics, metalergy, geometry, phase of moon, etc). But it is something notible, and repeatable --- so thus the recommendation.

The Q-500 BSE engines do run better. More precise bearing alignment is possible, closer control on tolerances seem to be more of a factor. (since you are not performing a secondary operation to create bores and mating features as you do with a casting). Again.... how much of a difference..... its hard to quantify. You really do not see it in the ground rpm or the way the engine behaves. But a consistant 1 or 2 seconds on the race course is proof enough something works better this way.

Bob

rmenke

My Feedback: (13)

Bob:

This is why the kiss on the head before start up does make a difference!!! And there is that 1 of 1,000 factor? ENJOY

daven

My Feedback: (1)

I've been running my Cast Jett Q40 (Square Stroke) for the past several weeks and I am normally a Nelson guy when it comes to racing motors. All I can say, is that I am very impressed. Needles much easier than the New Nelson, isn't all peaky on the line, and doesn't shake the bajeebers out of the plane on every flight.

Raced it in Amery, Wi this past weekend, and I wouldn't hesitate racing it against the New Nelsons, mine was equally as fast as every Nelson LS there, and in my opinion maybe a little faster.

bob27s

My Feedback: (19)

Dave,

Thanks for the report, and the honest evaluation.

Dub is always pleased to hear good news. And is just as inviting of 'bad' news too... helps develop better products in the long run.

Fortunately, the "Square" has worked out into a good engine so far

Bob

Destiny-RCU

This square version you're talking about is the Jett LS? It's out or only for testing?

bob27s

My Feedback: (19)

umm.... yeah, you could call it the Jett LS.

Misnomber is that it really a long stroke engine. Neither is Henry's.

The original engine was real big bore. This engine is built pretty much same bore and stroke.

So we loving call it the square.

Destiny-RCU

Swweeetttt!...When does it go on sale?

daven

My Feedback: (1)

Its for sale now as far as I know, the LS should really stand for "longer stroke", as neither are really long stroke. Just give Dub a call.

bob27s

My Feedback: (19)

Just to provide an official update here...

The product name for the new version QM40 engine is officially

QM-2

plankdriver

I had my LS for a couple of weeks and just fininshed break in. The engine is very smooth on the 2in spinner. I only had it in the air twice runing rich but it seems very promising.
It needles fairly easy and conssistent.
The engine is available from Dub, with about 3 to 5 week wait.

Chago

bob27s

My Feedback: (19)

Hi Chago...

Glad to hear it is running well !

Indeed a very smooth engine.

Bob