I have 11 Jett motors and a JR10X also. The point is that the MVVS is good the Jett motors are superb. The quality remains long after the price is forgotten.
Dennis

Yes, exactly. As noted, the engines listed are designed for lower rpm use for scale/aerobatic/3-d type applications.

Engines can be, and are, designed for specific purposes. The control line stunt application is very similar to todays 3-D application.

The Ro-Jett engines are slightly different for control line use since they run at "full throttle" all of the time, and a main goal of engine set up is constant aircraft speed. They are fabricated to Richard's specifications.

Dub's r/c versions are optimized for not only top end power and torque , but also for midrange power and torque... as well as good fuel draw throughout the throttle range, and superior throttle response.

Tex,
I haven't weighed the plane yet but I did go to the field today to run the engine again, using Byrons YS 20/20 and a APC 14x4 standard chord prop, it turned 12600 running rich. I then put a APC 14x4w and it turned 10580 running rich and peeked at around 11000 +- . The temp today at the field was about 10deg and very foggy. I did fly the plane for the first time (just couldn't wait to get it in the air) everything went good but it had allot of ice on the plane when I landed so I'll just wait untill tomorrow and try it again...Here are a couple of pics ....(check out the ice on the prop...JW

JW,
Those are some very good rpm numbers! It appears that your fuel and prop combination works well with the JETT 76l. I'll switch out my Zinger Pro 14x4 for an APC 14x4w and see if my rpm numbers increase. I think it will because APC props are reported to be more efficient. I can say that I've never had an icing problem here in Texas! Boy, that sure looks coooooooooold.

SC

Tex, If you are running 10% fuel try the APC 13x4w or APC 14x4 Standard chord prop mine was running in the 12600rpm range rich(ys20/20fuel) with the 14x4 std.....I didn't know it was running so fast, but when I tacked it I changed to the 14x4w...after a few more tanks I'll lean it out some more ....I didn't take pics of the tail feathers but there was allot of ice on the leading edge...... JW

tex,
today was allot nicer day at the field the sun was out and the temp was around 20deg ...I changed to a APC 13x4w and it put it right on the recommended rpm of 11500 ...I haven't peeked the engine yet but here is a pic of the tac...I'll go back to the 14x4w as soon as the engine has used a couple of more tanks. Then I'll peek it ....JW

Autoguns and Texan, that muffler on your Jetts looks different than a regular Jett or Ultrathrust muffler. Is it unique to the higher torque 76L?

Thanks,

Ernie

Ernie,

JETT gives you a choice of muffler when ordering the 76L. I chose the lite muffler option. Check the JETT website for more info.

TX

Ditto....This muffler looks and works great...JW

Ernie,

The Lite-Jett mufflers are available for the 40L, 46,50,60,65 and 76L. Its a very light weight, untuned muffler. Since the engines that use it tend to turn lower rpm, it tends to be somewhat quiet too. Right now Dub offers 3 sizes - "40", "60", and "76"

For the 3D and some scale appliations, you really do not want the 'pipe' effect coming on line between midrange and full power. The lite-jett muffler presents no issue there. You get a smooth throttle, and excellent fuel delivery.

In the case of the 76L, the purpose of this engine design was to provide power via displacement, rather than with the tuned exhaust. So although it does benifit from using the Turbo-Jett muffler (broad range tuned muffler), it does not fully benifit from the Jett-Stream tuned muffler (a bit more speficically tuned).

For my 76L installed in the "40" sized Edge, the turbo-jett worked out perfect for both performance and in the installation. For applications such as the profiles and such, the lite muffler is prefered since it provides the lightest weight and most compact engine installation.

Looks like Autoguns is doing well here. The tach numbers are right on the money. Thanks for the photos JW.

(note, in photos, the smaller muffler labled "40" is the .25-.40L size version)

Thanks guys for the muffler information! What a great company to be supplying you with these options.

Bob, on that side view of the engine with muffler removed, what are the two larger holes that are just inside of the muffler mounting bolt holes holes?

Thanks again,

Ernie

The exhaust outlet flange is machined as a seperate piece and bolts onto the cylinder.

Those are torx head bolts in there.

Ahhh, the outer flange can be replaced if it isn't mating square with the muffler any more.

Thanks Bob,

Ernie

Bump up....JW

Bob27s,

A couple of days ago, I sent several 76L questions to Jett but have not received the answers. I bumped into this post when I did a better job searching for 76L info in these forums.

One of the questions was related to running a 12" prop with the 76L. In particular, I was guessing that 12x7 or 12x8 might keep the 76L down to around 11K. Did you ever do the 12x8 or 12x10 prop tests that you mentioned? If you did some 12" prop tests, I'd like to hear what you think about running a 76L with 12" props.

Background info:
I'm trying to setup a 40-50 sport/pattern plane to fly at a field that has fairly low noise limits.

Thanks.
kec

Hi Kec

First, make sure you email him at the correct email address
[email protected]

Dub was out of town at the NATS last week. He just got back in the shop on Tuesday.

The 76L is designed to run in the 9500-11,000 rpm range.

Typically we fly with 14x4, 14x6 and 13x6 props. But as you surmized, it can run with other props that keep it in that primary power band.

A quick start to this selection is a very simple load estimation dia x dia x dia x pitch = constant (yes, wide blades and blade shape make a difference, but its a good start)
For example :

14*14*14*4=10976 (11,000 rpm - std blade higher rpm limit 14x4W is 10,500 rpm)
13x13x13x6=13182
12*12*12*8=13824
14*14*14*6=14464 (10,000 rpm - typical baseline)
12*12*12*9=15552

This is pretty much consistant with most of the bench tests I have run.

With the lite-muffler, I would suggest a 12x8, maybe pushing the 12x9 after break-in.
With a Turbo-Jett muffler you get a bit more power and torque - the 12x8, 12x9 would do quite well, and Id bet the 12x10 would run ok too. (I may have to try that this weekend)

Image here is a 14x4w with the lite-muffler

I trust this answers your question.

Of note, the control line version of the .76L typically turns a 13x4 or 14x4 3-blade stunt prop

Bob

From what many hobbyists say, the Jett 76L is known for strong performance and consistent power output, especially in sport and pattern flying. It tends to be well built and durable if tuned properly. I once spoke with an RC enthusiast from Luxury Rides LLC who appreciated its reliability.