azuz

Hi guys

I am a sport flyer need for speed types. Wanted to know what are the specs on these engines, actually i want to know how much HP does this tow engines have coz i went to the web site they just have the RPM on it.

And should I buy a SJ 50 or a Q500 40 ? i really dont know which to choose. Obviously Q500 is more RPM from 19000 + and the SJ is just 18000 RPM max i beleive as per the site.

The only thing is they have not mentioned the HP on the website. Anyone know whats the HP on these engines.

Any pros and cons about the engine

AAC or ABC piston ??

thanks

bob27s

My Feedback: (19)

Hi, thanks for writing.

The choice of engine has largely to do with the application. If you can tell me the type of aircraft you have in mind, I can help with engine selection.

Take a look at the Hall Of Fame of the web site photos. You can get some idea of the type and size engine needed for your application by seeing what others have done.

For example, for a sport type model (say like a Something Extra or scale aircraft), the Q-500 engine would not be a good choice, since it is limited pretty much to 8.75" to 9" diameter props to get it in the proper power range of above 19K rpm.

The SJ-46 or SJ-50 turns slightly lower RPM on a full APC 10x6. However, the number published on the web site specs is not a "limit". They are very willing to turn 9" props even higher RPMs, and infact enjoy it . Both can also turn 11x5 props, especially when matched with the Turbo-Jett muffler.

What drives the RPM is primarily the muffler. This is tuned device, and designed to operate within a certain RPM range.

Jett does not publish HP numbers for a few reasons. He has an article on the web site FAQ section addressing this. Primarily, it is because the HP numbers are meaninless unless engines are compaired on the same device, at the same time, under the same conditions. In many case the HP numbers published by manufacturers are a bit optimistic. The best way to actually compair power, is by comparing performance under defined load. Jett does this by publishing RPM figures for a know, commonly available prop typically used for the engine size. Comparing RPM gives you the best reference.

It is a valid claim, sport jett engines are unequalled in power.

Just as a heads up, Jett is now working on the BSE-40L engine. This is a .40 displacement in the .25 - .35 size case! Performance numbers from testing have been amazing. Still in work, but the power to weight on this one is way up there

Bob Brassell

azuz

Thanks for the info...

The plane that i want it for now at the moment is a Weston UK Magnum. I saw the Hall of fame some guys have put a SJ 50 on a Shrike I am not sure if that is a 40 size or a 10 size shrike but i presume it to be a 40 size.I have ordered a a 10 size shrike aswell but then i would be using a 25 OS for that. Anyways i dont intend to use the JETT engine for the scale models. Its only for my speed planes !!

So u mean to say that i can use a 10*6 on the QJ 40 ? or lets put it this way waht all props can i use on both the engines ? anywhere u have a list where i can see the diff props that are ok to use with ur engines. ?

bob27s

My Feedback: (19)

Hi Azuz,

First...yes, those are 40 size Lanier Shrikes

Just for info..your first post asked about ABC/AAC. The Sport Jett engnies (cast case) are now only available as ABC engines. The new BSE machined engines are available ABC or AAC. Both run basically the same, the AAC just weighs less, and cost a bit more.

The QJ-40 engine itself will run with a 10x6 prop, but it requires the SJ-40 muffler to do it.

Basically, the SJ-40 is the same engine as the quickie engine. It just comes with the longer, sport RPM muffler and a fully funtioning two needle red-jett carburator.

The Q-500 engine with the "air valve" carb is not intended to idle or midrange.

If you want the power, idle and reliability of the SJ-40 or SJ-50 along with the higher RPM of the Q-500 engine, you can order the sport engine with the SS-40 muffler (about 500 rpm higher) or the q-500 racing muffler, such as shown here

http://www.jettengineering.com/hall/index.html scroll down to Andrew Steadman's Predator.

As far as props go, you can pretty much use a variety of props. High quality reinforced props (APC, Bolly, etc) or good quality wood props are essential. You must make your selection so that the engine runs at or above the target RPM specified for the engine. Each engine/airplane combination will work best with a different prop.

Jett does not have a prop/rpm list. But we do have significant experience and feedback (such as on the HOF page) with differnent airplane/engine combinations.... so we can usually make recommendations based on that.

We fly the QJ-40 and BSE-Q40 engines for racing with the APC 8.75x9W, 8.8x8.5 or 8.8x8.9 props. All of these will turn over 19K on the ground, and well over 20K rpm in the air.

For the SJ-50 with its standard muffler, anything from a standard 9-7 APC, 9x8, 9x9, 10x6, 10.5x5, 11x5 (a bit tricky to set the needle, but it works). The APC q-500 series all work well, up to the 8.8x9. I have even run a 12x4 on my SJ-46.

A lot depends on how fast the airplane is capable of flying. For a Q-500,Diamond Dust, Whiplash, and even the Shrike, a smaller 9" or 8.75" prop turning higher RPMs will work well on the SJ-46 or SJ-50, because the engine will be able to unload in the air as the plane accelerates. A SJ-50 will turn a 9x8 APC at around 18K rpm. It will also turn a 9x9 at about 16,500 on the ground...and if you are careful and set the needle right... it will unload and go like heck in the air.

On something like my P-51 mustang (more of a sport plane), the airframe and thicker wing simply is not going to permit the plane fly quite as fast as a Q-500, so running the 10x6 or 10.5x5 prop at a bit lower RPM works best for me there. The plane is still pretty quick, and the SJ-46 easily turns an APC 10x6 at 16,300 while still rich. I have flown the plan with a 9x7, and yes, the engine screams, but the result is a longer take-off roll, and pretty much the same in-flights speed.

azuz

Bob....

Thanks for the information......really helpful. Now you made me feel like buyin both the engine .

well but i guess i will go for the qj 40 as i am looking for the high RPM.

I saw the HOF but didnt see anyone using a jett on a MAGNUM ?

have u ever heard of someone using it on those.....arf's .

or can the qj-40 pull my Magnum ?

u can see the magnum at www.westonuk.co.uk

thanks for the detailed answer once again...

bob27s

My Feedback: (19)

Hey..that is a sleek looking airplane! : ) I may have to order on of those myself! Just wondering...does it have landing gear at all ??

What I would suggest, is ordering the Q-500 engine along with the R/C red-jett carb. You lose 200 rpm or so, but this way you get a fully throttled engine. Combine that with one of the APC Q-500 props like the 8.75x9W and you will have a real speed demon . The SJ-50 with the Q-500 muffler may actually provide you with even more power.

azuz

Bob

Thanks..... yeah thats a magnum..... they dont come with any landing gear..... i have modified it for Skids......they dont look as ugly as a landing gear.......

If you were in my place which engine would you have put if you were flyin for only 3 months

yeah i am only a 3 month old flier with a certificate to my Merit

I love speeding and this is my first plane i flew it with a OS 46 Fx but didnt enjoy it... the recommeded engine with thiis plane is a WEST XL 50 which boasts a 2.8 BHP with 21500 RPM.

Compartively which jett would best suit it ........... Make me decide plz BTW doesnt the Q J 40 come with a carb ?? is that a different one

Thanks agian
bob...
if you need any more details on this plane let me know.... the kit quality isnt that good so.....if you have qs. or someething i can answer plus if you need more pics on the plane i shall click n sned

bob27s

My Feedback: (19)

well... based on what you have told me...

if I were you I would go with the SJ-50 . It will be pleanty of power, extreamly reliable, and very user friendly. Most guys flying Jett's in diamond dusts or the whiplash use the BSE 50 or the SJ50. Your application is not much different. Take the time to break it in per instructions, and you will not be disappointed.

The QJ-40 (q-500 engine) does not come with a "carb". It has something that looks like a carb (per Q-500 rules), which will control the engine speed a little, but it is actually little more than an air valve use to shut off the engine. It has no idle fuel mixture. Anything below 1/2 "throttle" and the engine shut off.

As noted though... the engine may be purchased with a regular r/c carb.

The numbers on the West are impressive, and I have heard of several people flying them with excellent results. As noted earlier, one of the reasons Jett doesn't attempt to publish numbers like that, is that it never ends up to be an apples-to-apples comparison. I am not sure what prop you would run on that to get up near peak HP around 20K rpm.

azuz

bob

Can i order the sj 50 with a AAC piston. As noted earlier that it comes already with a ABC piston. Since i am like a 1000 miles away and its difficult to keep ordering parts I would prefer to buy a engine with a AAC piston as it is longer and more leniant to lean runs.

thanks

azuz

Bob

One more thing I had mailed Dub and there isnt a reply till today would you be aware of that, why ?
Coz i want to mail and ask him how much would be SJ50 with a AAC piston.
QJ50 with a AAC piston & Red JettCarb.
QJ40 with a AAC piston & Red JettCarb.

bob27s

My Feedback: (19)

Dub is pretty good at returning emails...
although our email was out for a bit.

email to [email protected] or [email protected]

Prices for the engines are on the web site.

Sport Jett engines are only available ABC.
The BSE engines are available AAC.
QJ-40 Q-500 engine is AAC.
There is no QJ-50.

take a look here... (I have not updated the page in a couple of months, but I am sure Dub will still honor this special)

http://www.jettengineering.com/hanger/hanger.html

azuz

BOb

Thanks for the link I have seen that link, pretty good offer for the red carb jett and the qj 40. for 250 bucks is good. Hey QJ 50 !! was what i got from a guy who said Dub can send it on special request !. This is mentioned in this other thread i am following.

http://www.rcuniverse.com/showthread...79&forumid=145

Ok as far the engine goes then i would go for the QJ 40 with the red Jett Carb. That will be good choic for my quickee planes. Hopefully it should pull the magnum fine.......

cheerss

bob27s

My Feedback: (19)

I understand ... The "QJ50" you refered to is the SJ50 with the optional Q-500 muffler, as I suggested above.

Q-500 muffler is good for the 19K to 21K rpm range. Stock muffler is good for 16K to 19K.

azuz

BOB

Is there any possibilities to get the SJ 50 upgraded to a AAC piston ?

Coz if yes then its the best option for me with the Q 500 muffler.

what say ?

azuz

bob27s

My Feedback: (19)

you will have to email or call dub. he may have AAC parts still in inventory. Aluminum sleeve (AAC) does cost a few more $$

azuz

bob

Thanks i shall email at the other id then.....

Bye

azuz

hey bob still no reply from JETT ?

help !

bob27s

My Feedback: (19)

Unusual.

send to both
[email protected]
[email protected]

He may take a day or two to get back to you. He was out of town for several days this past week.

Worst part is waiding through all of the friggin SPAM that ends up coming into the web site email boxes.

I will give him a heads-up.

Bob