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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Manufacturers Direct Support Forum >> Jett Engineering Support >> Yet another pipe questions
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Yet another pipe questions - 1/1/2004 6:31:24 PM   
TopShelf



Posts: 648
Joined: 12/6/2001
From: West Linn, OR, USA
Status: offline 		Does jett sell a pre-tuned Macs quiet or regular pipe for the SJ-50? I though I saw them on your web site at one point but can't find them now. Does the tuning change if I'm using a perry pump?

Thanks

< Message edited by TopShelf-RCU -- 1/1/2004 1:32:51 PM >

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RE: Yet another pipe questions - 1/8/2004 2:35:53 PM   
bob27s



Posts: 4831
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hi,

Thanks for writing.... sorry for the delay.....

Jett does sell tuned pipes for all Jett engines. Either quiet or standard tuned pipes are available. Straight RE pipes can be ordered pre-tuned and welded.

Silly me..... I started working on a new version of the tuned pipe selection and order page back in October, and it got very lost in the shuffle. My fault on that... should be back on the site soon.

The pump will not change pipe tuning. All the pump does is provide consistant fuel delivery to the needle valve. They are typically used in installations with odd fuel tank placement or long fuel line routing. It does not change the way the engine operates or performs. The pipe is tuned to a desired RPM. RPM is determined by your application and the prop you will use for the application.

Let me know what your application is, and I can suggest a pipe and prop combination best suited for the installation.

If you order an engine and full pipe, Dub will tune and test the engine/pipe/prop combination for you, and provide you with the operating parameters (peak RPM and ground rpm target) it has been set for. On your end, you can experiment with different props as long as they stay near those target numbers.... and you will enjoy very consistant performance.

Over the past year, I have noted that Dub has set up BSE 50 engines/pipe to run everything from 9 x 9 props on a quiet pipe as low as 15,000 rpm, and with a 8.5 x 7 prop at 20,000. It all depends on the application.

Bob Brassell

(in reply to TopShelf)
       Post #: 2

RE: Yet another pipe questions - 1/8/2004 4:46:39 PM   
TopShelf



Posts: 648
Joined: 12/6/2001
From: West Linn, OR, USA
Status: offline 		Bob, thanks for the info. I thought I was going crazy not being able to find the tuned pipe info.

I already own a SJ50 with standard pipe and have run it and been very happy in a temporary plane. I have finally completed my Combat Models F16N and am now thinking I might want to go tuned pipe. I'd like to go with a 10x7 pusher prop. I'm getting decent bench result now but want to get maximum performance. I assume I could send the engine back to you guys for Dub to do the tuning correct? Is there an additional charge for that service?

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He Who is a Slave to the Compass has the Freedom of the Sky.
www.TopShelfRC.com

(in reply to bob27s)
       Post #: 3

RE: Yet another pipe questions - 1/8/2004 9:08:34 PM   
bob27s



Posts: 4831
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hi.....

Dub can tune and set up the engine, prop, pipe and pump too if you wish. He may charge a few $$ for bench time, and what ever shipping is involved. You may wish to email Dub directly at jett@jettengineering.com for a quote.

What prop are you using and what RPM are you getting with the current pipe setup? Is that the same pipe you plan to use?

A possible suggestion.....

Last fall I started experimenting with the Iron Bay fuel regulator/pump. Very nice unit! Works similar to the Cline regulator, but seems to function better with the Jett carbs. I am running direct crankcase pressure with a checkvalve. This was mainly on the BSE 100 and on my BSE 60L. So far, on the bench, I can move the fuel tank around just about anywhere, and the engine doesn't care. I have not tried it on a 40,46 or 50 turning higher RPMs.... as soon as it warms up ! (only about 20 deg today here in Cleveland).

It might provide an alternative to the perry pump. The perry pumps have worked well in the Combat models F-16 in the past.

Bob

(in reply to TopShelf)
       Post #: 4

RE: Yet another pipe questions - 1/8/2004 9:29:07 PM   
TopShelf



Posts: 648
Joined: 12/6/2001
From: West Linn, OR, USA
Status: offline 		It has been a while since I benched it with the perry pump and 10x7 but I think I was getting in the mid 15K's on the standard Jett Stream muffler.

So, I'm still a bit confused. If I buy one of your pipes, will I still need to "tune" it or is it already set up for a given engine/Prop/RPM?

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He Who is a Slave to the Compass has the Freedom of the Sky.
www.TopShelfRC.com

(in reply to bob27s)
       Post #: 5

RE: Yet another pipe questions - 1/9/2004 2:24:37 PM   
bob27s



Posts: 4831
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		You would be best off sending the engine so that Dub can test and tune the entire system. When you receive it, it will be tuned to run best with the prop you specify. Dub does have previous experience with the combat models F-16 set-up. Let me check on some details for you.

The last one I recall, the builder had a BSE FIRE 50 installed with the pipe inside the fuselage.

Do you know which header size/shape you will require for the installation ?

Ive attached a photo of a similar F-16 with a SJ-50 installed. The builder changed the fuel system a bit by installing a single 12oz tank up in the inlet area (just above the stock location), and added a 2 oz header tank closer to the engine. Plumbing and fuel line lengths were significantly reduced. Note that it has the stock Jett-Stream muffler with an exhaust extention installed to clear things. He did some other innovative things to the engine mount/nozzle area to permit easier engine access too. I can hunt down some details in my records if you desire.

Also of note, in checking some past emails, the prop of choice has been the APC 10x6 pusher. Lets the engine turn up a bit more. RPM is your friend

Bob

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< Message edited by bob27s -- 1/9/2004 10:07:56 AM >

(in reply to TopShelf)
       Post #: 6

RE: Yet another pipe questions - 1/9/2004 3:25:01 PM   
TopShelf



Posts: 648
Joined: 12/6/2001
From: West Linn, OR, USA
Status: offline 		Ok, If I decide to go the tuned pipe route, I will send my engine/pump back to you.

My plan up until this point has been to use the jet stream muffler with extensions. Therefore, I would be using a normal out the side header.

As far as props go, I have the 10x6 also and was going to experiment with that and the 10x7. I was thinking the 10x7 just to get more top end.

If you could get some ball park pricing for me, that would help me make my decision. I'd get it off the web site but....we have already covered that

Thanks,

Kent

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He Who is a Slave to the Compass has the Freedom of the Sky.
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       Post #: 7

RE: Yet another pipe questions - 1/9/2004 4:51:07 PM   
bob27s



Posts: 4831
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Pipe and header usually cost $65 - 90 for the setup. Depends somewhat on which pipe (quite or regular) and which header.

side header is $25. Regular pipe is about 40, quite pipe is about 65

If you want to order the pipe and header, cut for your prop, and just have it shipped to you, that is doable. Dub does have previous info to go by.

I spoke to Dub about this installation, and his experience with the perry pumps when using a full pipe shown it to be inconsistant. He said that for the F-16, using a small header tank and pipe pressure has worked better.

< Message edited by bob27s -- 1/9/2004 1:53:27 PM >

(in reply to TopShelf)
       Post #: 8

RE: Use of Iron Bay regulator with Jett carb - 1/12/2004 11:49:46 PM   
kec


 

Posts: 30
Joined: 10/29/2003
From: Mickleton, NJ, USA
Status: offline 		Bob,

I am getting ready to try the SJ-46 with the Iron Bay regulator when weather warms up again.

Do you have any helpful hints or warnings that you could give me? (e.g. Were did you drill/tap for crankcase pressure?)

I was also concerned that the Jett carb was tuned to work with the fuel pressure equal to muffler pressure. I expect the Iron Bay regulator to provide fuel at a little less than ambient air pressure.


KEC

(in reply to bob27s)
       Post #: 9

RE: Use of Iron Bay regulator with Jett carb - 1/14/2004 6:58:26 PM   
bob27s



Posts: 4831
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Hi,

So far, I have only tried the regulator on the large engines, using the Turbo-Jett muffler. The Iron Bay regulator seesm to work pretty well. Most of the jett carbs have a large bore, and a small venturi, which sometimes limits the amount of 'suck' effect that they have, which is required for the iron bay unit to work.......but the regulator seems to be responsive to even the slightest suction. It was designed to be used with ducted fan engines, which have similar carb designs. Fuel delivery, so far in tests on the BSE 100, was outstanding. The low flow rate tends to keep the fuel tank pressure stable, and provides very consistant delivery to the needle valve.

Having said that, I have not tried the regulator on the SJ-46 or 50 yet. I am hoping to when it warms up (as well... right now in Cleveland it is 15 deg and snowing.....!)

Pressure points.... on the OS160, located right in the provided boss on the backplate. On the BSE 100 I have replaced one fo the backplate screws with a custom pressure fitting. Upper left if I recall. The location provides an open path to the crankcase interior. If you look, I think you can do the same thing with the SJ-46.

(in reply to kec)
       Post #: 10

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