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Need tuned pipe advice for OS .46 VX-DF ABC

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Old 12-03-2002, 07:21 PM
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murrat
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Default Need tuned pipe advice for OS .46 VX-DF ABC

I need some tuned pipe advice for OS .46 VX-DF ABC

I will be putting this baby on my small delta. I plan on using either a pylon prop or a APC 11x8 cutdown to ~9X8

I have the Macs recommended Muffled Tuned Pipe
7.5cc (.40-.50) 15" Part Number 1240 , and was planning to order the header. Before I do this can someone answer the following questions?

Is this pipe going to work at 20K to 28K RPM?

Does anyone know if the Rossi Pipe for the R40 Pylon 25R40 ABC engine would work on an OS .46 VX-DF ABC?

The reason I am asking is that this pipe has a neat coupler that allows you to tune the pipe without cutting the header.
This pipe is a "nitro type pipe", with no muffler.

Thanks in advance for any input.
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Old 12-03-2002, 09:16 PM
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ChuckAuger
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Default 46 DF pipe

I tried to use a Macs 7.5cc pipe on a 46 VRDF and it ran terrible. I was not just blowing plugs, I was losing elements. I switched to a Nelson pipe per suggestion of Dave Shadel, he said he felt the Macs pipe didn't have enough volume to run at these RPM's. Then it ran, great, just perfect. I was turning 22K with a APC 7.4 X 8.25 CF prop. Not sure if you will get these R's with a 9X8, although the VX DF is stronger.

At 22K I ran no header..maybe 1/2" stub of header, the pipe hooked directly to the read of the engine.
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Old 12-04-2002, 03:23 AM
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Default Re: 46 DF pipe

Originally posted by ChuckAuger
I tried to use a Macs 7.5cc pipe on a 46 VRDF and it ran terrible. I was not just blowing plugs, I was losing elements. I switched to a Nelson pipe per suggestion of Dave Shadel, he said he felt the Macs pipe didn't have enough volume to run at these RPM's. Then it ran, great, just perfect. I was turning 22K with a APC 7.4 X 8.25 CF prop. Not sure if you will get these R's with a 9X8, although the VX DF is stronger.

At 22K I ran no header..maybe 1/2" stub of header, the pipe hooked directly to the read of the engine.
Thanks Chuck
Just the type of info I needed.
It seems this engine comes with a bolt-on exhaust adapter. From the attached picture I see the adapter has a rubber O-ring. Did the Nelson pipe simply slide over this O-Ring?
Was this a perfect fit?

Thanks for your help.
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Old 12-04-2002, 04:03 AM
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Default Not exactly..

The Nelson pipe would probably fit on the VXDF, but I had to make do..I slid a piece of silicone coupler material over the stub, and then slid the flange on the pipe over that. Tie wraps to hold it together. I could have cut the flange (swage, actually) off the pipe and hooked it on like a regular tuned pipe, but it was a gift, and I didn't want to ruin it should the owner ever want it back.

But you are on the right track..at the RPM's you want to run, there is no header per se..just a pipe. Take a look at

http://www.pspec.com/

at the Nelson FAI, this is the pipe I was using, and you can see it has the same o-ring attachment as the VXDF..and there is the clue...you need to try to turn as close to the FAI RPM's as possible, so the 9X8 is way out there.

DO you actually have the engine?? There was another guy who said his had been on backorder, and was once again backordered.
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Old 12-04-2002, 04:56 AM
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Default Re: Not exactly..

Originally posted by ChuckAuger
The Nelson pipe would probably fit on the VXDF, but I had to make do..I slid a piece of silicone coupler material over the stub, and then slid the flange on the pipe over that. Tie wraps to hold it together. I could have cut the flange (swage, actually) off the pipe and hooked it on like a regular tuned pipe, but it was a gift, and I didn't want to ruin it should the owner ever want it back.

But you are on the right track..at the RPM's you want to run, there is no header per se..just a pipe. Take a look at

http://www.pspec.com/

at the Nelson FAI, this is the pipe I was using, and you can see it has the same o-ring attachment as the VXDF..and there is the clue...you need to try to turn as close to the FAI RPM's as possible, so the 9X8 is way out there.

DO you actually have the engine?? There was another guy who said his had been on backorder, and was once again backordered.

This pipe looks alot like my MVVS GRRT FAI PIPE. I think I will give this a try once I get the engine. Haven't tried ordering one yet. Hope I can get something in for XMAS.

My GRRT Pipe kicks in at ~20K on my MVVS Q500 .40.

Thanks again
Todd
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Old 12-04-2002, 02:15 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

I was the "other guy" that had one on backorder. Good luck getting one - I was told the longshoreman strike on the west coast has messed up deliveries - not sure if that is true or not. Hopefully, by now these engines are readily available.
I gave up and bought a Jett 50 FIRE BSE - I'm sure happy with it so far.
Please, please keep us posted on this engine - how long it takes to get, and more importantly, how you like it when you get it.
I may re-order, if things are better.
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Old 01-20-2003, 09:47 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Gents,

There are several of us out there who are running the 46 VX-DF in the Turbax I ducted fan. The engine turns the fan at 24k+ rpm. We are all using a Macs 8.5cc muffled tuned pipe, with K&B pipe adapter and header. The VX does NOT come with an exhaust adapter/header, even though the picture shows it with one.
Larry Wolfe at Jet Hangar Hobbies has all the hardware you will need to set up a very reliable and excellent performing tuned pipe system on this engine.
There was also an article published in RCJI (Radio Control Jets International) a few years ago (authored my me) specifically on the subject of setting up tuned pipe systems on 45. sized DF engines. The OS 46 VX-DF was utilized as an example in my article.
If anyone wants a copy of that article, drop me an email at "pslaing@earthlink.net" and I will forward you an electronic version.

The OS 46 VX-DF is the most powerful and reliable .45 sized ducted fan production engine ever made. I have 3 of 'em and love them! I just pray that OS keeps them in production......

Good luck,

Peter Laing
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Old 01-20-2003, 10:59 PM
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Default VXDF Exhaust adapter..

Mine came with one like the VRDF had but with an o-ring on it.

The Nelson pipe fits right over it, I'll make one if I run the Macs 8.5 pipe.

MiragePilot..did your VXDF come with a fan adapter nut, or just a regular prop nut?? I just got a prop nut and washer...
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Old 01-21-2003, 05:47 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

None of my VX's, or any of my friends', came with the exhaust adapter; and all of them came with just a prop nut and washer. The fan adapter nut comes with the Turbax I fan unit.

P.S. For those of you that don't know, the OS 46 VX-DF is identical to the 46 VX-M, except for the air-cooled cylinder head and the thrust plate/washer forward of the front bearing. And, this thrust washer is the same part that was on the older 46 VR-DF engines. So, if you ever write off your VX-DF and want to replace it, don't pay the extra $40-50 (and wait the extra 6 months) for the DF version, just by the marine version (cheaper and always in stock) and convert it to the aircraft version with your "old" cylinder head and thrust washer. If you are able to unload the "NIB" water cooled cylinder head from the -M, it gets even cheaper!

Finally, the instruction sheet that comes with the -M version is infinitely more detailed than the miserable instructions that come with the DF version. The -M instructions detail the use of cylinder head shims, based on the nitro content of your fuel, and several other useful ***-bits of info that the DF instructions completely omit. What's up with that GP????

Later,
Peter
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Old 01-21-2003, 05:57 PM
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Default Thanks..

Could be the exhaust adapter I got with mine was from a VRDF..I got to looking and one of them (VRDF)has the adapter with a o-ring on it, the others just have the plain stub like OS sent with the VF's. I bought this engine (VXDF) off an individual.

But the VRDF's had a fan adapter nut with them..I wish the VXDF had one, it comes in handy when you go to mount a prop..

And thanks for the tip on the -M...
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Old 01-22-2003, 09:10 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Originally posted by MiragePilot
If you are able to unload the "NIB" water cooled cylinder head from the -M, it gets even cheaper!


Finally, the instruction sheet that comes with the -M version is infinitely more detailed than the miserable instructions that come with the DF version. The -M instructions detail the use of cylinder head shims, based on the nitro content of your fuel, and several other useful ***-bits of info that the DF instructions completely omit. What's up with that GP????

Later,
Peter
Isn't it strange how we airplane pilots are always supposed to know everything contrary to boat and car drivers?
I get this a lot!


What do you mean by unloading that marine head?
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Old 01-23-2003, 06:03 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

"What do you mean by unloading that marine head?"

Selling it, i.e. unload it at a swap meet etc.

Peter
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Old 01-23-2003, 09:57 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

MiragePilot

I have my OS 46 VX DF connected to a Macs 10cc pipe turning a 5" thorjets unit in an F20 and have been having a few problems with flame outs, what fuel/plug combination do you recommend. Bearing in mine I live in the UK I probably can't get the same brand of fuel as you, but if you let me know what oil/nitro combination you use I can almost certainly find an equivalent over here.

Stuart
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Old 01-24-2003, 03:08 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Originally posted by MiragePilot
"What do you mean by unloading that marine head?"

Selling it, i.e. unload it at a swap meet etc.

Peter
Ah, I see...
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Old 01-25-2003, 02:43 AM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Stuart,

We are using Wildcat Jet A (10% nitro, 23% oil, syn-castor mix) fuel over here with excellent success. THe Mcoy MC-9 plugs are the DF plug of choice here too. Also, we are using the MACS 8.5cc muffled tuned pipe (PN: 1250). I suspect your 10cc pipe it too much pipe for the engine.

I have well over 200 runs with the VX in a Turbax I fan, turning 24k+ rpm and have never had the engine quit in the air for any reason other than running out of fuel.

I also tried to run the engine with 5% nitro fuel (Wildcat Jet A brand) and the engine didn't run as well as it did with the 10%. Unlike its big brother, the OS 91 VRDF, the 46 VX does prefer higher nitro fuels.

Regards,
Peter
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Old 01-25-2003, 08:06 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Miragepilot

Thanks for the info. McCoy plugs are available here and I'm just checking my catalogs to find the nearest equivalent fuel. A company called Model Techniques over here do a fairly extensive range of glo fuels.

Stuart
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Old 01-25-2003, 08:24 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Stuart,

Good luck with your search for fuel.

BTW, that's a very cool Mirage F1 pic in your signature. I'm a Mirage F1 nut and have many r/c F1 projects in the works. The one nearest completion is a scaled down version of the Thorpe F1 (72%). It is sized to use the same inlet, fan and thrust tube components from the Marcel Lahaie mini Mirage 2000 (Philip Noel design). EDF or .25 glo DF power.
I have finished the flying surfaces and am putting the finishing touches on the fuselage plug. We should have a "semi kit" of this little gem ready in the late Spring 03.
Based on the performance of the mini Mirage 2000, this mini F1 should be ascreamer at 125mph+!

Regards,
Peter
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Old 01-25-2003, 08:54 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Peter

We have something in common then, because as we speak I am well into the build of the Thorpe Mirage myself, although mine will be as per the plans and OS 46 VX DF powered using their fan unit. I just love the look of the thing.

This will be my second D/F model, my first was the Thorpe F20 which flies beautifully on the same engine/fan combo.

Good luck with your project.

Stuart
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Old 02-02-2003, 06:56 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Will the 46 FX head fit on the 46 marine motor? Rick
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Old 02-02-2003, 07:03 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Not sure if the 46 FX head will fit on the marine motor, but the 46 VX DF head will. The only difference between the fan engine and the marine engine is the cylinder head and the crankshaft.

Stuart
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Old 02-02-2003, 08:29 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

What is different in the crankshaft? I thought it was just the spacer but same crank. Rick
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Old 02-04-2003, 07:14 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Stuart,

Not so, the crankshafts between the -DF and -M are identical.

Peter
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Old 02-04-2003, 07:57 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Apologies guys, just checked part numbers and indeed they are the same, but they sure look different when you look at the two motors side by side.
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Old 02-04-2003, 08:54 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

What should the pipe length be using the Macs 1250 from center of plug? Would the length also be the same for teh K&B46? Rick
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Old 08-14-2003, 09:27 PM
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Default Need tuned pipe advice for OS .46 VX-DF ABC

Hello,

I just brought an OS 46 VX-M engine and I plan to convert it to DF version.

In OS MAX instructions there is noted that the tuned pipe should
be little larger (.65 - .90 !) than stated here in previous posts.

Now I am little confused which type I should brought.

I would like to use unmufled MACS pipe, but wich one would be better:

No. 1150 - 8.5 cc unmufled
No. 1160 - 10 cc unmufled
No. 1365 - 11 cc unmufled

Does anyone used No. 1365 type ?
Would it work ok with the OS 46 VX engine ?

Regards,
Kristijan
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