Project magnum
 

Thanks :)
stay tuned for a new review that'll take longer to write than the kit to build this afternoon!

Project magnum
 

are you running a header on your GRRT or is does the pipe clip directly on the engine?

See for my GRRT there was no tuning or cutting. The pipe was one length and that was it. All I did from there was experiment with props until i it that sweet spot.

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i don't have a header, its the round exit type, the pipe came from a OS46 DF i think and when i used the fan on it it went like hell, the prop loads it up more and this is when i found I'm not close to this magic 25-30K
i've got a bit of silicon linking them about 1 1/2 long which is as much as the space can take, theres no gap between the engine and pipe, making it too short and then having to lengthen it would be a disaster space wise.
it has improved with each bit taken off but I'm not sure what rpm to expect on a 8x8, yes i know, 7.2x8.6 but i have a 8x8 :p I'm almost as fast as the west 50's so i dun wanna shorten more and rebuild the canopy area unless there IS more to come. will have to get the ground RPM next time out but it dun sound much.
when flying i've not heard it come on and off the pipe, just constant so I'm not there yet, tho i thought it might have touched it in a dive but soon came off. normally means to short?, weird.

Pic of the plane not pipe
 

I gotcha, Phillybaby!

As for the little Mini Pipe, you're wasting your time on it.
Why not buy the GRRT original pipe that was tuned for it?

If not and you want to tune a pipe for the GRRT, then take notes...

1. Get a tach and ears plug
2. Get a prop that the GRRT could pull (i.e. 8x7 or less)
NOTE: NOT 8x8, a GRRT can not pull that prop!
3. First, run the engine with no pipe with the 8x7 prop and take note on rpm
4. Now, run the engine with pipe installed and take note what rpm you're getting (NOTE: rpm will be less with pipe on if it hasn't been cut yet)
5. Next, start cutting pipe length 1/2" at a time until rpm reach above the rpm you get from engine run without the pipe
6. From there, start fine tuning the engine by cutting 1/4" at a time until the rpm no longer increase or dropped off. Once that's completed, you back the pipe by 1/2" to relieve the engine.
7. If you follow these instruction, you're good to go and can run different props with no problem's at all.

Note: There are many variable, but this is a standardize procedure to tune a piped engine. And most importantly, make sure the engine have a minimum of .015 head clearance for piped engine. Otherwise, you will be blowing plugs left and right.

Hope this help!

Project magnum
 

wow, what a noisy way to to do things lol
8x7, shouldnt be too hard to get hold of, i just worry about normal props on this engine, tho APC say the 8" is safe to 25K, so add a bit to that and im ok... When my mate ran his mini pipe he used 8x8 and 8x10, very quick, i dont have that pipe.
right, first job get taco. head clearence, i do have a shim, but the plug is holding out great so far.
I'll give it a go and let you all know the results.
thanks SSAN

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yeah waiting to hear how it goes! And when you do get it up on pipe and it unloads in air your love the sound it makes. And it will tear through the sky with no problem.

Project magnum
 

lol, i like the way it goes already, its my fastest plane yet, but dosnt feel it.
when we played with pipes my mate tried his pipe from his West 50, our club chair woman was standing near when i fired up, right away to full rpm with the venturi and she said "it's too lould" lol and that wasnt the full wave pipe. what is fun is you get little puffs of air hit you as you stand behind it.
great noise inthe air, high pitch, but other planes make it sound ok and not too lould.
more RPM yet hey, YER BABY!

Taco ordered with 2 8x7's and 2 8x8's i know for sure the 8x8 is working well at the moment, even the 8x7 does work better, pleanty of friends here use 8x8's and will have them.
might be here for tomorrow :D

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YEAH BABY! :cool:

I'll take two. And I prefer Taco Bell over Dell Taco. :D :D


PS
All fun and joke only

Project magnum
 

The little bugger burnt my hand when i touched the pipe by accident!
anyways my ears are ringing here's the results.
8x8 without pipe, ouch ears, 3 turns richer to allow for no pressure, 16.5K cant cut by putting hand over the exhaust, 1 it wont let me, 2 its damn hot
8x8 with pipe, 16.8k a low rpm, im surprised i kept with the West 50 Magnums, this aero dynamic pipe set up must work well.
8x7 no cutting yet 17.2 i expected a bigger jump than this
8x7 12ish mm cut off 17.8-18 better, wonder if the extra 1k will make up for dropping an inch in pitch
8x7 9ish mm cut off, 18k tiny improvement so i'll leave it here as it must be about right. the pipe now hits the canopy and i'll need longer screws to make sure it dosnt come off like last flight, i'll also use the sealing tape this time.
whats the propper GRRT pipe look like anyway?i have a little MVVS thing here... is it part 3247?

Project magnum
 

It should look something like this...

That engine doesn't even make half the power it could make at 17K rpm.... if the engine is in good shape and with the proper pipe and prop of course it should really get going at 25K rpm, or more...

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well.. the front bearing dun sound all that great after a run, but the engine is tight, starts and runs like a dream.
however i loose half a tank of fuel from flooding while getting ready, bloody thing leaks all over the place.
anyways, yep, the pipes look like that on the Just Engines site, but mine looks like..........
umm comparing lenght, i feel like a sub-man LOL
thing is, when i got the pipe ( look on 1st page ) it was that length, but only got 14k!!!!!

Project magnum
 

Where's the pipe retainer clip thingy?
Normally you shouldn't have to use silicon tubing to hold things together....
Yes the pic I posted comes from the Just Engines site.... It was just to give you an idea what the pipe should look like in general... It can't be the pipe for the GRRT IMO, because there is no flange for the pipe retainer... Or there would have to be a screw on type flange on the pipe...that's posssible too...

If you are unsure about the pipe length, try running the engine with a smaller prop first, so it revs up more easily...
That way it is easier to listen to it and determine if the engine-pipe combo is going into resonance...and at what rpm it does.

Then after you get a general idea of where you're at with your pipe length, you can start experimenting with props...

Pylon engines can be rather tricky on things like bearings...if you've got a worn out bearing, it might be the thing that's keeping you from getting full power from this engine...
A bearing that's not in brilliant shape can take a few 100 rpm off from your average sport engine...but on a fai pylon engine it can be disastrous...

About the leaking problem....since you haven't got a carb you'll have to use hemostats or a shut off valve or something to keep your fuel where it should be...

Oh and by the way.... I can see what you mean with having troubles with space... :p:p

And another thing... if you haven't blown a plug yet, your engine isn't tuned the way is should be...
When you're running this thing close to its maximum power output, you're bound to blow a plug every now and then...:p

Project magnum
 

my clip thing must be on a propper GRRT pipe ;) this isnt, its from a OS 46DF i think.
yep, the GRRT pipe dun look like mine anymore, im very mcuh shorter, i might try a long bit of joiner and see if it improves any.
im currently on a 8x7, any smaller and 1. the prop might fly apart, and 2. if i drop to 8x6 even a few extra K wont keep me up with the West 50 Magnums anymore. im close with the 8x8 at 16.8k, dont see how a 8x7 at 18 can be any faster let alone a 8x6 a couple of K higher.
it sounds damn fast now, the only resonance i hear is in my head lol. when i lean out from rich start i dont hear any big jump on the pipe
i think the noise is just because its a roller bearing, dosnt feel gritty or loose.
leaking... i keep it nose up untill i wanna start lol once it primed tho you have to start quick before Niagra starts up lol
yer, its all a bit crampped in there, if you look at post 1 you can see even with the pipe at full length space was tight, now the main bit is closer, its too much

Project magnum
 

phillybaby, check out my post I put on the other post about your GRRT.

Your rpm gain from off pipe to on pipe will not be gradual. It will top out off pipe then with a slight delay kick in fully to max rpm's. there will be a 7,000 rpm difference from off pipe to on pipe and it jumps right there. There is not in between. either it is on pipe or off pipe. It is not a gradual transition.

Kind of like an on or off switch

Project magnum
 

Yep....

Starting the engine should be something like this:

Close the pipe with your finger, and apply your starter motor to prime the engine.
Apply glow power, and again apply starter motor to start the engine...
If the engine hesitates but runs, close of the pipe a few times with your finger to get it going a little more...
Now your engine should be doing something like 18000 rpm (give or take a 1000...) and running erratic...

Now you start closing the needle valve to lean out the engine until the engine jumps on the pipe.... it will go from waaaabwaaaawraaaa to whiiiiiiiiiiiiiiiiiiiiiiii.....:p:p
The moment the engine jumps on the pipe, open up the needle valve again to prevent lean running...

You should really get a big jump, so much even that the person who is holding the plane should be aware of this, because when the engine jumps, the plane jumps forward also...

Project magnum
 

You should really get a big jump, so much even that the person who is holding the plane should be aware of this, because when the engine jumps, the plane jumps forward also...

Thats a good point! When the pipe kicks in it will yank pretty quick. I know sometimes when launching myself when it gets on pipe sometimes it yanks out of my hand before I let go.

Project magnum
 

OK, current starting.....

finger over pipe, 3 turns by hand, STARTER! are you nuts? one turn rich, flick over till starts ( its pretty good at this ) starts rough, let it warm and the RPM's pick up, starts to smooth out as it warms. remove clip, and lean out, it just gets smoother and revs higher, runs very smooth but no huge jump. it gets to 18-18.3 right now. im really gonna have to try flying it like this, see if it unloads in the air and gets on the pipe.
Just got a reply from Jaka, and his GRRT pipe is much longer than mine, infact, a little longer than mine was in the first place, makes me think i was too short in the first place!

Project magnum
 

How come you havent tried using the actual MVVS GRRT pipe?

I took a pic of my so you can see length. The picture is a bit small but it measured to be 15''

Project magnum
 

i have a quick question..roughly how fast do these planes fly..im thinking of getting one...but am unsure

Project magnum
 

ahh that pic will help, will take pic of mine when i find a tape measure.
theres a simple answer for that....
Magnum 35 quid, GRRT with this pipe 15, propper GRRT pipe 37, ummm no... i make it work on this pipe first ;)

Project magnum
 

man your stubborn!........LOL :D

Project magnum
 

I really want to be here when you are through with trying to get performance from the pipe you have now, and decide to get the MVVS pipe.....:p:p

If I add up the trouble you have already gone through...well, my guess is it will take another month, maybe one month and a half, and then we'll see a hilarious post where you suddenly get 25000 rpm from this engine with a prop you only got 16000 from before.... (and a Magnum that blows the West engines away...:p)

I can't wait...

Project magnum
 

well keep tuneed boys coz it looks like its gonna happen lol
well i plucked up the courage and got me old fella out and took a pic, looks like i spent too long in the cold Cornish air coz im only 12" :( and my little joiner is only 4" so i cant even try a 15" pipe, this one was maybe 13" when i first got it, so, i guess i ws always too short and never got on it, however, its strange the RPM's are climbing. I know with my dust we started to short, i ignored the others and added 1 1/2" and it came good.
Ah well, it WILL! be flown like this at the weekend ( weather allowing ) just to see what it does.
Stupid pipe

Project magnum
 

The exhaust pressure wave travels from the exhaust port backwards to the reflection cone, is then turned around and travels back to the exhaust port where it is supposed to prevent fresh mixture from being expelled through the exhaust...
After that it travels backwards again, because it is reflected by the closed exhaust port...
Now your pipe is set much too short... now i was thinking the following: what would happen if you make the pipe only half the lenght it should be? Would the pressure front not travel backwards, get reflected by the cone, travel forward again, bounce backwards again, get reflected by the cone a second time and finally arrive at the exhaust port to do what it was supposed to do the first time it was there?
Maybe this is what's happening on your setup...

I'm just trying to see all this happen in my head here....maybe I'm way off with my assumptions, but it might explain why you are gaining rpm again when you keep cutting it...

Project magnum
 

thats roughly what i was thinking, tho it would have to be half as short, and hell, im getting there lol
As far as i understood it the wave actully sucked the exhaust out of the engine forcing more mixture up the ports to fill the void. When i first ran the engine it was probably so slow because the wave was actully pushing everything back in there lol