Posts: 167
Joined: 11/28/2003 From: Benton,
LA, USA Status: offline
Hey guys, quick question. I have an MVVS rear exhaust q-500 .40 engine on a tuned pipe, Just got it broken in, and put a 9 x 6.5 apc pylon prop on it. Started cutting down the header to tune the pipe, and it went from 16000 to 17,800, and thats the best I got. I was thinking that I would get a little bit more, I have an 8 x 8 apc that I could try, but I didn't know if that would be the best prop plane combo, it's on a viper. I know that with some engine / plane / prop combos you can have a screamin prop but its just not right for the airframe. And if I change props, don't I have to re-tune the pipe? Not that thats a problem but it seems like you would have to. If an 8 x 8 is what will work then I am game for that, I just think this engine should do more. Thanks for the help!
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Joined: 12/11/2001 From: Upplands Vasby, SWEDEN Status: offline
Hi! Don't expect more from your MVVS Q-500 engine! And it will not rew more just by changing the lenght of the header pipe. If you want more power you simply have to get a better engine like a JETT , Nelson or Profi!
< Message edited by jaka -- 1/27/2008 9:53:02 PM >
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Jan Karlsson Airracing products MVVS, Motul "Micro" all synthetic oil
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Joined: 8/16/2004 From: Paola,
KS, USA Status: offline
Most of the pylon racing props with Q500 airframes are 8.75 - to 8.8" diameter. Much smaller, and there isn't enough disc area to pull the plane around the race course.
17.8 on a 9x6.5 doesn't sound all that bad for your MVVS, I'd say fly it and see what you think.
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Joined: 12/10/2001 From: Castaic,
CA, USA Status: offline
I make my first flight on a new quickie with a TT40/Nelson tunned muffler to get the first check on what it's going to do. I do this because I'm chicken. After getting balance and trims correct I switch to a Nelson or Profi or Jett or whatever. The TT40 with the tunned muffler and a 9/6 APC gets between 18300 and 18700 on the ground depending on the day.
Denis
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Joined: 1/6/2002 From: Team Coldies,
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quote:
ORIGINAL: willflyforfood
Hey guys, quick question. I have an MVVS rear exhaust q-500 .40 engine on a tuned pipe, Just got it broken in, and put a 9 x 6.5 apc pylon prop on it. Started cutting down the header to tune the pipe, and it went from 16000 to 17,800, and thats the best I got. I was thinking that I would get a little bit more, I have an 8 x 8 apc that I could try, but I didn't know if that would be the best prop plane combo, it's on a viper. I know that with some engine / plane / prop combos you can have a screamin prop but its just not right for the airframe. And if I change props, don't I have to re-tune the pipe? Not that thats a problem but it seems like you would have to. If an 8 x 8 is what will work then I am game for that, I just think this engine should do more. Thanks for the help!
Not sure which version of the MVVS 6.5 you have there,,, a pic would help,,, but its quite possible that you haven t raised the head to lower the compression for the fuel containing 10-15% nitro, according to the website. On the earlier MVVS engines you could rotate the cylinder to point the exhaust whichever way you wanted,,, front-back-L/H or R/H side exhaust configuration(not sure if you can still do that with the current 6.5).
If your using the RIRE GRRT engine,,, you are way down in the RPM department and not even close to "getting on the pipe" as these engine were designed to be run on FAI fuel and spin past 26,000 rpm using a Q40 type prop
The current MVVS Q500 engine is claiming 23,000 rpms but not sure what prop or fuel they used to get that number.
My old MVVS 6.5 Black Head version, with the big carb and the MVVS short tuned muffler would spin a 8.8x9 apc @ 18,500 using 15% with ease.
BV
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Posts: 167
Joined: 11/28/2003 From: Benton,
LA, USA Status: offline
Hey guys thanks a lot, I just need to get it in the air and see I guess. It still has a little breaking in to do as well so I am just going to take it easy for a little while. I figure said and done it will end up around 18,000 with that prop. I know it's not going to get near a nelson jett or profi, can't wait to get one of those but this is what I have for now. Just for fun. And by the way 18,300 - 18,700 is freakin impressive out of that TT .40. That a macs tuned pipe or a performance specialties muffler?
Posts: 167
Joined: 11/28/2003 From: Benton,
LA, USA Status: offline
It's not the GRRT, but thier q-500 motor that does have the head you can turn, and I turned it to rear exhaust. Macs header and pipe. I tried to get some pics up but they won't load.
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Joined: 1/6/2002 From: Team Coldies,
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ok cool, they are still great running engines and a good bang for the buck! Plus you can still get parts at www.morrishobbies.com I think?,,, its been a little while since I messed around with them.
You may also want to try the MVVS long header with the MVVS short tuned muffler, I achieved the best results with that combo.
just tried looking for those parts at morris hobbies,,, hard to find as their pics didn t come up for me,,, but at the www.mvvs.nl/ site,,, p/n for the tuned muffler is 3256 and 3249 for the header.
BV
< Message edited by Bill Vargas -- 1/26/2008 5:07:00 AM >
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Joined: 12/10/2001 From: Castaic,
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It's the performance specialties speed(short) tuned muffler made specifically for the TT40. Yes it is impressive and when I use it to test a quickie the quickie flies a lot more like a 428 than a 424 but still a lot slower than a 428. My last attempts to get a short tuned MVVS muffler from Morris failed. They told me they didn't know when or if ever they would get them in. They had been trying without success to get them from MVVS. They suggest I take a hack saw to the header on a Rossi tuned muffler and make that fit. I did just that and it worked great. I also got a substantial power increase over the MVVS tuned muffler. I had the inner pipe break on 2 MVVS mufflers. But if you can get the MVVS muffler from Europe I would go that route first and set it up as BV suggests
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I never met an engine I didn't like. Of the things I've lost I miss my mind the most.
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