Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Question about the MVVS GRRT

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Old 07-01-2003, 12:33 PM
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Stuntpiloot
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Default Question about the MVVS GRRT

Hai,

I have a questionabout the MVVS 6.5 GRRT (model 3065)
It has a rear intake and rear exhaust.

What are the bennefits of the rear intake, or is a front intake better?
Can this engine be equipped with a RC carb?

I got a good offer on this engine, and now I have to choose between the quicky and this one for a bit more.......
Tough choice??
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Old 07-01-2003, 07:25 PM
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Default Question about the MVVS GRRT

rear intake gets the fuel in quicker, and also allows a more streamline profile at the front. you can get a 9mm carb, but its smaller than the 11mm venturi and therefore that little bit slower.
rear intake can be annoying for getting air to it, pumbing, and if using the rc carb, linking up
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Old 07-02-2003, 11:19 AM
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Default Question about the MVVS GRRT

Are there any modifications need to be made to get extra air to the ventury, or can air out of the fusulage be used?
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Old 07-02-2003, 03:42 PM
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Default Question about the MVVS GRRT

i have a large hole under the carb, but mainly to let the dripping fuel out, it points at the large tank hole and enough air gets in. however, i think my belly hole is causing some problems with mixture in the air. it goes rich, i guess as the air is sucked out of the cowl.
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Old 07-02-2003, 09:23 PM
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Default Question about the MVVS GRRT

if you do get the carb make sure you get the q500 carb. It is a tad bit larger than the RC version. That is same one I am using and works great
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Old 07-03-2003, 07:36 AM
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Default Question about the MVVS GRRT

I'll see and find out myself, I get the GRRT tomorrow I'll try it first without a carb, with just the standard venturi

since I never had a motor with a venturi before, are there any tips/tricks on starting such an engine?
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Old 07-03-2003, 03:23 PM
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Default Question about the MVVS GRRT

it floods easy, prop the front of the plane up, fill.
put your finger over the exhaust, flick over 3-4 times. wack on the glow, flick. do this 1 turn rich. let warm up, it'll start to rev more. take it to the patch. lean out, shake to test. throw. pray
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Old 07-03-2003, 07:08 PM
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Default Question about the MVVS GRRT

You know thats something I never tried before is using the stock venturi. I know it is noticeable large than the carb so should be a difference.

I think I may just put it on and tac it and see what difference there is between carb and venturi. Be curious to see the numbers.

But I would be a nervous wreck flying with venturi WOT full time. I have to chain smoke as it is after each time flying it. Need to let hands stop shaking before next flight.
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Old 07-04-2003, 06:15 AM
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Default Question about the MVVS GRRT

Originally posted by FlooredCOBRA
You know thats something I never tried before is using the stock venturi.

But I would be a nervous wreck flying with venturi WOT full time. I have to chain smoke as it is after each time flying it. Need to let hands stop shaking before next flight.
Naaah... It's lots of fun!
We do that all the times.
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Old 07-04-2003, 10:33 AM
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Default Question about the MVVS GRRT

I got the beauty today ......

Now I wonder about the pressure from the engine back to the tank.
Normally I connect a pressure line from the exhaust to the tank, but on this engine there is a pressure nipple supplied that can be screwed in the ventury mount???

Does this engine need the exhaust pressure on the tank?
Does the nipple on the ventury works the same way?
Is it better to modify the tuned pipe and mount the nipple there?
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Old 07-05-2003, 03:39 PM
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Default Question about the MVVS GRRT

Originally posted by Stuntpiloot
I got the beauty today ......

Now I wonder about the pressure from the engine back to the tank.
Normally I connect a pressure line from the exhaust to the tank, but on this engine there is a pressure nipple supplied that can be screwed in the ventury mount???

Does this engine need the exhaust pressure on the tank?
Does the nipple on the ventury works the same way?
Is it better to modify the tuned pipe and mount the nipple there?
You mean one of the mounting screws of the backplate/venturi is a pressure tap?

Then you have crankcase pressure. It will work fine.

If you look into the engine case you will see that one of the screw holes is drilled through so it ends up in the case. Make sure you screw the nipple into the correct hole thought, or else you will have no pressure (that is if they're not all 4 drilled through)

This setup generally gives you some more pressure compared to pipe pressure.
If you put a one way valve in the pressure line you will have even more pressure... too much probably... Your tank will look like a balloon when the engine is running...
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Old 07-07-2003, 01:30 AM
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Default Question about the MVVS GRRT

I may have to try that Venturi then. You done opened another bag of worms man...

I been out of town and just got back in to find a new piston sleeve and rod w/ bearing for my GRRT. woooooohooooooo!

Now to put back together and start my need for speed again. I know its going to be like flying it for first time again its been so long.

One thing though I found out what one of the major differences is between the GRRT and the FAI GRRT. A while back I blew my GRRT apart due to leaned out running. I should have know better but anyways.

I ordered the GRRT with matching piston, sleeve and rod. I did not pay attention to the version I was ordering. When I got it in mail I opened the box and right off seen the difference.

The regular GRRT has a sleeve and piston like a normal engine. A rod also like a normal engine. The one I pulled out the FAI had a completely ported sleeve and larger shave down rod. It looked more stream line. Also the rod had actual bearings in side each end of rod. Compared the the regular GRRT it did not.

So today I finally got my right setup for my engine in mail. I am glad to see that the extra money I paid for the GRRT went somewhere besides round clip on rear exhaust. Now I know the difference.

I am going to get it together and make some videos now since I finally got me a digital vid cam. Should be fun playing around with it. I send some out if anyone would like to see.
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Old 07-07-2003, 01:44 AM
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Default Question about the MVVS GRRT

Sure thing man... let us enjoy that music... some would call it noise... suckers...

Don't forget to put some shieding over the mic of your camera, because the engine will make more "music" than that mic can cope with...
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Old 07-08-2003, 06:03 AM
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Default Question about the MVVS GRRT

Hi,

I started my engine yesterday..............It is a beast!!!
After only a few trys it started making music

It only ran for a few minute's very rich, but it the engine already showed it's hidden potential...........

I can't wait to take te engine out to our field and let it run in (and scare everybody away.......or get spanked about the noise )
Since the Vmax on which I plan to install my engine has to be build yet (see previous postings) I went up the attic to search for an oldy which could be used for running in and tuning the engine...............
I found my old Ninja, and also an modified eurofighter which I'm gonna use with my novarossi.......
But we're getting off topic, Ill post a new subject about these planes

(After a good night sleep I could type again.....yesterday my hand were a bit shaky after the GRRT experience )
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Old 07-08-2003, 07:22 PM
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Default Question about the MVVS GRRT

Oh yeah man. Sounds like you got the craving for speed now. Now even worse. That thing sounds awesome when it jumps up on the pipe..

That awesome sound of pipe kicking and jumping in rpm's sends out a signal that massages the pleasure lobe of the brain.


What prop did you end up going with and have you put tac on it yet?
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