Close look at GP .07 Thunder Tiger

Close look at GP .07 Thunder Tiger
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Close look at GP .07 Thunder Tiger - 12/6/2007 6:19:40 AM

4000686798

Posts: 158
Joined: 7/26/2004
From: USA, USA
Status: offline

Just bought one of these to use on my Sig Hummer I am building.
So far I really like this engine, it may be a little heavy but it has a lot of big engine features.
Upon the first run it was very tight and hard to turn over, I thought the piston cylinder was going to scuff or seize.
I ended up pre-heating the cylinder with my covering heat gun to get it to free enough to start.
It runs smooth and the throttle respones is great.

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Post #: 1

RE: Close look at GP .07 Thunder Tiger - 12/6/2007 6:56:48 AM

Remby

Posts: 610
Joined: 11/2/2002
From: Russell, PA, USA
Status: offline

Nice picts!

Never seen the "inards" of this one, looks to be well made. I've always been a Cox user, will do so as long as I can find parts and use them, but it is nice to see other, well made engines for the A class flyers.

I do like the look of this engine, and may try and pick up one when I can.

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Post #: 2

RE: Close look at GP .07 Thunder Tiger - 12/6/2007 2:43:08 PM

tri-pacer

Posts: 108
Joined: 5/20/2007
From: napa, CA, USA
Status: offline

4000686798,

Have you tried running it yet without that "Heavy" looking muffler? Just curious what the prefromance would be without it. One of the places I fly dosen't require a muffler.

chuck

(in reply to 4000686798)

Post #: 3

RE: Close look at GP .07 Thunder Tiger - 12/6/2007 3:42:55 PM

ptulmer

Posts: 4770
Joined: 4/28/2003
From: Brunswick, GA, USA
Status: offline

I don't think it's quality or swell throttling have ever been in question. If you tach it and weigh it the problem with this engine begins to surface. You'll need a light and lightly loaded airframe. If that's your style of flying, it's a decent engine. Kinda heavy compared to other engines with similar performance. Take OK Cub's for instance... no, really, take them. Take them away!

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Post #: 4

RE: Close look at GP .07 Thunder Tiger - 12/6/2007 5:53:03 PM

GrahamC

Posts: 535
Joined: 9/19/2005
From: Ottawa, ON, CANADA
Status: offline

let me start by saying that I don't have one of these yet but I have been considering.

From what I have read about others experiences and a couple of published reviews I think this engine has more potential that many give it credit for.

Randy Randoplh did a review and quite like it (not that you would expect anything else of a published report in MAN). However, his report of RPM versus propeller indicates (to me at least) that most users tend to over prop the engine with 7" dia props. Randy's report indicated that it seemed happier on a 6" prop - perhaps something inbetween might be better still.

Also, a button to take a Turbo or Nelson plug would probably see and increase as well.

And, like many of these sport engines (AP 09 and 15) they also seemed somewhat constricted in their breathing. If you opened them up a bit to let them breath a bit better you might just see more than a small incrimental improvement for just a little change.

I am open to donations if anyone has one lying around they are not happy with. I would certainly like to have a go to see if my thoughts have merit or whether I am just blowing in the wind as it were.

cheers, Graham

(in reply to ptulmer)

Post #: 5

RE: Close look at GP .07 Thunder Tiger - 12/6/2007 6:01:05 PM

boberos

Posts: 429
Joined: 4/22/2005
From: peterborough, ON, CANADA
Status: offline

We had one of these on a small plane recently.
Ran well but heavy & weak output.
Bob G

(in reply to GrahamC)

Post #: 6

RE: Close look at GP .07 Thunder Tiger - 12/6/2007 7:43:14 PM

fritzke

Posts: 837
Joined: 1/3/2002
From: Saint Paul, MN, USA
Status: offline

Hey 4000-
Do you see any mis-match between the transfer ports in the case and the openings
in the sleeve? An earlier post suggested that a little tweaking to make the ports
line up better resulted in much better RPM's
Dave
See post #15 by Cat 1:
http://www.rcuniverse.com/forum/m_966230/anchors_966244/mpage_1/key_power%252Crobber/anchor/tm.htm#

< Message edited by fritzke -- 12/6/2007 7:46:27 PM >

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Post #: 7

RE: Close look at GP .07 Thunder Tiger - 12/7/2007 1:05:42 AM

4000686798

Posts: 158
Joined: 7/26/2004
From: USA, USA
Status: offline

Right now I am getting 16,200-16,500 with a 6x3 prop with 15% nitro.

Is this a good RPM?

I don't have much to compare it to for an engine this size?

I did try it without the muffler, it ran with the needle backed way out, but would probably need the case tapped to pressurize the tank. I didn't tach it with the muffler off because the sun was getting low and my tach would not work in the low light.

When I had the engine apart I didn't check the transfer ports to see if there was any miss-match. I wanted to try the stock out of the box set up first anyways.

(in reply to fritzke)

Post #: 8

RE: Close look at GP .07 Thunder Tiger - 12/7/2007 2:41:05 AM

fireman7875

Posts: 618
Joined: 2/26/2002
From: Durham, NC, USA
Status: offline

Yeah, those are pretty good RPM numbers... for an .049. Unfortunately, despite the fact that it is probably the best running engine under .10 that I have seen, it just doesn't have much power. I had one of these for a while but sold it. The engine ran beautifully but it was only suitable for .049 applications where you will have to add nose weight otherwise.

Brian

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Post #: 9

RE: Close look at GP .07 Thunder Tiger - 12/7/2007 2:45:25 AM

lildiesel

Posts: 459
Joined: 11/18/2005
From: Cincinnati, OH, USA
Status: offline

I wonder if DDD could be induced to produce a diesel head for the TT .07? That would be a combination I'd like to try.

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Post #: 10

RE: Close look at GP .07 Thunder Tiger - 12/7/2007 2:49:02 AM

build light

Posts: 1356
Joined: 11/30/2005
From: Crete, NE, USA
Status: offline

Would this engine respond to high nitro content to produce more revs? Also as has been pointed out in another thread, revs aren't much good without torque. Will this plane swing a seven incher with any authority? I have my doubts for sure but I just hade to ask.
???

Robert

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Post #: 11

RE: Close look at GP .07 Thunder Tiger - 12/7/2007 3:37:14 AM

Toad

Posts: 428
Joined: 12/3/2001
From: Hurricane, UT, USA
Status: online

I can see where this little guy could be made to turn well with some tender cutting here and there, the only thing that really turns me off about it is that carb being intrigal with the case.

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Post #: 12

RE: Close look at GP .07 Thunder Tiger - 12/7/2007 4:18:47 AM

4000686798

Posts: 158
Joined: 7/26/2004
From: USA, USA
Status: offline

I have some wildcat 35% 1/2A.

I had planed on trying it on this engine after some break in.

Do I need to do anything to the engine before trying this higher nitro fuel?

When using high nitro do you want to raise or lower compression?

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Post #: 13

RE: Close look at GP .07 Thunder Tiger - 12/7/2007 6:09:30 AM

Luna_Rendezvous

Posts: 143
Joined: 8/12/2007
From: Brisbane, AUSTRALIA
Status: online

quote:

ORIGINAL: 4000686798

When using high nitro do you want to raise or lower compression?

Lower the compression a tad...

When trying out new fuel, I will put 3 extra head gaskets in and then remove one at a time, until the RPMs don’t increase, monitoring with a tachometer.

(in reply to 4000686798)